Bell B-3 accident near Annette Bay, Alaska, June 18, 1993
On June 18, 1993 at about 2:00 am local time, a Bell B-3 (helicopter), registered N21424, was substantially damaged in an accident near Annette Bay, Alaska. It was a business flight under general aviation rules (Part 91). 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 FAILURE OF THE TAIL ROTOR DRIVE SHAFT COUPLING AND THE INADEQUATE INSPECTION OF THE TAIL ROTOR DRIVE SYSTEM BY COMPANY MAINTENANCE PERSONNEL AFTER THE FIRST TAIL ROTOR STRIKE.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- June 18, 1993 · about 2:00 am local time
- Place
- Annette Bay, Alaska · map
- Type
- Accident
- Injuries
- No one was hurt; 4 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Bell B-3
- Registration
- N21424 · no longer on the register · serial 3466
- Damage
- Substantial damage
- Flight
- Business flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
THE HELICOPTER HAD BEEN INVOLVED IN A PREVIOUS TAIL ROTOR STRIKE AND THE DRIVESHAFT WAS INSPECTED. THE ADAPTER ON TAIL ROTOR DRIVE SHAFT NUMBER 4 DEBONDED AND ROTATED ON THE SHAFT. METALLURGICAL EXAMINATION SHOWED DEBONDING BUT THE MODE COULD NOT BE DETERMINED DUE TO ROTATIONAL DAMAGE. OTHER SHAFT ADAPTERS SHOWED DEBONDING AND WERE CAUSED BY PLASTIC BLASTING. THE INSPECTION PROCEDURE CALLS FOR INSPECTIONS ON THE SHAFT USING MAGNETIC PARTICLE OR FLUORESCENT PENETRANT METHODS AND DOES NOT CALL FOR PLASTIC MEDIUM BLASTING.
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: multi-engine land; single-engine land; instrument: airplane; instrument: helicopter; rotorcraft: helicopter
- Flight time: 5,493 hours in all; 2,380 in this make and model; 80 in the last 90 days; 40 in the last 30 days
- Medical certificate: Class 1 (valid medical--w/ waivers/lim.)
- Seat: rgt
The aircraft
- Airframe total time: 9,850 hours
- Last inspection: approved inspection programme, June 3, 1993; 5 hours since
- Maximum gross weight: 3,200 lb
- Seats: 5
- Landing gear: fixed
- Engine: Allison 250-C20B (turboshaft); 0 hours total
- Operator: Rocky Mountain Helicopters INC
The flight
- Runway 0
Weather at the time
- Light: daylight
- Visibility: 15 statute miles
- Sky: clear
- Temperature: 50°F (10°C), dew point 0°F (-18°C)
- Observation at 6:00 pm
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 N21424 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.