Brantly Helicopter B-2B accident near Plymouth, Massachusetts, July 24, 2005
On July 24, 2005 at about 3:25 pm local time, a Brantly Helicopter B-2B, registered N9018Y, was substantially damaged in an accident near Plymouth, Massachusetts (Plymouth Municipal Airport). It was a personal flight under general aviation rules (Part 91). No one was hurt; 2 people were on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
Fatigue failure of the intermediate tailrotor driveshaft, which resulted in a loss of directional control at a hover.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- July 24, 2005 · about 3:25 pm local time
- Place
- Plymouth, Massachusetts · Plymouth Municipal Airport · map
- Type
- Accident
- Injuries
- No one was hurt; 2 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Brantly Helicopter B-2B
- Registration
- N9018Y · no longer on the register · serial 2002
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
While at a hover, the helicopter made an uncommanded sharp turn to the right, which could not be arrested with a left pedal application. When the helicopter completed approximately 3/4 of a rotation, the pilot "chopped the power" to stop the spin. The helicopter descended, struck the left skid on the ground, and then rolled over onto its left side. Examination of the intermediate tailrotor gearbox revealed that the tailrotor driveshaft was fractured at the input side of the gearbox. A portion of the fractured driveshaft remained in the flanged bushing of the gearbox. The fractured pieces of the driveshaft displayed significant mechanical damage from the driven end of the driveshaft after the fracture occurred. The driveshaft section recovered from the intermediate gearbox input bevel displayed multiple fatigue fractures with multiple origins around the attach-bolt holes. The fractures propagated from the attach-bolt holes in the direction of rotation, and opposite the direction of rotation. Fractured tail rotor vertical driveshafts from two previous events in the same make and model displayed almost identical modes of failure. As a result of those examinations, the FAA issued Airworthiness Directive 2006-08-07 on May 2, 2006, to help prevent fatigue cracking and subsequent failures of the vertical shaft.
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: single-engine land; instructor: airplane single-engine; instructor: instrument airplane; instrument: airplane; rotorcraft: helicopter
- Flight time: 4,000 hours in all; 90 in this make and model
- Last flight review: June 1, 2004
- Medical certificate: Class 3
- Seat: left
- Injury: no injuries
The aircraft
- Airframe total time: 191 hours
- Last inspection: annual inspection, May 1, 2005; 32 hours since
- Maximum gross weight: 1,670 lb
- Seats: 2
- Landing gear: fixed
- Engine: Lycoming O & OV-360 (piston); 0 hours total
The flight
- Departed from: PYM Plymouth MA at 3:00 pm
- Destination: PYM
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 020° at 12 knots, gusting 17
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 75°F (24°C), dew point 45°F (7°C)
- Altimeter: 30.04 inHg
- Observation at 2:52 pm from PYM
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 | |||
| Passengers | 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.
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.