From: Epijk@aol.com
Message-ID: <18f.5029b57.29c78ea7@aol.com>
Date: Mon, 18 Mar 2002 13:40:39 EST
Subject: Re: Propeller Damage
To: lancair.list@olsusa.com
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Reply-To: lancair.list@olsusa.com

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In a message dated 2/20/2002 12:04:36 AM Pacific Standard Time, 
dfs155@earthlink.net writes:

<<<...From the forces resulting from a prop strike/sudden stoppage, the crank 
can
suffer a crack if not outright failure...>>>

Dan:

Sage advice, but perhaps wasted. 

Do you think a guy who does taxiway departures is going to be influenced by 
the experience-developed procedures regarding sudden stoppages contained in 
such publications as Lycoming Service Bulletin 533-A, Continental Service 
Bulletin 96-11, Woodward (prop governors) Service Bulletin 33574B, McCauley 
(prop governors) Service Bulletin SB 215B, or the Slick (magnetos) Overhaul 
Manual?

For anyone interested, a prop strike has the potential to severely damage NOT 
ONLY the prop and crankshaft/propshaft, but ALSO all accessories, 
accessory-drives, and recip parts in the engine. Lycoming, Continental, and 
others define a "propeller strike" as follows (from Lyc SB-533-A):
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(a) Any incident, whether or not the engine is operating, 
that requires repair to the propeller other than minor 
dressing of the blades;

(b) Any incident during engine operation in which the 
propeller impacts a solid object which causes a drop 
in RPM and also requires structural repair of the 
propeller (incidents requiring only paint touch-up 
are not included). This is not restricted to propeller 
strikes against the ground, and although the propeller 
may continue to rotate, damage to the engine may 
result, possibly progressing to engine failure.

(c) A sudden RPM drop while impacting water, 
tall grass, or similar non-solid medium, where propeller 
damage is not normally incurred.

The above definitions encompass any propeller strike 
occurring at taxi speeds and during touch-and-go operations, 
involving propeller tip ground contact. In addition, they 
also include situations where an aircraft is stationary 
and the landing gear collapses causing one or more 
blades to be bent or substantially damaged, or where 
a hangar door (or other  object) strikes the propeller 
blade. These cases should be handled as a sudden 
engine stoppage because of potentially severe side 
loadings on the propshaft flange, front bearing, and seal.
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Complete disassembly and inspection (per ASTM E-1444 or E-1417) of engine and 
accessories is required by all the abovementioned publications. Some will 
argue it's overkill; I would respond that if you believe it's overkill, you 
are deeply involved in wishful thinking (as opposed to rational thought). 
Yes, many post-strike inspections find no damage. But when actual damage is 
discovered, it has the high potential of being fatal.

For more info on prop strikes 
(and info on the forced landing of a Lancair-4P), visit:

http://www.epi-eng.com/Propeller_Damage.htm

Jack Kane
EPI, Inc. 

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