How to thread drift in 720 posts!!!

[Ilikeflying]

Howdy. I want to put to you guys a few questions that might hypothetically be happening to someone who isn't me.

1: This person has accepted a job on an aircraft flying privately, yet happens to be doing an insane amount of flying and duty hours that would beach CAO 48 pretty much every day. Considering this is a private operation, legally, is it this persons own responsibility to monitor their own fatigue, performance levels and flying hours or could some unforeseen issues arise with it? Whether it be insurance or otherwise.

2: The owner of this hypothetical Lycoming io540 equipped aircraft has neglected a 50 hourly oil change for in excess of 50 hours. As in, it has done over 100 hours since it's last oil change. The maintenance release does not stipulate any oil change beyond the first which has already taken place, but being a private operation, 100 hourlies are not required. Would you have any input as to the status of a near end of life aircraft engine operating under such conditions? Whether it be physical damage, insurance issues, decreased margin of safety, mandatory manufacturer guidelines or anything else? The hypothetical pilot of the aircraft has serious concerns about the insurance and passenger liability status of the aircraft as well as general failure potential of the engine.

[BlatantLiar]

being a private operation, 100 hourlies are not required

Wait, what?

[yr right]

No. A maintenance release is not required but all maintenance require dMUST be done. This include all ADs if the flying time has exceeded the limits.

[uncle8]

I believe that, for private ops, an annual inspection is required to renew the maintenance release but there is no hourly limit between inspections i.e you may exceed 100 hours in the year. Also, oil changes at 25 and/or 50 hours are recommended, not compulsory.

[Jabawocky]

Interesting questions. I think that if it is PVT and the MR does not have inscribed a 50hr oil change then it is not legally required.

For that matter it only requires as a bare minima an annual inspection. The engine manuals do state oil change intervals but they are not a mandatory thing depending on the system of maintenance applicable.

I think......but I am not 100% sure and I bet you get lots of opinions.

All the legal BS aside, lets examine some reality of engineering.

Oil changes are not as necessary when the oil is not old, is regularly topped up(progressive replacement) and the plane is flow a lot. That said, depending on how the engine is operated (read mixture management) the oil deposits could vary significantly. This is why oil change intervals are recommended depending on usage. In particular H2O which helps form acids.

Next is spark plugs and magneto's. If they are fine wires, then no big deal. 100 hrs is fine. All they need is a resistance check and checked for cleanliness. If they are Champion, this is far more critical.

Air cleaners, this is a 100hrly thing but depending on locations this may be prudent at 50 as well.

Is there an engine monitor? Is it downloaded regularly and the data examined. Is it examined by someone who really knows what they are looking at? (only 1% of pilots and LAME's are in that boat)

Are the cylinders borescoped each 100 hours. Oil analysis as much as this is a variable test?

There are so many variables.....if you wanted to talk in private I would happily help point you in the right direction but here could be a wild ride.

Last of all, remember this. Just because it is legal does not mean it is prudent. All maintenance should be viewed with this integrity test. Does it do everything it should and nothing it shouldn't?


Feel free to PM.:ok:

[Progressive]

The requirement for the oil change/filter inspection is clearly set out in AD/ENG/4 requirement A3 for private ops - within the manufacturers recommended period + or - 10%

Although a 100 hourly is not required for private (annual only) AD ENG 4 requirements A1+2 require a compression test and engine test run to be conducted @100hrs + or - 10% in addition to the above oil change and filter inspection which is/was due again at 100 hrs.

No amount of Schedule 5 / private ops leniency will allow you to avoid the above AD.

If your friend has been flying the aircraft with these items overdue on the MR then he is in breach of the regs!:uhoh: The owner may be relying on the pilot to tell him when maintenance is due.

If they are not on the MR the aircraft is on manufacturers maintenance schedule in which case and the inspections are required under that OR the maintenance guys failed to put it on and THEY are in breach of the Regs

Since your friend is obviously keen to keep his flying job I suggest he go to the owner (non pilot?) bearing a copy of the AD and the responsibility for the owner to maintain the aircraft IAW the regs for a friendly discussion. This may turn out to be a case of owner and maintainer ignorance combining in the perfect storm.

As for the flying hours if there is a good relationship with the owner perhaps your friend could review their flying pattern and suggest alternate schedules which could save them both time. As a single pilot for a private operation your friend may just have to accept the role of maintenance and flight scheduler as well.

[Progressive]

Jaba,
As per my other posts Oil changes and filter inspections ARE a required thing either under the Manufacturers Maintenance schedule or AD/ENG/4 as an engineer you should know that.

Fine wire plugs are good for over 100 hours but "champions" are not? Since Champion is a brand that manufactures both fine wire and massive electrode (the other type spark plugs) this make no sense at all. If you are suggesting that fine wires need less maintenance than massive electrode plugs then this is also untrue. Both require cleaning and gapping, both have electrode wear (faster in massive electrode but spread over two electrodes instead of one in the FW)

As for the magnetos, type of plug fitted has nothing to do with the rate of wear in points, gears, capacitors and other components so advising that less than normal maintenance is "no big deal" is just plain wrong.

I know what I am looking at during oil analysis, engine monitoring, and bore-scope inspections and none of these things will identify a cracked crankcase, cracked cylinder head (not yet separated), holed muffler or any one of 100 other things that can kill you and can only be found by good old MK1 eyeballs.

Not to mention the airframe parts that would also be inspected at the 100hr

It may be legal to operate a private aircraft over 100 hours without inspection but it is definitely not prudent.

Also feel free to PM for advice

[Creampuff]

Some slight tweaks to yours, progressive, so that you’re giving the whole picture.

The requirement for the oil change/filter inspection is clearly set out in AD/ENG/4 requirement A3 for private ops - within the manufacturers recommended period + or - 10%.But ….

AD/ENG/4 only applies to piston engines fitted to aircraft maintained to Schedule 5.

Further …

AD/ENG/4 ‘points’ to the engine manufacturer’s data.

So…

What you meant to say was:

(1) if a piston engine is fitted to an aircraft maintained to Schedule 5; and
(2) the engine manufacturer’s data specifies oil/filter changes more frequently than e.g. Annually/100 hourly,

the outcome is that AD/ENG/4 mandates the more frequent changes, subject to the margin specified in the AD.

What those periodicities happen to be change from engine-to-engine type/part number to engine type/part number.

Also…

It’s possible for the aircraft to be maintained in accordance with a system of maintenance (i.e. neither Schedule 5 nor the manufacturer’s maintenance schedule, although I concede that a system of maintenance would normally reflect the engine manufacturer’s oil/filter change recommendations).

Re ignition systems: You obviously think you know lots about ignition systems, but have learnt very little. Do a search on the Champion massive electrode internal resistor problem.

You 'gap' fine wire plugs? You’re not going anywhere near my engine.

[4Greens]

If he is paid to fly, it is not a private operation.

[Creampuff]

Not accurate.

There are lots of operations during which the pilot may be paid, handsomely, but it's still a private operation.

One example of many is the transport of the owner of the aircraft ...

Another is agricultural ops on land owned by the owner of the aircraft ...

Decades of this classification of operations system, and still ignorance pervades.

[evilducky]

Another spanner in the works here.... Didn't specify what type of operation. Given the hours and skimpy maintenance, one might guess that your friend is parachute dropping? If so there is a requirement for 100 hourlies and oil changes every 50 hours even though it's a private op under the apf's casa instrument.

[Old Akro]

It disappoints me that there is often a flavour on pprune that all bosses are exploitative crooks taking advantage of young pilots.

The relationship with your boss should be good enough to ask honest, open, enquiring questions like these. This applies whether you are a pilot or the office girl. If your relationship with the boss is not good enough for this, it would be a signal to look for a new job.

Regarding the oil changes, I agree that I would prefer to change oil more frequently. But from the pilots perspective its what's on the MR that counts. It will have a validity date, airframe hours and notes on interim maintenance. If the MR does not require the oil change, then its legal. If the MR requires an oil change that has not been signed off, then its not legal and he shouldn't fly it. If the MR is not requiring an intermediate oil change, then frankly its as much a question for the LAME that signed it as the owner. If there is an accident attributable to lack of oil change (which there won't be) then it will be the LAME in the gun, not the owner. Once again, this would be an entirely reasonable question to ask the signing LAME. The owner will pay the price of lack of oil change in increased engine wear / shorter engine life. Its very unlikely to be a safety issue.

Regarding duty times, frankly who cares about CAO 48. Its probably the single worst written CAO. If you want evidence, just look at the huge volume of exemptions granted by CASA. The real question is whether the pilot is happy with the duty hours? This varies hugely with the style of operation. If the aircraft is flying VFR in good weather west of the J-curve and the owner is also a pilot who shares some of the duty (not an uncommon scenario), then I'd suggest you could easily, safely and happily fly twice the duty hours of (say) a single pilot IFR freight run in bad weather (ie across Bass Strait).

But, really these are both conversations that an employee should have with his / her employer.

[desert goat]

Why not just change the oil yourself, rather than continuing to worry about it?:confused:

[Ilikeflying]

Yeah it's based out of the middle of no where and there isn't enough oil to change it themselves.

The pay is fantastic and the hours just as good. it is not skydiving ops, just many 1 - 3 hour legs in a day, and it is considered a private op.

The pilot is looking to quit because of the abrasive personality of he owner and the fact that he gets yelled at whenever he voices concerns.

Thanks for all the replies so far, they have been very enlightening.

The maintenance release stipulated the first oil change at a predetermined time, but not any subsequent ones. The engine is a Lycoming 540.

And yes, the pilot has no problems with the long days, but was still enquiring in the event of a logbook review or something similar.

[VH-XXX]

We covered the MR thing a few months back on here.

An annual inspection is an annual inspection, not a 100 hourly, but of course they can be done at the same time.

If you have 2 hours on the VDO for the last year, you still get an annual inspection.

If you do 300 hours in one year, you are still up for ONE annual inspection, but potentially 6 "services" or oil changes.

[drogue chute]

You 'gap' fine wire plugs? You’re not going anywhere near my engine.

Then why do Champion, the manufacturers of said 'fine wire' plugs recommend gapping them and provide instructions as to how to do it? Oh and why do they make the tools to do this as well?

[Creampuff]

Ain't no engineer going anywhere near my fine wire plugs with any gapping tools.

[Old Akro]

If you do 300 hours in one year, you are still up for ONE annual inspection, but potentially 6 "services" or oil changes.

The MR should specify both a TTIS & calendar date validity - whatever it is. It should also specify periodic inspections / maintenance required within the validity period of the MR (ie oil change requirements should be listed).

The pilot should not need to do anything past reading the MR. If the MR is OK, and the required inspections are completed (including the daily) then the pilot should be able to fly it. If the MR requirements are not complied with, the pilot cannot legally fly it.

[Jabawocky]

Progressive,

I think you may have confused yourself with what I said Vs what we both know is prudent and generally legal.

It is possible that a certain manufacturer does not specify a 50hr oil change. I have never seen one, but there could be, and so if by Sched 5 and AD/Eng/4 it points to the aircraft manual and it does not, then legally it does not. As best I can tell.

As for Creamies post, I think that explains it all.

Ok spark plugs. I am not sure how you did not follow what I said. If you need to call me please do, happy to chat, but let me try to explain in more detail.
Next is spark plugs and magneto's. If they are fine wires, then no big deal. 100 hrs is fine. All they need is a resistance check and checked for cleanliness. If they are Champion, this is far more critical.

Massive electrodes need to be cleaned and gapped every 50 hours (+/-10%) not by law but because the gaps change out of spec in that time. By 100 hours they are usually outside 0.018" and I can pick them on the EMS and with my calibrated butt!

Fine wires, they rarely need cleaning, unless the operator is a poor mixture knob user. (I have a solution to that) and the gaps stay very reliable even out to 1000+ hours. As Creamie noted.....nobody is touching his fine wires!

Champion Vs another major brand. Champions are a great plug and work fine but they have a very short life in the resistor, typically 300 hours is when they start to drift and once at 5k ohms they go in the bin. This is important for other reasons than just good smooth running.


As for the magnetos, type of plug fitted has nothing to do with the rate of wear in points, gears, capacitors and other components so advising that less than normal maintenance is "no big deal" is just plain wrong.

As for magneto's......where on earth did you get the idea I said anything of the sort...go back and read again please. This thread was about 50 hour oil changes and out to 100 hours. Now you are talking about 500 hour Magneto inspections. :ugh: By the way I agree with your comments about checking them, very strongly, you have 100% support there :ok:

But I must pull up one point. You suggest that spark plugs have nothing to do with magneto's. Well this seems to be something that even CASA failed to address in a recent AWB on magnetos where they talked about coils suffering from heat stress yet they have no idea where this magical extra heat stress comes from. No it is not the continual heat from years of operation. It is from years and hundreds or thousands of hours of operating on plugs with high resistance. Problem is not many folk know this and it is a long forgotten bit of knowledge. I hope that helps :ok:


I know what I am looking at during oil analysis, engine monitoring, and bore-scope inspections and none of these things will identify a cracked crankcase, cracked cylinder head (not yet separated), holed muffler or any one of 100 other things that can kill you and can only be found by good old MK1 eyeballs.

Maybe I am over reacting here but where did I say that this was a good idea not to do these things? I think we are in an extreme case of agreement here. :ok: BTW my plane gets an almost 100hrly every 50 or less, and it gets two 100hrlys and an annual per year. So I am on your side here. :)

Now just a note though, you say that there are things you can't see with an EMS, well holes in exhaust systems can at times be found, broken flame cones too. Maybe you might be surprised what an EMS tells you. By the way I have a suggestion on where that and many more things can be learned. But I will be accused of advertising a course which is run not to make profit, but is a company none the less. ;)

It may be legal to operate a private aircraft over 100 hours without inspection but it is definitely not prudent.

Yep....we are in severe agreement once again. :ok:

[Jabawocky]

Gapping spark plugs. I have written articles on this, much to the delight of Tempest, who at first I thought were going to sue me for something, until I realised that was not their intent at all and quite the opposite. But rather than blab on here, go to this link.

DO NOT try to gap fine wires, because they do not need it and NO you can't buy tools for it. The ones you buy are for Massive Electrode plugs

http://www.tempestplus.com/Portals/0/PDFs/TechTips/Light%20My%20Fire%200813.pdf

http://www.tempestplus.com/Portals/0/PDFs/MaintenanceandService/Sparkplug%20Cleaning%20The%20Right%20Way%20081412.pdf

http://www.tempestplus.com/Portals/0/PDFs/TechTips/Changing%20Spark%20Plugs%201012.pdf

Enjoy!

[GTang]

you must hypothetically be getting paid the big bucks for all that

[Progressive]

Jabba,
Champion provide both a tool and a procedure for gapping fine wires see here:
http://www.championaerospace.com/assets/technical/93-2.pdf

There may have been some misunderstanding in my last post, i thought you were advocating for annual only on private aircraft with engine monitors and fine wire plugs hence my comments regarding eyeball inspections and magnetos.

The mention of magnetos at the start of your paragraph on plugs led me to believe that you felt plugs were sum of ignition system maintenance.

I have never had a problem with massive electrode plugs gapped properly every 100 hours, although few do this properly.

Unfortunately you seem to be conducting the tempest resistance check on champion plugs. This test works fine on tempest plugs which have a ceramic resistor (linear resistance). Unfortunately champion use a silicone carbide resistor (not carbon pile as suggested by Tempest - true carbon pile were phased out in the early 90's).

Silicone carbide resistors are generally NON-LINEAR in resistance and optimized for resistance at operating voltages so they would need to be tested at operating voltage/conditions.

Champions advice here is simple if the plug is making a proper spark when tested in a properly calibrated (there is a procedure) plug tester then the resistor is doing its job. Using the tempest procedure on champions is just wasting potentially good plugs.

http://www.championaerospace.com/assets/technical/72-10.pdf (yes this is old)

Incidentally tempest based the resistance value on the spark-plug MIL-SPEC, since the mill spec is a production standard this is hardly appropriate for maintenance. (Like maintaining your aircraft using the original build specs instead of wear limits). The last revision of the MIL-SPEC was 1990 and it does not include iridium plugs as far as I can tell.

[Creampuff]

Debate is good. :ok:

My personal view is that “silicone [silicon perhaps?] carbide voltage dependent resistors” are comprised mainly of unicorn farts and reptile lubrication, but let’s concentrate on the laws of physics and the results of empirical testing.

The laws of physics dictate that before the spark, the voltage in the ignition secondary circuit is the same up to the plug tip, whether the resistor in the plug is 1 Ohm or 1,000,000 Ohms. It’s an open circuit at the plug tip.

When the voltage in the secondary builds sufficiently to jump the gap, current flows in the secondary circuit. I haven’t the formula at my fingertips, but the laws of physics dictate that the voltage must build to about 2,000 to 2,500 to jump a 0.018 gap. The spark itself has low resistance.

It must be at this point onwards that the resistor in the plug does its high voltage-dependent magic. Before the spark the voltage across the resistor is zero.

The laws of physics dictate that, after the spark starts, the current flowing in the secondary circuit and the voltage at the plug tip are determined by, among other things, the resistance of the resistor in the plug. (The secondary coil has resistance as well.)

The higher the resistance, the lower the current and the greater the voltage drop across the resistor.

And the important bit: The higher the resistance, the weaker the spark and the shorter the duration of the spark.

There is a very strong correlation between Champion plug resistors that measure very high on a ‘standard’ low voltage Ohmmeter and improvement in engine performance when replaced with a plug that doesn’t measure very high. My personal view is that the resistance measured by a ‘standard’ low voltage Ohmmeter is an analogue for what’s happening at higher voltage. Whatever is the actual cause, the change in performance is a fact.

I’ll bet your bench test doesn’t measure strength and duration. And there are lots of plugs that pass bench tests and fail LOP at altitude.

By the way, an expert in high voltage circuits (he has the patent for the Taser technology) did a test on one of his plugs. The spark jumped around the resistor in the plug. Imagine how high the voltage had to get to do that, and imagine what that was doing to the coil in the magneto.

And there ain’t no engineer coming anywhere near my fine wire plugs with gapping tools. (No debate.)

[Old Akro]

The laws of physics dictate that, after the spark starts, the current flowing in the secondary circuit and the voltage at the plug tip are determined by, among other things, the resistance of the resistor in the plug. (The secondary coil has resistance as well.)

The voltage of the secondary circuit is primarily determined by the rate of collapse of the magnetic field of the primary circuit. This might be Faraday's law. I forget. Its part of the reason that point gap & condition is important.

I think spark voltage is around 20,000 volts but might be as high as 40,000 volts. If the primary side draws 10 amps (guess, I'm not sure what the real figure is) then the secondary current will be 0.003 to 0.006 A.

Using V=IR if the plug resistance is 5 k Ohm, then the voltage drop due to the resistor will be 5000 * 0.006 = 30 volts. Hardly significant.

I think plug performance is about the insulator and its integrity. I suspect that plug resistance might just be a metric of insulator condition.

The resistor is there for suppression of radio interference. So, I think its real job is to damp some of the transient voltage spikes that surround the main spark voltage.

Here is a bit of an explanation by NGK

PLUG STUDIO / NGK (http://www.ngk-sparkplugs.jp/english/techinfo/qa/q08/index.html)

[Aviater]

DO NOT try to gap fine wires, because they do not need it and NO you can't buy tools for it. The ones you buy are for Massive Electrode plugs

Is this what you teach at your pilots courses?

Not enough information here mate. Without further details, this information is not accurate. Disappointing to see you post this.

[Creampuff]

Not sure I agree with your numbers or logic there, OA.

The spark event occurs when there is zero current flow in the primary circuit. That’s what causes the collapsing magnetic field in the primary coil and consequential build up of voltage in the secondary coil. The amount of primary current therefore seems irrelevant to how much current flows in the secondary during the spark event.

There is a very useful waveform at this link: Engine Management - Primary versus Secondary Circuits (http://www.picoauto.com/tutorials/primary-vs-secondary.html) (see figure 1.0).

The red line is the secondary voltage, and the scale for that is on the right hand side.

The primary voltage and secondary voltage build up quickly when the current stops flowing in the primary (on most steam-driven GA engines, that’s when the mechanical points open).

Then the spark happens. The spark event is happening during the approx 1.1 milliseconds during which the measured secondary output voltage is about 2,500 volts. (The ‘ringing’ happens when the spark stops. Current ceases in the secondary circuit and coils do what coils do when current stops flowing through them.)

During the spark event the ‘sparked gap’ has very low resistance. Therefore the amount of current flow depends on the total resistance in the secondary circuit.

If we assume the plug resistance is 2,500 Ohms (to make the numbers simple), the current flowing during the spark event is 1 Amp.

(E = IR; I = E/R; E = 2,500 volts; R = 2,500 Ohms; I = 1 Amp.)

However, it’s not quite that neat. For example the secondary coil has resistance as well. The tech data suggests that a ‘normal’ coil secondary resistances have a broad normal range that varies between brands, but the very rough average is about 10,000 Ohms. Also, inductive circuits do really weird things ...

However, the spark event is for most intents and purposes a (very short) DC event. The voltage necessary to bridge the spark gap will always be the same but, once it sparks, the amount of current flow in the secondary circuit is determined mostly by the voltage and resistance in the secondary circuit. The higher the plug resistance, the lesser the current flow during the spark event. The higher the plug resistance, the ‘weaker’ and ‘shorter’ the spark.

Of course, these aren’t ‘1’ or ‘0’ things. There is so much ‘slop’ in these systems that it’s a slow deterioration.

But you can feel it in your nether regions and see it on the engine monitor, eventually. And there’s lots of real world experience that shows that if you throw away ‘that brand’s’ plug if the internal resistance measures in excess of 5,000 Ohms on a ‘standard’ low voltage multimeter, the problem goes away (even if the plug was squeaky clean and perfectly gapped, and even if it sparks on the test bench).

Aviater: From the first link in Jabba’s post:For fine wire iridium plugs, setting the gap is rarely an issue. … If you do try to bend the fine wire ground electrode, you’ll probably break it. …Ain’t no engineer going anywher near...

[Aussie Bob]

Is this what you teach at your pilots courses?

No, this is not what he teaches. What he does teach is awesome! Take it from someone who has attended.

[Old Akro]

creampuff. That's pretty technical for a bush lawyer!! :)

The voltage in the secondary coil is generated by the collapse in the magnetic field of the primary coil and is dependant on the rate of collapse of the magnetic field. Its governed by Faraday's law of Induction. I guess you could say that the magnetic field has collapsed with the current is zero, but its about the magnetic field, not the current.

I used 10 amps in the primary only to make an estimate of the current involved in the spark. But I think I got it wrong. I think energy should be the common parameter not power as I did. It did take me 2 goes to pass my electrical engineering subjects!

The point I was trying to get to was that the amount the spark voltage is diminished by the spark plug resistor is dependant on the current. And the current is bugger all, so the voltage drop from the spark plug resistor is small.

My good friend Google tells me you need a minimum of 12,000 - 25,000 volts for a spark which is consistent with other figures. I think your 2,500 volts might have a decimal point wrong. The Bosch handbook will be the oracle, but its at work. I'll check later.

The point I was trying to make was that I don't think the resister per se is the issue. I think the changes in resistance you measure are indicators of insulation breakdown, not deterioration of the resistor itself.

[Jabawocky]

Progressive, no worries :ok: I figured you had misread.

I have never had a problem with massive electrode plugs gapped properly every 100 hours, although few do this properly.
You might be surprised, usually around 75-80 hours you can tell the difference. I have proven this with many a set, and let them go past 100 and it is dead easy to spot. Most pilots would never know.


Silicone carbide resistors are generally NON-LINEAR in resistance and optimized for resistance at operating voltages so they would need to be tested at operating voltage/conditions.

OK this argument has been made before in the USA, however a few things come to mind. Confuscious say do not tell man something impossible when he is already doing it. Now besides the funny aspect, when you take a set of Champion fine wire plugs that the pilot says is running not as smooth as he thinks they should and you measure them, with the Tempest method, and they are anywhere from 100,000 ohms to 1,000,000+ ohms and you replace them, and yet the gaps were still fine, because they hardly wear at all, with a new set and it runs baby bottom smooth. What does that tell you?
It tells me that the non linear tests even though it is not at 20000 volts it is still detecting a sub optimal plug, so the end result is what matters.

Now I could say I do not have the test equipment here to go testing plugs at very high voltages, although I do have the gear here at work, I am not doing it. But what if i said I know a bloke who has?

Perhaps one of the founders/directors of the TASER company, who has or had a C421, might also have a 441, anyway after being semi stranded due poor plugs on the ground with family etc loaded aboard, he decided to do some research.

I think this guy is somewhat qualified, here is what he had to say; Max Nerheim (edited to remove irrelevant stuff for brevity)
I decided to take the Autolite UHRB32E (same as Tempest?) spark plugs I had from before I put in the Champion Fine Wire plugs, as well all the Champion fine wire plugs and test the continuity in them using a Digital Volt Meter (DVM). The Autolite plugs read from 1115 to 1351 ohms. The Champion plugs read from 1330 ohms (the one new plug) to open/infinity. So not only did the fine wire plugs crack, they also had resistive readings that were seemingly totally random!

I suspected the open readings were due to slight corrosion buildup between the elements of the Champion spark plug: The Champion spark plug is assembled with a resistive “slug” that is held in place by a spring and a screw, which (at least in theory) can both develop some surface corrosion. I thought, if there is just some slight surface corrosion, this would be no big deal as the magneto would “burn” a path through the bad contact areas, and the resulting “high voltage impedance” should be close to nominal. To test this theory I utilized a high voltage source (a TASER X26 stun gun), an oscilloscope, a non-contact current probe, and a 25kV high voltage/high frequency probe. The oscilloscope captured the current and voltage waveforms across the plug from the spark plug wire terminal to the front round electrode (not including the spark plug gap) during the high voltage discharge. The voltage and current readings were captured after all the “bad” circuit elements had been "burned" through. By using the captured voltage and current, the plug resistance during the firing of the plug could be calculated.
I tested all the plugs using this setup. The X26 is capable of generating up to around 50,000 volts, and had no problem jumping across the spark plugs (from the back spark plug wire connection to the round electrode on the front).

Using the High Voltage oscilloscope approach, all of the Autolite plugs measured within 11% of their corresponding DVM readings. Very nice. This demonstrated an acceptable consistency and also validated the approach.

The 16 Champion plugs (4 that were replaced initially, and the remaining 12) measured from 194 to 11,000 ohms using the oscilloscope method. A big surprise was that 6 Champion plugs measuring from 135 to 534 ohms. These plugs had all measured “open” on the DVM. When discharging the TASER across these plugs I noticed there was arcing noise within each spark plug. The arcing noise is caused by the TASER having to arc across an air gap. This caught my attention - why would the TASER have to arc across INSIDE the plug (the spark plug gap was not part of the test).

To investigate I opened up the Champion spark plugs by unscrewing the screw where the spark plug wire is normally inserted. The spring and the resistive element was then removed from the plug. With good access to the element I used a DVM with sharp test clips attached to try and measure the resistance of the element. OPEN!!! Well, it must be "surface corrosion" I still thought. I then attached the TASER X26 to both sides of the resistive element, and discharged the X26, hoping to observe the current going through the resistor, so I could measure the resistance. Instead, the X26 formed an arc on the outside of the resistor: Champion Fine Wire Spark Plug RHB32S resistive element testing - YouTube (http://www.youtube.com/watch?v=DERIHonZT-k) Each time the X26 discharged, a blue arc of ionized air formed across the surface of the resistor. The resistor element itself was completely OPEN. It did not conduct any electricity at all! Normally in a test setup like this, the current would flow through the body of the resistor, not arc across it. In this case, the resistor element acted as an insulator. Hence, spark plugs with “resistive” elements like this one would present the magneto with roughly a 0.5” extra spark gap in series with the approximately 0.02” spark plug gap! With this much extra gap to jump, there is not much point in arguing if a “proper” spark plug gap should be 0.02” or 0.03”!!! With my limited understanding of how a magneto works, I am also concerned regarding the possibility of the high voltage required to arc across a plug like this, could instead jump from the rotor to the next cylinder contacts (instead of to the current one). The probability of this happening would increase if the adjacent magneto contacts had normally working spark plugs. Hence, if one plug is bad and requires a much higher voltage, it is better if they are all bad!

The arcing across the resistive element also explains the very low resistive oscilloscope readings during my previous experiment: The X26 generates enough voltage to arc and ionize the air across up to around 2 inches through air or even longer across a partially contaminated surface. Once the air has been ionized the resistance of the air (gap) drops from “open” to close to zero (that is how a TASER device can across up to 2 inches of clothing.) The resistive element that was open also read “open” on the DVM TEST. I weighted the resistive element on a laboratory grade scale. It came in at 0.23 grams. The TASER X26 discharging 19 pulses per second for 5 seconds (compared to a magneto at 28 pulses per second continuously) through a working resistor made it too hot to touch. Is it a possibility that the resistor is too small to dissipate the electric energy from the magneto without degrading..? How much energy does a magneto put out? It sure seems like a good idea to have the plug resistor thermally and mechanically coupled to the spark plug body to help dissipate the electric heat (like the Autolite plugs).

Arcing Spark Plug Voltage:
I also measured the peak voltage necessary to arc across the various spark plugs. This was a slightly different test setup, as now the spark plug gap is part of the circuit. The voltage was measured from the spark plug wire attachment point to the body of the plug. In order to fire the plug, the magneto would have to put out this voltage in addition to the extra voltage needed to jump through the compressed air mixture present in the cylinders during compression – more cylinder pressures at higher manifold pressures requires higher magneto voltages. At ambient pressures the old Autolite URHB32E plugs measured somewhat consistent (nothing in High Voltage is entirely consistent) peak voltages from 6200 to 9300 volts. With the Champion RHB32S the voltages measured from 6300 to 17000 volts. With some of these I had intermittent arcing at the back connection of the spark plug – from the screw connection, across the ceramic to the metal body. In this case there would be no arc across the spark plug gap. Operating the spark plugs in a running engine with cylinders compressing the air would require a higher break-down voltage across the spark plug gap, and thus would make this condition more likely to happen.

Summary/discussion:
I think there are two separate problems with the Fine Wire Champions:
-Roughly half the plugs I removed had ceramic missing (1 plug) or cracked ceramic.
-Only one Champion plug read around 1300 ohms (this was the one new plug from Provo). The other 15 plugs, including 3 that were only “slightly used” (installed in Provo) displayed readings on the DVM from 4000 ohms to “open”. 9 of the plugs read “open”. I had only one plug out of 16 that read close to 1300 ohms. I would not use a plug that read higher that 1500 ohms.

FOLLOW-UP April 11

The TASER brand stun guns do have a current limit, which is why the output of these devices do not wary much depending on if they are discharged into a "short" or a high impedance load (fat person). Most of the cheap contact type stun devices use only a capacitor discharge across the front, and hence they are loud, and not current limited. Different technology.

Luckily I have access to equipment to measure high voltage and current at the same time, calculate the resistance of the spark plug resistor WHILE the current is flowing through it, and also measure the peak arcing voltage across the plug and across the resistive element. These measurements raised my concern. The engine will run fine as long as he magneto can jump across the burned out resistor AND the spark plug gap - without the rotor inside the magneto arcing to the next contact point. That scenario is my largest concern. I fly a pressurized twin to 28,000 feet, and am concerned about keeping the ignition system fault-free. As we all know, the lower air pressure at high altitude makes it more likely for an arc-over inside the magneto (to the next cylinder with a "good" spark plug requiring lower arc-over voltage).

I also thought there were inherent low-voltage effects that prevented the fine wire plug resistance from being measured by an ohm meter. I proved myself wrong: What makes the plug read a higher resistance (with an ohm meter) is not surface corrosion or effects from the type of resistor used, but rather that the resistive element is burned out. Notice that the only Champion plug I had that tested close to resistance specification was the ONE new plug I had. All the other ones had various resistances, up to infinity/open. The ones that read "open" were loud when I arced across the plug from back to front electrode. The plugs with low resistance reading, including all the old Autolites were "quiet" when I passed the current through them. After taking them apart, I discovered that the resistive elements were completely open. The loud arcing was the current having to arc across the resistor to make a connection.

I think the parts should work according to specification/theory. I am afraid that if my plugs malfunction at altitude I will be out a new engine.....
The mag check is done at lower manifold (cylinder pressure) and therefore require less spark-over voltage across the plug gap. At altitude I run higher manifold pressure, resulting in higher cylinder compression/pressures and therefore higher spark plug arc-over voltages. In addition, there is less air pressure in the magnetos, making the possibility of an internal magneto arc-over higher....

[Creampuff]

OA

I’m pretty sure that the rough approximation of the breakdown field for air is 33KV per cm, or 3.3KV for 1mm or about 1.7KV for 0.018 inches. (I realise the conditions in a cylinder are not quite the same as ‘free air’ but let’s not complicate things with that yet.)

But I'll have to confirm. :ok:

[A Squared]

and NO you can't buy tools for it. The ones you buy are for Massive Electrode plugs


Oh, Reeeeeeeaaaly???

Well, I'll be damned ! Somebody should let Champion Aerospace know. For some odd reason they are printing "fine wire gap tool" on This tool. (http://www.championaerospace.com/assets/AV6-R-Nov2004.pdf) Not sure what it is, but I have one in my tool kit, and I've mistakenly used it for setting the gap on my fine wire spark plugs.


Oh, disregard, I see Progressive has already addressed your inane twaddle.

[Old Akro]

Creamy, are you sure you chose the right profession?

The Bosch Automotive Handbook (Robert Bosch invented the magneto / spark plug system) says you need about 12,000 volts for a spark, but most ignition systems deliver about 30,000 volts.

It goes into some detail about the energy of the spark (0,2MJ is required) and the voltage profile. It seems modern systems need a sharp defined initial spark for what they call "flashover" followed by a continued lower voltage spark which "helps stabilise combustion".

It reminds us that the spark intensity required varies with A/F mixture, BMEP (ie turbocharging) and spark timing.

The debate on plug gaps also reminds me that a spark initiates more easily from a sharp edge. In the olden days (when we re-gapped automotive plugs rather than throwing them out and replacing them) part of the procedure was to file the centre and outside electrodes to get square edges again. This is impracticable with massive electrode aircraft plugs.

[Jabawocky]

AxA

Yes I was wrong, despite having seen them in that Champion catalogue filed away.

Tempest do not sell one I should have said. As I was using them as reference material. My humblest apologies. Something about the president from Tempest telling me "do not gap them and we don't sell a tool to do it anyway" might be why :ok: And they do not encourage it because of damage to the tips.

Bottom line is they should not need gapping.

Will pay more attention to detail in future. Sorry! :ouch:

[Creampuff]

AO: My profession is "goat herder". I love my goats... :ok:

Max Nerheim is not a goat herder. He knows what he's talking about, and he's proved that, consistent with the laws of physics, you don't need anywhere near 25,000 volts to get a spark out of a good spark plug.

The secondary coils in a standard steam driven magneto can indeed put out lots of volts. Lots and lots of volts.

It builds up and up and up until it finds a path to earth ....

That's what eventually kills coils.

I prefer to use plugs that put the least stress on the coil for the best spark.

A squared: As a matter of interest, have you ever paid for a set of iridium fine wire spark plugs out of your own pocket, and let someone loose on them with a 'gapping tool'? My guess is you haven't.

[Old Akro]

Creampuff

We are pretty much in agreement. Except I don't herd goats. Nor do I own a cattle prod. We do have electric fences for my wife's horses, but the main thing I've learned about them is that I'm chicken and prefer to use a fence testing device and not the farmers wet grass method of checking the fence.

Max Nerheim is not a goat herder. He knows what he's talking about, and he's proved that, consistent with the laws of physics, you don't need anywhere near 25,000 volts to get a spark out of a good spark plug.

Bosch, your Pico reference (fig 1.1, point A) and other references are all consistent that you need about 12 kV for a spark. Bosch note that most ignition systems however deliver up to 30 kV.

The spark needs a point to launch from. The better automotive plugs (eg NGK, Bosch) have the centre electrode ground flat and a sharp edge side electrode to promote the spark. I think Champion are better now, but they used to cut the centre electrode with shears. They were truly dreadful plugs. I have never understood why massive electrode plugs are made with electrodes shaped as they are because they do not really have an edge that creates a focal point for spark initiation.

Fine wire plugs, on the other hand do this. And the whole point of using unobtainablium for the wire is so they don't wear and don't need maintenance (ie regapping).

This post from the Vansairforce kind of deals with Jaba's conundrum

Not knowing any better I "sand" blasted mine and have noticed no difference - but I'm considering not doing it again after reading this thread. However, I adjusted the gap and the very brittle platinum electrode broke on one of my $76 (as I recall) plugs. I used the fine wire adjusting tool from ACS to bend the side electrode. I called the company and the tech support specialist said never try to change the gap on them. He said you can get away with one slight adjustment in one direction if they are out of spec but the second tweak back will often break the electrode it as it did in my case.

It seems that the companies who make gapping tools for fine wire plugs don't advocate using them!

[Creampuff]

Alas, I remain wifeless. Just me and the goats…

It’s interesting to note where lots of manufacturer R&D time and dollars have been spent, because often that provides some insight into the underlying technical issues and constraints.

The ‘holy grail’ of GA piston engine ignition systems remains, of course, catching up with the 1980s and electronic ignition. (Plus no lead AVGAS…) Some ‘no moving parts’ electronic ignition systems for GA piston engines are making their way through the glacial certification process – a couple have made it through. Meanwhile, for almost all of the piston GA fleet for the near future …

It’s obvious that lots time and money has been spent on trying to get the spark plug to spark at the lowest possible voltage. As you (OA) have noted, one of the variables in the formula that determines the voltage at which a spark will jump a gap relates to the surface area of the conductors at the gap. Hence the manufacturers have gone to the trouble of tooling up to produce “massive dual electrode” plugs, “massive triple electrode” plugs, “massive extended dual electrode” plugs, “single fine wire” plugs and “double fine wire” plugs, as well as use different ‘unobtainium’ materials for the electrodes.

Yes: some of this can be attributed to ‘new toothpaste’ syndrome and the propensity of people to believe that ‘new’ and ‘different’ is always ‘better’. But note that nowhere near the same amount of time and money has been put into the rest of the standard, steam-driven GA ignition system. The innards of magnetos have been the same for half a century or so. So have the distributor caps and plug leads.

[Jabawocky]

OA
It seems that the companies who make gapping tools for fine wire plugs don't advocate using them!

Good research, and yes :ok:

I am but a mere piece of Plankton in the aviation food chain, and do get accused of inane twaddle at times, but hey, having learned a thing or two away from the normalised deviation of mainstream monkey see/do, I do expect to cop a bit of flack. A bit like the amazing pasting dished out to John Deakin in another thread yesterday. He thanked me for sending him the link, it was a great source of entertainment. :}

[Progressive]

I was wrong about silicone carbide:

From champions own literature (with emphasis added by me):
SAC-9 Suppressor
Champion developed the SAC-9 suppressor in the early 1980’s. This extremely reliable
resistor/suppressor is formed from strontium carbonate, aluminum oxide and copper
oxide powders. In fact, out of billions made, not a single SAC-9 suppressor has ever been found to fail in service. They are used in Champion “R” type resistor plugs. An
important feature of Champion plugs with the SAC-9 suppressor is that the resistance of
the plug cannot be accurately measured with typical low voltage ohmmeters.

This resistor is a proprietary type (hence why tempest do not use them) and very little info is available except that they are the resistor used in every champion plug with a R designation (aviation plugs).

As for magneto operation the primary coil is 200-300v secondary is 20-30,000V however this is only used for a nano second at the start of spark when ionization of the spark gap occurs. After this the spark voltage decreases exponentially. Thus excessive voltage in the coil is more likely to be created by excess plug gap which increases both the voltage required for ionization and the duration that voltage is required for.

As for gaping fine wires, generally they will need it once in a life. At approximately half wear life they will exceed .019". they can then be delicately re-gapped. I have not broken one yet. But would much rather risk breaking a fine wire than operating with too large a gap (with increased resistance at the point of spark gap ionization and thus excessive voltage and heat.

Your only other option is to throw the plug out when it exceeds .019" gap which is a waste when you can re-gap it with a $10 tool and 5 minutes of patience.

Tempest advocate for resistance testing of all plugs and no re-gapping for two simple reasons: They do not understand how the SAC-9 resistor works (and champion wont tell them) and they would rather sell another $70 plug.

Champion do not tell you NOT to test their resistance for two reasons; You should be doing what they (not their competitor) tell you to maintain their plugs and if you buy another $70 plug because you didn't that is their gain.

Creamy,
Perhaps the inventor of taser doesnt know that most variable resistors are subject to a sustained voltage limit after which the material fuses and goes to infinite resistance and that by putting 50,000V across it he was effectively making it open circuit with greater resistance than the air gap. The tazer then did exactly what it was designed to do and provided a high voltage current at low amps which ionized the air gap (which is easier to ionize than the pressurized fuel air mixture) between he electrodes and bypassed the resistor. Use of a voltage in the 12-30k range would have produced a better result.

[Progressive]

It is true that the spark will jump more easily to an edge however having a narrow edge would result in rapid opening of he gap as spark erosion occurred in the soft electrodes. Fine wire plugs can have a smaller electrode size and sharper edge because of the reduced wear rates of the iridium material.

[Creampuff]

Strontium carbonate, aluminum oxide and copper oxide powders.Phwoooarrh! That stuff's gotta be more expensive and better than unicorn farts and reptile lubrication.In fact, out of billions made, not a single SAC-9 suppressor has ever been found to fail in service.Wow! That's gotta be the mostest reliablest electronic component ever!

Funny thing is, like Mr N, I took one of my ditched Champion plugs and unscrewed the cap holding the 'magic resistor' and removed it.

After an appropriate period of respectful awe as a consequence of being in the presence of 'strontium carbonate, aluminium oxide and copper oxide powders' which, notwithstanding their reputedly deadly awesome high voltage powers and the expectation of an ethereal glow, seemed to look just like a bit of black baked crap, I applied a mulitmeter to it. Imagine my disappointment when no matter what I did to it, I got a big fat 'infinite'.

Imagine my further disappointment when the same multimeter applied to the 'magic resistor' from another Champion plug gave a resistance reading and didn't look like a bit of black baked crap.

And apparently the tests carried out by Mr N were at too high a voltage? Gimme a break...

This is just my personal opinion and I have no insight into what happened, but if I had to guess I'd say that for a short time Champion outsourced its 'magic resistor' manufacturing to the Chinese company that specialises in baby formula. ;)

[Jabawocky]

Champion do not tell you NOT to test their resistance for two reasons; You should be doing what they (not their competitor) tell you to maintain their plugs and if you buy another $70 plug because you didn't that is their gain.

No. Degradation of performance tells you, Not Champion. They suffer degradation, and pretend it does not happen. Amazingly it is a direct correlation with a known causation. The fact a competitor has latched onto it does not alter the facts.

They have head buried in the sand on this and some other more serious matters that will not be discussed openly here.

Once discovered, it is obvious. A bit like fairies in your garden, they do not exist. Until you discover they do. Then what?

I would not have believed it several years ago. But data is hard to argue with, especially when a bunch is collected by yourself. I have never found one engine yet that runs smoother with high resistance plugs. Not one.

[yr right]

Interesting comments like you can change any thing, Once again costing into view here as in why did you change that plug for its got plenty of meat on it left. Champion state that when the plug is half worn its U/S. Generally before this you don't have any problems with plugs. Now one thing you half all missed that when a mag fires it has multiple discharge, It is not one spark but several. Also you have positive spark and negative sparks, this means that it fires from and to the centre electrode and this gives different wear patens. 4 cly engines a plug will not change per cylinder. Meaning that #1 cly will be a positive spark and #2 will be a negative. Now a 6Cly each time the plug fires it will be different one fire pos and the next will be neg and this gives a more even wear on the plug.
Next thing is if you follow the manufacture advice and have you mags and plugs change and serviced you really don't have a problem.
As for gapping you can gap both types of plugs period.
Now depending on the operation of the aircraft what engine it is there are variables to everything . The worse plugs for fouling I've found is training aircraft.
As for anyone being able to say that they can feel an engine with high gaps I truly find this hard to believe what was the engine ? The only way I know anyone can do that was on the large radial engine s that had oscilloscopes and the really good flight engines could pick which plug it was on a 28 cly, before my time but can remember story's and reading about it as a an apprentice

[Creampuff]

Now one thing you half all missed that when a mag fires it has multiple discharge, It is not one spark but several. ...I don't think that's correct for most standard ignitions on standard GA piston engines. One spark and that's it. I think I've even seen a video of it. Look at the trace at the link in one of my earlier posts. (Of course, there are usually two plugs, each of which usually sparks at nearly the same time.) ... Also you have positive spark and negative sparks, this means that it fires from and to the centre electrode and this gives different wear patens. 4 cly engines a plug will not change per cylinder. Meaning that #1 cly will be a positive spark and #2 will be a negative. Now a 6Cly each time the plug fires it will be different one fire pos and the next will be neg and this gives a more even wear on the plug. ...Correct. That's why you need to 'rotate' plugs from a positive spark position to a negative spark position. ... Next thing is if you follow the manufacture advice and have you mags and plugs change and serviced you really don't have a problem. ...True. It's also true that any manufacturer of any product occasionally has quality control problems and produces bad batches. As for gapping you can gap both types of plugs period. Yes you can, but you'll likely break iridium fine wires if you do. Ain't no engineer going anywhere near my fine wires with any gapping tool ... Now depending on the operation of the aircraft what engine it is there are variables to everything . The worse plugs for fouling I've found is training aircraft. That's probably because training aircraft spend a lot of their time in service at low powers and full rich, such as during taxiing. They should be aggressively leaned on the ground, but most instructors learn and pass on ignorance. ... As for anyone being able to say that they can feel an engine with high gaps I truly find this hard to believe what was the engine ? The only way I know anyone can do that was on the large radial engine s that had oscilloscopes and the really good flight engines could pick which plug it was on a 28 cly, before my time but can remember story's and reading about it as a an apprentice/Magneto check LOP at altitude will usually be the first indication of degradation, but if you're used to the feel of the specific engine and the usual indications on the engine monitor, you can feel and see it as well.

You can do it the other way around: Collect some plugs with magic resistors that measure high or open resistance on a standard low voltage multimeter. Find an engine that's performing well. Change the plugs with the one's you've collected (after cleaning and gapping). Go fly. (Not my engine, please).

Jabba will probably chip in with his experience.

[yr right]

mmmm cream puff.
Ever heard of the hi performance ignition systems used in the aftermarket car industry. Its called MSD do you know why its called that. It multiply spark discharge. Its used to simulate a magneto.
I would have you have a look at the LAME syllabus and do some reading. A magneto has a multiply spark.
Ok the second ignition system is totally independent of each other, and propagates a more compete burn and a more even burn across the piston head. Also a redundant system which is it primary use.
Next thing is also is the mixture in the burn the leaner the mixture the slower the burn, the richer the mixture the faster the burn.
Basic LAME training.
As for breaking a plug well you can break any thing if you wish but you can also not break any thing. It would seam you possibly no more than your LAME may be you should change your profession ?
There are no one answer for any problem the rules are not always universal for any aircraft.
Cheers

[Creampuff]

How much 'hands on' time do you have on GA piston engines, yr right?

[yr right]

cream puff you say
True. It's also true that any manufacturer of any product occasionally has quality control problems and produces bad batches


Sorry this is totally incorrect.
Aircraft servicing is a preventative engineering process. This means we repair replace etc before it breaks or fails. Hence a in this instance we change plugs a the manufacture's recommendation's and have the magneto serviced at the 500 hrly inspection period as per manufactures service period instuctions.


If there is a bad batch then this is taken up else where, ie SB, MSB. AD etc etc

[yr right]

Cream Puff
Excess of 34 years and your self ?

[Creampuff]

Me? I'm just a wheel-chair bound geek from Hicksville USA. Flying machines scare me and engines are dirty!

So how many of those "hi performance ignition systems used in the aftermarket car industry" have you seen fitted to GA piston engines during your 34 years of hands-on GA piston engine experience? In round figures.

[yr right]

Well Cream puff
In Australia we would call you a ******** take it which ever way you like. You didn't answer the question so how long have you been in aviation for a start.
As for fitting a MSD unit you really showing your disregard for your own intellicahnce. Like I said it what MSD stands for there was no intent to say it is fitted to aircraft. However there are some units that can now be fitted to home build aircraft which are similar. Although they still use one magneto.
The Porsche engine used in the mooney hover dint use magnetos from memory but had dual independent ignition systems. This was a complex engine management system, Rotax also have a similar system although not as complex.
So as for fitting a MSD no I have not fitted one to any aircraft. But if you can read what I said and what it stands for then do some rescrach into magnetos.
Also the most powerful internal combustion engines a 10000hp top fuel nitro or funny car engine or so use magnetos that are made by guess who MSD

[Creampuff]

No, that won't do at all, yr right.

It was you who cited "hi performance ignition systems used in the aftermarket car industry" as the basis for your assertion that magnetos fitted to GA piston engines deliver multiple sparks. You could be correct (I very much doubt it), but if you are it won't be on the basis of what aftermarket car ignitions happen to do. Do you have any actual data or credible reference to cast doubt on the veracity of the trace at figure 1.0 at the link in my post at #26?

And you clearly spend very little time, if any, behind a GA piston engine on which your life depends. If you did, you'd know that occasionally manufacturers' commercial interests influence their recommendations and willingness to 'own' problems. (In that regard they are lot like engineers: Problems with engines are always caused by pilot mismanagement and never by poor design, poor manufacture, poor fitment or ham-fisted maintenance. Just ask the manufacturers and the engineers... )

And if you'd spent any real time behind a GA piston engine on which your life depends, you'd also know how plug problems manifest themselves in the air. Most of the plugs I've ditched were ditched due to actual, in-air problems, and those plugs were within manufacturer's specification and tested OK on the bench on the ground.

I'm sure you have many, many years of experience yr right, just like Trent 972. It's just that it's been the same year, over and over again.

[yr right]

Cheers Trent
I not here to peace to anyone just transform my knowledge onto others.
Cheers again
Always happy to share

[yr right]

Cream Puff you are a dill.
As an engineer I cant go above or beyond what the manufacture says. So end story.
They say 1 and I go 2 then you have an accident then you sue me then what grounds do I have,
Industry behind a piston engine, well my dad has over 20000 hours is that enough for you, like I said before I wont place a pilot or anyone I wont fly in my self. Never had a problem with a commercial pilot.
Sorry I guess if you have so much time on your hand you do some research on aircraft ignition systems and then learn a bout "E" gap but I guess you already know about that.

[Creampuff]

I see your point now.

Because I'm a dill and my brother grows elderberries, that proves there's nothing wrong with some resistors in some spark plugs.

Gotcha! :ok:

Yep, I know nothing about E gaps. I don't own a Unison T150 "E" gap gauge, which isn't part of my T-100 Assembly and Timing Kit and I've never used it in accordance with L-1363. ;)

[yr right]

Cream Puff
Great so please for you. I guess champion etc put them in so that you have some thing to complain about and know other reason spend all that time and energy and money for no reason at all

[Creampuff]

http://i60.tinypic.com/2cy5heg.jpg

So anyway ...

The little slug on the left is the magic resistor under discussion. The thing in the middle is an old plug.

(And the shiny gadget to the right of the plug is not a Unison T150 "E" gap gauge, which isn't part of my T-100 Assembly and Timing Kit and I've never used it in accordance with L-1363.)

[yr right]

We'll done a pic of a plug with a broken resistor. Only time you see it if you drop and break that plug. Think you will find it's main use is radio surpesion. Not 100% sure on that though. Do remember reading about it some time back. Like I've said earlier if you change your plugs regular they really don't give much trouble.
It's all in the detail.
Btw cream puff I use to sent aircraft in the middle of aust and never had a problem this was we on top of our planes and pilots. Might won't to have a look what's in the middle of aust and see what support is there. See it cost an awful lot to send an engineer on a break down here. It would seam if you are having trouble it may be something else wrong with you machine
Cheers

[Creampuff]

Whatever experience you may have, you haven't learnt much about bog standard Champion plugs.

You don't have to drop and break one to get the resistor out. You just unscrew the grub screw that holds it in.

The resistor in the picture isn't 'broken' in the physical sense. That's exactly the size and shape they are when they leave the factory. However, the one in the picture has a problem you can't see.

[yr right]

Sorry yes you can unscrew it but like I said only time you see it if you drop a plug other wise you don't see it as you don't unscrew it !!!!

[Mick Stuped]

Guys, don't know a lot about exactly what makes what happen with the spark system in exacting scientific detail, although I try to educate myself as much as I can on what makes an engine tick over nicely and what to look for in engine data to try and keep ahead of issues.

However I would like to share from experience in looking after our small fleet doing 3,000 to 4,000 hours a year combined, mostly all LOP and how spark plug health seems to effect our operations.

I read an article (about 5 years ago) on maintaining a good spark it made good sence and straight away I told our engineers to switch all aircraft at their next 100 hrly to all tempest fine wire plugs and every 100 hrly there after every plug was to be resistance checked and to throw away anything over 5,000 oms resistance.

It was an expensive exercise to change all plugs and the engineers thought I had lost it however within 6 months a few things happened that stood out. The aircraft average time of line dropped, our mag issues went away and we could get even lower average fuel burns LOP.

So don't acactly know the science behind why the mags are running happier although I have my suspicions but the bottom line is we seem to have much happier, efficient engines.

Maybe someone can touch on how plug health is related to mag health. The expense of switching to all fine wire and chucking what appears to be perfectly good plugs has been offset by sweet running mags and no more premature mag overhauls.

I maybe wrong but that's just what my data shows.

[yr right]

Mick
well im not quite sure exactly what to say, but when you have a closed fleet and you can manage and use the information that you can get from trending your engines you can make changes and monitor your changes in a positive or a negative. So by changing your plugs what else did you do..
Trending your engine wether turbine or piston is such an important tool. You are able to develop a knowledge of your machine and make changes to your fleet accordingly, use properly you will have a much more reliability.
I will just say well done
cheers.

[Mick Stuped]

Yr right, in my early years as a farm boy and fixing engines and pulling them apart just to see what makes them tick and trying always to improve things from trial and error is what I was taught on the farm. I grew up with briggs and Stratton, Holden and land rover motors, the old Cooper stationary engine and lister diesel engines. As a kid I found a glass plug that was used mechanics in go cart racing so they could tune the engines by looking at the color of the spark. I spent hours in the farm workshop playing around with spark timings and mixtures and leads whilst watching what it did to spark color and HP and found in the mag driven big old stationary pump engines that if a good strong spark was present then you could have a mass of problems else were and they would still run smooth.

If I think of the spark as water and apply things learnt about trying to keep pumps and pipelines going and keep a good supply of water up to stock isn't it the basic same principle. Look after the pipeline the pump will keep running smooth. Introduce any type of restriction or hammer in the line your flow slows, the pump, it knocks and hammers and self destructs and the stock fight for water and loose condition.

It maybe a non scientific and basic look at a very complex issue but I feel by taking away the restriction and allowing the mag to provide the spark in a way it is designed and a good even flame in the cylinder provides a nice even burn translates to a nice even power flow even timing and a happy engine.

From my experience I feel spark is the most neglected but most important step on the path to happy engine. At the moment I am looking at the next step and trying to work out the importance plug leads play and how reliable they can be.

I am happy to be corrected and learn more, just my experience and cheque book tells me I have stumbled onto something that works for me out here in the bush. Maybe it might for anyone else who has had problems in the past with premature mag failures and rough running engines.

[Creampuff]

Mick

It’s pretty simple.

Most of the things that can go wrong with a plug will result in the corresponding magneto having to work harder to make the plug spark. If, for example, the secondary coil voltage has to build to (and these are hypothetical numbers) e.g. 25,000 volts rather than 20,000 volts before the plug sparks, the coil is working harder, the coil is therefore working hotter, and the coil will therefore fail sooner. (By the way, on most standard GA piston engines, the coil is built into the magnetos.)

If you take a bog standard massive electrode plug, the gap is slowly getting bigger and therefore the voltage in the secondary has to build a little more to jump the gap. If left long enough, you can feel it in the engine. That’s why you gap massive electrode plugs.

Swapping to fine wire plugs solves at least the gapping problem, at least for 1,000 hours. (And please: Do yourself a favour and instruct your engineers not to go anywhere the fine wire plugs with a gapping tool unless they check with you first. If you’ve purchased Tempest fine wires, Tempest would rather replace or repair them for you, than have them wrecked by attempted gapping. And no: I have no direct or indirect pecuniary or other interest in Tempest or any seller of Tempest plugs. And yes: Your engineers might have successfully gapped old-style ‘dual fine wire’ plugs in the past, but they ain’t the same as the new iridium and other fine wire plugs.)

The internal resistor issue that is the subject of the discussion (for those capable of intelligent discussion) is the potentially more insidious problem. What’s undeniably happening is that when you measure the resistance of the internal resistor of a certain brand spark plug, using an ordinary, low voltage multimeter, the value becomes higher and higher as the plug gets older.

Now, the manufacturer of that brand plug says that the design and composition of the internal resistor is such that a measurement with an ordinary multimeter is meaningless. The manufacturer says that its internal resistors only work when exposed to the high voltages present in standard ignition systems.

The real world experience is this: When that brand plugs with resistors that measure very high or open circuit on an ordinary multimeter are replaced, the engines to which the new plugs are fitted run better.

Now it may be mere correlation rather than causation, but it’s an amazing correlation: The known symptoms of bad plugs – poorer engine performance and ultimately magneto problems – seem to go away when the plugs with very high or open circuit resistors as measured on an ordinary multimeter are replaced with plugs that maintain a constant resistance below 5,000 Ohms as measured on the same multimeter.

Your first-hand, real-world experience seems to be consistent with everyone else’s! :ok:

[yr right]

Mick
As ive said before its called preventive maintenance. What you say is what we do very well in the bush here in aust. Your thoughts are correct. Trend trend and more trends. If you run the same aircraft it doesn't take long to make a plan. Trends don't just mean engines. It can be every component. If you have a fleet you can work out when they fail and make a plan around that. A failure dose not nessacilly mean before a component is due on an M/M schedule. If you build up your component record you can get extensions although a little harder these days.
Fine wire plugs generally used on lower cylinder's where oil and lead can cause a problems. A little of topic but I just change the plugs on my turbo falcon after 100000k nearly no wear. Champion place a resistor in there plugs for a reason. You will also get longer wear out of a fine wire as oppose to a massive electrode plug.
For the average GA aeroplane there really isn't much gain in either plug. However the more you fly obviously the greater the gain you can have. The thing I transfer to owners is fuel is the cheapest thing you can put into your aircraft.
One place I worked the 500hrly mag inspection was turned into an O/H this was due that the conditions that the aircraft was fly to get the reliability it was required to do.
At the end of the day it all comes down to costs and if you wont to do it.

[Aussie Bob]

The thing I transfer to owners is fuel is the cheapest thing you can put into your aircraft

yr right perhaps you could give us your opinion on lean of peak operations?

[Progressive]

Mick,
I am not surprised you saw an improvement in performance with fine wire plugs over your old massive electrodes fine wire plugs (regardless of the brand) will produce a hotter spark than massive electrode plugs every time. this is because iridium has a higher melting point than the massive electrode material and so can support a hotter spark without excessive wear. In order to create the greater spark the plug employs a bigger air gap (more resistance hence greater voltage build up to ionize the gap). Also teh smaller electrode does not shield the fuel air mixture from the spark.

As for testing the resistance that's fine, you chose tempest plugs and they require resistance tests, I only have a problem with testing champions which CANNOT be tested in this manner.

Creamie:
I wish you would back your arguments up with some reality, on the one hand you argue that extra voltage due to plug gap wears out the magneto faster on the other you argue that fine wires are better for your engine than masssives. Well guess what: fine wires have a greater gap and a higher discharge voltage than massive electrode plugs.

NGK suggests that excess voltage can damage a coil by overheating but that in order to do this (at least with their coils) they would require an air agp greater than 1 inch which does not occur with plugs.

And when you post the spurious blog post of a man (granted a switched on guy) connecting a TAZER to a plug as proof of your theories perhaps you could include the paragraph where he contacts the plug manufacturer and they say they would consider resistance testing: With a max resistance of 80,000Ohms!!!!!

Yr Right:
There are two reasons for the resistor: To prevent radio interference and to reduce something called capacitance after-firing, a condition where back EMF builds up in the lead shielding and then re-discharges across the spark gap after the firing sequence. The resistor in the plug ensures the back EMF discharges to ground via the shielding (easier path).

[Creampuff]

C'mon progressive.

You know perfectly well that the difference in gap, standard massive to iridium fine wire, makes a tiny difference to the necessary flashover voltage, all other things being equal.

As to the rest, I will comment after I've had a rest!

[yr right]

Lean of peak yep. DONT
When you lean an engine you slow the speed of the of the fuel burn. This means as the exhaust valve is opening instead of the fuel being completely burnt it is now burn out past the valve. Yes im aware of the article but I've seen the results of over peak leaning as many engineers have. Makes money for us. Simple how much fuel do you have to save to replace a $2500 cylinder. Oh and plus the other 5 cylinder's that have to be changed. Even worse if you try it with a turbo engine, added boost can cause a detonation and complete engine failure. Case in point the PA 31-350 in SA while he had an engine failure on one engine he went to a high power setting and didn't increase the mixture as I recall. Now what that means although he didn't intentionally lean to an over peak the result was the same. He then lost the good engine resulting in the loose of the aircraft and all on-board. Yes there lots of other thing that compounded that accident but engine failure stopped the aircraft fly, Was extremely sad.
At the end of the day the exhaust seat and valve don't lie.


So I guess its the owners choice but at the service its the engineers.
This is my personal view and not to be taken as a recommendation. At the end of the day you have to go by what the aircraft flight manual says.


Look owners says this this that, engineer looks sees that that ,this. The machine doesn't lie. Things don't fix them self's.

[yr right]

As an LAME we looked at indifferently. We cost you money, we are seamed as a nesacarry evil. We not out to cost we not evil.
We do a job which at time can be extremely difficult. The industry is bleeding engineers a greater rate than you all can imagine. GA engineers arnt black box change or open cheque book ex military engines either. Most know there stuff and are there to help.
The difference between an Engineer and a surgeon is that a surgeon burry there mistakes and generally only take out one at a time oh and get paid a **** load more than I do

[Jabawocky]

Yr right.

1. Please explain what happens to exhaust valve and seat temperature as you lean the engine, from rich to peak and beyond.

2. Is the exhaust valve and seat hottest at; A. 150ROP B. 75ROP C.35-50ROP D. 20LOP



but I've seen the results of over peak leaning as many engineers have.
Are you sure? Lean operations occur on the LEAN side of Peak EGT. Rich operations occur on the Rich side of Peak EGT.

What you have seen is the results of poor manufacture at the OEM, and at times accelerated by temperature and pressure by operating at a mixture either not rich enough, or not lean enough. But it is not from operating LOP. To say such a thing shows a lack of understanding of the science.

American Airlines had 400,000,000 hours of data in the 60's about why their engines were now lasting to a TBO of 3600 hours when compared to around 700-750 hours when run ROP as you might be suggesting. That is ROP but not rich enough, or lean enough.

The Whyalla engines were run in the climb not rich enough, they were never LEAN operations as chemically they are ROP mixtures. The flaws in those engines were a defect in the crank, accelerated by mag timing advanced causing higher ICP's and CHTs. The other one had been operating in detonation from not rich of peak enough operations. This one failed due to a preignition event.

Detonation. This is something I am heavily involved with, I have seen more aviation gasoline detonation testing than I guess anyone in Australia, so I feel qualified to comment here. Under what circumstances can detonation be invoke?

A:Full Rich-150dF ROP ?
B:40dF LOP - Peak EGT ?
C: 35-50dF ROP?

With a conforming Normally Aspirated engine, on conforming 100LL can detonation be induced?

With a conforming Turbocharged engine, on conforming 100LL can detonation be induced, and if so under what conditions?

If you are interested, the NACA (pre NASA) did studies on valve temperature at varying mixture and other parameters circa WWII and later n the 60's Lycoming did the same, and oddly enough got the same result. In more recent years with far more sophistication the same data was collected and plotted with Internal Cylinder Pressure. The results of this are found in this well known graph.

http://i849.photobucket.com/albums/ab58/jaba430/Landmarksgraph_zpsbfb07cbb.gif

If you are willing to learn some things new, from the 1940's I am happy to help.

All the best. :ok:

[cockney steve]

Gentlemen, Thanks for a fascinating thread. Ilove how you Aussies can call a spade- a spade without chucking your toys out the pram and storming off...pretty sure this would have died a death if posted in Engineers and Tech, (where it probably belongs)

Right, I'm NOT an aircraft mechanic. I eventually had my own village repair garage, had a Crypton engine-tuner with a 'scope and knew how to read the trace

I grew up with side-valves, copper plug-wires, 6v electrical systems.
Plugs were simply an insulator with an electrode wire down the middle, held into a steel body......you could clean and regap indefinitely, until the ground-electrode was no longer over the end of the centre-one, but pointing at the side.....or the centre was burned away and recessed unto the insulator.
OK it wasn't efficient, but neither was the carb, camshaft, porting etc.

This wasn't good for Champion, the brand-leader, who exhorted you to clean and regap every 3,ooo miles, replace every 6,000
They sold a machine to sandblast, pressurise and fire the plug, ,with an observation- window and a chart to compare plug condition.......
Plugs were 4 for a pound (five bob each) and the marketwas saturated andstatic ,by the early 60's.

The advent of cheap transistor radios caused a huge growth in sales, Also it caused a lot of concern with the "crackle" of interference which was not addressed by add-on supressors- plug-caps with a resistor, and an in-line one in the King-lead.
The plug-makers quickly latched onto this! build -in a supressor-resistor, the insulator will bake it and in 12K miles it'll be fxxed! punters will HAVE to buy replacements....on top of that, we can up the price, 'cos it's now a highly-technical Resistor- plug....A marketing-man's dream!
Add in supressor cables for HT and you've another money-spinner. rubber insulation had already given way to PVC on HT leads and so a lot of damp-starting problems vanished.

I consistently had more problems with Champion ,than other brands
Afriend, an ex-transport driver, claimed to have seen skips full of rejects out back of their (now gone) (wonder why:} ) Liverpool factory.

I can confirm Ohm meter readings well outside spec. I can confirm the service-life of Bosch and NGK and Nippon -Denso (now just Denso) and resistor stability were far superior to the Champion product, which I, and thousands of others, stopped using. I can also confirm the scope-trace told the story...Champion failed sooner!

The bean-counters and marketing-men are probably to blame, but I find it indefensible to sell such a mission-critical component where the emporical evidence points to an in-built service-life limitation.

Recently talked on the net to a european Aviator....after fitting a new high-efficiency starter, the engine would not start or run .....he methodically fault-traced (Electronics engineer) and replaced the "almost new" Champions...having found the huge variation in resistance as reported by others...initially, just the "dead" ones were replaced, to confirm they were, indeed, the problem. engine started fine, but an excessive mag-drop prompted changing the others.....like fitting a new engine.! Of course, this problem is unique to him, they have never come across it before! thick, patronising c:mad:s Don't they realise the internet will expose their bull in a flash?

@Progressive are you on a Champion retainer? seems like you , along with Yr right,are sticking your fingers in your ears and shouting "la la la" until the detractors run away.......Well, lads, the evidence is overwhelming When Champion have gone the way of Lodge and other fine brands killed by fools and asset strippers, we'll have no joy in saying "TOLD YOU SO"

[yr right]

Jaba
Radial engines cant be compared to Lyc or Cont engines. To say that its manufacting faults is way to simplistic for a start. Ive change more than enough cylinders to see that. Operators that don't overly lean with no problems and others that do and have problems. Heat is transferred from the valve stem to the guild and from the valve to the seat. You all seam to be worried about the temp its the fact that the gas flow is not fully combusted and is still burning as it passes the valve. Hence it burns the valve. Once the valve is breached it then cant seal and more gas passes and it gets worse.


You can have all the graphs in the world, im sorry but real life has shown me a totally different out come. Im happy to keep change them out if you all wont to keep doing it, your not hurting my wallet.


Now on the accident. The ASTB started pre ignition from the lead on the top of the piston, how ever Lcy said that this was not the case, As I recall the first engine had a crank failaure and the second engine was move to a higher power setting with out the mixture being placed into full rich. Now pre ignition how is that caused ?????? leaning out perhaps. See fuel is also cooling and specially for air cooled engines. To get to an O Peak you must go though the hottest part of the burn. Like I said real world shows what happens.
Jaba always happy to learn btw

[yr right]

Remember rich mixture fast burn , lean mixture slow burn.

[yr right]

Steve
1st I am not saying that champion plugs are better or worse than any other plugs. Please read what I've said. If you change your plugs service your mags you generally have no problems. I'm happy to install fine wire plugs, its the owner that generally don't wont to move due costs.
Cheers

[Hempy]

Staying out of the p155ing contest, this is how I understand fine wires and the combustion process.

0 to 100 microseconds after 'spark' begins the primary field collapses due to no longer receiving voltage and the secondary field begins discharging. As it is discharging, it is ionizing the fluid in between the center and ground electrode of the spark plug (the air/fuel mix). As the ion fields grow out from the center and ground electrodes, they eventually meet, and an ion path is formed. Essentially this is a wire in the air made out of ionized air particles, like a mini lighting bolt.

This is the point where voltage spikes. It takes a lot of electrical pressure (aka voltage) to create the ion path, up to 40,000v depending on the ignition system design. THIS is where spark plug gap plays the biggest role. The longer the distance between the electrodes, the more voltage is needed to create the ion path (i.e from the coil)

Once the ion path is created, the voltage drops. Combustion still has not happened yet.

After the ion path is formed, it begins to transfer all of that energy stored in the secondary coil. THIS is where combustion begins. As the energy is transferred between the electrodes, some of the air/fuel mixture is ignited. The combustion event is VERY small at this point (the "little buddy flame"). At this point, there is not much energy, so any that is absorbed means there is that much less energy to multiply out into the rest of the cylinder. This effect is known as quenching.

This quenching action is where fine wire plugs plugs win. There is less material to cause quenching, therefore, more energy to get out into the cylinder. This gives a more even burn. With LOP and high EGR strategies, low quenching becomes VERY important.

This quenching effect is also the reason gap is important. The bigger the gap, the farther away the 'little buddy flame' is away from the electrodes, therefore less quenching occurs.

At the point the energy from the secondary coil is released into the surrounding fuel/air mix (this point is the 'holy grail' for a good plug, how efficiently that energy is transferred), combustion occurs in the fuel/air mix and the spark plug is now irrelevant (although it's effects are not).

New plugs should be gapped correctly already from the factory these days, but any uneven burn across cylinders will eventually result in the gaps increasing unevenly as well with resultant issues. Replace them if you can't regap them (i.e fine wire plugs..they are too delicate)

[LeadSled]

Radial engines cant be compared to Lyc or Cont engines.yr right,
With the very greatest of respect, absolute bollox.
Engineering wise, the individual cylinder don't know how they are arranged around the crankshaft.
I have been operating both radial and flat engines for about 50+ years, with the same results.Good results.
You have undoubtedly seen some lousy exhaust valves and seats, as I have, but you have absolutely no way of determining that running lean of peak caused the problem.
I am always fascinated by the idea that opiniated non-flying LAMEs or LAMEs with a pilot license but limited flying experience so often claim to know more about engine handling than a properly trained pilot, properly being the operative word.
I disagree with JABA on quite a few subjects, but on engine handling and running lean of peak, he is spot on. He understands, in this day and age, what was common knowledge 50+ years ago.
The only difference is that, with GAMIjectors and modern engine monitoring gear, it can now all be done with greater efficiency
Tootle pip!!

PS: With the first aircraft I owned,a Chipmunk, I could tell when the plugs needed attention, by the way the engine, when gliding with the throttle closed, rattled the canopy.

[Aussie Bob]

yr right, as you are no doubt very aware, there are only a small handful of aircraft engine re-builders here in Australia. Of this small handful, the number of outstanding organisations can be counted on one hand with fingers to spare.

I attended an APS course (see this thread (http://www.pprune.org/pacific-general-aviation-questions/535876-thankyou-aps-course.html)) and was heartened to see that the manager of one of these outstanding establishments was a presenter and the manager of another was a participant. That is, almost 100% of the best aircraft engine builders in Australia were in attendance!

Thank you again for your input, it is great that an engineer takes time to read and post on this forum. If you want to know which engine re-builders were at the course, feel free to PM me.

[yr right]

Ok lets start here then.
Radial engines are different , every heard of crank angle for a start and the difference I was referring to is the manufacture of the cylinder and then you have cooling as well.
GAM injector work because of the differing crank angle and are matched to each cylinder accordingly.
Also how are you monitoring the different cylinder's with muti cht egt or single probes.?


Jaba I sad earlier that how much fuel do you have to save to replace one cylinder if you run LOP. By your own admission you said that poor quality from the OME. Sorry you cant have it both ways.
What im saying is what I see, broken engines. I guess it keeps me in a job.


Now, I have read and sorry don't have the information here with me. Plugs have different heat ranges. Also when the plug fires the plug itself is a mini combustion chamber. It ignites then travels into the plug before shooting out across the piston head creating a flame front. This is totally different to a turbine igniter plug which has a flat face, im guessing that this provides a better flame front and as such a better more complete burn with a fine wire plug as opposed to a massive electrode which is mostly shielded mmm not sure but perhaps food for thought.

[Jabawocky]

yr right

Your changing cylinders is undeniable. Your correlation and causation are where the issues are.

I notice you avoided all the simplest of questions I asked. Please have a go at them. I am not here to to embarrass an anonymous person, but if I can help educate all the better.

As Leadsled has pointed out, the cylinder does not know how it is arranged, whats more the fuel does not know either, nor who made the cylinder. And why does brand C have several orders of magnitude more trouble than brand L, or P&W or......?

You are correct in saying the heat is transferred through the seat (65-75%) and through the stem (25-35%), and it is the incomplete contact through the face/seat that starts the burning of valves, not the exhaust gas going past. In fact you could be surprised at a little data here dating back to before WWII.

Gases going out the exhaust not fully combusting can be made happen at VERY lean mixtures, so lean the engine is hardly producing power. People with good balanced air/fuel ratio's some times see this as a "second peak" of EGT. This happens when they are well past peak, off the curves above and then EGT rises slightly (just off the graph) and the drops as no more combustion occurs. More commonly known as ICO.

Which temperature is hottest? 50dF ROP or 50dF LOP ? And which has the highest valve temperatures? You might find this helpful from NACA http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930091891.pdf

Whyalla, I have the coronial reports where all the real data came to the surface. Two of my colleagues were at the centre of this very material and I can assure you this helps a lot because reading a coronial is a cure for insomnia. But let me summarise it for you.

1. The left engine failed with a crankshaft failure, a manufactured in defect, which may have gone many more hours was exposed due to very high loads imposed on it during the period from installation and up until a few weeks prior to failure. This was a result of magneto timing being advanced several degrees. This failure was likely to happen some time, however the excessive loads brought the failure on sooner and unfortunately the swiss cheese started to have holes lining up.

2. The right engine failed by way of a preignition event. Preignition events are catastophicly destructive if let go for more than a minute. These engines were routinely run in the climb with the mixture leaned to a setting that was not rich enough but they were still RICH mixtures. This engine had the power increased considerably to deal with the loss of the right engine and the failure sequence of preignition followed once the circumstances were created.

Please note that the detonation in the engines cruise climb life could vary from light to medium and the engine could survive this and they often do their whole lives, particularly light detonation (as scientifically defined). However periods of heavy detonation will start to damage things and the most likely victim is in fact the spark plug ceramic. Once this fails, you now have a source of ignition long before the magneto fired spark event should happen. And I mean long before. On a Chieftan with statically correct timing, the actual spark event goes of in a range of 13-16 degrees before TDC, and yes that is not where you set the magneto for static timing purposes.

Once the preignition is started, it will continue unless it is deliberately stopped or until the cylinder pressures eventually beat the piston into submission and it fails.We have lots of data files to show you this and the post failure evidence to go with it.

I will answer one of my questions above for you, as this is crucial to your understanding how these events happen.
Detonation happens at?
A:Full Rich-150dF ROP ?
B:40dF LOP - Peak EGT ?
C: 35-50dF ROP?

The answer is C

I have a dyno-detonation test run with several fuels being tested on my laptop right now. The engine is 300HP standard compression (not low) and the detonation starts around 23GPH and is extinguished around 17-18 GPH. This detonation was all on the RICH side of peak EGT and thus by definition can only be a rich mixture. We can never get a typical LOP mixture to detonate when LOP.

You would be surprised at what we have to do to get even a min spec avgas to detonate. In includes, running CHT's up above 430dF (not as high as red line) run the oil temp up at 220df, get the IAT up to 150dF and use about 34-35"MP. This then gets you into the kind of territory the engine on MZK was in. I would dearly love to post the screen shots but it is highly confidential test data. Happy to let you see it on my laptop screen though.

Light detonation is not particularly harmful, medium can be stressful and reduces longevity, heavy is damaging to plug ceramics and other area's such as pistons.

Fuel cooling. Another of the worlds best OWT's. Fuel only ever adds heat. ONLY. One post on pprune is not able to pass on the full education of how extra fuel on the rich side of peak reduces CHT. It works EXACTLY the same way that having a LOP mixture does it by reducing fuel. You will have to believe me on face value here, but the rate of transfer of BTU's to the head are affected by ICP and that alone. ICP is a function of spark timing and thetaPP which affects the volume when the peak is reached. I could write for days and not convey this properly.

Remember rich mixture fast burn , lean mixture slow burn.
This is only half the story. Rich mixtures (by true definition) can burn faster or slower depending on where on the mixture scale they are. You are assuming that fast burns are a good thing and slow are bad. But you seem happy with the same slow burn with a richer mixture, which coincidently would have more fuel available to burn in the exhaust.

Take Aussie Bob's lead and book in for Perth. If you are not satisfied at the end that you did not learn a heap....money back :ok:

PS: Leadsled....thanks for the recognition. :ok:

[yr right]

Jaba
Ok let me say that what works on the computer is not always what happens in real life.
Simply put there are a lot of differences between manufactures, what material they made of comp ratios ignition timing etc etc etc. Detonation is always harmful period. Just because it didn't break now doesn't mean its not going to break. Stress now may not show now but will. The most harmful thing is that force is placed onto the big end bearing. This is the part that generally fails first.


As I recall the ATSB said it was pre ignition due to the lead and carbon on the piston head. Lyc rejected this totally. You said that was not overly lean well it must have been. full power full rich.
You said that fuel dosnt have a cooling affect. MMMM so how come when I pull the red knob back the egt cht rise, ?


At the end of the day I see the results. Ill just keep changing them out. Im Happy to do that.
Cheers always happy to learn

[yr right]

Jaba
Sorry so much going on I missed this,
You said the cylinder dose not know where it is. Well this is true it doesn't have a brain.
How ever there a a multitude of difference between each cly on an opposed engine, Crank angle for a start, cooling is different front to back, fuel require for the burn is different between them that's why you can use GAMI injectors. Is it injected or carby, if carby then you get a different flow between each cylinder.
Now ever wondered why P&W never made an opposed engine ? I have.
Areo engines are like no other internal combustion engine. Automotive engines don't work no matter how had they try I guess exception is a VW engine but that's not in commercial use.
Rotary's where to be the next best thing they couldn't make a gear box to take the hymonic load light enough.

[yr right]

At the end of the day you have to go by the POH.
But simply put it ill say it like this.
Man goes to the dr , ive got this cough, mmm dr says xray for you come back and see me next week. Comes back , well sir ive got some bad news sorry you have cancer, Oh he says. Dr do you smoke, yes he says a pack a day. Oh but that cant have caused it, Oh why is that the dr asks, Cause the smoke companies says it doesn't and its not proven.
Guess you could call me a Dr lol

[tail wheel]

Hope the thread title is now more appropriate?

:bored:

[LewC]

All very interesting but a tad confusing.I suppose it comes down to which of the major protagonists,the Puffster,Jabba or yr right,would you want doing your next 100 hourly?

[A Squared]

You said that fuel dosnt have a cooling affect.

Actually, he *didn't* say that

[Aussie Bob]

Hope the thread title is now more appropriate?

Ahh Tailwheel, my favourite mod. I see you still retain a sense of humour!

[yr right]

I'm sweet, as I've said I don't have to pay for the repairs. I just see the end results and then get the tears. Just trying to give a little different point of view. If you wont to go over peak go your hardest. A part from cream puff whom im not sure about who has leaned over peak and not had any trouble.


Now if you do a risk assessment on it lets get real here how much fuel do you save. Now if you damage a valve and seat and require a new cly how much is that now. Cost involve, freight, cly , labour and cost of your machine whilst it out of the air.
At the end of the day fuel cheap.
Im not saying don't lean just not over peak


Now someone ask me to give my comments on this subject so that's what I've done. If you notice my post I don't tell anyone how to fly, on this subject im just telling what I see and what I have come across on more than one occasion.
Cheers but im all good

[yr right]

Jaba
Ive never heard the tern light detonation. Detention is the un controlled burn or better explain explosion of the mixture. it either burns or detonates no light heavy. Damage to rods bearing piston heads occur after dentation.
Then you state pre ignition on the engine. Static timing on the TSIO-540 is 20 deg BTDC. The retard points around TDC for starting. You said that pre ignition was 13 BTDC this is after the normal firing point of the magneto. The late the firing once again can cause damage to the valve as the complete consumption of the burn has not had time to be carried, thus a loss of power.
I will add here I have never removed a plug with a broken ceramic in my whole career , omg have I done a lot of plugs in my time.
Im not exactly sure of what you do. You obviously have a high intelligence.
But if I may say lacking a little with hands on in the real word, I don't mean that as a come back or any thing nasty but just what I see on a day to day bases working in the real world get my hands dirty.

[Mach E Avelli]

Talk about thread drift! The OP had all the answers to the original question by post #15.
From post #16 onwards this belongs in Tech Log.

[No Hoper]

Detonation isn't preignition, just saying

[Andy_RR]

yr right, you've obviously spent a lot of your time spannering with aero engines, but that's not the same thing as playing with the parameters as they run on a dyno.

There really is such a thing as light detonation (I prefer to use the term knock) and indeed when you run a cylinder pressure transducer, you can do lots of maths with the result to calculate a Knock Intensity (KI) number that is a unit-less scale of how much knock is occurring. Auto engines are tuned to run right on the borderline of knock, whereas the FAA mandates that aero engines run so far away from the knock limit (at rated power) that everything carbons up and goes smeggy, not to mention the outrageous fuel consumption.

As far as exhaust valve temperatures go, they correlate more closely with cylinder head temperature than exhaust gas temperature because they spend most of their time seated and gas flowing past them at 1-2Bar or so is not a very good heat transfer mechanism. The key point is that cylinder heat temperatures are the most important long-term indicator of cylinder and exhaust valve/seat life.

Oh, and knock begins at the coolest part of the combustion chamber - not the hottest as is generally believed. I can explain why, but not in a few words.

[LeadSled]

the Puffster,Jabba or yr right,would you want doing your next 100 hourly? LewC,
I better not answer that, on the grounds that it may be defamatory.

I never cease to be amazed that aviation is such a concentration of old wives tales, "rules of thumb" and generally immovable prejudices, despite it being one area of human activity where the technical answers, the engineering answers and the operational answers are more thoroughly known than in most fields of human endeavor.

For those apprentices that go on to be LAMEs, it starts with TAFE, and is consolidated on the hangar floor, with disinformation passed down from master to apprentice, with too may pilots, it is the flying club or school, with the blind leading the blind.

I am reminded of the days when at least one "Royal" had the mixtures of its DH Gipsy engines wired off, and the carb. hear wired on ---- what a substitute for proper training.

Tootle pip!!

[yr right]

steve sorry I missed this before. Your friend with the engine that wont start is probably more to do wit the starter. If he has fitted a geared starter they turn so fast the impulse coupling will not engage and such the magneto is still to slow to produce a big enough spark to produce ignition.


well as for who dose the next 100 hourly im a LAME the others im not sure. As for being passed down the line well mmm you cant buy a LAME ticket but you can buy a pilots licence. You also cant buy experience.


I also understand running engine on a dyno and knock sensors. You cant compare areo engines to auto engines they not the same. The loads are different they way they make there power is different, yes the basically the same but they so far out from being the same.

[yr right]

Ok look at it this way. The old 308 holden roughly 200 hp and just above 300ci and what 5000rpm and 8 cly. now a Cont 0-300. 100 hp 4 cly and on a good day 2500 rpm. so when you get det in the 308 the cly is roughly half the size of that of the little cont. Now im not sure of the forces but I bet they more than doulble.Hence have a look at the rods and crank in what is just about the smallest areo engine. Then swing a 6 foot prop of it. Now look at a TSIO-540 at full song at around 350hp and introduce det at 2700 odd rpm.
Ive sean an engine that over speed too 2900 rpm after a governor failure for 30 sec. the engine was removed as it was junk.
I've been heavy involved with drag racing over the years detonation kills engines.
Modern car engines run on the limit only due to the electronics that control the engine and they run them like this for emission control and run them as lean as they can. Difference is if they stop you pull over.

[LeadSled]

---- but you can buy a pilots licence.yr right,
Can you let me know where, I'll go and buy a couple of spares, just in case I mislay one.

You also cant (sic) buy experience. That can't be right, if I can buy a pilot's license I must be able to buy the experience a license requires.Can't I buy a few experiences at the same place I buy the pilot's license.

Tootle pip!!

PS: The engine over-speed to 2900rpm ---- what sort of engine?? How about a few facts.

[Creampuff]

Gosh, you lot have been having fun, haven’t you.

One of the key contributors to GA safety is that the standard GA piston engine is extraordinarily simple and can be operated and maintained by extraordinarily simple people. It can take quite a lot of counter-productive maintenance by ignorant maintainers, and it can take quite a lot counter-productive handling by ignorant pilots. It can take it for quite a while.

It can have the magnetos inadvertently set at 24 degrees BTDC rather than 22, because the maintainer has always used that mechanical protractor to set them and he don’t need no fangled electronic gadget to get it closer. That engine will run and put out lots of power. And keep running. The 10 or 20 degrees C extra CHT – who cares? It’s below redline on the gauge. You see: that proves mr maintainer’s wisdom right!

It can have the fuel flow out of the engine driven fuel pump set to the lowest rate permissible by the book procedure. The maintainer sets it there ‘cause the book says it’s OK at that setting and he’s gonna save fuel for the owner. That engine will run and put out lots of power. And keep running. The extra and unnecessary CHT at climb power – who cares? It’s still below redline on the gauge. You see: that proves mr maintainer’s wisdom right!

It can have plugs that pass a bench test and comply with manufacturers’ specifications, but don’t work as well as they could, or not at all at some power settings. That engine will run and put out lots of power. And keep running. The unnecessary load on the magnetos and the unavailability of the range of power setting options – who cares? It runs and the maintainer says the plugs are within spec. You see: that proves mr maintainer’s wisdom right!

It can be a CMI engine and set to 25/25 by the pilot in the climb, to ‘keep the engine cool’. That engine will run and put out lots of power. And keep running and climb. The loss of the enrichment function and the move of the PPP towards TDC, and the corresponding increase in CHT, who cares? It’s below red line on the gauge. You see: 25/25 has been proved right!

It can be run at 25 degrees C rich of peak. That engine’s putting out lots of power at that setting. And the maintainer says that lean of peak’s gonna wreck your valves. He knows it’s true, ‘cause he’s been doing this for decades. And the engine keeps on running below red line CHT. You see: 25 degrees C rich of peak has been proved right!

It can have an imbalanced fuel and induction system, such that each cylinder reaches peak EGT at different times. Doesn’t matter! The engine can put out lots of power rich of peak, and the maintainer says that’s the best place to run engine anyway. Lots of lovely lead to lubricate the valves. And the engine keeps on running. You see: that proves engines don’t need balanced fuel and induction systems!

LewC asked the - frankly inane - question: All very interesting but a tad confusing.I suppose it comes down to which of the major protagonists,the Puffster,Jabba or yr right,would you want doing your next 100 hourly?All I can say is, I don’t let people like yr right anywhere near my engines.

I get the timing fairy to set the magnetos to 22 degrees BTDC, using the correct equipment. And the CHTs go down 10 – 20 degrees C in the climb.

I get the fuel flow fairy to set the EDP so that the maximum fuel flow is at the top of book range, so that the CHTs go down further in the climb.

I fit plugs that work properly, as measured by actual performance at a proper range of mixture settings in the air rather than the snake oil of plug manufacturer PR departments or a maintainer’s opinion as to their serviceability.

I don’t set 25/25 in the climb, because I want the fuel enrichment function enabled and I want the PPP as far away from TDC as practicable for the power I need.

I don’t set the EGT to 25 degrees C rich of peak, because I don’t want my engine running at the setting at which it’s getting the hardest flogging I can give it.

I fit injectors, in consultation with real experts, that result in all the cylinders reaching peak EGT at about the same point during the leaning process. And then I run the engine lean of peak when I want to, so that it’s very cool and not wasting fuel.

And, most importantly, I keep my engine as far away as I can from engineers who think that their decades of ignorance somehow validate their opinions.

That’s why I expect my current engine, like the previous one, to go way beyond TBO (if it was manufactured and assembled correctly).

[yr right]

It was IO-540 in an Aztec. Gov failed on take off. About gosh 20 years ago


Cream puff


All I can say is, I don’t let people like yr right anywhere near my engines


34 years ive been doing this. I never had an in flight shut down nor an engine failure. So I must be doing some thing right you would think ?


What I meant about a pilot lic is ive never heard of anyone not being able to get one, has anyone and not just for a medical.

[Mick Stuped]

Yr right, I respect your thought process and I agree with you, re LOP as this is way I was taught to fly years ago and how to manage engines and I thought there were dragons over the lean side of peak EGT edge. You should have seen my hand tremble the first time I went to 50 degrees Lop EGT. I listened to the engine like a teenage boy alone in his room listening for his mum to walk in.

I was first introduced to LOP about 8 years ago when reading a Cessna Pilots article on LOP and I went to a Advanced pilot seminar. I came away like a born again Christian feeling betrayed by past teaching and after doing some sums and reviewing my maintiance costs and trend data with the want to try a different engine management style.

We had two new IO 550 upgrades going in same serial numbers so comparing apples with apples going in two separate aircraft both the same type C210 at the time so also decided to install EDM,s and Gami in both aircraft, run one at 50 Rop and the other 40 Lop. Run both at power settings less than 70%. Pilots were trained in Lop and EDM and how to make sence of EDM info. Data was downloaded from EDM every week and pilots asked to review their own data and discuss with myself and CP. Training is the most important part of engine management. Without giving to much away in a commercial environment I would now after 8 years of Lop operations say all injected aircraft in our fleet are run LOP and if we went back to ROP Ops I feel we wouldn't have a business.

We have had IO-520,IO-550 and TIO-540 all gone TBO without touching a valve,pot and 2000 hour compression tests still all over 70. Boroscope showing very healthy top ends and really if it wasn't for 1800 or 2000 TBO our LAME feels they could have easily do same hours again without overhaul. This is not to say we haven't pulled a jug due to bad compressions in 8 years we have but our fair share however our LAME feels that is more due to bad overhauls in the past and valve seats/guides either not installed correctly or not lapped properly and having uneven wear. And of course we had a lot of cylinders recalled under an AD with cracking between the injector and spark plug. We feel the problems were not caused by LOP operations but by bad repair shops. We got warranty on some of these.

I agree with Jabba that maybe what you are seeing in your shop is the result of bad operators/training and that want to run LOP but are either not running lean enough at maybe higher power settings. Pilots can tell you anything but EDM data never lies. Have you ever checked any data on these fried valves if they had any sort of a EDM?

Oh and the experiment that shifted all our aircraft to LOP.
ROP in 1500 hrs valves lapped due to low compressions 4 times. 4 pots replaced.
Avg CHT 375 - 390 Fuel burn 60 - 65 lts/hr then we went LOP for last 300 hrs.
LOP in 1800 hrs - never touched all good compressions @ TBO
Avg CHT 290 -325 fuel burn 48 - 51 lts per hour.

I fully understand your objection to LOP if I had seen what you have seen and the operator/pilot telling me they were LOP. I felt the same and my LAME did as well for a start when we jumped off the edge, but trend monitoring and EDM data and trial and experiment changed my mind. Data doesn't lie.

You seem to be very intelligent and a very switched on LAME and that's a dying breed. You seem to really care and have a thirst for knowledge, so I urge you if Jabba is running these schools and they are along the same lines that the Americans did a few years ago, to at least go and have a listen, not about LOP, but engine management and the new data that has been archived by being able to measure the ICP and how that proves a lot of what we were taught is as they say OWT.

If you don't know how to get the most out of and interpret EDM data then this alone, could help your bussiness as a good diagnostic tool and an extra service you could offer to you clients. I have heard of a few maintiance orgs now offering this as a part of trend monitoring and engine health checks. Before we changed to fine wire plugs I was picking up weak plugs 50 hours prior to failure.

Just urging you to not wave this all away as mumbo jumbo just go with an open mind see what they are talking about, it seems you have nothing to loose as looks like Jabba has said he will give you your money back if you think it is crap. We are all witness to his offer.

[yr right]

Hi Mick
The difference is you trend your engines. Jo blow average doesn't and that's a big difference. I at the end of the day see burnt valves by people experimenting with it. Then they cry at the cost. The fuel saved will never make up for the cost of the repairs. As I recall Cessna allows it in there POH. I don't think by memory Beech do I will stand corrected on this.


A classic example of trending is the RFDS they get 8000 o/h out of a PT6 due trending when the o.h limit set by Pw is 3600. Things are fixed before they become problems.


Like I said earlier, you should be commended on your approach to your business, I just wish there where more operators like you it would make my life easier. I am open for ideas. Bit hard to do any courses for me I am in the middle of no where.

[LeadSled]

It was IO-540 in an Aztec. Gov failed on take off. About gosh 20 years ago

yr right,
If that engine was seriously damaged by going to 2900 RPM, when the T/O RPM was 2650 or 2700 RPM, there was something else seriously wrong with that engine.
I personally have had a governor control rod drop of on an IO-540, fitted to a 260C Comanche, fast as I pulled the power off and pulled the nose up, it went over 3000 on the tacho. The LAME who looked after the aeroplane, as per the manual, gave it the necessary going over, there was no damage.
Tootle pip!!

[yr right]

Time lead sled time. How long was your over speed. ??????? Also it was a long time ago we brought the two engine ill ask tomo if we still have the log books for it and get the correct figures if we still have it

[Creampuff]

yr right

I’ll list a few of the (many) mistakes I’ve made and some of the (many) misconceptions under which I’ve laboured, during the 30 or so years I’ve been trusting my life to piston engines in aircraft that I operate (at least to the extent that I can remember them).

1. The leaner the mixture the hotter the engine.

2. Lead lubricates valves.

3. The vibration from an engine during the leaning process is ‘lean misfire’ due to very hot exhaust gas temperatures.

4. Setting 2500 RPM / 25 inches manifold pressure in the climb will make the engine cooler than 2700 RPM and wide open throttle (e.g. 28 inches after take off).

5. 25 degrees C rich of peak is a good place to run an engine.

6 to double digits. Innumerable imprudent operational decisions that were fortunately saved by other slices of the swiss cheese not having aligned holes. I think they call this one: Being human.

I’d be interested to know some of the mistakes you’ve made and the misconceptions under which you’ve discovered you were labouring, over your 34 years’ experience as a LAME.

What were the circumstances in which you took a step back and thought: “Hang on sec’, I have this all wrong.”

[Progressive]

Cockney Steve,
I was not going to contribute to this thread any longer since it turned into a P***ing match between Yr Right, Creampuff and Jaba but your accusations that I am on a retainer have forced me to respond.

1) I am not and will never be on a retainer to promote any particular aviation product without declaring it first. I will happily fit spark-plugs of any approved brand. the only company that has ever asked me to promote their product to my customers (tempest oil filters) were refused.

2)I am not supporting one brand of plugs, I am supporting testing Tempest plugs to tempest specs and leaving champion ones alone since champion say the test is not accurate for their plugs PERIOD.

3)I do not support Yr Right's stance on LOP: LOP is not a problem when done by the right people with the right equipment. Unfortunately most of the pilot community do not fit into that field. Thus we teach new pilots to fly ROP and the right ones get motivated and go to Jaba's course to learn LOP.

4)And this is where I do that aussie "Spade is a Spade" thing. Cockney: Your post regarding sparkplugs on cars 40 years ago and the installation of early carbon pile resistors has as much relevance to this debate on testing the resistance of modern aircraft plugs as the you tube video on cats I just watched on the other tab. And your Source "a European aviator online" doesn't stand much credibility especially since failure to start has never been a symptom of high resistance from champion plugs. The most likely source of his fail to start was the high speed of the new starter bypassing the impulse coupling in the magneto - common on 0-200 engines and other small low compression jobs.
If champion really just a bunch of jokers out to sell plugs then they would have been the FIRST to accept a need for resistor testing.

5) Lead Sled: I cannot agree more that this disinformation starts at TAFE and is backed up on the hangar floor. i have dedicated a good part of my career to studying and to be at the top of my trade and am now working part time to put that knowledge back into the education system but there is a long way to go to make it right.

As for your governor over speed with no repairs required: Assuming your engine was rated to 2575 RPM then your LAME is one of those who needs some education: More than 10% overspeed = bulk strip.

http://www.lycoming.com/Portals/0/techpublications/servicebulletins/SB%20369C%20%2804-18-2012%29/Engine%20Inspection%20after%20Overspeed.pdf

I have done a few inspections on overspeeded 540's from robbo's and they are often not pretty inside.

Thats my last two cents.

[Walter Atkinson]

I feel like I've stepped pin the "Way-back Machine" and am reliving the internet conversations from 18 years ago in the US.

Yr Right, you're saying a lot of things that I once said… but, through intensive research have learned were dead wrong. That was a painful experience but a worthwhile one.

Remember, according to Sir Isaac Newton, the physics are everywhere the same…. SO show us some hard data to support your positions. I can show you 2 ½ days of hard data to support the misguided nature of the notions you are presenting. You are making valid observations but assigning improper causality.

So much of what you have posted is simply at odds with the known science that I don't know where to start or have the time or bandwidth to respond.

BTW, I hold the ATP, CFII, MEI and A&P ratings… and, once upon a time I was just as misinformed as you seem to be. Please understand, I do not equate uninformed with ignorant. It has been suggested where you can become informed as to the factual science. It's up to you to follow through.

[Jabawocky]

Progressive, you have written a very common misconception about LOP operations and just what an APS course is designed to teach.

I do not for one minute blame you for this. I do not blame yr right for having some very strong beliefs that are scientifically incorrect. It is the entire system of education that is to blame. So let me explain, which as you would agree can be difficult in just a post on a forum. You will need to trust my information here. I have no reason to add to misleading myths.

LOP is not a problem when done by the right people with the right equipment. Unfortunately most of the pilot community do not fit into that field. Thus we teach new pilots to fly ROP and the right ones get motivated and go to Jaba's course to learn LOP.

Lean of Peak operations have been around since Charles Lindbergh flew over the Atlantic. I do not think there was any AuRacle or JPI gear on board that flight.

I can teach anyone to fly safely LOP in under 5 minutes, more like 2-3 minutes including a briefing and demonstration. Mid 2013 during the Aust Womens Pilots conference in Hervey Bay, I took Kreisha Ballantyne, the editor from Australian Pilot flying over Fraser Island. I asked her to fly, and we departed YHBA climbed to 1500' and head rougly towards Lake Mackenzie. Once at 1500 and already over water, I gave a briefing on how to do it, with her eyes closed (1-2 seconds) she did it. This was all done and dusted before we reached the Island shores. She nailed it first go. Simple as that, even a girl can do it we joked! We did not need or use anything of the EMS, no lean find functions, nothing more than the human sensor pack and a 1-2 minute briefing. She did it so well I said I guarantee you are around 70-80dF LOP, so we used the EMS to prove this by carefully (for accuracy sake not engine concern) sneaking up on peak from the Lean side to find it. BINGO! Spot on she was.

So, who needs the engine monitor and a massive amount of training by comparison you ask? Simply the ROP pilot. Especially at higher power settings. There is no way possible of knowing without instrumentation where to operate on the Rich side of Peak. That is safely at an appropriate level ROP. Without an EMS you can't tell 200dF ROP from 75dF ROP. The reason most engines survive so long with mixture mismanagement on the rich side is because it mostly happens at low enough powers to not do harm. It is wasteful and filthy on internals, but that is another matter.

To understand this point further, let my describe the story of two pilots, two identical say TNIO550 powered Bonanza's. They take their planes to a diligent and hard working LAME like yr right, 100hrly done and the injectors have been out and cleaned. The LOP pilot specifically asked for this not to be done but the LAME was being thorough and ignored this while the ROP pilot did not care. They both had the same piece of thread from a shop rag inadvertently introduced to an injector during reinstallation (not as uncommon as you think).

The ROP pilot jumps in and blasts off home, full rich and away, running happily, for another 100 hours.

The LOP pilot jumps in climbs out, does a BMP or sets LOP in whichever way he normally does and it runs like a hairy goat. Goes full rich, smooth, back to his normal LOP fuel flow, rough as an outback road after a wet season. He returns to the field and says.....you touched my injectors didn't you!! Sheepishly the LAME says yes, I always do at 100hrly's. Why? Well one of them has a partial blockage and sure enough it does. Problem corrected, LOP pilot blasts off home and all is sweet for another 100 hrs.

The ROP pilot is still blissfully unaware that his turbocharged engine is running with one cylinder in mild to medium detonation for the next 100 hours (provided it does not start a preignition event) because that one cylinder is running around 50 - 75dF ROP most days and the rest full rich at about 250dF.

Neither of these two pilots used engine monitors.....but which one needed one the most?

Simple. The ROP pilot did.

Myth busted.

It is not to say we condone this at APS, we believe all engines and pilots deserve a good EMS and the education to understand what it is telling you.

So this brings me to the next myth. One of Jaba's courses as it seems to be known, is actually the EXACT same course as developed by Walter Atkinson, George Braly and John Deakin. Two of whom frequent here.

This class spends very little time indeed teaching you how to run LOP. We actually spend more minutes on teach you to run ROP properly. How is that for a myth busting!! What we do is teach understanding of the combustion process from a data backed scientific approach. This is a few hours worth. We teach the effects on these scientific parameters by the pilot via the three control inputs, and you learn to not only read but understand the data from the Dyno. We then transition you to the typical engine monitor. After that we teach a lot of understanding of the myriad of faults that can be diagnosed in flight. Some life threatening ones and others that will save you a fortune in workshop expenses.

We also teach you the pilot how to communicate all this well with the LAME. We also teach you the LAME how to understand your customers and their data files. The last course in Sydney had at least 3 LAME's in the room. I had emails afterwards saying word for word..."where were you 20 years ago when I needed you". This is a great resource for both pilots and LAME's.

Last of all we teach a lot of critical thinking, so both pilots and LAME's can actually read between the lines and the BS that is printed randomly through many manuals. And yes we use real POH's and it is amazing the looks we get in class :ooh: and :sad: are typical.

This process takes two and a half days and it is intense, several on pprune have done them in the last year, they will most likely confirm this and why it is impossible to convey it all in a few posts on pprune. If we could we would. And contrary to some opinion, we do not do it for profit. We try to keep it from costing us and possibly we don't. We do it because we enjoy sharing the knowledge and nobody else does.

So Myth 2 BUSTED!

I will let my keyboard cool off for a minute and come back to assist yr right with some understanding of things. One thing I and Mr Atkinson, Braly, Deakin and Denyer promise is that if someone is actually willing to learn and shows signs of being determined to learn, despite the strongly held beliefs we were all once taught, we will do our best to share the education. This is not at all about being in pi##ing contests.

[LeadSled]

Time lead sled time. How long was your over speed. ???????yr right,
About five seconds, less than ten seconds, as short as the standard procedure for the failure could reduce the RPM.
The IO-540 is a solid old girl, just look at the RPM/BMEP used on the TSIO versions. The biggest danger in an overspeed is damage to the harmonic balance weights, if they are OK, the likelihood of engine damage is limited, if there is any suggestion of balance weight problems, it is a bulk strip. (The overspeed was as near a makes no difference, 10%)
You should read what Creampuff has to say, and consider it very carefully. What he (and Jaba) is saying is good common sense.
Having "opinions" that are directly contrary to the well established and unchallenged (by knowledgeable persons) facts is not helpful in Aviation.
Tootle pip!!

PS: The ATSB accident report on the Whyalla loss of the Chieftain was one of ATSB's less credible efforts.

[Creampuff]

The ATSB accident report on the Whyalla loss of the Chieftain was one of ATSB's less credible efforts.That’s putting it rather mildly, Leaddie! Mr Deakin’s article, still available on the web, was a little more blunt.

Some of my favourite bits: In December, 2001, the ATSB (Australian Transport Safety Bureau, similar to the U.S.'s NTSB) published one of the worst accident reports I can remember reading.

In my opinion, the ATSB has taken junk science, pure speculation and profound ignorance to levels seldom before seen.
…
The ATSB used a picture from John Schwaner's "Sacramento Sky Ranch" website, and made it one of the central issues of the whole report! The picture can be found at (Link). In the report, the ATSB claims that the swirl pattern on the piston in the picture is a swirl pattern that is characteristic of detonation. This statement by the ATSB is one of those monumental blunders in report writing. It is the kind of blunder one makes when trying desperately to find evidence to support an erroneous pre-conceived notion of how some series of events took place.

The author of the ATSB report seems to have failed entirely to read what John Schwaner (correctly) said in the caption right under the picture! Here it is:

“Swirl markings on top of piston are normal combustion pattern markings. They show how the hemispherical (dome shaped) cylinder head and the induction system swirls the mixture for better mixing and burning. [Emphasis by Deakin.]”

[LeadSled]

That’s putting it rather mildly, Leaddie! Mr Deakin’s article, still available on the web, was a little more blunt.

Creamie,
Too true, I guess a more accurate & technically correct aeronautical description would be "total crap".
But you know me, Mr. Mild personified.
Quite apart from the lack of knowledge of engine operations, the ATSB description of the mechanism of the crankshaft failure was so far removed from engineering reality, as to be beyond a joke.
However, I must say that the misinformation about engine operations did reach the highest levels, with the then Minister, John Anderson, questioning yours truly about "aggressive leaning" as the cause of one failure.
As we have seen in the current Minister's "answer" to the Senate inquiry, such people rely heavily on "the Government appointed air safety experts", it is very difficult to intercept such misinformation.
Tootle pip!!

[Creampuff]

But you know me, Mr. Mild personified.Now that right there’s funny! :)

My shout next beers. :ok:

(Time to change the thread name again? :confused:)

[No Hoper]

Creampuff, it would appear that the myth that lead is an "upper cyl lubricant" was started by snake oil salesmen when lead was removed from super petrol.
The original patent sites anti knock characteristics only.
Yet in 2014 you can still buy replacement upper cylinder lubricant. It is a difficult one to debunk. BTW I run a early ford 302 without UCL

[Creampuff]

Hi NH

Among the many lessons I'm grateful to have learned from the APS guys is the real and only reason for lead in AVGAS: Increased latency.

That 302 of yours is doomed to failure ... after a few decades more of no UCL operation!

Safe (no lead) driving and (low lead) flying!

[LeadSled]

that lead is an "upper cyl lubricant" was started by snake oil salesmen when lead was removed from super petrol.

Folks,
To this day, the literature about avgas from at least two of the "Big Oil" lineup quote exhaust seat hammering and TEL as a lubricant ------ don't shoot the messenger !!
Tootle pip!!

[No Hoper]

Tetraethyl lead was developed by Midgley working for GM, it was one of many compounds tested to prevent the knock.
It was marketed as Ethyl so that lead wasn't mentioned.

As leadsled(Honda GoldWing?) said it morphed into a cure all, preventing valve seat pounding and tuliping of the valve head and lubricating the valves.

As for preignition I would be looking at ignition timing.

[topdrop]

I am enjoying the thread titles. :ok:

[yr right]

Well lets say about leaning out in it most aggressive state. Now this aggressive to the max but proves beyond doubt what happens . As ive stated before as you lean you slower the burn rate is. If you really lean you have the chance to have the burn on overlap the wrong way, That is now the intake is open and the charge ignites the in the manifold. Don't believe me well I suggest that you take a short trip to your local drag strip and watch blowers being lifted of.
Now lead actually acts a lub on the valve seat. Its a seconder action its primary use is raise its octane rating. Low leaded car engines require harden valve seats to stop wear on the seats and valve. Also something from my memory bank that radial engines are different by memory they also use 130 octane fuel that was around back then cant quite remember the exact figures though im sure someone knows it.
The cost of putting additives in any product cost $$$$$ in these days if they don't need them they don't use them.
Work beckons now go see what your science shows me today pmsl

[Dexta]

With regard to TEL as a lubricant/Valve seat wonder-all that has basically been debunked, how is it that Petersen who does the MOGAS STC state that every 75 hours a tank of AVGAS must be run through the engine. Is this because of;
a) Petersen believe in the OWT.
b) Some officious entity made them put it in "Just in case"
c) it provides some other function.
If you need a quote re: the 75 hours, I'll dig up my documentation and post it, otherwise it might be on their website.

Dexta.

[No Hoper]

Dexta, perhaps to lubricate the seals in the fuel system.

Extending the duration of valve overlap as well as cam lift and the speed of the ramp are used to increase VE at high RPM to 100percent and theoretically higher. The effect of this is little vacuum at idle and backfiring and afterfiring one sees in Funnny cars and Top Fuelers

[Creampuff]

Now I get it.

yr right is actually Jabba in disguise, deliberately spruiking every OWT ever invented to whip up interest in APS.

Good one Jabba! :D

Let me guess the next one. Hmmmmm, I know: I should idle stationary on the tarmac for 3 minutes after each flight, to ‘cool’ the turbo?

(The engine monitor data demonstrating that the end of the landing roll after a lovely long descent is the coolest that baby’s gonna get during the flight, and it’s all hotter from there on, is of course irrelevant.)

[No Hoper]

And you all would be keeping those cylinder head temps up during this long glide in?

[Creampuff]

That's the next one, NH: "Shock Cooling" - it's the one and only cause of cylinder and crankcase cracks. :ok:

[Aussie Bob]

Dexta, I hear what you are saying, I too have a Peterson STC. What I want to know (not) is how the lead lasts the 75 hours :rolleyes: between usage.

[No Hoper]

Creampuff, that could be interesting; shock cooling versus engine mismanagement as cause of cylinder and head cracking.

[Avgas172]

well as for who dose the next 100 hourly im a LAME the others im not sure. As for being passed down the line well mmm you cant buy a LAME ticket but you can buy a pilots licence. You also cant buy experience.

Ummm isn't the continental 0300 a six cylinder engine ... It is on my 172 anyway ...
Continental O-300 - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Continental_O-300) :confused:

[Creampuff]

Errrrm, you might want to take a slightly closer look under the hood of your 172, 172

I thought bog standard 172s had a 320, which have 4 cylinders.

Maybe your 172 isn't bog standard, or you engine's been breeding cylinders in the dark. :confused:

[Tankengine]

Now you are showing your ignorance cream puff!
Early 172s are six cylinder, later ones four.:rolleyes:

[Creampuff]

True, as anyone who can read wikipeadia knows.

But how many 172s with O300s are still flying? I realise Australia is a backwater, aviation-wise, but I thought that all surviving examples of the O300 were in the museum.

[Avgas172]

now a Cont 0-300. 100 hp 4 cly and on a good day 2500 rpm. so when you get det in the 308 the cly is roughly half the size of that of the little cont.
Creamy old mate the argument on my part was only about what or was not a Continental 0 300 engine as you no doubt learnt from Wiki I was right, and yes my machine is a H model which comes standard with only a motor as previously described. .... Now back to your corner :ok:

[No Hoper]

Out of the ether they come, or is that the Ethyl? We who know so little of our craft sit in AWE

[cockney steve]

Yr Right, Progressive....Thanks, Gents, but had the cranking-speed inhibited the Impulse-coupling, I'd have said so :\

There seems tobe some ignorance on that score.....So.....
The timing on an Aero-engine is, in technical terms, a compromise.
Retarding, via Impulse is , really a Kludge.....because of low cranking speed, the fixed-timing flame front would develop and cylinder -pressure would rise unacceptably, whilst the piston was still coming up to TDC...the delay introduced by the impulse,starts the burn later in the cycle, thus allowing the main "push " of the combustion to push the piston down the correct side of TDC. A secondary effect is the rapid "flick" to the Mag, giving a much stronger spark.

This particular correspondent had difficulty starting and due to the effect we've all seen....prop momentarily stopping as starter overcomes too-early ignition....(Don't believe me? crank with mags off...youll get it slowing, but no "kickback") So he changed the starter.
AFTER changing -out the faulty plugs, the engine now starts promptly.

The impulse coupling is a red-herring, you only need it because the cranking-speed is so slow that A- the mag doesn't generate a spark, due to the flux break being too slow.
B-cylinder combustion pressure rises too quickly, whilst piston is still BTDC.

To explain my remarks re-timing......
Fixed timing is a compromise, Fortunately, the average piston aero-engine spends most of it's duty-cycle at constant speed....therefore, ignition timing can be optimised for that speed.

Back in the day, cars had a manual advance-retard and a manual mixture control...some also had a hand-throttle. Agood driver used these controls to get the best out of the crude engines of the pre-war cars.

Anyone who has ridden a motorbike with Mag ignition and manual A-R ,knows how this affects Kick-starting, their shins and their ankles :}

The Panther 600 "sloper" single was capable of launching you over the handlebars, if you forgot to retard!

Plugs...I grew up believing the maker's tosh.....massive electrodes were needed 'cos they'd otherwise glow red-hot and cause "pinking" AKA pre-ignition or running-on The design of the ceramic insulator, was to ensure the plug got hot enough to burn off oil and lead deposits, whilst remaining cool enough to not pre-ignite.
Fine-wire plugs defy that logic and give a service-life far in excess of the usual massive-electrode alternatives.

Yes, I'm in agreement with LOP as well. Scientifically, it makes sense....ROP doesn't....It's supporters fail to explain what happens to the "extra" fuel....(hint...It carries on burning after the exhaust valve opens and the piston boots it out of the combustion chamber)
OTOH, the LOP charge has used most of it's energy, pushing the piston down ;)

Gents, thanks for a very interesting and reasonably civilised debate.

[Jabawocky]

Sorry folks I have been unable to sit down to write a response for a few days. Will try to cover the major points as best I can.

From the 6th
As I recall the ATSB said it was pre ignition due to the lead and carbon on the piston head. Lyc rejected this totally. You said that was not overly lean well it must have been. full power full rich.
You said that fuel dosnt have a cooling affect. MMMM so how come when I pull the red knob back the egt cht rise, ?

The ATSB report was full of rubbish. There is no scientific data to prove deposits on the piston can cause preignition, this is an OWT. It comes from only a few sources, the vast majority are spark plugs with failed ceramics, the occasional heli-coil tang protruding into the cylinder, or from a cross firing mag/harness.

The topic of mixture causing detonation was from being a RICH mixture that was not rich enough. It was never a lean mixture. It had been leaned from full rich, that is true, but it is still a rich mixture. This is an important concept that many can't grasp.

I said fuel does not cool, because that is fact. Fuel changes the combustion event, refer to the colourful chart I posted previously. As you can see as you lean the CHT gets hotter, as you expected. However once you pass about 50dF the CHT cools off, as does the valve temperature, despite the EGT still having a little further climbing to do as you lean further, then once you reach peak EGT, CHT is falling already, and then as you lean further EGT drops also.

This is not how you understand things to work, and that is not your fault because you were never taught about anything past the point of 75dF ROP everyone disregarded, and it is a natural assumption that if things get hotter as you lean it is a fair assumption this continues. Wrong assumption, otherwise at ICO the thing would melt down.

Detonation;
Yes there is a very well defined set of criteria for detonation and it's intensity. The FAA have very sophisticated algorithms for determining what is Light, Medium and Heavy Detonation. As I stated previously, I am in the fortunate position of being involved in more detonation testing of aviation gasolines than probably anyone else in Australia. There is far more to this than just it explodes or it burns.

As for the Chieftain those engines live a fair part of their life with a little light detonation and if operated as per the POH, it certainly will at times be doing so.

The static timing on the Chieftain is as you state 20 degrees BTDC. What I said was the ACTUAL spark timing , when the plug actually fires is anywhere up to 13-16 degrees BTDC. I can show you this on the dyno runs during the APS class. It varies a lot. If you set the static timing at 15 degrees, this would result in an actual spark event at maybe 10-11 degrees and this would result in very high EGT(not harmful) and very high TIT (harmful for turbo's), and be very lethargic indeed.

Preignition;
This is an event that has a flame front initiated by some other source before the spark plug is fired. This could be maybe 40+ degrees BTDC, and the result is extremely high peak pressure, and occuring close to or at TDC. This is very destructive. We can show you some data files from real events and it is quite impressive to say the least.

Leaning;
As ive stated before as you lean you slower the burn rate is. As you lean the burn rate speeds up, once you get to about 30-50dF ROP it peaks and starts slowing down as you head towards peak and onto the lean side. The idea that you have a risk of combustion in the intake from an aggressively lean mixture is so far fetched for a 2700RPM or less engine that I think we should move past this, except to say as you have pointed out the difference to auto engines and those in drag cars ....they are clearly different in these areas and hence the risk.

Lead, or more correctly TEL.
ow lead actually acts a lub on the valve seat. Its a seconder action its primary use is raise its octane rating. Low leaded car engines require harden valve seats to stop wear on the seats and valve. Also something from my memory bank that radial engines are different by memory they also use 130 octane fuel that was around back then cant quite remember the exact figures though im sure someone knows it.
Again a topic with which I have a lot of involvement with. TEL does not provide any soft cushioning material to anything. Think about the path of the fuel. In the inlet port, fuel and air is being sucked in, the valve guide is under negative pressure, no fuel is going to help the guide and if it does get there it is a highly effective solvent, not good for lubricating the guide or the seat.

Lets move to the exhaust gasses now after combustion event, the TEL has been converted to the a compound of lead and bromine, this is the deposits you see on the piston, and it is a salt. Salts make crummy lubricants, so they hardly help the valve seat and guide and these are the deposits you get giving some poor leak downs which you try to avoid.

TEL was the only thing to boost octane when the military needed more compression ratio and forced induction in the quest to deliver more bombs further. The 115/145 had higher doses. This was for the big engines with massive HP. It worked well, but those are the same engines that had 750hr TBO, until they were run LOP, and then up to 3600hrs. These were the CW R3350's and similar.

FAA did back to back twin flight testing on some close to avgas spec unleaded fuel Vs Avgas and there was no benefit to the lead.

Dexta, the reason some folk started to think avgas lead content helped was a new OWT called "lead memory". The FAA almost believed it, in fact they did for a while I believe, but the tests that showed correlation were flawed, there was later found to be no such thing. Just because Petersen have an STC does not mean things printed like that are true and correct.

Happy to take questions, and for those who attend in Perth on the 16-18th of May, most if not all your questions will be answered.

Cheers all :ok:


TW: time for a new thread title, perhaps something less silly? ;)

[yr right]

.Steve
Yr Right, Progressive....Thanks, Gents, but had the cranking-speed inhibited the Impulse-coupling, I'd have said so


Do you know how the impulse coupling works.
1st it retards the ignition firing
2nd it introduce at better spark by spinning the mag faster than cranking speed.
Now this is done with smoke and mirrors.
Well actually springs and bob weights
With these geared starters they spin so fast that the impulse cannot do either of it functions. Hence extremely hard to start.
Now someone here going to tell me I don't know what im talking about so be fore you say anything ok I don't no sh^t.


Now someone ask me about data with dead cylinders well for F&*^ sake, I don't have any, but I do and have changed a **** load because of excessive leaning and when you have to change multiple cylinders on a engine gee may be im making that up as well and you can tell when it happen all you have to do is look at the exhaust valve. Its as clear as black and white. Now who here has actually changed a cly that has had that damage.


Next ive used a 10000hp race engine as and extreme example are you all to thick to see that. And by the way the idle speed on a nitro engine is approx. 2000rpm takes nearly 1500hp to drive the blower and produce zero vacuum as it manifold in in positive px up wards of 60psi so when it leans out and the intake valve is open the thing goes bang. extreme but the point im making is the flame front is still burning when it should be all gone.


Next no one has answered one simple question I have raised.
By going over peak how much saving in fuel are you making and hour difference LOP and say 50deg from peak .


Now where in the POH in a PA 31 dose it say you can lean out the engine in full power. to say its was rich enough is crap it failed if it was full rich are you saying it still would have failed and the point here im making is all this is great when it is all going right but when something goes wrong you have reduced your own safety margin. ie lost one engine increase power to full on the other didn't increase mixture to full rich and it also failed. Im not saying before anyone else has a go that he was using LOP as you cant on a positive px engine but on simple action and chances are he would have been alright. Fact remains the aircraft was lost. As for the other things you raised cracked ceramics miss firing harness once again im amused, umm what wasn't picked up in the engine run up. now ive have a lot of experience on this type of airframe and engine, what you have stated is im sorry but fiction. If there is one thing that has to be right its the ignition system other wise the engine will let you know be fore you even left the ground. So Jaba with out being rude you can PM if you wish but actually how much hands on in a shed have you actually had.


Now Aussie bob at no time did I ever mention that it was a 172 or any thing else for that matter. the reason I used a C-300 as it was close to a Holden 308. I could have use a o320 etc. the comparison is the size of the cly to a v8 of roughly the same size and the forces that happen if detonation happens.


Now someone said about cleaning nozzles and how it had a blockage, So whats the first thing in in trouble shooting that partial problem dose any one know ?
Cheers all and by the way im not pi&sed in any way just amused .

[Progressive]

I started formulating this post because the discussion had gotten civilized again but after yr rights last post i'm not so sure....

Cockney Steve,
1) Your friends aircraft had old massive electrode plugs and a low torque starter but presumably worked ok

2) He changed the starter and now it wont start

3) This is the plugs fault?

Anyone with a minimum common sense would see that with a high torque starter the engine will turn faster, the magneto will generate higher voltage and the resistance of the plugs will matter less than it dd before the starter change.

However I have been wrong before so please enlighten me on what difference the new starter made to operation of the plugs if the impulse worked fine.

Jabba,
You are correct is should have said many pilots should not TRY to run lean of peak - successfully running lean of peak is fine and regularly practiced by those who are educated.
It is the pilots have no desire to learn the correct method but who read "lean of peak can save me money" on the net and have a punt at it without any education who do damage. Mostly by being a little to timid with the red knob (due to misconceptions) and ending up just a little on the rich side of peak.

Also check ur PM's

[gerry111]

Goodness.. This is all becoming rather confusing for me.

Is 'yr right' perhaps one of the LAME's that maintained the Whyalla Chieftain?

On big oil company marketing: Who remembers the 1970's AMOCO adverts for their "Final Filter"? Or the supposed benefits of Shell's super grade petrol with Methyl Benzene? :eek:

[LeadSled]

It was marketed as Ethyl so that lead wasn't mentioned.
Folks,
I think what is being referred to here as "Ethyl" was a brand of motor fuel which was a brand of Standard Oil of New Jersey, originally.
In Australia, a brand of petrol called Ethyl was sold by the old Vacuum Oil Company -- the trademark was a flying gargoyl, I have an old original baked enamel garage sign as proof.
Tootle pip!!

[tail wheel]

In Australia, a brand of petrol called Ethyl was sold by the old Vacuum Oil Company

Goodness me Leadie, you are old!! Welcome to the Geriatrics Club! :}

Do you also remember Plume, Golden Fleece, Texaco, Ampol, Marfak lubricants and Red-X upper cylinder lube? :ok:

When a Chippie was £4/10/- per hour dual, I earned ten bob on Saturday morning and ten bob on Sunday morning, pumping petrol the old fashioned way.

Time to change the thread title I think???

[Creampuff]

Now someone ask me about data with dead cylinders well for F&*^ sake, I don't have any, but I do and have changed a **** load because of excessive leaning and when you have to change multiple cylinders on a engine gee may be im making that up as well and you can tell when it happen all you have to do is look at the exhaust valve. Its as clear as black and white. Now who here has actually changed a cly that has had that damage.But it’s only your wild *ssed guess as to what caused the damage.

Because you believe there is such a thing as “excessive leaning”, you attribute every problem to it.

There is no such thing as excessive leaning (except at the point where combustion stops but you need power …).

There are rich mixtures that aren’t rich enough, and there are lean mixtures that aren’t lean enough.

I know an aircraft that has a POH that says the ‘best power’ setting is 25 degrees C ROP. It has a CMI engine. The guys who fly it take off, set 25/25 and climb at best rate of climb speed to cruise altitude. That engine will almost certainly have valve and other failures way before TBO. (But it’s being operated ROP, so I suppose the 'cause' will have to be attributed to something else.)

By going over peak how much saving in fuel are you making and hour difference LOP and say 50deg from peak .About an engine’s worth, over the ‘book’ TBO of an engine.

At cruise power at altitude the difference between being rich enough ROP and LOP enough on the engine I usually fly is around 8 litres per hour (my fuel flow monitor is calibrated and validated to an accuracy of about 0.1 litre per 300). That’s about $20 per hour. That’s about $40,000 over 2,000 hours. (Of course it’s not quite that simple, because a substantial number of those hours are at climb power and much higher fuel flows. I’d expect to save at least $25,000.)

And BTW, the engine will likely last a lot longer, because it isn’t being run in cruise at the setting at which it will be getting the hardest flogging it can be given (ie around 50deg F ROP). Have a look at where ICP peaks on the graphs Jabba posted.

[aldee]

Have a look at where ICP peaks on the graphs Jabba posted.

Or take a look at the FREE APS online seminar taster & then do as I did, pay the $395 for some data based education

Shame Perth is so far from Christchurch :(

[No Hoper]

It would appear that basic facts about what causes higher than normal operating temps are being massaged to suit particular view
The following are some causes
1. Ignition timing advanced
2. Lean mixture during sustained running
3. Cam timing dialed incorrectly
4. Hole in intake manifold - lean mixture
5. Engine baffling broken/US

your turn. Facts,just the facts

[yr right]

So ok I've got it all wrong and that's just not me. So recently we had to change 6 cly on 210 where the operator was experimenting with lop. Fuel flow px where check on cal gauges as per m/m. Mags check no further defect where found but we still has 6 dead cly. May be my imagination. Any way operator was ok about it. Yo see wasn't his areoane he just operated the owner had to put the bill for the cly and that with the aircraft out of service we'll mmmm $$$$$$. We used to do top o/h here and then get an extension on engine tbo but casa stop that. One place I worked had a system of maintenance that gave an enormous life extension to there tsio 540s with tops done same as hazeltons airlines. Now with all of this have a look what's in front of you. The weakest part is the exhaust valve. M/M states nil leakage past the valve on a leak rate test. Now if I'm wrong what causes 6 cly to all be u/s at the same time. Maybe I should give it all away and do some thing else.
Now still anyone tell me what the first indication is of a blocked injector is.

[Creampuff]

No Hoper

I think your ‘2’ should be: Mixture not rich enough, ROP, or not lean enough LOP. 4 should be amended accordingly.

Re your 3: How many standard piston aero engines have cams that you can ‘dial’?

5: Partially blocked injectors (resulting in a ROP mixture that’s not rich enough. Really a subset of 2.

6: Fuel enrichment function disabled during climb (throttle should be set to ‘full’ on engines with FCUs with this feature.

7: RPM reduced at high powers (moving PPP close to TDC).

[Jabawocky]

yr right

Depending on which Chieftain POH you read, the climb power is 38-40", 2400 RPM, TIT of 1500 and fuel flows between 27USG-30USG per hour.

Well it might surprise you but I have just run the live data recoding of exactly that scenario, just to recollect my facts. FACTS that is, not WAG's.

Now lets look at Full Rich, 42" 2600, about 40-41GPH and Internal Cylinder Pressure (ICP) = around 800-900 PSI.

40"/2400 and Full Rich = 36GPH and 750-800 PSI.

Climb power as per the Piper POH as noted above = a whopping 100-1100 PSI and that is with a nicely cooled (forced) engine. Imagine that in a sub-optimal installation.

ICP's that high are not good for the engine. No matter who makes it. By the way I noted the Detonation Index for cylinders 2,3,4&5 were all triggering the mild detonation level and at times were medium. This was at 28USGPH, imagine it getting worse at 27 GPH or mishandled and even worse again.

This is the effect of RICH mixtures that are not Rich enough.

To answer your question on diagnosing a partial injector blockage, assuming the engine was a "Conforming Engine" to begin with it is real easy, use the EMS, do a mixture sweep and it will show up. In fact do a BMP and you will know straight away. Did you read my post about who needs an EMS most? The answer lies within. Please read it.

If you are going to suggest the old coke bottle check, please explain how that is going help. If you did that with my injector set, and were accurate enough to get a good catch, the volumes would be all different, and by a noticeable amount. Now the question would be which is blocked? The one with the lowest amount? Or the one with the fullest amount?

It could easily be the fullest, because if it were partially blocked it would flow even more compared to the others when clean. So what does the old coke bottle test prove? Absolutely Nothing.

A coke bottle test is useful in testing the lines with the injectors removed. Not with them installed.

How about going back and answering some of the questions I asked. They were not hard.

Lastly, I have spent a fair amount of time in some pretty sophisticated sheds, but not doing the same tasks week after week. So my hours of hands on the tools will come nowhere near yours, I guarantee that. However this in no way discredits the validity of the data. Do not believe me, believe the data. I do not see the value in trying to discredit me. I am not doing that to you, however the presentation of scientific data is going to be rather challenging to those who have grown up on a diet of misinformation and OWT's. You are not alone there, I was also, we all were. In fact it is still being taught. You have to answer exams wrong in order to be marked correct.

[yr right]

No in no way did I or have I worked or did work or have any thing in anyway way do to with that org. How many chieftain flying here in aust. How many accidents is there with that machine. It's been a great work house and still can and will be for years to come if it's looked after. Look I see the results on the hanger floor. As I've said I'm happy to change out your dead cly.
Now some one said hole in the intake cause in leaning ok what's the autism of that when troubleshooting. Next cam timing. We'll tats set up from o/h next mag timing we'll you check that at a service and if you have a problem you look else where.
Baffles mmm also checked at a service.
And you say lean mixture we'll f me you saying that but you saying it's not or are you saying it is I'm not sure.
Anyway I'm off to check science again today.
Cheers

[Jabawocky]

no hoper
It would appear that basic facts about what causes higher than normal operating temps are being massaged to suit particular view
The following are some causes
1. Ignition timing advanced
2. Lean mixture during sustained running
3. Cam timing dialed incorrectly
4. Hole in intake manifold - lean mixture
5. Engine baffling broken/US


Which operating temps are you referring too? :E The most important is CHT.

1. Will cause LOWER EGT and higher CHT.
2. Lean Mixture will result in lower CHT. A Rich mixture that is not rich enough causes higher CHT. (refer the graph a few pages back.
3. Where did we get that one from? Might be lucky to run at all :uhoh:
4. Intake leaks will cause higher CHT when operating ROP, this is again a RICH mixture but not rich enough. Those without an EMS or able to understand it will fly like this for hundreds of hours and never know. A LOP pilot will find it straight away and wonder why his plane runs rough when normally it is smooth. So to say a lean mixture with an induction leak will cause high CHT's is FALSE as it will run VERY cool indeed, if it is truly a lean mixture.
5. "Baffling baffles" if any of you have had recent AOPA Australian Pilot or SAAA Airsport magazines you would have seen an article of Baffles by two fellows, David Brown and Walter Atkinson. A good read indeed :ok:

Cheers. :ok:

[yr right]

Jaba
I'm not in any way trying to dis credit you or anyone on this forum. I'll put that straight right away.
Now for a blocked injector now remember what every injectoted engine is a quip ed with. It's called a fuel flow gauge. You don't need a fancy trended monitor or any thing. All you need is your fuel flow. Now I've said that what is resulting indication of a blocked injector.
Now sorry but you can all the simulation in the world on a computer but the information out is only as good as what is put in the first place.
Cheers

[yr right]

Jaba ok you given fuel flows etc for that engine. Fact remains if the pilot had of applied full rich would the engine failed.
Cheers

[VH-XXX]

I should have a read of that thanks Jabba. I have been baffled by baffles for the past month or so, sorting out my CHT's.

[OZBUSDRIVER]

Jaba, back on page 6, you expounded running LOP just using your ear for setup. Agree that Lindi didn't have the gear and no doubt you were using your gear already equipped with everything. Are you saying that even in non equipped carbie engines you can safely set up LOP? Airflows and uneven mixtures to individual pots with no idea of temps has me wondering.

[Walter Atkinson]

***Are you saying that even in non equipped carbie engines you can safely set up LOP? Airflows and uneven mixtures to individual pots with no idea of temps has me wondering.***

Yes.

IF, you understand the five landmark graphs. If you do not have a very clear understanding of them it will be a serious challenge.

I've done it many, many times.

As for how to tell if an injector is partially clogged, it is impossible to be certain by FF alone. If one has an EMS it is easy. What is the result? That depends on how blocked it is.

What I am observing is the classic example of someone having a lot of experience with only the rich side of the landmarks chart. Their understanding is limited. That is understandable, but there is no one so blind as one who will not see. There is a complete "other half" of the chart that one should become acquainted with to be able to have this conversation in an enlightened manner.

So, Ye, Right, are you willing to become familiar with that "other half" of the data? It could change your business for the better.

[No Hoper]

3. Dialing in of the cam is a technical term that refers to the positioning of the cam lobe in relation to crank angle and or piston position.
In essence the fitting of the camshaft IAW the approved data is dialing in. Yes a dial gauge and protractor are used.


Continental engine, after instrument check and harness check, d
Fuel flow check and ensuring baffles etc were in good order, DDI check revealed about three tooth out.
Signs of a problem are not a symptom.

Jaba,
I have concerns for your wellbeing should this anecdotal LAME, he that cannot ensure a nozzle is clear before fitment, is infact working on you flying machine.
BTW altering the cam timing to change the coming in speed is common practice in racing cars and can be different for each track surface. Although that is a low tech industry when compared to Aero Engines mmmmm

[Aerozepplin]

(Regarding carby engines)
Now, those in the know can correct me if I’m wrong, but when operating a carbureted engine the standard leaning technique will resultin at least some cylinders operating LOP.

The old “lean till rough then enrich till smooth” is because one or more cylinders have fallen off the HP curve. Enrichening the mixture pulls them back in line with the other cylinders, with the leanest at around 50 degrees LOP I would imagine. This means that likely some will be LOP, some around peak, and some ROP. So there you go, we’ve all been operating carbureted engines LOP, the only difference from Deakin, Jabba, etc, is that we’re only operating part of our engine LOP!

When I show my students how to lean I first check the RPMwill produce a sensible power setting at “best power” (say 65%), because the worst case cylinder would be at 50 degrees rich, or “best power”. By ensuring that cylinder is at 65% (the restwill be less, being either richer or leaner) I can be confident it will not be operating at a high CHT/ICP.

Can any knowledgeable folk offer feedback? After all, I’m the most dangerous person inaviation: I know a little bit, and teach other people using that little bit.

[yr right]

Ok. We'll for them that don't know the fuel flow gauge is a pus sure gauge calibrated in flow. A blocked nozzle will indicate a higher full flow as it is a direct measurement of the fuel px. Basic engine 101
Cheers

[Walter Atkinson]

What you say about carby engines is correct if the F:A ratios are not balanced. Once they are balanced (by a knowledgeable operator using carb heat appropriately) the engine can be run quite successfully with all cylinders at the same F:A ratio and, therefore, all ROP or LOP with smooth operation.

There are many carbed engine operators doing just that.

It is important to realize that the problem is NOT one of air imbalance to the cylinders, but of inadequate fuel vaporization early in the induction system to deliver the same F:A ratios to all cylinders.

[Walter Atkinson]

**Ok. We'll for them that don't know the fuel flow gauge is a pus sure gauge calibrated in flow. A blocked nozzle will indicate a higher full flow as it is a direct measurement of the fuel px. Basic engine 101
Cheers**

Not in all cases, or in a degree discernible to the pilot. That is an over-simplification and is erroneous. Many FF gauges are not simply pressure gauges.

I'm finding that one can only be certain about that which is insufficiently understood. Advanced engine 201.

[yr right]

I give up I'm a dumb f$&@. Pilots know more than I.
Cheers

[No Hoper]

Walter that has to be a windup.

[Creampuff]

I give up I'm a dumb f$&@. Don’t give up: Intelligence has very little to do with it. It’s mostly to do with knowledge.Pilots know more than I. Not true. Many pilots are as misinformed as many engineers.Walter that has to be a windup. No it doesn’t.

[No Hoper]

Creampuff,Yes it is,
yr right would know the different methods of the measurement of fuel flow.
High indicated fuel flow in the system yr right refered,This is a sign that you may have a blockage What sent you looking may have been missed matched flows on twin engine installation or inflight issues with high CHT or EGT.
It is a troubleshooting tool and could well indicate some other issue. You pilots need to stop being knobs

[Jabawocky]

Jaba,
I have concerns for your wellbeing should this anecdotal LAME, he that cannot ensure a nozzle is clear before fitment, is infact working on you flying machine.

I have concerns for a lot of folk and LAME's as this is not common, but it is not uncommon.

Very few LAME's are allowed to touch my engine. I can only think of two people besides myself that do. Mr David Paynter (Brisbane Aero) and Andrew Denyer (Riverina), and not that he has but I am sure happy enough with Garth at Bilyara and a few other LAME's off the top of my head, Steve Hobson, Ben Bowden, Tony Brand. There ya go scattered around the country and all :ok:

yr right
Ok. We'll for them that don't know the fuel flow gauge is a pus sure gauge calibrated in flow. A blocked nozzle will indicate a higher full flow as it is a direct measurement of the fuel px. Basic engine 101
Well that is Basic engine 55, as its only 50% correct. This is true for TCM engines, but I can assure you the fuel flow on my Lycoming 540 does not read pressure, and nor will the fuel pressure indicate a partially blocked injector.

If you would just drop the chip on shoulder attitude you could learn a vast amount from guys like Walter. Besides being a highly experienced pilot, Dr, Dentist, (almost vet), he is a CFI and an A&P, has participated in many STC projects including cooling systems and baffles for various aircraft and that is just the tip of the ice berg. If I go on it will look embarrassing for the rest of us.

I have no doubt you are a passionate hands on spanner man, but there are numerous knowledge and understaning gaps appearing the more we converse on this thread. I have offered to help in this regard, you can choose to fight the laws of physics, or take the opportunity to learn why we all, me included were taught so many things that are simply not true.

"It is not what you don't know that hurts you. It is what you know that isn't so! "

PS: You did ask, I have spent the last 4 days hands on getting my hands dirty (aviation not gardening). So are you going to have a go at answering any of the questions I asked you?

[yr right]

Jaba.
I for a start don't have any chip on my shoulder. I can assure you of that. Now unless you have change your system on your aircraft the basic bndix ESA fuel injection also uses px then calibrated into fuel flow. Now I really don't care what people won't to do with there own engines I've said that before. How ever when they broke I fix them simple really. You also have not answered one simple question that I ask you. If the wayalla accident if the engine was placed into full rich would it have failed.
Sorry been doing this on my phone when I get a chance to go back I'll relo ok at what you have said.
And by the way most of the people you spoke of I also know.
Cheers
Sience awaits me.

[yr right]

Oh btw the world is flat elvis is still alive and labour is good for the economy

[Creampuff]

Aerozepplin

Your level of knowledge is as little as mine (very low), but vastly higher than many others.

The ‘traditional’ method of leaning a basic carby’d piston aero engine demonstrates why the received wisdom is mostly nonsense.

As you know, the traditional method is to lean until the engine runs ‘rough’, and then enrich to remove the roughness.

The traditional explanation for the roughness is ‘lean misfire’: The mixture is apparently so lean that it’s very hot and causing all sorts of engine problems (including all that piston damage that yr right has to deal with). Enriching the mixture removes the ‘roughness’ and restores the engine ‘safely’ to rich of peak.

In fact, the ‘roughness’ is caused by an imbalance in the fuel/air ratios being delivered to each cylinder, resulting in each cylinder ‘giving up’ (being so lean as to cease supporting combustion) at different times during the leaning process. If there are imbalances in the fuel/air ratios being delivered to each cylinder, each cylinder will put out different power at the same place on the ‘lean curve’ and sooner or later one of the 4 or 6 cylinders will stop delivering power completely during the leaning process, and the engine will feel ‘rough’. The ‘roughness’ is actually vibration due to the imbalance caused by one or more cylinders not contributing any power.

Now the hilarious bit is that it’s possible that the point at which that ‘roughness’ occurs is when all the pistons are over on the lean side of peak and, further, that all the pistons are still on the lean side of peak when the mixture is enriched to remove the ‘roughness’. (Although that would be unusual, given the design of standard carby’d piston aero engines. That is why the folks with the real experience advocate the application of some carby heat to even up the fuel/air ratios being delivered to each cylinder.) Where each cylinder happens to be on the lean curve when ‘smoothness’ is restored is anyone’s guess.

Nonetheless, the pilot will be able to look yr right in the eye and say: “I always run it rich of peak”.

Hi No Hoper

If I’m a knob for preferring to heed Mr Atkinson’s advice, roll me in lead oxybromide and call me ‘Nobby’!

The best engine troubleshooting tool is an engine monitor and knowing how to interpret what it’s displaying. If I want to know what an engine monitor is telling me, I’ll listen to and learn from Mr Atkinson and his colleagues, thanks very much. After all, it’s no skin off your or yr right’s nose. If Mr Atkinson and his colleagues are selling snake oil, some lucky engineer will make money out of fixing my prematurely failed engine.

(BTW: I should declare that have no direct or indirect pecuniary interest in any brand engine monitor, any brand engine, any brand spark plug, the Advanced Pilot Seminars or any other course. My main interest is in staying alive, which always depends on me treating my engine with tender loving care.)

[tail wheel]

If you think Mr David Paynter (Brisbane Aero) is good, his father Max Paynter was a genius!

[Jabawocky]

yr right

No I have not changed the RSA fuel servo from Precision at all. The engine driven pump provides a pressure, and it can vary from about 19PSI in flight to about 27 PSI with the boost pump on, but the flow rate will not change. A CMI(TCM) uses the pump (RPM dependent) to provide a pressure and the faster it goes the more it delivers. They are two different ways of delivering fuel. The Beech gauge is exactly what you describe, a pressure gauge and they are pretty crappy at that.

So, I am sorry I missed one of your questions, my apologies, I have been a bit busy myself. The Left engine was going to fail it was just a matter of when. The defect in the crank had less to do with mixture control as it did with magneto timing. Mind you the mixture management of the company combined with the advanced spark from mistimed magneto's will have made things worse.

The second engine had it been run full rich, when called for yes the preignition event would have been snuffed out, but without an engine monitor and knowing what to look for the pilot would have had no clue there was a preignition event happening. Heck we have data files of folk who have had engine monitors and recorded the whole sequence of events and still let it happen.

So the Whyalla RH engine would not have failed had it been routinely run RICH ENOUGH, and if during that flight it was run RICH ENOUGH also.

Of course had they operated these engines at 32-34" /2300 and 80dF LOP they would never have had any detonation to damage the plug ceramics. Had they run full rich in the climb instead of skimping (not rich enough) the same would apply.


Now...have I missed any more of your questions?

Will you have a crack at all mine? Do I need to re-list them? I can email you a bunch to have a go at just for fun. Or have a go yourself free of charge Advanced Pilot (http://www.advancedpilot.com/freesignup.php)

I nominate three of the folk you know, give all three of these a call, Ben Bowden, David Paynter and Andrew Denyer. You have my name and details, after you call them and checked out my story, and the course value, drop me an email, I expect you will want to book in. ;)

[Jabawocky]

If I’m a knob for preferring to heed Mr Atkinson’s advice, roll me in lead oxybromide and call me ‘Nobby’!

That is POTY material right there! :D:}

[yr right]

Sorry Jaba you are in correct. The fuel pump has nothing to do with fuel flow in either tcm or bedix system. The fuel pumps supply fuel to the fcu. That is there only function. They do not in either system control any fuel flow to the engine. True both are different I. The way they supply fuel to the engine. But both can and do use a px gauge calibrated in fuel flow to show it's reading. Now they pick this up in different positions as we'll. tcm from the spider and bedix off the fcu.

Now had the engine been placed into full rich it would not have failed period. Start at the right move red one first to full then the blue to full and then increase the power lever forward as required to say that he did have a meter to know what's happening is just &@"/'$28. The engine was lean as and it self destructed it was not in any other mode than that. Now I u stand what px the pilot was under and now this leads to my next point. When it's all going good it's all good. When the **** hits the fan and it goes pear shape it happens so fast. You don't have a chance to look if you in a single pilot operation.

[Jabawocky]

Posting from your phone is not helping convey your story. I am not sure what you were trying to say here. :confused:

[scavenger]

Serious question: why doesn't whoever writes the POHs advocate LOP?

Second, if I attend the course and install engine monitors, do they come with an AFM supplement or similar that would make it legal to operate LOP in defiance of the stated procedures (CAR 138).

Cheers

[Agrajag]

To add to the wealth of evidence here, which some seem reluctant to acknowledge:

I spent many years away from flying piston engines. When I returned to it, I made it my business to learn all I could, much of which had changed in my absence. Some of it came as a surprise, but a lot of curiosity and an open mind satisfied me that it had merit.

The engine on our single is Bendix fuel injected. It has a fuel pressure sender, which measures pressure, as well as a fuel flow sender, which measures flow. Yes, I know my fuel flow, and no, it's not just pressure expressed differently. The flow meter has been calibrated to be extremely accurate, so if it departs from its normal range we will notice very quickly.

The flow isn't tied directly to pressure, because the pump supplies more than the engine needs. Our fuel pressure goes up significantly when the boost pump is switched on, and so does the flow... briefly. Then the fuel servo adjusts to the new pressure, and the flow goes right back to where it was.

I can, and have, diagnosed a partially blocked injector by means of the engine monitor and the flow gauge. It was obvious which injector was at fault, and the proof was in the contamination later removed from it. Without the monitor, and the training in interpreting it, there would only have been unexplained rough running.

A carbed engine can be run successfully LOP, because I've since done that too. It ran smooth and cool.

Now, I know I'm just a dumb pilot, so I was probably just imagining all the above. But, funny thing, this extended hallucination sure did fit very well with the theory I'd recently been taught.

Isn't learning fun!

[yr right]

Scavenger
Simple answer is they don't won't you to do it. It leaves them wide open to being sued if something goes wrong.
And I would think the engine monitor will not allow you to lop. To do it legally you will have to have an stc to cover you if it's not in the poh. The aircraft manufacture states what parrameters that the engine is to be run to and not the engine manufacture. Same goes for the maintenance of the engine. It is the airframe manufacturer that take pressidence over the engine manufacturer. Ie they set fuel flows rpm prop angles etc etc.

[yr right]

The engine on our single is Bendix fuel injected. It has a fuel pressure sender, which measures pressure, as well as a fuel flow sender, which measures flow. Yes, I know my fuel flow, and no, it's not just pressure expressed differently. The flow meter has been calibrated to be extremely accurate, so if it departs from its normal range we will notice very quickly.

The flow isn't tied directly to pressure, because the pump supplies more than the engine needs. Our fuel pressure goes up significantly when the boost pump is switched on, and so does the flow... briefly. Then the fuel servo adjusts to the new pressure, and the flow goes right back to where it was.


Sorry but do you know what you are talking about at all. Two different things
! fuel px is as it says, it measures pump px pre fcu. It leys you know if you have a edfp failure and allows you to turn your electric boost pump on which is required by certification to be able to run your engine to max power.


Now next.
The fuel flow is a px measuring gauge calibrated in fuel flow it is taken from the fcu. it is not part of the fuel px sysyem. it measures flow via px to the fuel nozzles. this is the same for both types of systems. now you also may have a digital flow vane which measures in units and not px but you will have the first system as it is mechanical and requires no power.


Now when you hit the boost pump this places more fuel to the fcu the fcu limits and bypasses the excess fuel. thus recreating the fuel balance to the engines requirements.


So may be you can explain how the Bendix RSA fuel servo and metering system works please.

[Agrajag]

The engine on our single is Bendix fuel injected. It has a fuel pressure sender, which measures pressure, as well as a fuel flow sender, which measures flow. Yes, I know my fuel flow, and no, it's not just pressure expressed differently. The flow meter has been calibrated to be extremely accurate, so if it departs from its normal range we will notice very quickly.

The flow isn't tied directly to pressure, because the pump supplies more than the engine needs. Our fuel pressure goes up significantly when the boost pump is switched on, and so does the flow... briefly. Then the fuel servo adjusts to the new pressure, and the flow goes right back to where it was.


Sorry but do you know what you are talking about at all. Two different things
! fuel px is as it says, it measures pump px pre fcu. It leys you know if you have a edfp failure and allows you to turn your electric boost pump on which is required by certification to be able to run your engine to max power.I would also know of an EDP failure by the sudden silence! To protect against that, during critical phases of flight (such as takeoff and landing), the boost pump is switched on. And lo, the fuel pressure rises, the flow also briefly rises, and then returns to its original value. The behaviour is the same from idle to takeoff power.

This isn't theory. It's what actually happens in our aircraft... unless the gauges are participating in the same elaborate hoax.

Now next.
The fuel flow is a px measuring gauge calibrated in fuel flow it is taken from the fcu. it is not part of the fuel px sysyem. it measures flow via px to the fuel nozzles. this is the same for both types of systems. now you also may have a digital flow vane which measures in units and not px but you will have the first system as it is mechanical and requires no power.


Now when you hit the boost pump this places more fuel to the fcu the fcu limits and bypasses the excess fuel. thus recreating the fuel balance to the engines requirements.We do indeed have a fuel pressure gauge. Like the flow gauge, it's electric. Or did I merely imagine connecting the wires from it to the sender when I installed it?

Now, of course, I'm going to have to go back to the fuel system and remove the flow sender from its inline position before the FCU, where it measures nothing but flow through it, and tee it into the line from the flow divider along with the separate pressure sender. That will make it measure pressure all right, as flow sensors clearly should. :ugh:

And we must have forgotten to install the return line too. Damn, I wonder where all that bypassed fuel has gone. But since our engine isn't a Continental, I'm fairly sure we got it right. And, also because it's not a Continental, the boost pump can be run at full pace as a backup without flooding the engine into spluttering submission.

I think Jaba pointed out that not all injection systems are the same. I won't presume to expound on how all of them work. But I do know a bit about ours...

[gassed budgie]

Serious question: why doesn't whoever writes the POHs advocate LOP?

IIRC, Piper used to (and perhaps still does) advocate operating some of their products LOP. I'm fairly certain that in the '83 and later Warriors you could set the engine power using just the mixture knob.

The drill was to set full throttle and full mixture then lean the mixture, reducing the RPM to the desired power setting. They covered their arses to a certain extent by suggesting that if you ran LOP above 75% for extended periods, you might damage the engine. Other than that, running LOP was fine. Evidently the O-320-D3G (I think) has quite an even mixture distribution to all cylinders, allowing for a smooth ride LOP.

So there you go yr right and others. A major GA manufacturer from over thirty years ago more than happy for people out there to operate LOP, well and truly way before it became fashionable to question decades of engine management folklore.

[gerry111]

yr right, Thank you so much for now not posting via your mobile phone.:)

(Very good advice, ONYA Jaba). :)

You are now so much easier to understand. If you care to re read some of your earlier postings on this thread, you'll possibly see what I mean... :ok:

Surely we should all be good friends in our rather small Australian GA world? Pilots and LAMEs. And we sure all mean well and want to have all our aircraft fly safely? So it may be a good idea for all of us keep open minds when we hear of credible information that challenges what we were all once taught.

(A confession: I'm also a convert to the APS LOP).

[Aussie Bob]

Here is how I get my carburetor O-360 to run lean of peak at low level.

1. Set 23 MAP 2300 RPM or thereabouts
2. Apply full carby heat (there is no useable partial setting on my plane)
3. Pull out the mixture control about 75 mm and wait for EGT to stabilise
4. Pull out mixture control until all cylinders are LOP. This takes miniscule adjustments
5. When all cylinders are LOP, push the throttle to full open.
6. Make miniscule mixture and RPM adjustments till lean "stumble" disappears (if present)

Given that I seldom fly very high this can result in the following:

27 - 28" MAP, 2300 - 2400 RPM, fuel flow around 28 - 30 LPH and cylinder head temperatures in the low 300's. Once upon a time I considered CHT of 350 good. LOP way improves this.

This gives me a cruise speed equivalent to a "normal" setting of 23 MAP 2400 RPM and 34 LPH so I am saving around 4 litres per hour or more with no trade off in speed. 4 litres is nearly 10 bucks. About $1000 per annum if I do 100 hours between annual inspections. This goes a long way towards the cost of an annual!

For this to happen I needed an engine analyzer and the confidence gained from an Advanced Pilot Course.

Does the POH allow this? Good question, my POH refers engine operations directly the the Lycoming engine book and these settings do not seem to be prohibited but it is a difficult book to read. Truth be known I don't really care, this is not a charter aircraft and 99% of the time its just me, or me and Mrs Bob on board.

[Creampuff]

Serious question: why doesn't whoever writes the POHs advocate LOP?

Second, if I attend the course and install engine monitors, do they come with an AFM supplement or similar that would make it legal to operate LOP in defiance of the stated procedures (CAR 138).

CheersHi scavenger

Some POHs do include LOP power settings. But let’s assume none do and the effect of CAR 138 and all POHs is that LOP operations are illegal and your gonna’ go to gaol if you’re caught running LOP.

An engine monitor will tell you lots of useful information when the engine is running ROP. It will tell you what plug is fouled. It will tell you what injector is partially or completely blocked. It will tell you what exhaust valve is sticking. It will tell you whether all cylinders are at a comfortable margin below red line during the climb (rather than just the cylinder that happens to drive the single sensor that drives the steam driven CHT gauge). It will tell you if a cylinder is suffering pre-ignition and you may have sufficient time to take action to save your engine and your aircraft.

Most importantly for those who don’t want run at settings that dare not speak it’s name, you’ll know that all your cylinders are actually ROP, and far enough ROP that you are not beating your engine to death. (That’s what cracks me up about all the LOP disaster and illegal brigade. Many of them are probably already operating LOP, or at least with some of their cylinders operating LOP, while being blissfully ignorant of the fact. Most of the damage that yr right sees is due to not running the engine far enough ROP, or bad manufacture or bad fitment.)

In short: An engine monitor will assist you to operate safely ROP, and demonstrate to you, with actual real-life data why, for example, it’s really, really silly to run an engine at 25 degrees C ROP, and it’s really, really silly to set 25/25 in the climb on a standard CMI engine. It will also assist you to diagnose faults and save you lots of time and stress. Compare: “The lower plug on 3 is fouled”, with “The engine ran rough on left mag”.

And, if you have an engine monitor and a fuel/induction system that result in balanced F/A being delivered to each cylinder, one day, while you’re at 8,500’ and mum and CASA aren’t around, you can grab that red knob and pull it while ogling those EGT bars. (The APS guys will even teach you how to do it with your eyes closed!) And watch the CHTs go down on you ...

[yr right]

it doesn't matter if it cont or bendix both do the same job. fuel px is measured post pump and pre fcu. wf is measured post fcu. it can be measure as px and conveverted as I've said to read wf or you can have a vane or spool type that measures flow pre spider and post fcu and it must have a in and a out, if it doesn't have that its measuring px.


Perhaps you wont explain because you don't know ? but do enlighten me how then it measures its fuel air ratio to provide the correct settings.


Now yesterday I worked on 3 different engines including turbine types and one airframe and gave advise on one other airframe. Now its impossible for me to know each individual aeroplane that you all have but the principles are the same when setting up your system and how and what px are there. so if its read directly via px line or electrical via a transducer it still reads wf as a measurement of px unless you are using a spool/vane inline unit.

[Brian Abraham]

why doesn't whoever writes the POHs advocate LOPSome do, the Chieftain for example, yet if you read the Lycoming manual for the engine, it makes no mention of LOP. This of lack of consistency only adds to the confusion among some of we plebs.

The IGO and IGSO-540 was likewise approved for LOP. From the manual

"Lean the mixture until EGT peaks and continue to lean until the EGT drops 25 to 50 degrees on the gauge. Flying on the lean side is permissible if extended range and cooler engines are desired. Operation at peak EGT is only recommended for mixture control adjustments or when induction icing occurs. The Amount of temperature drop can be determined by resultant fuel consumption and engine smoothness.

"When operating on the lean side of the power curve, the pilot may observe that airspeed and power are less. If you desire to regain lost airspeed and continue to fly on the lean side of the curve, two steps are important. If sufficient throttle is available at the lower altitudes; first add two inches of manifold pressure to the standard cruise setting and then lean 25 to 50 degrees, (lean of peak). Occasionally, some pilots prefer to fly on the rich side of the power curve; this is permissible. Adjust the mixture control until EGT peaks and then enrich mixture until you get 25 to 50 degree drop on the EGT gauge. Acceptable continuous (cylinder) head temperature is an important reference here."

yr right, I might ask, if LOP is bad, bad, why then do Lycoming, in this case, approve LOP on these particular engines?

[Jabawocky]

Serious question: why doesn't whoever writes the POHs advocate LOP?

Second, if I attend the course and install engine monitors, do they come with an AFM supplement or similar that would make it legal to operate LOP in defiance of the stated procedures (CAR 138).


The majority do, and I would guess they all do if you dig for the detail and quite looking for the express words "operate LOP".

The problem is many manuals actually give guidance (poor as it is) on how to operate LOP, the most recent one I have had my head in is the G36 Bo. It is quite explicit but is so generalised that the advice is technically poor. But hey...it is there.

Many others describe operating parameters, which while contradicted on the previous pages, are actually telling you how to operate LOP.

This misconception that the POH's wont allow it are another one of lifes OWT's. POH's often set boundary points or extremes, and in other areas they give an example, but it does not mean you have to stick to just that one example.

By the way Sunday afternoon we spend an hour or so looking at POH's and engine manuals so you learn "critical thinking" something that pilots and mechanics seem to leave behind when they learn aviation. It is a rather fun session as the awakening happens.

There are even some POH's that expressly prohibit ROP ops.....and not many folk will know that story. And it is one of the big three (C, B, P.).

Once educated you see things for what they are, but let me give you a helping hand, when reading and studying any of these manuals determine which is material provided by the engineering department and which is the sales/legal/work experience kid. This will help guide you a lot more effectively.

Agra, good observation :ok:
The flow isn't tied directly to pressure, because the pump supplies more than the engine needs. Our fuel pressure goes up significantly when the boost pump is switched on, and so does the flow... briefly. Then the fuel servo adjusts to the new pressure, and the flow goes right back to where it was.
And most of what you see with the flow is the turbulence affect of switching on the electric boost pump.


All this debate about fuel flow and pressure started by this one posting;
yr right said
Ok. We'll for them that don't know the fuel flow gauge is a pus sure gauge calibrated in flow. A blocked nozzle will indicate a higher full flow as it is a direct measurement of the fuel px. Basic engine 101

What he meant is on some engines the fuel flow gauge is actually a pressure gauge with a calibrated scale on the dial to reflect fuel flow. Have a look at all the classic Beech panels and that big green faced fuel flow gauge is the one. This works a treat on the TCM engines.

If you plumbed this gauge up to the typical Lycoming it would read one value ALL the time as flow varied radically from 10LPH to 100LPH.....because the pressure is constant (relatively that is).

So lets get back to some far more educational stuff! :ok:

I have rounded up the questions I asked earlier, which yr right should try to answer as he demands nothing less of me. This is the start of the learning process. They are;

1. Please explain what happens to exhaust valve and seat temperature as you lean the engine, from rich to peak and beyond.

2. Is the exhaust valve and seat hottest at; A. 150ROP B. 75ROP C.35-50ROP D. 20LOP

3. Under what circumstances can detonation be invoke?

A:Full Rich-150dF ROP ?
B:40dF LOP - Peak EGT ?
C: 35-50dF ROP?

4. With a conforming Normally Aspirated engine, on conforming 100LL can detonation be induced?

5. With a conforming Turbocharged engine, on conforming 100LL can detonation be induced, and if so under what conditions?






Hey I just found this post by Mick Stuped; thanks :ok:
If you don't know how to get the most out of and interpret EDM data then this alone, could help your bussiness as a good diagnostic tool and an extra service you could offer to you clients. I have heard of a few maintiance orgs now offering this as a part of trend monitoring and engine health checks. Before we changed to fine wire plugs I was picking up weak plugs 50 hours prior to failure.

Just urging you to not wave this all away as mumbo jumbo just go with an open mind see what they are talking about, it seems you have nothing to loose as looks like Jabba has said he will give you your money back if you think it is crap. We are all witness to his offer.

We do not do this for profit, but we are happy to risk the expense. If John Deakin is reading this he will no doubt offer his view of the statistics so far over 13 years and thousands of students.

This has turned out to be a great thread, keep the questions coming. :ok:

[43Inches]

They covered their arses to a certain extent by suggesting that if you ran LOP above 75% for extended periods, you might damage the engine.

The caution applies to all leaning, ROP or LOP above 75% power including the quote "if unsure use full rich mixture". There is a statement also in the Warrior manual that states no more than 15 seconds above 75% with the mixture leaned, this is in regard to should the engine power exceed 75% power during the leaning process.

Of course had they operated these engines at 32-34" /2300 and 80dF LOP they would never have had any detonation to damage the plug ceramics. Had they run full rich in the climb instead of skimping (not rich enough) the same would apply.

That's about 80% power at cruise altitude, not sure I would use that higher power setting at 2300 RPM on a J2BD. A 65% power setting would be around 30"/2300 at normal cruise altitudes, 33"/2400 for 75%.

Piper also advocated a leaned climb at 85% power, but it was in accordance with the chart above 75% and basically was min 27 GPH (hard fuel flow limit to 18000') max 1500 EGT and max 475 CHT.

I used to fly these things by the book and they seemed happy, including the min EGT leaning for decent rather than the 2" per minute etc... It would be good to see some monitored data on these things to see how efficiently you can fly them though.

[Jabawocky]

43"
It would be good to see some monitored data on these things to see how efficiently you can fly them though.

We have plenty of it. If you want to see it, PM me.

That's about 80% power at cruise altitude, not sure I would use that higher power setting at 2300 RPM on a J2BD.

I am glad you raised this, when done as I stated LOP the engine is not being abused, a ROP setting is another story. Again in the same data set I refer to above, you get to see this too. It is an eye opening experience.

The POH recommended climb settings as I detailed several posts back, and as your memory is correctly recalling is very hard on the engine. Again in the Dyno run data, we have this too. The data does not lie, and it tells a wonderful story.

The fact these engines do so well is testiment to the great engineering standards they were built to. Despite that there are kinder ways (more longevity) to operate them. In the words of George W Braly, "Its not how hard you run your engine, its how you run your engine hard!"

There are two options to generate cruise or climb power settings, one is gentler, cooler and cleaner, the other is for max everything. When one understands the full spectrum and not just the one half traditionally taught, the use of both become very effective tools in the toolkit. ;)

[Walter Atkinson]

Advanced Pilot Seminars has been offering a money-back guarantee on the Live Course for over 13 years. So far, not one of the thousands of participants has asked for their money back--and that includes OEM representatives, FAA personnel and engine manufacturer reps, engine rebuliders and hundreds of LAMEs. Not one--and some came as seriously doubting Thomases.

We have also offered a $1000US reward for any repeatable data which is offered to contradict anything we present. So far, no takers.

If you don't believe what we present and what Jabba or Deakin or I say, why not take us up on that offer and offer your data?

If anything we present can be proven wrong, we want to know it more than anyone--and we're willing to pay for that education.

Remember that, without data, all you are is another person with an unsupported opinion.

[Walter Atkinson]

FWIW, POHs and operations manuals have been recommending LOP mixtures since the 1930s. Some do not address it in the text but almost all do in the engineering data.

We show this during the APS class.

ALSO, the Wayalla issue would NOT have avoided disaster had it been run full rich. There was a crank issue as well. The engines were NOT run lean. THEY WERE NOT RUN LEAN. They were run "not rich enough" ROP. If one does not grasp the significance of that, one is lacking in the understanding necessary to evaluate the event properly.

The Coroners Inquest came to Ada, Oklahoma, to see this data first hand.

This report is one of the classic examples of an investigation run amuck. They got most of it wrong--according to the HARD DATA.

[scavenger]

Thanks Jabba. I guess I am looking for something in an AFM that says, look at the EGT, lean until peak, then continue leaning until 50 (or whatever) cooler. Are there any examples of this? The Lycoming Flyers (http://djholman.csde.washington.edu/Yankee/Lycoming/LycomingKeyReprints.pdf) I've read specifically deal with leaning using EGT but don't mention this technique.

Do any of the engine monitors come with AFM supplements that specifically say to operate LOP?

You've all convinced me that you each believe in your opinions, and I would be keen to come to the course advertised in this thread, but it would be pointless for the operation I'm involved in without compliance with CAR 138 (my mother's presence aside - thanks for that one) as CASA sees it. All the flight manuals in the operation I'm involved with say lean to peak EGT (best economy) or peak + 100 ROP for best power.

Creampuff et al, you have convinced me you believe in the danger of operating slightly ROP, no need to rehash that again, when I am asking about operations LOP.

[43Inches]

ALSO, the Wayalla issue would NOT have avoided disaster had it been run full rich. There was a crank issue as well. The engines were NOT run lean. THEY WERE NOT RUN LEAN. They were run "not rich enough" ROP. If one does not grasp the significance of that, one is lacking in the understanding necessary to evaluate the event properly

This was always the problem with flying Pa31s (or any other GA aircraft), every operator did things differently, how they arrived at their procedures probably came from different types and rumour rather than good condition monitoring and trend maintenance.

I guess I am looking for something in an AFM that says, look at the EGT, lean until peak, then continue leaning until 50 (or whatever) cooler. Are there any examples of this?

There is a procedure in the PA-31-350 manual para 4.37 "lean side of peak" procedure.

(a) set desired power setting and lean until peak;

Do not exceed 1650F EGT

(b) if peak is below 1650F or less continue to lean until maximum of 50F reduction in EGT. Readjust manifold pressure to desired setting.

(c) (long winded procedure for use if 1650F is achieved prior to peak)....

It does not state when to use this, or what fuel flow will be achieved.

In smaller pipers such as the Warrior and Arrow it states to lean (power settings below 75% only) until rough then enrich only enough to allow smooth operation, if the engine is able to run smooth LOP it will be LOP.

[Old Akro]

In smaller pipers such as the Warrior and Arrow it states to lean until rough then only enrich enough to allow smooth operation,

Its worth remembering that the aircraft manufacturers POH's were written around the standard instrumentation of the time. For a lot of aircraft this meant no EGT instrumentation at all.

As better instrumentation becomes available, so does better operating techniques.

When we get lambda meters the discussion of EGT will fade and we'll talk about Lambda (air / fuel ratio) readings.

Aircraft with a single point EGT measurement may have an EGT setting specified by the manufacturer designed to protect the cylinder with an outlying reading given that its known many engines have significant cylinder to cylinder variation.

If engines weren't so heavily regulated and changes were not so expensive / difficult, I suspect we'd see aftermarket intake systems that provide better cylinder balance rather than the band-aid of tuned injectors. Until then, GAMI injectors are the best option for engines that require cylinder to cylinder correction.

[Agrajag]

it doesn't matter if it cont or bendix both do the same job. fuel px is measured post pump and pre fcu. wf is measured post fcu. it can be measure as px and conveverted as I've said to read wf or you can have a vane or spool type that measures flow pre spider and post fcu and it must have a in and a out, if it doesn't have that its measuring px.Yes Conti and Bendix do the same job of supplying fuel to the injectors, though in very differing ways. That understanding means that we as pilots operate them in a different manner, from starting technique down to usage of the boost pump. And I'll say it again: our fuel flow sender is pre-FCU; in fact it's pre-fuel pump.

Perhaps you wont explain because you don't know ? but do enlighten me how then it measures its fuel air ratio to provide the correct settings. I could indeed, and I could probably also do so for a RR Dart, but both would be equally irrelevant to this discussion. I don't believe I need to prove my credentials in order to demonstrate that you have no idea of what is in our particular aircraft, and therefore how it's best utilised. You're lecturing me, and others here, on the basis of some broad assumptions that were never true.

Now yesterday I worked on 3 different engines including turbine types and one airframe and gave advise on one other airframe. Now its impossible for me to know each individual aeroplane that you all have but the principles are the same when setting up your system and how and what px are there. so if its read directly via px line or electrical via a transducer it still reads wf as a measurement of px unless you are using a spool/vane inline unit. I hope you didn't offer strident, condescending advice on these varied aircraft without even setting eyes on them, or knowing what engines and equipment were installed. Because that's what you've been doing here!

Sorry yr right, but all the way along you've been pushing the hard line that there's only one way to operate all piston aero engines, and that's simply not true. I was taught the same stuff when I started, but I've since become aware that it was an over-simplification. We now know more about what's going on inside the engine, and we can use that information to optimise its operation in every phase of flight, instead of a one-size-fits-all rule. And since we didn't just buy our licences, as you sneeringly inferred a while back, we have the capacity to do so.

[43Inches]

When we get lambda meters the discussion of EGT will fade and we'll talk about Lambda (air / fuel ratio) readings.

All I need is Torque(BMEP) & RPM to set power, I think manifold pressure is a very poor gauge of power output, it is only good for letting you know when your manifold will eject in TC engines. The other monitoring equipment such as EGTs, CHTs, FFs etc to let me know its healthy. Knowing the fuel/air ratio going in doesn't really help to operate it.

Its worth remembering that the aircraft manufacturers POH's were written around the standard instrumentation of the time. For a lot of aircraft this meant no EGT instrumentation at all.

And it works just fine without an EGT on these aircraft, the EGTs fitted to them tend to barely work at the best of times along with pilots able to correctly follow the leaning procedure.

[Progressive]

"Sorry Jaba you are in correct. The fuel pump has nothing to do with fuel flow in either tcm or bedix system. The fuel pumps supply fuel to the fcu. That is there only function. They do not in either system control any fuel flow to the engine"

Yr Right,
If you are going to call someone incorrect - make sure they are.
TCM fuel system is a pressure dependent fuel metering system, this system does not measure airflow through the engine it works by metering fuel in proportion to the relative position of the throttle valve (there are no blast tube or venturi suction measurements taken from the air side).

Fuel is supplied from the pump at a set pressure (un-metered pressure) to the fuel metering valve where the mixture and throttle metering valves (variable orifices) which reduce the pressure down to a metered value before sending it to the spider. With a known pressure across a known orifice (injector nozzles) we get a known fuel flow for the particular throttle setting.

Fuel pump output pressure is critical in this system as any change in pressure to the going into the metering device will change the metered pressure output.

All of this needs to be adjusted to get the engine running right, failure to do this will lead to low fuel flows at takeoff power and exactly the kind of cylinder damage you are talking about.

If you dont believe me believe continental:
http://www.tcmlink.com/pdf2/SID97-3F.pdf

Or for a more simple description of the system:
http://www.kellyaerospace.com/articles/ContinuousFlow.pdf

And before you bemoan pilots giving you advice I AM NOT A PILOT.
I am a LAME (and aircraft owner) who has:
Worked in a fuel overhaul shop
Overhauled radial, opposed and V engines
Spent 8 years maintaining a fleet of Chieftain engines
and instructed students in aircraft piston engines/theory/systems and maintenance for the last 3 years

PLEASE STOP FIGHTING A LOOSING BATTLE and making LAME's look bad. Take the free course!! If you don't believe it dismiss it AFTER you have tried it, otherwise take what you can from it to be a better LAME.
That is the sign of professionalism in ANY field.

[Tinstaafl]

To counter that no POH has LOP operation described & approved in it, a 1980 PA31-325 I operate has LOP ops in its POH, just like 43" described - and that's with the factory single point EGT & CHT gauges. Mind you, I had the owner install an EDM before I'd do LOP, other than a demo of the fuel savings to be made. According to my logbook I've flown this particular aeroplane 700+ hours, and I've run it LOP in the cruise by default for nearly all those flights.

[Jabawocky]

Scavenger
I guess I am looking for something in an AFM that says, look at the EGT, lean until peak, then continue leaning until 50 (or whatever) cooler.

Well you could find it in some but not others, explicit good education that is. Problem is as described by others above, you will struggle.

As a comparison, the POH does not tell you how to comply with the Instrument Flight Rules, yet the aircraft is approved for IFR flight.

For some reason the thought process is unless it is spelled out explicitly in the POH you can't do it. No thinking allowed.

Also for LOP ops or for that matter ROP ops, the appropriate amount either ROP or LOP varies as the power increases. The book gives one set point and it is only one recipe in the cookbook, not all of the infinite possible variations.

[Lumps]

What he meant is on some engines the fuel flow gauge is actually a pressure gauge with a calibrated scale on the dial to reflect fuel flow. Have a look at all the classic Beech panels and that big green faced fuel flow gauge is the one. This works a treat on the TCM engines.

So hang on - fuel flow is displayed as a product of pressure in Continentals only?

The BE95 (Travelair) has Lycomings yet fuel flow gauge is pressure, or that's what it says on the gauge anyway (there's a little red line saying 10.5psi or something, can't remember the number)

Does this just mean the gauges are plumbed in to a different part of the fuel delivery system?

[heated ice detector]

I think YR (with his interesting methodology ) is posting that the fuel flow gauge on a Lycoming or Continental is actually a pressure gauge calibrated for fuel flow. I think!!!
:confused:

[yr right]

Well I think will be my last posting. So ill clear so stuff up.
I was ask to comment on lop, so I did and all my experience meant nothing cause I had no data. Of course I don't have data no one dose cause we never recorded it as such. But ive seen plenty of upset faces in my time when given the cost of repairs.


Now I know exactly how the fuel pump works. But its still a pump that's it role a pump. You also forgot the regulators and what about the bellows as well. Now the pump dose not drive the fcu The fcu drives the pump in both cases lyc and TCM. Flows from both pumps will increase as the rpm rises. Now also fuel flow can be changed via the mixture lever as well as throttle position. The Fcu leads the pump follows.


Next ive ask everyone I know and no one ive talk to has any idea how you are getting fuel flow pre pump and pre fcu this includes some extremely smart EIR guys I know.


Now this one has puzzled me for a little while now. The reason why everyone has duck for cover made excuses . Why the e second engine stoped. Now to say it was rich enough and it was doomed to failed is sorry f&*king bullsh7t. Simple put it if that engine had full fuel it would have made it back. It didn't even Jabby said well yes it would have kept going. Simply put it it engine was under maximum load trying to keep the machine flying. You can not use oh the crank was crack so it was going to fail any way, when was it going to fail. The aircraft took off didn't it.
Now this leads me to this point.


The engine failed due not enough fuel to be supplied to the power setting that was asked for, simple. Now not really related to LOP but if you read between some line and think about it to your selfs. I really don't care what you think about me you don't even know who I am. But I wont put a pilot in a machine that I wont fly in my self, on that note there are a lot of pilots that I will not fly with.
Cheers

[Jabawocky]

yr right

I can't understand your last post.

Would you please give me the courtesy of answering my questions. I did for you?

I am trying to help you here.

[Brian Abraham]

I was ask to comment on lop, so I didBut you've not answered the question as to why some of the flat engines, as in the Chieftain, are approved for LOP. What is so special about those engines, vice a properly fitted out aircraft as Jabawocky possesses?

http://i101.photobucket.com/albums/m56/babraham227/z258_zpse73fd094.jpg

[Walter Atkinson]

It is a very painful thing to experience when your long-held beliefs are upset with hard data. We have been watching that painful experience in this thread. The only way to assuage that pain is to learn the truth and expand one's knowledge.

[gerry111]

So true, Walter A. :ok:

[cockney steve]

Yr Right....I suggest you revisit first principles of Internal Combustion Engines....
The key to reliable running was an accurate fuel-air ratio....too rich, wets the plugs and puts the fire out....as you progressively lean the mixture, you reach a point at which it will burn, BUT THE CHARACTERISTICS OF THAT BURN ARE UNSTABLE (DETONATION)

continue leaning, you'll get better power, no detonation but excessive heat within the engine

Continue leaning LOP, you've got rid of theSURPLUS ENERGY IN THE FUEL-AIR CHARGE IN THE CYLINDER....So, you get a clean, cool burn with the exhaust being predominantly waste gases.

Your dragster analogy is an entirely different scenario.....very little of the consumed fuel is actually pushing down the pistons...that is self-evident by the huge columns of flame out of the exhaust stacks.
Of necessity, I've tried to give a much simplified account of why LOP is , of itself not doing the damage. hope this gives you something to chew on!
Back to another poster....my European contact changed the starter because he thought the cranking performance was well below par (he was correct) IF the new starter whizzes over the engine, sufficiently fast to lock-out the Impulse mech. THAT IS EXCELLENT!
The piston is travelling sufficiently fast, that the now-advanced spark can ignite the mixture and the piston goes OVER TOP DEAD CENTRE BEFORE the burning mixture can develop enough pressure to knock it back.
Q.....Do you tell all pilots to start on single-mag (impulse) only??

If not, why not?

It was after the starter change that he investigated further, as it still was extremely reluctant to start,despite battery, solenoid, cables, return-path all being OK plus a new, permanent-field starter which punishes the battery far less than the wound field-coil variety.
IIRC, plugs had done under 50 hours they were not a prime suspect until all else had been eliminated.

Another customer lost to Champion. Ask any motoring enthusiast what
the best plugs are...invariably it is NGK Bosch and Denso....Champion are now a poor "also-ran" trading on past reputation......Sad, because pre-war and into the 60's they set the standard and others followed.
I speak from personal experience and as "the man on the Clapham Omnibus" (average joe public!)

[No Hoper]

Cockney Steve, Detonation on startup?
Dragster flaming at idle is caused by cam timing overlap duration as previously explained.
Maybe this thread name should be " LOP- True Beliebers"
A starter that rotates the engine at an RPM that "locks out" the impulse coupling would not be approved for fitment on that particular installation.

[No Hoper]

I declare I have no dog in this "fight".
Without giving away propriety information, Consider stoicheometric mixture of 17: 1 or there abouts. What is peak, what is less than peak and what is more than peak? Note the terms more and less as I find lean of and rich of misleading in this case.

[OZBUSDRIVER]

Back on judicious use of carb heat to improve fuel distribution...are we after better mixing due to heat or higher induction velocity(better induction signal through carb throat)...granted, methinks I am after free info but pertinent question. Just cracking carb heat a little until roughness improves then attempt to lean again?

[Agrajag]

Now I know exactly how the fuel pump works. But its still a pump that's it role a pump. You also forgot the regulators and what about the bellows as well. Now the pump dose not drive the fcu The fcu drives the pump in both cases lyc and TCM. Flows from both pumps will increase as the rpm rises. Now also fuel flow can be changed via the mixture lever as well as throttle position. The Fcu leads the pump follows.

...no.

On the Lyc (Bendix) system, the pump is merrily pumping away, potentially supplying more fuel than the engine needs. The FCU simply limits that output via a diaphragm which responds to pressure drop across a venturi, to arrive at the desired flow. The pump can go as hard as it likes, but the FCU controls flow. That's why the flow doesn't change when you switch on the boost pump and raise the input pressure.

Sorry, but you lost me ages ago when you claimed that TCM and Bendix systems work the same.

Next ive ask everyone I know and no one ive talk to has any idea how you are getting fuel flow pre pump and pre fcu this includes some extremely smart EIR guys I know.

You didn't ask me, and I'm not even that smart.

Boost pump -> inline sender -> EDP -> FCU. The sender measures the flow through the pipe, on its way to the engine.

[Jabawocky]

Cockney Steve,

Just a finer point, but the most detonation prone mixture is one that occurs around 35-50dF ROP. This happens after leaning past the best power point of 75dF ROP.

This is not to say that when conditions are right that you can't get mild detonation starting a bit earlier, because it depends on the severity of the conditions. These boundaries are very fuzzy ones but they do not extend past peak or if they do it is not easily perceivable as no LOP mixtures support detonation. One caveat here, perhaps some poor octane mogas in just the right conditions (read hard to achieve) will continue to detonate mildly at just LOP but not for long after that. Avgas at min spec or G100UL at min spec does not.

In the quest to provide the world with a certified unleaded Avgas with equal or better properties GAMI have been doing hundreds of hours of detonation testing on all manner of fuels, and I am privileged to be involved in a small way. The Data shows where common misbeliefs are simply that.

I am sure over the last 15 years Walter Atkinson has seen plenty more of this himself and would validate this.

Just to provide some balance here as many people get these two things mixed up, pre ignition events can occur while LOP, although most likely at higher powers so typically for that to happen it will need to be in a turbocharged engine.

[Aussie Bob]

Back on judicious use of carb heat to improve fuel distribution...are we after better mixing due to heat or higher induction velocity(better induction signal through carb throat)...granted, methinks I am after free info but pertinent question. Just cracking carb heat a little until roughness improves then attempt to lean again?

I can only comment from my experience with one engine. The carby heat evens out the EGT's but it takes time for it to happen. I suspect that the inlet tubes need to be a bit warmer than OAT (hence the time). There is no judicious use here either, its full carby heat or nothing (again only my aeroplane where according to the carb temp gague, it is on or off). Looking at the route the carby hot air takes, I would suspect the inlet velocity is reduced.

Hopefully someone else can help with more info on this subject.

[yr right]

We'll some people are smarter than I. I used the nitro engine as an extreme as you can see what happens. I said they work the same because they do. The both have pumps an fcu and nozzles. They go about getting the fuel in a different way. As I said before. 34 years I've been doing this. Not one whine in flight shut down. Not one engine failure. God knows how many engine services I've done but you all seam to know and won't to tell me how I do my job. That's fine when you start signing your own M/R. And like I said fuel flow is measured from the FCU to the spider know one I've talk to has any idea where you get fuel flow pre fuel pump. Also every thing I've said has come out off my head. I've not gone to any books and not done any research with exemption of ask a few pilots and friends there thoughts on lop and fuel flow sensor. So sorry Jaba when you ask a very technical questions with out technical data I won't and can't answer them. The information I give is in it's basic form and there is a genuine reason for that.
I fully understand how a fuel system works. I also understand how a turbine fuel system works and make a piston engine system look like it should be on a lawn mower. I am also turbine lic.
I am always learning. It never stops. I also said if the manual says go lop do it. I don't care what you do. All the pa 31 I've look afyer over the years to my knowledge none of them flew lop. I said it before. Fuel is cheep.
Anyway I off to learn my silence.
Cheers

[rnuts]

If you are running LOP and using carby heat to do so. What happens if you get some situation whereby you start to get carb ice? Could you then be in a situation where engine failure is possible?
I doubt this was the intended use for carb heat.
Very interesting thread!!
I am now very keen to learn more about LOP operations for my 421C.
Previously I was too afraid to operate these engines differently to what I had been taught due to possibly screwing it up and causing damage.

[Aussie Bob]

If you are running LOP and using carby heat to do so. What happens if you get some situation whereby you start to get carb ice?

Cruising with carby heat on keeps the carby well out of the icing range. An EMS includes a carb inlet air temp gague. My experience with carby ice is always with a low inlet temperature, but again, more opinions please. I am a beginner with this stuff.

[Old Akro]

If you are running LOP and using carby heat to do so. What happens if you get some situation whereby you start to get carb ice?

Do you want to think about that again? To get carby ice you need....

Previously I was too afraid to operate these engines differently to what I had been taught

Unfortunately, often what we are taught is not consistent with the engine operators manual. Go to Essco or wherever and buy a copy of the engine operators manual for the 421 engines. Most of the time that is consistent with what the Advanced Pilot Seminars teach. If you want to learn more, enrol in one of Jaba's courses.

The geared turbocharged Continental 520's require a lot more caution and you may find that you have trouble maintaining pressurisation at the power levels used for LOP operation. John Deakins has a couple of articles specifically on turbocharged engines. Go to Avweb and find them. Print them and read them more than once.

Note: By some freak of luck, TCM have a pdf copy of the engine operators manual for the GTSIO 520 D fitted to the 421.

see here:

http://www.tcmlink.com/pdf2/maintenancemanuals/x30044/x30044.pdf

There are a few things to note:
1. TCM recommend climb at 75% power full rich. Your climb will be a different thing than the average BO because instead of climbing to 4-6,000 ft you're probably climbing to 20,000 ft or more (hopefully at Carson speed). Cooling deteriorates and becomes more critical as the air becomes thinner / dryer so inlet charge cooling from rich operation becomes more important. Especially since Australia is typically 15 - 20 degC above ISA temperatures.
2. There is a strong chance that a LAME somewhere has screwed up your fuel pump settings. Its tedious to set properly and many don't bother or think they know better and can do it by "feel". The engine operators manual shows a maximum fuel flow for 75% power. Check your fuel flows against that. Our aircraft is too rich, so I lean in the climb to achieve the Continental figure.
3. The Continental instructions are based on TIT, not EGT. On a turbocharged engine they can be quite different. Do not apply the APS / Deakin teaching to TIT. You need to fit an engine monitor to follow their teaching.
4. There is a lot of data, but not presented in a user friendly manner. You'll need to do some unit conversions to make sense of it all. Get out a pencil and change the charts.
5. The Continental manual defers to the Cessna POH for cruise leaning instructions. The Cessna POH seems to be saying to lean to a fuel flow derived from a fuel computer. However it also suggests leaning to peak EGT below 65% power. Deakins et. al. will cry that this is inside one of their red boxes. However, you need to know where the temperature is measured first and the Cessna POH doesn't say. If it is in fact a turbo charger inlet temperature (TIT) rather than an EGT (near the exhaust valve) then Cessna may be correct.
6. In my (limited) experience with pressurised aircraft, you might find that it doesn't maintain the cabin altitude at the flight levels that give best efficiency at 65% power. There are more gains from optimal altitudes than optimal leaning. Someone will correct me if I'm wrong, but I don't believe APS advocate LOP above 65% power.

[rnuts]

Old Akro.
Ok mate no need to be a smart a$$.
Was just asking the question.
I know you need moisture, which is always present to a varying degree.
Also you need the temperature drop at the Venturi to be below the freezing level.
I gather you are saying that it would be impossible for the formation of ice with carb heat on all the time.
The guys here for the most part have been keeping these discussions civil which I think is fantastic.

[Old Akro]

Didn't mean to be a smart arse, just cheeky. Sorry.

Besides, you have injected engines, so no venturi.

Continental engine operators manuals & Cessna POH's are about the worst combination you can get. They really don't make it easy to run the engines optimally. And a turbocharged engine providing cabin pressurisation as well as engine boost works pretty hard in the flight levels where the engines can be cooling limited as well.

[rnuts]

No worries.
Intent can be difficult to judge at times.
I fly many different aircraft from little Cessnas to Jets.
The carb ice question was just something I thought was worth addressing.
It worries me that people try some of these practices without proper equipment, training and understanding of what they are actually doing.

[Brian Abraham]

rnuts, you may want to get in contact with the guy here. See the bottom of page for contact details.

Operating a Cessna 421 C LOP ? Insurance Approved Training (http://www.flighttrainonline.com/technique/operating-a-cessna-421-lop/)

[Creampuff]

From the text at the link in BA's post:The other benefits are quite typical for aircraft which are operated LOP, and included lower CHT temps, cleaner oil, better oil samples, better cylinder life, and overall better engine service. It is not all that atypical to put a set of cylinders on a GTSIO about every 600 hours. We were able to fly all the way to 1400 SMOH before we had to look at any cylinder work.How could that be so, yr right?? :confused:

[yr right]

We'll cream puff I said I not posting any more. But I will say this and you can correct me if I'm in correct. Tcm knew they had a problem with the cly on gsio engines. They change some stuff and wow really no one has a problem any more. As a matter of fact I'm working on them today oh also biggest problem do gstio engines is the driver.
Cheers

[Creampuff]

I’m still interested to know some of the mistakes you’ve made and the misconceptions under which you’ve discovered you were labouring, over your 34 years’ experience as a LAME.

What were the circumstances in which you took a step back and thought: “Hang on sec’, I have this all wrong.”

If your answer is: "Never", that would explain a lot.

[yr right]

Cream puff.
I'm more than happy to stand behind my record in aviation. I take your comments like the toilet paper they written on. I have a failing that I don't suffer fools lightly you fall into this category.
We have a saying here in aust.
I would not piss on you if you where on fire and in the gutter. In this case you also fall into.
You will not get any further response for my self.
Cheers

[gerry111]

Creampuff, Please don't say it! Just go and have one of those 'Pabst Blue Ribbon' beers... ;)

[Aussie Bob]

If your answer is: "Never", that would explain a lot.

It has been explained.

[yr right]

What. No engine shut down no engine failures no wheels up no accidents cause by my self. What do you people won't it is
Your life's in our hands.
You all amaze me no end.
Cheers.

[Oracle1]

yr right you are now playing the man and not the ball :ugh:


you are showing that you are not even willing to analyse new ideas much less judge them on their merit. Jabawocky et al know their sh@t and have evidence based on the scientific method of analysis. LOP has a well proven history and when conducted in the correct manner can be beneficial.

A true professional accepts when they are wrong admits it and moves on with a higher standard of knowledge. A true professional always accepts there is more to learn. Theories get disproved all the time.

You should do some more study before you deride others based solely based on the fact that you are a LAME and they are not. :oh:

Just because you are a LAME does not mean you are the suppository of all knowledge on engine management

[cockney steve]

suppository of all knowledge on engine management

THAT has to be the best Freudian slip, ever , on here.:ok::}

For those in doubt, Googoo "Suppository" and "Repository" :8:p

[Oracle1]

The term was used deliberately and is a parody of a comment by our Prime Minister no less, however the term's usage is totally appropriate in this instance.

[cockney steve]

@ no hoper I was,of necessity, somewhat simplifying. The vast majority of SEP's are Carburetted and the starting-procedure is , in technical terms, the epitome of crudity....Basically, you squirt a few dollops of fuel into the inlet tract, then crank, thus your induction-air evaporates this puddle of fto oo rich to fire first time, but continued cranking will lean-out as the puddle reduces, to the point where the ratio is right...the engine fires, and typically a sooty cloud of exhaust is ejected as the engine "catches" and the operator resets Mixture and throttle. if, indeed, during this brief period of starting (accelerating from cranking-speed to , say 900 rpm idling......the mixture-ratio is in the "danger of detonation" range, it is unlikely to do so, simply because the engine-loading is so light......no doubt, with the correct laboratory setup and the engine on a test-stand, you could produce this and analyse the real-time combustion events.

For all practical purposes the firing-to-idling phase is so brief, and lightly-loaded, that detonation is not an issue.

WRT to permanent-magnet," high-speed" (a relative term!) starters. They are approved!

Again , you raise a red herring....IF the starter was sufficiently fast to throw-out the impulse coupling, that would indicate that the engine manufacturer thought retardation and impulse were not required at that rotational speed....QED.

Have hand-cranked stationary-engines with impulse couplings and twirled it fast enough to start without impulse....no broken wrist or thumb!....likewise many motor vehicles and the odd few marine engines.
Normal Lycosaurus piston engine timing is fixed and works extremely well, simply because !- the average pilot is not an engineer and would be incapable of operating an Advance-retard mechanism correctly,
2... the engines are, effectively, operated as "constant-speed" devices therefore timing can be fixed and optimised for that speed.

[No Hoper]

Cockney steve, if you are "flood" starting your engine I would suggest altering your technique which will eliminate the the various issues you are having.
As for this anecdotal high speed starter that is able to rotate the engine at an RPM to lock out the impulse coupling, please supply brand name.

[Jabawocky]

I see a new topic emerging here. Starting Carby Lycomings!

This as described above has been one of pure bastardry for decades. The primers on the humble carby engines are a source of mostly trouble. Besides the hard starting issue, the risk of flooding, and all that goes with it, there is leaks in the cabin and induction leaks in the engine.

Most of these aircraft have no EMS so the leak in the engine is rarely found, or not found promptly.

Take your simple O-320/360, remove the primer, plug the port and live happy ever after. The start technique is simply start cranking, and after the blades move give a couple of sharp push/pull's through the full movement of the throttle and it will start every time. Hot or Cold.

As explained by Steve above getting the "right" Fuel Air ratio is what it is all about.


yr right
I'm more than happy to stand behind my record in aviation. I take your comments like the toilet paper they written on. I have a failing that I don't suffer fools lightly you fall into this category.

I really do feel that with your vast years of experience you would be a little more perceptive. Creampuff has quite a significant engineering training and some other high level diverse qualifications that would surprise you.

Have you had a go at the 25 question fun test in the free trial on the APS website? I am happy to compare your results with Creamie's in private for you if you like. I am sure he will not mind. It is a Fun Test. :ok:

Do you need the link again?

[Ultralights]

what would be fun? everyone taking the short test, then comparing their results here!! for all to see, and maybe learn!

[Tankengine]

The most important point to take from Jaba's last post for me is that you start cranking BEFORE pumping the throttle!:ok:
I have seen air cleaner fires and damage from the old pump, pump pump, crank.:eek: (simple really-inverted carby):rolleyes:
Despite this I have seen the wrong method written into ops manuals.:ugh:

[No Hoper]

If you be pumping that acc pump as described you are back at flooded engine, surely?

[43Inches]

If you have trouble starting an 0-320 D3G in a Warrior it's broken or you're doing something very wrong.

Do not pump the throttle, this only results in an nice bonfire under the engine.

Definitely do not prime with the throttle. As stated above this just puts a trail of fuel dripping out the bottom of the engine ready to light off with the slightest back fire.

The correct amount of prime is basically all that is needed for the conditions.

I know this because I've had to clean up the mess numerous times after Cessna pilots, including instructors jump across to PA28s and try to start them with throttle pumping. My theory is the Cessna 150/152, 172 have a higher speed starter than the PA28 which allows the fuel to be sucked through. The PA28s much slower starter I reckon inhibits much fuel being drawn through until it fires and speeds the process up, so throttle pumping just puts a pool of fuel dripping out the bottom.

If you be pumping that acc pump as described you are back at flooded engine, surely?

Depending on the engine the fuel may not even make it into the engine to flood it, the flooding may occur in an even more undesirable location.

[yr right]

Jaba
Cream puff can be a rocket scientist he can pack shelves in Walmart for all I care. The response he got is what he deserves. To attack my credabilly I will not stand for. Ask the casa solicitor that tried the exact method to me in court. I made him look like a fool and destroyed him in the court. I will not stand for some one that dose not know me and what I stand for period. Like said I don't care what he dose. And I stand by my record of providing 100 % safety in all what I do in regard to aircraft maintenance. If this don't suit some people here on this forum so be it.
I might add the the org use gstio here dose not do lop. We also have no dramas with our engines. Tcm whilst the basics engine looks the same the manufacture and the materials has changed considerably over the years.

I will also add that I and ever lame can only set an engine to the data that is provided. The pilot can destroy and machine at his will. I and every other lame have know control over that.

Easiest way to start a carb engine is to prime get out hand swing the prop serval rotations hope back in and hit the starter with mags on. It will start every time 1st time if every thing is up to speed. But hey what would I know.
Cheers

[Hempy]

yr right,
As I read this thread I don't see anyone here doubting your ability to maintain aeroplanes, obviously you can if you've held a job for as long as you have. What I see is people who know more about the subject of engine management than you do telling you that your training is outdated and if you intend to pass advice on engine management to pilots then perhaps you should educate yourself on current best practice first. Keep fixing your planes mate.

[Creampuff]

So anyway…

On the subject of priming, does anyone have trouble starting CMI engines when they’re hot? Some people have successfully tried the ‘run the electric fuel pump for a minute or so with the mixture to idle cut off, then prime per cold start’ method, but others haven’t tried it or have tried it without success.

I’d be interested in hearing whether people have tried it with success.

[T28D]

Puff, yes running the pump works to flush cold fuel through the upper deck fuel manifold and distributer valve thingo at ICO, then go for a normal start.


Problem only comes if you then screw up and miss the start, a hot flooded engine is a difficult start without a burn't out starter motor, better to go back inside and have a cup of coffee and start all over again in 20 minutes.

[Aussie Bob]

Personally I have never had much success running the pump. Two methods I use:

1. Idle engine then stop using the mags (turn off key). Do not touch mixture, leave rich. Then, no prime, start like car, use high prime to keep running. Great for stop/start

2. Use half of normal cold prime then crank while opening throttle. Most will start somewhere around 3/4 open. Pull back throttle, use pump to keep running. Great for a 15 minute stop.

[yr right]

T2rd

Negative. Once the mixture is placed into ICO no fuel is past to the fuel nozzles at all ie upper deck.

[Creampuff]

Hi T28D

Not sure of the brand/model engine you’re talking about there. On a bog standard injected CMI engine most or all of the fuel should be blocked by the FCU (being in ICO) and therefore not make it through to the manifold and injectors. (Although the tech data for the FCU does show that a conforming item can still let a little fuel through. It's also different on turbo models, though, because apparently the mixture mechanism is in the EDP, not FCU.)

The aim of the technique, as I understand it, is to flush cool fuel through the heat-soaked EDP (not the manifold or beyond).

[yr right]

ICO is what it dose at the fcu any leakage that may come out is stoped the a little known function of the spider valve(distribution valve ) it also has a cut off built it to it. but hey you would all know that wouldn't you.
Cheers

[43Inches]

Never had any problems starting Conti TSIO-360 rich whether hot or cold, unless of course you flood it priming with the pump. I did find sometimes the 200hp ones didn't want to stay started without the fuel pump on occasionally when very cold.

The more important issue is when you stuff up the priming and it doesn't start, then it needs divine intervention to get it going;

better to go back inside and have a cup of coffee and start all over again in 20 minutes.

sounds about right.

I can't recall if I've used the non-turbo ones.

The funny one was the PA31, I have been told about 50 different starting methods, the one that worked the best almost every start was the one in the book.

[yr right]

WTF
1. Idle engine then stop using the mags (turn off key). Do not touch mixture, leave rich. Then, no prime, start like car, use high prime to keep running. Great for stop/start




OMG

[yr right]

Aussie Bobs new book entitled


How to perfectly Hydraulic your engine in one easy step.


Seriously you cant be serious and if you are that you wouldn't let me work on your aircraft I think my later statement of me not working on it is a truer statement.
Cheers

[Creampuff]

For people who fly behind CMI engines, this is one of many useful on-line articles: Continental's Cram Course: TCM's Aviation Technician Advanced Training Program - AVweb Features Article (http://www.avweb.com/news/maint/182832-1.html?redirected=1)

Apropos of the function of the manifold on CMI engines, from the article:The manifold valve is also a lot trickier than it looks. In addition to its basic role as a four- or six-way flow divider, the manifold valve is responsible for providing a clean fuel cutoff when the mixture control is retarded to the idle cutoff position. It takes a bunch of moving parts — a spring-loaded poppet valve and a spring-loaded diaphragm — to accomplish this function.That’s why you need to take a close look at the bleed vent on the manifold during pre-flights. If there is blue staining, it indicates the diaphragm is damaged. :ok:

[No Hoper]

Creampuff, that should silence your critics

[Creampuff]

I have critics? :confused:

[Aussie Bob]

Seriously you cant be serious and if you are that you wouldn't let me work on your aircraft I think my later statement of me not working on it is a truer statement.Can anyone understand what this guy is trying to say?

yr right: please explain why turning off the engine by turning off the magnetos is bad when a restart is imminent? It is not my method, rather, it was shown to be by a senior seaplane pilot who is also a LAME, one of the best I have ever met. C185F is the aircraft.

Please also note, I have never posted anywhere ever that I would not use your services. I would. Whether you would provide them would, of course, be up to you.

[yr right]

Um I fail to see how that will silence any thing. The spider valve dose not stop fuel flow. It is a secondary valve meaning the fcu is the primary ICO and the valve when fuel flow is less than spring px closes. This stops dripping into the nozzle and stops after run giving as it says a cleaner fuel shut off. But once again what would I know.
One other quick thing. Lop is not new at all so for those of you that think it's is I guess you need to look back. It was also taught at tech. I no I won't be advocating it to anyone at all. It is there decession to do it if they wish and they will get the rewards of a $20 saving in there pocket if they wish to do it.
Cheers.

[yr right]

The only time you ever ever cut of the engine via ignition is in an emergency. Never never never ever ever do it. You run the risk of hydraulic lock and destroying your engine not to mention flood the cly walls with fuel and washing away any lubication that is there.
Yes I heard of float plane operators doing this for a dead quick stop on water. But I can't say this more seriously than don't ever ever do it. And especially never do a compete on off on both mags above idle.

[Creampuff]

Do your parents know you're posting material on-line? This stuff will haunt you when you grow up, you know.

[No Hoper]

Aussie Bob, you do not shut off fixed wing engines using magnetos. Any hot spot in the cylinder is waiting to cook off the fuel load and the prop can kill someone. The Bell47 is shut down by offing the mags as the cut off was removed. No danger off rotation of rotor as the clutch is disengaged

[Ultralights]

Never never never ever ever do it. You run the risk of hydraulic lock and destroying your engine not to mention flood the cly walls with fuel and washing away any lubication that is there.

i must have been close to locking the engines of the countless cars and bikes i owned! :hmm:

not to mention the dangers to my Rotax 912's! or my Jabiru aircraft.......

[Aussie Bob]

Aussie Bob, you do not shut off fixed wing engines using magnetos

Err, Gipsy Major with no mixture, Rotax, Jabiru? Err, why not?

I will cease the method on real aircraft engines and take yr rights opinion as correct. By the way No Hoper, this is a regular practice with some seaplane operators just as yr right said. Personally I never did care for it that much, but if you are restarting instantly and you use the very low idle set on most seaplanes first, perhaps it is not as bad as you think.

[Aussie Bob]

Any hot spot in the cylinder is waiting to cook off the fuel load and the prop can kill someone

BTW No Hoper, that is another OWT