ASN Wikibase Occurrence # 355243
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| Date: | Thursday 18 September 1997 |
| Time: | 07:45 LT |
| Type: |  Bell 407 |
| Owner/operator: | Petroleum Helicopters, Inc. |
| Registration: | N467PH |
| MSN: | 53142 |
| Year of manufacture: | 1997 |
| Total airframe hrs: | 177 hours |
| Engine model: | Allison 250C-47B |
| Fatalities: | Fatalities: 0 / Occupants: 5 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Grand Isle S108, -
 United States of America
|
| Phase: | En route |
| Nature: | Unknown |
| Departure airport: | Ewing Banks-286, GM |
| Venice, LA (7R1) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The helicopter was in cruise flight over open ocean water at 130 knots and 800 feet MSL, when the pilot felt a "violent jerk or yaw" and heard a grinding sound coming from the rear of the aircraft. The pilot attempted to correct the yaw with the anti-torque pedals, but there was no response, and the aircraft continued to yaw to the right and the nose pitched down. The pilot reduced the throttle and initiated an autorotation. He stated that the helicopter made "almost" a 360-degree right turn before contact with the water at a level pitch attitude with "slight" forward speed. One of the 4 passengers recalled seeing an object fall and hit the water, "leaving a circular motion" on top of the water, just prior to the helicopter landing in the water. The helicopter remained afloat on its deployed skid mounted float system and was recovered on the day of the accident, with the exception of the aft section of the tail boom, including the tail rotor gearbox, vertical fin, and tail rotor hub and blade assembly, which was missing. The aft section of the tail boom was recovered approximately 3 months later. Detailed examination of the tail boom separation area revealed multiple fractures and tears between tail boom stations 148 and 162. Examination of the fractured area revealed no evidence of fatigue. There was evidence of 4 tail rotor blade strikes between tail boom stations 150.9 and 153.2. One of the tail rotor blades was fractured about 14 to 18 inches from the inboard end, with the outboard section missing. The metallic leading edge of the remaining inboard section of this blade was deformed and twisted toward the tail boom. The other tail rotor blade was relatively intact with an indentation near the leading edge on the side toward the tail boom located about 18 inches from the inboard end of the blade. White paint, similar to the paint on the tail boom was found smeared onto the tail rotor blade's black paint in the area of the indentation. Detailed examinations of the tail rotor hub and blade assembly, tail rotor mast, tail rotor controls, tail rotor drive system, and the 90-degree gearbox mounting system did not reveal the reason for the in-flight contact of the tail rotor blades with the tail boom.
Probable Cause: The tail rotor blade strike(s) that severed the aft portion of the tailboom, subsequently rendering the pilot with no tail rotor control while in cruise flight. A factor was the lack of suitable terrain for the forced autorotative landing.
Accident investigation:
 |
|
Sources:
NTSB FTW97FA352
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 12-Mar-2024 09:49 | ASN Update Bot | Added |
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