Bell 206B3 N1075G

Summary

On 21 April 1990 at about 21:10 local time, a Bell 206B3 registered N1075G was involved in an accident near Williamsport, Alaska, United States. 4 people were 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

21 April 1990 at 21:10

Classification

Accident

Location

Williamsport, Alaska, United States

Nearest airport

Iliamna Bay (NONE)

Coordinates

Not recorded

Aircraft

Bell 206B3

Registration

N1075G

Category

Helicopter

Engines

1

Operator

Not recorded

Operating rule

Part 135: Air Taxi & Commuter

Purpose of flight

Unknown

Phase of flight

Not recorded

Route

Homer → Homer

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

ANC90LA063

Nobody was injured.

THE MANUFACTURER'S INADEQUATE PART DESIGN AND THE IMPROPER MAINTENANCE TECHNIQUES BY THE OPERATOR.

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

Read the full NTSB narrative

THE HELICOPTER PILOT REPORTED A TOTAL LOSS OF POWER AND A SUBSEQUENT HARD AUTOROTATION LANDING. AN EXAMINATION OF THE ENGINE DISCLOSED A FRACTURED PC TUBE FROM THE COMPRESSOR TO THE PC FILTER. FAILURE OF THIS TUBE WILL CAUSE THE ENGINE TO LOSE POWER BELOW IDLE OR FLAME OUT. AN NTSB METALLURGIST WHO EXAMINED THE TUBE BELIEVES THAT THE TUBE FRACTURED DUE TO FRETTING AND FATIGUE, MOST LIKELY PRECIPITATED BY MISALIGNMENT OF THE PC TUBE DURING FIELD MAINTENANCE. ALLISON, THE ENGINE MANUFACTURER, HAS RECENTLY REDESIGNED THE TUBE WITH A THICKER WALL AND A DIFFERENT SHAPE TO FACILITATE MAINTENANCE PROCEDURES IN THE FIELD, AND TO MAKE THE TUBE MORE RESISTANT TO FATIGUE.

Quoted verbatim from the NTSB record.