HILO, HI, USA
N4193
BEECH D18S
ABT 45 MI FM LNDG, THE L ENG RPM BGN TO FLUCTUATE, THEN AT ABT 15 MI FM LNDO, IT LOST POWER ALTOGETHER. THE PLT SAID THE ACFT WOULD NOT MAINT ALTITUDE. UNABLE TO RCH THE RWY, HE DITCHED THE ACFT IN HILO BAY ABT 1/4 MI FM SHORE & 1.5 MI FM THE ARPT. AFTER RETRIEVAL, THE ACFT & L ENG WERE EXAMINED. THE ACCESSORY GEAR DRIVE SHAFT WAS FND TO HAVE FAILED IN TORSIONAL OVERLOAD. ON THE INSIDE OF THE CASE, AN AREA OF GOUGING & ABRASION WAS FND DRCTLY IN FNT OF THE STARTER GEAR. (THE LEFT MAG, FUEL PUMP & PROP GOVERNOR WERE DRIVEN BY THE ACCESSORY DRIVE GEAR.) DEEP IMPRESSIONS WERE NOTED ON ABT 70% OF THE GEAR TEETH, WITH MTRL DISPLACEMENT & GOUGING EVIDENT. THERE WAS EVIDENCE THAT THE COLLECTOR DRIVE FLOATING GEAR MAY HAVE MOVED FORWARD & HAD CONTACTED THE ENG CASE. ALSO, THERE WAS EVIDENCE OF MECHANICAL INTERFERENCE WITHIN THE ACCESSORY DRIVE GEAR SYS. THE ACFT GROSS WT AT THE TIME OF THE ACDNT WAS ABOUT 9108 LBS.
THE AIRCRAFT'S LACK OF SINGLE ENGINE PERFORMANCE TO MAINTAIN ALTITUDE AFTER THE ENGINE LOST POWER. FACTORS RELATED TO THE ACCIDENT WERE: DISPLACEMENT/MECHANICAL INTERFERENCE WITHIN THE ACCESSORY DRIVE GEAR SYSTEM OF THE LEFT ENGINE, FAILURE OF THE LEFT ENGINE ACCESSORY DRIVE GEAR SHAFT, AND THE FAA'S INADEQUATE CERTIFICATION/APPROVAL OF THE OPERATOR, IN ORDER TO ASSURE COMPLIANCE WITH 14 CFR 135 CONCERNING THE ENGINE-OUT CAPABILITY.
Source: NTSB Aviation Accident Database
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