Hughes 369D N9163F

Summary

On 27 October 1989 at about 19:30 local time, a Hughes 369D registered N9163F was involved in an accident near Neah Bay, Washington, United States. One person was on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

27 October 1989 at 19:30

Classification

Accident

Location

Neah Bay, Washington, United States

Coordinates

48.3293, -124.6307

Aircraft

Hughes 369D

Registration

N9163F

Category

Helicopter

Engines

1

Operator

Not recorded

Operating rule

Part 133: Rotorcraft Ext. Load

Purpose of flight

Other Work Use

Phase of flight

Not recorded

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

SEA90LA010

Nobody was injured.

FATIGUE FAILURE OF ALL FOUR ATTACHMENT STUDS OF THE TAILROTOR GEARBOX RESULTING IN SEPARATION OF THE GEAR BOX, AND INADEQUATE MAINTENANCE INSPECTION.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

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.

Quoted verbatim from the NTSB record.