Avgas quality concerns ... helicopters
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Originally Posted by Bend alot
While I don't fly helicopters nor do mustering I have been told that during mustering mostly it is not high power used. Lots of manoeuvring yes, but cows don't run very fast.
Last edited by A Squared; 1st Oct 2018 at 04:38.
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Originally Posted by rutan around
Actually it slows down the start of burning after the ignition spark.(Ignition lag) Once the burn gets going it burns at the same rate as unleaded fuel.
From the people that I know that do mustering in R22 they say it is not high power more the noise and slowly moving them forward. If power was indeed used often then the carburettor machines would have long ago been replaced with the fuel injected models.
I guy I know that bent his machine (an owner operator musterer) had the option to go the fuel injected way but could not make a case for the extra cost.
I guy I know that bent his machine (an owner operator musterer) had the option to go the fuel injected way but could not make a case for the extra cost.
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A squared says
You forgot the reason lead is added to fuel. It's to stop detonation during the normal power range of a properly timed engine. You could certainly correct the timing BUT at high power settings combined with a hot day and or a long climb you would get detonation if the octane rating was too low. The lead slows down or stops auto ignition ahead of the flame front. It's a public holiday here in Australia for QE2s birthday. Having toasted her health you're doing my head in answering technical issues this late in the day.
I've just solved the aviation leaded fuel issue: Simply remove all the lead and retard the ignition on all the engines.
Originally Posted by Bend alot
rutan - I was taught that lead also assisted in heat removal by the unburnt fuel air mixture out of the cylinder.
It appears that for some reason the exhaust valve and its guide area are now getting and remaining hotter than they use to, given that it is not just Lyco' but also PMA cylinders and even TCM's. I can only conclude that it is pilot error in operation of engines. ( I have my AWI interview next week).
It appears that for some reason the exhaust valve and its guide area are now getting and remaining hotter than they use to, given that it is not just Lyco' but also PMA cylinders and even TCM's. I can only conclude that it is pilot error in operation of engines. ( I have my AWI interview next week).
) but to reef this back as pilot error shows a total lack of understanding of helicopter operation and engine management. This has been extant for some 18 months and change to fuel additives is clearly being associated with the failures: that they are occurring in helicopters can be attributed to the lower cooling available plus the higher power demands, which are not related to airspeed but to handling requirements in a low level environment.
Low in hot ambient air temps and constant large power changes in slow moving helicopters mostly seems a large factor.
Sadly not many of these aircraft have multi egt and cht devices fitted, but even then we could be looking at a heat change just 2 inches from the previous point with a new fuel.
Sadly not many of these aircraft have multi egt and cht devices fitted, but even then we could be looking at a heat change just 2 inches from the previous point with a new fuel.
Originally Posted by John Eacott
I wouldn’t expect an Air Warfare Instructor to know better ( ) but to reef this back as pilot error shows a total lack of understanding of helicopter operation and engine management. This has been extant for some 18 months and change to fuel additives is clearly being associated with the failures: that they are occurring in helicopters can be attributed to the lower cooling available plus the higher power demands, which are not related to airspeed but to handling requirements in a low level environment.
) but to reef this back as pilot error shows a total lack of understanding of helicopter operation and engine management. This has been extant for some 18 months and change to fuel additives is clearly being associated with the failures: that they are occurring in helicopters can be attributed to the lower cooling available plus the higher power demands, which are not related to airspeed but to handling requirements in a low level environment.Again I am told that high power is not a requirement of most muster operations in R22 or R44, power changes and manoeuvrability are attributes of a muster operation in helicopters. This is certainly true in fixed wing that I have been a pax in a 172, would love to see a 210 or even a 208 do a muster.
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but to reef this back as pilot error shows a total lack of understanding of helicopter operation and engine management.
Originally Posted by A Squared
If that is literally true as stated, I've just solved the aviation leaded fuel issue: Simply remove all the lead and retard the ignition on all the engines.
But, alas, the engines would no longer make their rated power.
There is usually no simple solution to a complex problem.
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Originally Posted by rutan around
You forgot the reason lead is added to fuel. It's to stop detonation during the normal power range of a properly timed engine.
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Originally Posted by A Squared
Ahhh, so you agree that lead affects the combustion of the fuel charge beyond merely delaying ignition then.
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Originally Posted by Tankengine
Does not lead aid in piston-cylinder lubrication as well?
The mustering machines are worked very hard.
The recording of flight hours leaves a lot to be desired.
Low time pilots are the norm for the industry.
If it still flies it must be serviceable.
The damage to the valves is indeed interesting, there doesn't appear to be pounding of the seat or tuliping of the valve head.
The broken/pitted edges seems more mechanical damage rather than over heating.
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Originally Posted by Tankengine
Does not lead aid in piston-cylinder lubrication as well?
Piston engine fuel itself is also an aid to lubrication/cooling, a change in the fuel chemistry maybe having an effect as seen.
I think most agree here that IC powered piston Helicopters especially in the mustering role in hot dusty conditions are subject to a multitude of stresses such as high power settings changing constantly with varying operating temps & environmental conditions hence the high maint required on these machines. Perhaps that seeing as there is a perceived increase of late of rapidly deteriorating engines (due whatever actual reason/s) the maint sched needs to be increased?
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Machtuk Perhaps that seeing as there is a perceived increase of late of rapidly deteriorating engines (due whatever actual reason/s) the maint sched needs to be increased?
Perhaps the Lycoming servicing schedule should be adhered to, including the first 100 hour inspection criteria after overhaul/initial fitment.
Perhaps the Lycoming servicing schedule should be adhered to, including the first 100 hour inspection criteria after overhaul/initial fitment.
Megan, 20.7.4 is quite clear on this
There is even a thread on the subject.
CASA opinion: Aircraft must be grounded in temps over 40 degrees
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Originally Posted by megan
Well, it seems not tio540. CASA issued a letter forbidding operation above 40C, to which I personally replied, with clarification rebutting their argument obtained from the manufacturer (Cessna). That's about twelve months ago, I'm still awaiting a reply.
There is even a thread on the subject.
CASA opinion: Aircraft must be grounded in temps over 40 degrees
There is even a thread on the subject.
CASA opinion: Aircraft must be grounded in temps over 40 degrees
Read CAO 20.7.4 again.
.
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Machtuk says,
Where did you get that idea? Just for starters if it's such a good lubricant why do bores wear if you run far too rich or in a car with the choke on.
As to the current problem wouldn't it be a good idea to look at what has changed in the last 18 months and what hasn't changed. If the same pilots are flying the same choppers in the same way they have been flying them for years it's hardly likely to be an operational problem. Has the fuel changed? Is it only effecting engines overhauled in the last couple of years? Is it effecting engines across the board? If it's only effecting new and fairly recently overhauled engines then maybe the cylinder manufacturers are playing silly buggers and experimenting with new ideas all the while using their customers toe beta test their ideas.
AXA says:
Yes of course. It delays the onset of detonation. What should be taken from this is that changing fuels should not be taken lightly and timing varies with different fuels. When you chop and change fuel in a modern car it doesn't matter because they have knock detectors and the cars computer takes care of the problem.I don't personally know of any aircraft engine with a knock detector but there may be some.
Piston engine fuel itself is also an aid to lubrication/cooling,
As to the current problem wouldn't it be a good idea to look at what has changed in the last 18 months and what hasn't changed. If the same pilots are flying the same choppers in the same way they have been flying them for years it's hardly likely to be an operational problem. Has the fuel changed? Is it only effecting engines overhauled in the last couple of years? Is it effecting engines across the board? If it's only effecting new and fairly recently overhauled engines then maybe the cylinder manufacturers are playing silly buggers and experimenting with new ideas all the while using their customers toe beta test their ideas.
AXA says:
Ahhh, so you agree that lead affects the combustion of the fuel charge beyond merely delaying ignition then
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Originally Posted by tio540
Megan, CASA did not forbid operation above 40 deg C. The correspondence stated "a pilot must not operate an aircraft outside the limits set out in the AFM.
