- Date
- June 14, 1989, 11:50 local (18:50 UTC)
- Place
- Baring, WA
- Injuries
- 1 serious, 1 minor
- Damage
- Destroyed
- Phase of flight
- Maneuvering
- Aircraft
- N157LCOregon Helicopters UH-1L
- Weather
- Visual (VMC) · Day
- Status
- Completed · report June 26, 1992
- Report
- Approved by Office Director
- FAA report
- 19890614015569A
- Case key
- 40922
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
Fatigue failure of the tail rotor 42 degree gear box due to pilot induced overstress. Navy data and FAA type certificate limitations were not adhered to.
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.
Analysis
While lifting a log the crew heard unusual noises & felt vibrations. They released the log & flew to a landing site to check the aircraft. While at a high hover the aircraft began spinning and the pilot executed a hovering autorotation. The aircraft landed hard and rolled down a hill. Investigation revealed a failed tail rotor 42 deg gearbox. The board's metallurgical examination showed that the gearbox's input spiral bevel gear had failed in fatigue. The eng N2 torque was red-lined at 55 lbs. Pilot stated that a dash-5 transmission was installed rated for 60 lbs, but observed marked 55 lb limit. Navy operators manual and FAA type certificate both list N2 torque limit as 50 lbs.
Aircraft
- Registration
- N157LC
- Reported as
- Oregon Helicopters UH-1L
- Category
- Helicopter
- Serial number
- 157856
- Airframe hours
- 8,299
- Engine
- Lycoming T53-L13B, 1,400 horsepower, turbo shaft
- Damage
- Destroyed
- Flight
- Other work use · Part 133
- Registered owner
- Timberline Air Service, Inc.
- Airworthiness certificate
- Special, Restricted (Special)
- Last inspection
- 100 hour · June 11, 1989 · 16 hours before
- Departed
- Baring, WA
Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.
Flight crew
As NTSB recorded them. NTSB leaves out names.
- Role
- Pilot
- Age
- 44
- Certificates
- Commercial, Flight instructor
- Airplane ratings
- Multi-engine land, Single-engine land, Single-engine sea
- Instrument ratings
- Airplane
- Medical
- Class 2, Valid Medical--no waivers/lim.
- Seat
- Left
- Flight hours
- 15,000 total · 1,500 in this make and model
Weather
- Conditions
- Visual (VMC) · Day
- Wind
- 340° at 10 knots
- Visibility
- 20 statute miles
- Lowest ceiling
- 5,500 ft broken
- Temperature
- 61 °F, dew point 54 °F
- Altimeter
- 30.00 inHg
- Observed at
- PAE, 33 nm away
FAA reports on this event · 1
The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.