It's time I came out...
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It's time I came out...
... and just really vented my annoyance at people who start their aircraft with loads of power on.
Are there rogue checklists about that say "Throttle set 4 inches"
It grates me when I hear it especially when it's clearly the first flight of the day.
Interestingly it's normally on club aircraft who's pilots aren't going to have to sell their pets to afford the overhaul when it creeps up early...
I feel better now
Are there rogue checklists about that say "Throttle set 4 inches"
It grates me when I hear it especially when it's clearly the first flight of the day.
Interestingly it's normally on club aircraft who's pilots aren't going to have to sell their pets to afford the overhaul when it creeps up early...
I feel better now
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Not as annoying as people who start engines without any form of brakes set.
Same thing really, I don't suppose there are rogue 'before start checklists' out there saying:
"BRAKES....... OFF".
Same thing really, I don't suppose there are rogue 'before start checklists' out there saying:
"BRAKES....... OFF".
'tis funny that, Mono. Because my lady friends tell me that what men consider to be an inch is actually probably nearer to a centimetre....
If that.
If that.
Jet Blast Rat
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Yes; to other instructors - how come when I check some people out, they read the checklist as "Throttle 1/4 open"? Ever aircraft I have ever flown that burns petrol has the instruction "Throttle 1/4" open".
That little "inch" could be the root of monocock's problem
{think with a user name like his I should leave it to your imagination...}
That little "inch" could be the root of monocock's problem
{think with a user name like his I should leave it to your imagination...}
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....and is it just me that finds for the perfect start 1/4 in is too much. Just a crack of throttle is all that is required.
I would like to know the secret that gets a plane started with 4in throttle 'cos it never works for me.
I would like to know the secret that gets a plane started with 4in throttle 'cos it never works for me.
If memory serves me correctly, on the Bulldog we used to start it with full throttle and mixture to cut off. When it fired you closed the throttle and set mixture to rich; felt like you needed 3 hands until you got used to it!
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Blimey I thought you were going to confess to being the only one in the village
to sail beyond the sunset
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Never really thought about it until some poor bastid where I fly started up with full power and chopped one wing off a shiny new a/c. Oops.
Now I start up facing away from anything expensive with a millimetre of throttle, in case the brute power of my 65 HP runs away with me.
Now I start up facing away from anything expensive with a millimetre of throttle, in case the brute power of my 65 HP runs away with me.
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Not as annoying as people who start engines without any form of brakes set.
Of course those with the third wheel at the wrong end don't need to bother with this consideration
Making sure you are not pointing at something close is more reliable than using the brakes anyway.
Mike
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I operated 3 parachute aircraft some years ago, all of which went to TBO without failure. The initial start of aircraft piston engine is about the most important part of looking after an engine and ensuring it's reliability and longevity. The second is regular oil changes, usually more frequently than scheduled because none of us use the aircraft enough to clear contaminants from the oil correctly.
The engines we mainly use are large capacity, air cooled, old fashioned engines. They do not have any of the sophistication of current car engines, neither are they made to the same tolerances - this is a direct result of the huge effort to improve and certificate new technology.
The cylinders bores are tapered, i.e. the top of the piston stroke is 'tight' when cold, this is so that when the engine warms up, the bore is correct for the piston and rings. So, the first 2 minutes of running are critical to even the bores, bring the heads up to temperature and get things moving gently. Engines should not be run above 1,000 rpm during the first 2 minutes from cold. When you see someone start an engine and run it faster, they are damaging the engine.
There are good resources about engine management on t'internet, particularly on the TCM site and Lycoming site and on Avweb. A little research, care of operation and thought will save you lots of money and reduce the risk of a premature failure
The engines we mainly use are large capacity, air cooled, old fashioned engines. They do not have any of the sophistication of current car engines, neither are they made to the same tolerances - this is a direct result of the huge effort to improve and certificate new technology.
The cylinders bores are tapered, i.e. the top of the piston stroke is 'tight' when cold, this is so that when the engine warms up, the bore is correct for the piston and rings. So, the first 2 minutes of running are critical to even the bores, bring the heads up to temperature and get things moving gently. Engines should not be run above 1,000 rpm during the first 2 minutes from cold. When you see someone start an engine and run it faster, they are damaging the engine.
There are good resources about engine management on t'internet, particularly on the TCM site and Lycoming site and on Avweb. A little research, care of operation and thought will save you lots of money and reduce the risk of a premature failure
Avoid imitations
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Javelin,
Your concern about the bore tapers causing an engine to be tight at the top end might not be completely correct in all engines, at least for the first few seconds of a start sequence.
Pistons expand relatively more than their bores do, as they are of aluminium alloy and tend to expand relatively more than the steel cylinders.
Because of this they are made with clearances that leave them slightly SLACK in the bores when the engine is fully cold. I fully agree that if the engine is not warmed up correctly, the pistons may expand to a point where they might BECOME subsequently tight and cause scuffing, because they absorb heat relatively quickly and expand at a greater rate than do the cylinders.
But another problem is the potential lack of lubrication after an engine has stood for a while. If the engine is idled too slowly immediately after start, insufficient oil pump flow may delay lubrication to the components furthest from the oil pump, namely the camshaft and valve gear.
Years ago, I was strongly advised to kick over my high compression / racing cammed BSA M/C engine (uprated valve springs) with the ignition off until oil began to return to the tank. The drill was then to hold a forefinger over the oil return stack pipe to ensure the rocker gear was pressurised with oil immediately after start up. You really needed three legs and two pairs of hands to do this and it took quite a lot of kicking, but owners who didn't do this got cam surface and follower damage.
Best thing is to follow the engine manufacturer's guidance to the letter.
Your concern about the bore tapers causing an engine to be tight at the top end might not be completely correct in all engines, at least for the first few seconds of a start sequence.
Pistons expand relatively more than their bores do, as they are of aluminium alloy and tend to expand relatively more than the steel cylinders.
Because of this they are made with clearances that leave them slightly SLACK in the bores when the engine is fully cold. I fully agree that if the engine is not warmed up correctly, the pistons may expand to a point where they might BECOME subsequently tight and cause scuffing, because they absorb heat relatively quickly and expand at a greater rate than do the cylinders.
But another problem is the potential lack of lubrication after an engine has stood for a while. If the engine is idled too slowly immediately after start, insufficient oil pump flow may delay lubrication to the components furthest from the oil pump, namely the camshaft and valve gear.
Years ago, I was strongly advised to kick over my high compression / racing cammed BSA M/C engine (uprated valve springs) with the ignition off until oil began to return to the tank. The drill was then to hold a forefinger over the oil return stack pipe to ensure the rocker gear was pressurised with oil immediately after start up. You really needed three legs and two pairs of hands to do this and it took quite a lot of kicking, but owners who didn't do this got cam surface and follower damage.
Best thing is to follow the engine manufacturer's guidance to the letter.
Last edited by ShyTorque; 28th Jul 2005 at 14:32.
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I agree with Send Clowns - a lot of peole seem to ignore the " in the instructions and assume the throttle should be 1/4 open - perhaps the checklists should spell out the word 'inch' ie "Throttle 1/4 inch open"
I've also notice the same thing as 18 greens, 1/4 inch is often too much, and I have to dive for the throttle to reduce rpm.
The nicest engine for starting that I've found is the O-540 in the C182-RG: you can leave the throttle at idle, give it a couple of squirts of primer and she fires up no trouble at all, then you just increa the rpm as needed.
Brooklands
I've also notice the same thing as 18 greens, 1/4 inch is often too much, and I have to dive for the throttle to reduce rpm.
The nicest engine for starting that I've found is the O-540 in the C182-RG: you can leave the throttle at idle, give it a couple of squirts of primer and she fires up no trouble at all, then you just increa the rpm as needed.
Brooklands
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The R22 also has the O-320 or 0-360 engine. If ever you fly one, never ever start it with the throttle anywhere but fully closed and held there. You would not believe how fast an unloaded engine can accelerate through the rev band and right out through the top of the gauge.
Last edited by muffin; 28th Jul 2005 at 19:48.
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As has been stated, some checklists leave alot to be desired. The one on the cub @ White Waltham states 1/4 open with no reference to any units. Sensibily one only opens the throttle a small amount, but you can see where these kinds of errors come from.
