- Date
- October 27, 1989, 11:30 local (19:30 UTC)
- Place
- Neah Bay, WA
- Injuries
- 1 uninjured
- Damage
- Substantial damage
- Phase of flight
- Enroute
- Aircraft
- N9163FHughes 369D
- Weather
- Visual (VMC) · Day
- Status
- Completed · report October 7, 1992
- Report
- Approved by Office Director
- FAA report
- 19891027043679A
- Case key
- 41142
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 all four attachment studs of the tailrotor gearbox resulting in separation of the gear box, and inadequate maintenance inspection.
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
During an external load operation, the pilot had just released the load and was transitioning to a climb attitude when the tail rotor gearbox separated from the tail boom. The pilot was unable to maintain control and the helicopter collided into the rough terrain. The gearbox was metallurgically examined, revealing that all four attachment studs had failed due to fatigue. Further examination revealed contaminants on the gearbox mounting pads between the tail rotor gearbox and the tail boom; fretting was noted. AD88-17-09 and service information notice DN-151/EN-39/FN-28 both mandate initial and recurrent inspection (every flight) of the gearbox attachment area.
Aircraft
- Registration
- N9163F
- Reported as
- Hughes 369D
- Category
- Helicopter
- Serial number
- 690540D
- Airframe hours
- 8,187
- Engine
- Allison 250-C20B, 375 horsepower, turbo shaft
- Damage
- Substantial damage
- Flight
- Other work use · Part 133
- Registered owner
- Eagle Air Helicopters, Inc.
- Airworthiness certificate
- Standard, Normal
- Last inspection
- Annual · May 9, 1989 · 96 hours before
- 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
- 41
- Certificate
- Commercial
- Airplane ratings
- Single-engine land
- Medical
- Class 2, Valid Medical--w/ waivers/lim
- Flight hours
- 9,796 total · 3,512 in this make and model · 9,505 as pilot in command · 332 in the last 90 days · 11 in the last 24 hours
Weather
- Conditions
- Visual (VMC) · Day
- Wind
- Calm
- Visibility
- 40 statute miles
- Lowest ceiling
- None
- Temperature
- -0 °F
FAA reports on this event · 1
The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.
Other investigations on N9163F · 1
Matched to the same aircraft by N-number and date.