Bell UH-1B accident near Tok, Alaska, August 8, 2013
On August 8, 2013 at about 10:30 pm local time, a Bell UH-1B (helicopter), registered N70NW, was substantially damaged in an accident during enroute (cruise) near Tok, Alaska (Tok Junction airport). It was an external-load flight under external-load helicopter rules (Part 133). No one was hurt; 1 person was 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 crosshead bearing, which resulted in a loss of tail rotor control.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 8, 2013 · about 10:30 pm local time
- Place
- Tok, Alaska · Tok Junction · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Bell UH-1B · all UH-1Bs on the register
- Registration
- N70NW · no longer on the register · serial 60-3568
- Damage
- Substantial damage
- Flight
- External-load flight · external-load helicopter rules (Part 133)
The NTSB's narrative final · quoted from the NTSB record
The pilot had just completed a water drop with a long-line and water bucket when he noticed a degradation of the helicopter's directional control. He returned to the airport, released the bucket, and attempted a "stuck-pedal" run-on landing. During the attempted landing, the helicopter began to drift left toward trees. Unable to maintain directional control, the pilot initiated a go-around, and the main rotor blades then struck the treetops. After realigning with the runway, he executed a "slow-speed" run-on landing to a gravel area adjacent to the runway. During touchdown, the helicopter bounced multiple times, and it then came to rest upright. The helicopter sustained substantial damage to the fuselage, vertical fin, and tail rotor blades. A postaccident examination of the tail rotor assembly revealed that the tail rotor crosshead bearing's split inner ring's inboard shoulder was spalled and completely worn away, which allowed the outboard set of bearing balls to run over the pitch change rod's seating flange for the split inner ring's inboard shoulder. The pitch change rod was then free to migrate outboard, and it machined a hole through the end of the crosshead. The movement of the pitch change rod decreased the effectiveness of the left antitorque pedal and increased the effectiveness of the right antitorque pedal.
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
What happened, in order
- Loss of tail rotor effectiveness during enroute (cruise) defining event
- Collision with terrain or object (not controlled flight into terrain) during emergency descent
The NTSB's findings
- cause Aircraft › Aircraft propeller/rotor › Tail rotor drive system › Tail rotor gearbox › Failure
Pilot
- Certificate: commercial pilot
- Ratings: multi-engine land; single-engine land; single-engine sea; instrument: airplane; rotorcraft: helicopter
- Flight time: 500 hours in all
- Last flight review: May 10, 2013
- Medical certificate: Class 2 (with waivers/limitations)
- Seat: left
- Injury: no injuries
The aircraft
- Airframe total time: 11,144 hours
- Last inspection: 100-hour inspection, July 27, 2013
- Maximum gross weight: 8,500 lb
- Seats: 6
- Landing gear: fixed
- Engine: Lycoming T-53L13B (turboshaft); 9,594 hours total
- Operator: Northern Pioneer Helicopters LLC
The flight
- Departed from: PFTO Tok AK
- Destination: PFTO Tok AK
- Runway 25, 2,509 ft by 50 ft
Weather at the time
- Light: daylight
- Wind: from 120° at 6 knots
- Visibility: 10 statute miles
- Sky: broken clouds at 11,000 ft; a few clouds at 5,500 ft
- Temperature: 70°F (21°C), dew point 45°F (7°C)
- Altimeter: 29.76 inHg
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 |
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 N70NW 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.