- Date
- September 9, 1992, 10:10 local (18:10 UTC)
- Place
- Nunavaugaluk Lk, AK
- Injuries
- 2 serious
- Damage
- Substantial damage
- Phase of flight
- Enroute
- Aircraft
- N8697FHughes 369D
- Weather
- Visual (VMC) · Day
- Status
- Completed · report September 29, 1993
- Report
- Approved by Office Director
- NTSB office
- Alaska Regional Office
- FAA report
- 19920909035639A
- Case key
- 5649
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 separation of the tail rotor abrasion strip and the subsequent total loss of the tail rotor. Factors contributing to the accident were: insufficient manufacturer's maintenance design changes, inadequate aircraft equipment design by the manufacturer and insufficient standards of the FAA certification organization.
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
Shortly after takeoff, at 1,000 ft AGL, the pilot experienced airframe vibration and a grinding sound. He entered autorotation, and at 200 ft AGL the tail rotor and part of the t/r gear box separated from the helicopter. It then rotated approximately 720 deg and impacted the ground. One of the t/r blades was missing the abrasion strip. An airworthiness directive (AD) & service bulletin (sb) were in effect directing installation of rivets within 300 hrs to prevent possible loss of tailrotor control. Due to seasonal use, helicopter had less than 160 hrs since issuance of the AD. Tail rotor blade found intact was 40% debonded, but would pass a 'tap test' iaw manufacturer's sb. Failed blade estimated to be 90% debonded. Daily visual inspection required by sb reportedly did not detect debonding in progress.
Aircraft
- Registration
- N8697F
- Reported as
- Hughes 369D
- Category
- Helicopter
- Serial number
- 1170221D
- Airframe hours
- 3,527
- Engine
- Allison 250-C20B, 375 horsepower, turbo shaft
- Damage
- Substantial damage
- Flight
- Business · Part 91
- Operator
- Eberle, Terrance, doing business as Whirlwind Aviation Ltd
- Registered owner
- Eberle, Terrance
- Airworthiness certificate
- Standard, Normal
- Last inspection
- Annual · May 16, 1992 · 152 hours before
- Departed
- Crystal Cr Lodg, AK
- Destination
- Kokwok River, AK
- Flight plan
- Company VFR
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
- 39
- Certificate
- Private
- Airplane ratings
- Single-engine sea, Single-engine land
- Medical
- Class 2, Valid Medical--w/ waivers/lim
- Seat
- Left
- Flight hours
- 1,679 total · 500 in this make and model · 1,400 as pilot in command · 150 in the last 90 days · 50 in the last 30 days · 2 in the last 24 hours
Weather
- Conditions
- Visual (VMC) · Day
- Wind
- 340° at 8 knots
- Temperature
- 45 °F, dew point 34 °F
- Altimeter
- 29.00 inHg
FAA reports on this event · 1
The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.