NTSB Identification: ANC89FA034.
The docket is stored on NTSB microfiche number 38759.
Nonscheduled 14 CFR AKLAK AIR LTD
Accident occurred Friday, January 13, 1989 in FORT YUKON, AK
Probable Cause Approval Date: 05/22/1990
Aircraft: BEECH BE-99, registration: CFBCH
Injuries: 2 Uninjured.
NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.
DURING CRUISE FLIGHT AT 8000 FEET ABOVE MEAN SEA LEVEL THE CO-PILOT NOTICED A 100 POUND TORQUE INCREASE ON THE NUMBER TWO ENGINE. DURING HIS ATTEMPT TO REDUCE THE TORQUE HE HEARD AN EXPLOSION, SAW SPARKS COME FROM THE NUMBER TWO ENGINE EXHAUST STACKS AND OBSERVED A SLOW TURNING PROPELLER AS THE ENTIRE ENGINE NACELLE DISAPPEARED BENEATH THE AIRPLANE. FULL POWER ON THE NUMBER ONE ENGINE ALLOWED THE CREW TO REDUCE THE RATE OF DESCENT TO 1,500 FOOT PER MINUTE AND THEY CRASH LANDED ON THE FROZEN RIVER. ON SITE EXAMINATION REVEALED ONE PROPELLER BLADE FROM THE NUMBER TWO ENGINE WAS MISSING AND THAT THE NUMBER TWO ENGINE HAD SEPARATED DURING THE IMPACT SEQUENCE. SUBSEQUENT METALLURGICAL EXAMINATION SHOWED A FATIGUE FRACTURE ON THE REMAINING STUB OF THE MISSING BLADE.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: THE SEPARATION OF A SINGLE PROPELLER BLADE WHICH CAUSED THE DOWNWARD AND REARWARD DISPLACEMENT OF THE NUMBER TWO ENGINE.
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