Bell 214B1 accident near Thorne Bay, Alaska, May 8, 1993
On May 8, 1993 at about 5:30 pm local time, a Bell 214B1 (helicopter), registered N314CR, was substantially damaged in an accident near Thorne Bay, Alaska. It was a flight of an unrecorded kind under external-load helicopter rules (Part 133). 2 people had minor injuries. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
FOREIGN OBJECT DAMAGE TO THE COMPRESSOR ASSEMBLY, PROBABLY DUE TO LOOSE NUTS FROM THE COMPRESSOR CASE AFTER IMPROPER MAINTENANCE (INSTALLATION) BY MAINTENANCE PERSONNEL.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- May 8, 1993 · about 5:30 pm local time
- Place
- Thorne Bay, Alaska · map
- Type
- Accident
- Injuries
- 2 people had minor injuries.
- Weather
- visual conditions (good weather)
- Aircraft
- Bell 214B1 · all 214B1s on the register
- Registration
- N314CR · no longer on the register · serial 28055
- Damage
- Substantial damage
- Flight
- Flight of an unrecorded kind · external-load helicopter rules (Part 133)
The NTSB's narrative final · quoted from the NTSB record
THE HELICOPTER WAS BEING USED TO MOVE LOGS IN A LONG-LINE LIFT OPERATION. THE PILOT REPORTED THAT AS HE INCREASED COLLECTIVE TO LIFT A LOG, HE HEARD A LOUD NOISE, WHICH WAS FOLLOWED BY A LOSS OF POWER. AN AUTOROTATION WAS MADE TO A LANDING ON ROUGH, DOWNHILL TERRAIN, DOWNSLOPE FROM WHERE THE LOG WAS BEING LIFTED. A TEARDOWN OF THE ENGINE REVEALED EVIDENCE OF FOREIGN OBJECT DAMAGE AT THE 6TH AND 7TH STAGES OF THE N1 (GAS PRODUCER) COMPRESSOR. SELF-LOCKING NUTS (PN STD3064-4) WERE MISSING FROM 2 COMPRESSOR CASE BOLTS (PN MS9566-36), WHICH WERE LOCATED OVER A BLEED PORT, LEADING TO THE 6TH STAGE OF THE GAS PRODUCER. METALLURGICAL EXAM REVEALED NUT FRAGMENTS OF A CHEMICAL COMPOSITION, CONSISTENT WITH THE MATERIAL SPECIFIED IN STD3064-4 NUTS. THE ENGINE HAD BEEN IN OPERATION ABOUT 283 HOURS, AFTER BEING REASSEMBLED WITH A NEW COMPRESSOR SECTION.
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: commercial pilot
- Ratings: rotorcraft: helicopter
- Flight time: 7,860 hours in all; 800 in this make and model; 180 in the last 90 days; 75 in the last 30 days; 72 as pilot in command
- Medical certificate: Class 2 (valid medical--no waivers/lim.)
- Seat: left
The aircraft
- Airframe total time: 5,647 hours
- Last inspection: approved inspection programme, May 6, 1993; 9 hours since
- Maximum gross weight: 16,000 lb
- Seats: 7
- Landing gear: fixed
- Engine: Lycoming T55-08D (turboshaft); 0 hours total
The flight
- Runway 0
Weather at the time
- Light: daylight
- Wind: from 020° at 8 knots
- Visibility: 20 statute miles
- Sky: scat at 4,000 ft
- Temperature: 39°F (4°C), dew point 0°F (-18°C)
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 2 |
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.
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.