A Little Gem from CASA Experts
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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!!
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!!
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.
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.
Last edited by Lead Balloon; 3rd Apr 2018 at 09:22.
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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?????
Perhaps that is what was meant to be said?????
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.
If it’s an attempted late April Fool’s joke, it ain’t funny.
Muppets.
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For appropriate fuel leaning practices refer to the aircraft POH (pilot's operating handbook) or AFM (aircraft flight manual), as applicable, for specific instructions.
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.
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.
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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.
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?
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?
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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.
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.
At what mixture setting is cylinder head temperature at its highest?
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.
Under what conditions are unburnt gases exposed to the most heat for the longest time?
You’re completely bonkers.
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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.
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.
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.
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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. 😁
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. 😁