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How to thread drift in 720 posts!!!

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How to thread drift in 720 posts!!!

Old 5th Apr 2014, 23:19
  #81 (permalink)  
 
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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
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Old 6th Apr 2014, 02:53
  #82 (permalink)  

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Hope the thread title is now more appropriate?

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Old 6th Apr 2014, 03:08
  #83 (permalink)  
 
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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?
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Old 6th Apr 2014, 03:11
  #84 (permalink)  
 
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Originally Posted by yr right View Post
You said that fuel dosnt have a cooling affect.
Actually, he *didn't* say that
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Old 6th Apr 2014, 04:29
  #85 (permalink)  
 
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Hope the thread title is now more appropriate?
Ahh Tailwheel, my favourite mod. I see you still retain a sense of humour!
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Old 6th Apr 2014, 05:00
  #86 (permalink)  
 
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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
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Old 6th Apr 2014, 05:29
  #87 (permalink)  
 
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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.
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Old 6th Apr 2014, 06:02
  #88 (permalink)  
 
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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.
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Old 6th Apr 2014, 06:13
  #89 (permalink)  
 
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Detonation isn't preignition, just saying
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Old 6th Apr 2014, 06:15
  #90 (permalink)  
 
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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.
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Old 6th Apr 2014, 06:22
  #91 (permalink)  
 
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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!!

Last edited by LeadSled; 6th Apr 2014 at 07:44. Reason: spelling
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Old 6th Apr 2014, 06:39
  #92 (permalink)  
 
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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.
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Old 6th Apr 2014, 07:00
  #93 (permalink)  
 
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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.
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Old 6th Apr 2014, 07:38
  #94 (permalink)  
 
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---- 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.
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Old 6th Apr 2014, 07:58
  #95 (permalink)  
 
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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).

Last edited by Creampuff; 6th Apr 2014 at 08:14.
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Old 6th Apr 2014, 08:12
  #96 (permalink)  
 
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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 donít 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.
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Old 6th Apr 2014, 08:12
  #97 (permalink)  
 
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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.
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Old 6th Apr 2014, 08:29
  #98 (permalink)  
 
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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.
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Old 6th Apr 2014, 09:11
  #99 (permalink)  
 
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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!!
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Old 6th Apr 2014, 10:00
  #100 (permalink)  
 
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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
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