- Date
- January 13, 1989, 17:12 local (21:12 UTC)
- Place
- Fort Yukon, AK
- Injuries
- 2 uninjured
- Damage
- Substantial damage
- Phase of flight
- Enroute
- Aircraft
- CFBCHBeech BE-99
- Weather
- Visual (VMC) · Night/bright
- Status
- Completed · report May 22, 1990
- Report
- Approved by Office Director
- NTSB office
- Alaska Regional Office
- Case key
- 5098
From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.
On this page
Probable cause
The NTSB’s determination of the probable cause, and any contributing factors.
The separation of a single propeller blade which caused the downward and rearward displacement of the number two engine.
Analysis
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.
Sequence of events
NTSB’s coding before 2008: each occurrence and phase of flight, and the causes and factors under it. The codes are defined in NTSB’s coding manual.
Aircraft
- Registration
- CFBCH
- Reported as
- Beech BE-99
- Category
- Airplane
- Serial number
- U162
- Airframe hours
- 20,967
- Engine
- P&W PT6A-27, 680 horsepower, turbo prop
- Damage
- Substantial damage
- Flight
- Part 129
- Registered owner
- Aklak Air Ltd
- Airworthiness certificate
- Standard, Normal
- Last inspection
- 100 hour · December 10, 1988 · 50 hours before
- Departed
- Inuvik
- Destination
- FAI · Fairbanks, AK
- Flight plan
- IFR
Flight crew
As NTSB recorded them. NTSB leaves out names.
- Role
- Pilot
- Age
- 39
- Certificate
- Airline transport
- Airplane ratings
- Multi-engine land, Multi-engine sea, Single-engine land
- Instrument ratings
- Airplane
- Medical
- Class 1, Valid Medical--w/ waivers/lim
- Seat
- Left
- Flight hours
- 4,350 total · 4,300 as pilot in command · 75 in the last 90 days · 5 in the last 24 hours
Weather
- Conditions
- Visual (VMC) · Night/bright
- Wind
- 30° at 3 knots, gusting 17
- Visibility
- 15 statute miles
- Lowest ceiling
- None
- Temperature
- 39 °F, dew point 48 °F
- Observed at
- FYU, 17 nm away