lml@lancaironline.net Mailing List Archive

<<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> << Lancair Builders' Mail List >> <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> >> 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): ------------------------------------------------------------------------------ ------------- (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. ------------------------------------------------------------------------------ ----------- 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. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> LML website: http://members.olsusa.com/mkaye/maillist.html LML Builders' Bookstore: http://www.buildersbooks.com/lancair Please remember that purchases from the Builders' Bookstore assist with the management of the LML. Please send your photos and drawings to marvkaye@olsusa.com. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>