richard.goode(at)russiana Guest
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Posted: Mon Apr 24, 2006 6:55 am Post subject: Ground Strikes with M14P |
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Ground Strikes with M14P
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I am alarmed�that people consider it to be general practise to replace a prop after ground strike and go on flying.�
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The issues to consider are:
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There are several areas where the M14P can suffer in a ground strike:
- The satellite gears in the gearbox are small and can crack with a shock-load.
- The crankshaft is pinned together and a shock can move the� separate parts of the crankshaft in relation to each other.
- The supercharger assembly is turning at over eight times engine speed and even at idle has a fair amount of inertia.
- The manufacturer,s strict instruction is that any ground strike must have an engine replacement.� This is over-cautious, and the real issues are the speed of which the engine was turning; whether it came to an immediate stop or continued; and the amount of prop damage, which will indicate the blow to the engine.�
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We have a Sukhoi customer who had a significant ground strike, but at idle; changed the prop, and about ten hours flying later one of the satellite gears broke up, and the engine locked solid.� Fortunately�he was taxiing in after an aerobatic sequence.�� Had it happened a minute earlier the engine would almost certainly have been torn out.�
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The prudent approach is to�say that a small amount of propeller damage, and�where the prop was�not totally stopped should mean that a prop change alone is fine.�
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If the engine was at higher power, then the gearbox should be removed and the components crack tested.�
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If the prop stopped suddenly I personally believe the whole engine should be checked or changed.�
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Richard Goode
Richard Goode Aerobatics
Rhodds Farm
Lyonshall
Herefordshire
HR5 3LW
United Kingdom
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Tel:� +44 (0) 1544 340120
Fax: +44 (0) 1544 340129
www.russianaeros.com
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