Bell 206B3 accident near Williamsport, Alaska, April 21, 1990
On April 21, 1990 at about 9:10 pm local time, a Bell 206B3 (helicopter), registered N1075G, was substantially damaged in an accident near Williamsport, Alaska (Iliamna Bay airport). It was a flight of an unrecorded kind under charter and air-taxi rules (Part 135). No one was hurt; 4 people were on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
THE MANUFACTURER'S INADEQUATE PART DESIGN AND THE IMPROPER MAINTENANCE TECHNIQUES BY THE OPERATOR.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- April 21, 1990 · about 9:10 pm local time
- Place
- Williamsport, Alaska · Iliamna Bay
- Type
- Accident
- Injuries
- No one was hurt; 4 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Bell 206B3 · all 206B3s on the register
- Registration
- N1075G · no longer on the register · serial 2958
- Damage
- Substantial damage
- Flight
- Flight of an unrecorded kind · charter and air-taxi rules (Part 135)
The NTSB's narrative final · quoted from the NTSB record
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.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
Pilot
- Certificate: airline transport pilot, flight instructor, commercial pilot
- Ratings: multi-engine land; single-engine land; single-engine sea; instructor: instrument helicopter; instrument: airplane; instrument: helicopter; rotorcraft: helicopter
- Flight time: 7,069 hours in all; 600 in this make and model; 146 in the last 90 days; 146 in the last 30 days; 6,626 as pilot in command; 625 on instruments
- Medical certificate: Class 1 (valid medical--no waivers/lim.)
- Seat: rgt
The aircraft
- Last inspection: annual inspection, April 14, 1990; 20 hours since
- Maximum gross weight: 3,200 lb
- Seats: 5
- Landing gear: fixed
- Engine: Allison 250-C20B (turboshaft); 0 hours total
The flight
- Departed from: HOM Homer AK at 1:49 pm
- Destination: HOM Homer AK
- Flight plan: VFR
- Runway 0
Weather at the time
- Light: daylight
- Wind: from 115° at 10 knots, gusting 5
- Visibility: 100 statute miles
- Sky: clear
- Temperature: 39°F (4°C), dew point 0°F (-18°C)
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 | |||
| Passengers | 3 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Other NTSB records under N1075G the same tail number, which may have belonged to a different aircraft at the time
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.