A Little Gem from CASA Experts
 

Folks,
From a new AWB:

AIRWORTHINESS BULLETIN
AWB 85-023 Issue 1 – 3 April 2018
Piston Engine Spark Plug Insulator Cracking

Fuel Management - Lean-of-peak operation where precise control over the engine's performance cannot be assured is to be avoided to negate the possibility of detonation. For appropriate fuel leaning practices refer to the aircraft POH (pilot's operating handbook) or AFM (aircraft flight manual), as applicable, for specific instructions.

And we are supposed to take CASA seriously???

Tootle pip!!

That is pure gold. I thought we got passed this and the enlightenment was starting to spread... guess I was wrong.

Yep. 50F ROP cruise is still their idea of perfection. :ugh:

Where's Jaba and the APS guys?

To quote the Spodman once again: May Jesus pee in a bucket. What are these wombats on?

A complete misunderstanding of what causes detonation.

A complete misunderstanding of what caused the cracked spark-plug insulators.

Apparently the spark-plugs on engines fitted to aircraft with POHs that deal with LOP operations ‘know’ they’re fitted to those engines and aircraft, and therefore ‘know’ not to crack. Not so when the spark-plugs are fitted to the same engine fitted to an aircraft without a POH that deals with LOP.

Complete muppets. :ugh:

I do wish CAsA would stick to doing what they know best, whatever that maybe.

CC

Fuel Management - Lean-of-peak operation(missing comma) where precise control over the engine's performance cannot be assured (missing comma) is to be avoided to negate the possibility of detonation.

Perhaps that is what was meant to be said?????

It was released on 1 April!

It’s dated 3 April: https://www.casa.gov.au/file/197511/...token=7BkVew_q

If it’s an attempted late April Fool’s joke, it ain’t funny.

Muppets.

Perish the thought! What a ridiculous suggestion.

Sadly, it is an objectively risky suggestion in the case of POHs and AFMs that enshrine the sort of hogwash repeated in the AWB.

The primary causes of spark plug insulator cracking?

(1) LAMEs dropping plugs then surreptitiously refitting rather than replacing them.

(2) Manufacturing defects.

To the extent that the way in which an engine is run may cause insulator cracking, (3) would be running the engine RICH OF PEAK, but not far enough rich of peak.

But an evidence-based regulatory system should be run on the basis of folklore. It must be the fault of pilots running engines LOP. FFS. :ugh:

You are obviously an APS convert.

What I have learnt since I first read the Deakin articles about 15 year ago:
1) APS don't know as much as they think they know.
2) Engine manufacturers know a lot more than APS give them credit for.

In a disagreement between the engine manufacturers and APS I give the benefit of the doubt to engine manufacturers.

What causes detonation? How about:
1) Heat
2) Time

Detonation is definitely associated with insulator cracking, but APS do have a tendency to put anything that doesn't fit their narrative down to LAMEs dropping plugs or manufacturing defects.

The laws of physics and the causes of problems aren’t about being a “convert” or the “benefit of the doubt” (and more fool you and your wallet in giving the benefit of the doubt to engine manufacturers).

You’ve identified “heat” as a (or is it “the”?) cause of detonation. OK then, on your superior knowledge:

1. At what mixture setting is cylinder head temperature at its highest?

2. At what mixture setting is exhaust gas temperature highest? Is it lean of peak, or rich of peak?

APS have a few problems here and there with the laws of physics (and chemistry).

I said heat and TIME. If you understand a little of how tetra ethyl lead suppresses knock you will see where time comes into it.

That is the wrong question. The right question is "Under what conditions are unburnt gases exposed to the most heat for the longest time?"

The answer is: when combustion is slow, because you have heat from the already burnt gases acting on unburnt gases. Very lean mixture makes it worse because uneven mixing can give you very lean spots that are very slow to burn.

Cylinder head and valve temperature can contribute, but they are far from the only factor.

Well that’s a relief.

You’re completely bonkers.

Whatever you say.

If you're interested in information from people other than APS, here is a good article:
Engine Basics: Detonation and Pre-Ignition by Allen W. Cline

I would wager that Allen Cline has done a lot more detonation testing with more instrumentation and under a greater variety of conditions than George Braly and co.

Again, if the article at the link is what you’re citing as authority for the proposition that running an engine LOP is the (or even a) cause of spark-plug insulator cracking, you’re completely bonkers.

At risk of calling out the popcorn, I suggest a truce between andrewr and Lead Balloon.

For those that don't have an engine monitor and prefer to run 50F ROP, I say good on you. For those that appropriately run LOP, I say good on you too.

But personally, I'm a fan of the science that tells me that running LOP in the cruise can be a very good idea.

Dammit, Gerry, I was just organising the deck chair and the esky, getting ready for the show.

Never let the turth get in the way. Even when they proven wrong they never give up. They just delete the thread. When they dont even know or understand the combustion temperatures very between rich and lean and which way the thoose changes go. Prove them wrong and hey presto thread deleted.

But the greatest one was when 70% lop is the same as 70%rop..
Wtf anyone knows that a reduction of airspeed running lop is greater than running rop. Therefore it cant be the same not even close.

Any way run it i dont care keeps me in employment. 😁

You just made this up, admit it now.

I didn’t make it up.

I’ve just been through the usual cycle of working out what damage and defects have been inflicted on my aircraft during annual maintenance. This year was pretty good compared to others.

Only four loose washers and one loose lockwire offcut found in the engine bay. The ‘good’ news is that I don’t think the washers were left off anything important but were rather dropped and ignored because - well I suppose it might be inconvenient to try to find them. A missing adel clamp from one of the fuel hoses meant it was rubbing against the engine crankcase. But it’s only a fuel hose.

And they always set a special, hard-to-find trap. This year it was the pilot’s seat not being engaged on one of the rails. They nearly got me, because when I sat on the seat and adjusted it fore and aft it felt normal: two of the rails were engaged and the third anchor was pressed against the top of the third rail due to my weight. Luckily I had to taxi to get fuel, first, and discovered the seat was off the third rail through sheer luck while embarking a second time.

But all round a pretty ‘good’ outcome compared with some previous years.

People who do this quality of work would never, never accidentally drop a spark plug and surreptitiously refit it. :rolleyes:

Andrewr just one question. Have you ever been to an APS seminar?

Anecdotal evidence, as impressive as your's may be, could still be made up.

The obvious answer, if the lack of quality control is true, would be to change service provider.

Whilst there is no doubt that spark plugs have been dropped and damaged, I struggle with the concept that the said plug would not have been replaced. It would behoove the mechanic to sell you a new one, considering that you would have no idea when it had been damaged.

To be honest, I would agree that there are indeed some dodgy workshops operating in the GA environment, and in fact have rolled my swag twice due to disagreements with the practices in outback workshops.

On your comment in a recently closed thread, I see your bet and raise you a carton of beer.:ok:

How much information have you read about detonation, mixture etc. that did NOT originate from APS? It is always wise to gather information from multiple sources. There are a few critical areas (particularly chemistry) where they get things very wrong. Even references to "the laws of physics" when everything they are referring to is chemistry.

I have no doubt many people run their engine LOP without problems. However, the APS attitude where if you DO have problems it means the mechanic dropped a plug, or it was a manufacturing defect, or you simply weren't doing it right concerns me.

They claim science, but I have never seen anything from them that actually looks like science. As far as I know none of them have science qualifications.

(If you're wondering what real science might look like, try some of the NACA reports. They have detailed descriptions of the tests that were done, exactly what was measured and how, the results, conclusions etc. Enough information that someone else could re-run the experiment to verify the result.)

It’s not “anectdotal”. It’s fact. Witnessed. My post-maintenance pre-flight inspections and test flights are always carried out these days accompanied by another person. I do that precisely because of the pervading folklore - manifested in your post and the AWB - that LAMEs never make mistakes.

I have changed LAMEs. The one I use now seems less mistake-prone than the one I used previously.

The other pervading folklore is that plug manufacturers never produce a defective product, and nor do engine manufacturers.

If I ran my engine in accordance with the POH, I’d be giving the engine the hardest pounding I could give it. Unnecessarily. There’s a reason POHs say these things: Back in the heyday of GA, it was a speed race between the brands and a couple of knots on the competion was a key marketing advantage. So what if the engine was getting the hardest pounding it could get? The chump who purchased it had deep pockets and any damage done was always their fault.

No I haven't. And they probably don't want me, because I would keep interrupting with questions every time they said something questionable. For example:

"Peak EGT is the worst place to run your engine."

Why?

Every mixture vs fuel efficiency chart shows peak EGT corresponds very closely to mixture for best efficiency. If the engine designer cares about fuel efficiency, this is exactly where he wants the engine to run in cruise. If the engine manufacturer says you can run there in cruise why would you doubt them?

"But the heat..."

Engines are designed to burn fuel and get hot. It's what they do. As long as the cooling is adequate you will be fine. And if the engine gets too hot running at the settings it was designed for, you have a cooling problem.

"But it will last longer if it's cooler..."

Evidence please. How much longer? How did you measure it?

Who said “peak EGT is the worst place to run your engine”?

I ran my engine at peak EGT on Monday, because that happened to be the ‘best’ setting for the altitude and range requirements.

You do understand that the data prove that at peak EGT the CHTs are cooler than at around 25C ROP?

You are either being purposely obtuse or cannot read and comprehend basic English. No where has it been said or implied that LAMEs do not make mistakes.

I would counsel you to read the AWB in its entirety and not concentrate on the spark plug issue. Most of the advice given in the AWB is very sound and should be followed to ensure the longevity of your engine.

If you have the correct equipment to follow the APS LOP method, by all means do so as long as you are comfortable with it and do all that APS teach.

The day that I have to rely on a CASA AWB as the source of any wisdom is the day I give it away. To the extent that the content is accurate, it will have been based on primary sources that are available directly anyway. I prefer the primary sources.

Therein lies the dichotomy, you are willing to use the AWB to pursue your vitriolic agenda against CASA and LAMEs but not as a source for correct maintenance.

I don’t think you meant “dichotomy”.

And guess what: It’s a free country and I’m allowed to criticise anyone I like. Especially when the criticism is based on fact. I’m allowed to use whatever sources I like for “correct maintenance”, just as CASA does in its AWBs.

andrewr who has never been to an APS says that they say:


I have been to one of their seminars and they have never said that. Careful they don't sue you.

They probably would love to have you attend one of their seminars. It would be greatly to your benefit and also to aviation in general if it stopped you presenting demonstrably incorrect information tangled up with random bits and pieces of fact.

Fair enough; it was the closest I could get, out here at the station kitchen.

If, like you, my machine was coming out of a servicing with a plug with cracked ceramic or any other physical damage which had showed when I taxied to the fuel bowser (righteous indignation moment), my suggestion would be: negotiate to have the rest replaced with known good ones, preferably new, but seconds would do as long had atleast as much time in service remaining as mine.

If your near Cable Beach any time this season, PM for a sherbet, could talk over beers looking out to the Indian Ocean.

Surely that’s already addressed by the General Competency Rule?
https://www.casa.gov.au/file/131276/...token=kzbe519K

andrewr: I will pay for your place to attend the next APS seminar delivered in Australia. PM me when the next one’s advertised, if you’re available to attend.

Folks,
Once again, the anti-LOP troglodytes are out in force, again! All those airlines, over years of "big pistons" had it all wrong!! Pratt & Whitney and Curtis Wright had it all wrong.

Our semi-illiterate mate Connedrod, has chucked his two bob's worth in --- Rod, for your information, at a given HP output, the aircraft performance will be the same, the only difference at, say 65% power, ROP and 65% power, LOP is the fuel flow -- unless you have invented ROP/HP and LOP/HP.

As for the whole document, it is a simplistic "teaching you to suck eggs" effort.

Amazingly, I did know you are supposed to get all the blast cleaning material out after I have cleaned a plug --- and I would hope every LAME, indeed every first year apprentice (if there is still such a thing), knows.

I do highly recommend the small Champion book and card for reading plug condition. And please use a recommended tool to adjust gap, not as I saw quite recently, a plug clamped in a vice, and the "adjustment" being "achieved" with a hammer and cold chisel.

Engine manufacturer's manuals for particular engines are a far more reliable guide to the engine capability, than an AFM/POH for reasons made obvious (marketing edge) in a previous post.

Tootle pip!!

PS: Eddie, our mate Lead Balloon is actually very well qualified in the aero MRO field, I hope he doesn't mind me letting the cat out of the bag.

Such sound advice too, is a great tool for troubleshooting engine condition. For those that want to modernise their thinking on piston engine maintenance there are many resources available on the internet, APS being only one source.

As for the other, I'd be requesting he can't work on my machine, unless under direct supervision. That being my obligations as an owner in CASA regulations.
I always make sure to be shown the disassembled filter and strained engine oil from the engine and ensure that both engine screens and the main oil filter are serviced and inspected. CASA AWB 85-014 shows very good reasons to do so.

Does APS represent me in court when I get a $50 million lawsuit, following an accident, and the lawyers subpoena trend sheets operating contrary to the manufacturers POH?

Maybe I get a $250 refund.

Put this Supplement in your POH, and the engine magically knows that it’s OK to run LOP: http://www.gami.com/gamijectors/afms...20rev%20ir.pdf

Then the documents subpoenaed by the lawyers won’t disclose operations contrary to the POH.

So I save $15 per hour in fuel, but the lawyers get your house.