ASN Wikibase Occurrence # 367112
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| Date: | Saturday 21 April 1990 |
| Time: | 13:10 LT |
| Type: |  Bell 206B3 |
| Owner/operator: | Maritime Helicopters |
| Registration: | N1075G |
| MSN: | 2958 |
| Year of manufacture: | 1980 |
| Engine model: | Allison 250-C20B |
| Fatalities: | Fatalities: 0 / Occupants: 4 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Williamsport, AK -
 United States of America
|
| Phase: | En route |
| Nature: | Unknown |
| Departure airport: | Homer, AK (HOM) |
| Homer, AK (HOM) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
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.
Probable Cause: THE MANUFACTURER'S INADEQUATE PART DESIGN AND THE IMPROPER MAINTENANCE TECHNIQUES BY THE OPERATOR.
Accident investigation:
 |
|
Sources:
NTSB ANC90LA063
History of this aircraft
Other occurrences involving this aircraft
| 1 July 1991 | N302MH | Maritime Helicopters | 0 | Sheep Mountain, AK | |
sub |
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 22-Mar-2024 07:36 | ASN Update Bot | Added |
Corrections or additions? ... Edit this accident description
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