Bell 407 accident near Vermillion 44, May 4, 2001
On May 4, 2001 at about 9:16 pm local time, a Bell 407 (helicopter), registered N917AL, was substantially damaged in an accident near Vermillion 44. It was flown under charter and air-taxi rules (Part 135). No one was hurt; 2 people were on board or involved. The weather was visual conditions (good weather).
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The NTSB's probable cause their words, unchanged
Failure of the engine-to-transmission driveshaft coupling due to fatigue.
Source: NTSB aviation accident database, copy made October 4, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- May 4, 2001 · about 9:16 pm local time
- Place
- Vermillion 44 · map
- Type
- Accident
- Injuries
- No one was hurt; 2 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Bell 407 · all 407s on the register
- Registration
- N917AL · registry record · serial 53381
- Damage
- Substantial damage
- Flight
- Flight · charter and air-taxi rules (Part 135)
The NTSB's narrative final · quoted from the NTSB record
While in cruise flight, the pilot reported that a "slight vibration became noticeable." After a few minutes, the vibration became more pronounced, and was accompanied by a noise. During an attempted precautionary landing to an offshore platform, the vibration and noise level increased again, and total engine power was lost. The pilot then initiated an autorotation to the water, deployed the skid floats, and landed safely. While the helicopter was being towed in the water, the helicopter rolled inverted. Examination of the helicopter after recovery revealed that the KAflex engine-to-transmission driveshaft was fractured, and the forward tail rotor driveshaft segment was separated. Examination of the KAflex driveshaft revealed fatigue fractures that originated from a bolt hole in the first flex frame of the coupling at the transmission end of the shaft and fatigue fractures in the end fitting at the transmission end. The primary fracture was a fatigue crack that occurred in a bolt hole where a bolt joined the first flex frame to the center flex frame. The driveshaft was determined to be manufactured within engineering specifications. The fractured tail rotor driveshaft showed evidence of torsional overstress. The KAflex driveshaft coupling had a total time of 2,114.2 hours and an airworthiness life limit of 5,000 hours. Following the accident, the manufacturer issued a service bulletin introducing a new KAflex driveshaft with a 1,250-hour overhaul interval.
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
- Ratings: multi-engine land; single-engine land; instrument: airplane; instrument: helicopter; rotorcraft: helicopter
- Flight time: 15,100 hours in all; 2,800 in this make and model; 180 in the last 90 days; 72 in the last 30 days; 14,100 as pilot in command
- Last flight review: March 24, 2001
- Medical certificate: Class 2 (valid medical--w/ waivers/lim.)
- Seat: rgt
- Injury: no injuries
The aircraft
- Airframe total time: 2,114.2 hours
- Last inspection: approved inspection programme, April 1, 2001; 139 hours since
- Maximum gross weight: 5,250 lb
- Seats: 7
- Landing gear: fixed
- Engine: Rolls Royce Allison 250-C-47B (turboshaft); 0 hours total
The flight
- Departed from: 368 Hi-338 GM at 8:35 pm
- Destination: 7RA Intercoastal LA
- Flight plan: VFR
Weather at the time
- Light: daylight
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 82°F (28°C), dew point 0°F (-18°C)
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 | |||
| Passengers | 1 |
About this page
Everything above comes from the NTSB's public accident database: the narrative, probable cause and findings are the NTSB's own words, and the coded tables behind its report (pilot, aircraft, flight, weather, injuries, sequence of events) are written out in plain English. Pilots' ages, home towns and medical details are left out on purpose. The docket at the NTSB holds the report as a PDF and the investigation's photographs and documents. This site never names pilots, passengers or anyone else involved. A preliminary report describes what is known soon after the event and can change; the final report, with the probable cause, usually follows one to two years later and this page is refreshed when it does. Case number FTW01FA115.