ASN Wikibase Occurrence # 295491
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| Date: | Monday 21 July 2003 |
| Time: | 08:00 LT |
| Type: |  Hughes 369D |
| Owner/operator: | Temsco Helicopters Inc. |
| Registration: | N1091S |
| MSN: | 300691D |
| Year of manufacture: | 1980 |
| Total airframe hrs: | 9553 hours |
| Engine model: | Allison 250-C20B |
| Fatalities: | Fatalities: 0 / Occupants: 3 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | KETCHIKAN, Alaska -
 United States of America
|
| Phase: | Unknown |
| Nature: | Unknown |
| Departure airport: | KETCHIKAN, AK (17AK) |
| KETCHIKAN, AK | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The commercial certificated pilot was conducting an on-demand air taxi flight in a turbine-powered helicopter. While performing an aerial survey, about 100 feet agl, the engine-out annunciator sounded, and the pilot entered an autorotation. As the helicopter touched down in a small clearing, the pilot had the collective pitch control full up to cushion the landing. When the helicopter touched down, the engine power suddenly surged, and the helicopter then began to climb. During the pilot's efforts to control the helicopter, the main rotor blades collided with several trees, and the blades then severed the tail boom. Following the collision with the trees, the pilot rolled the throttle to the off position, but the engine would not shut-down. He then pulled the emergency fuel shut off. Examintion of the helicopter revealed that a bolt, used to connect the N2 governor input arm to an airframe mounted bellcrank, was missing. The bellcrank is connected to the helicopter's collective control linkage. As the pilot moves the collective control, through the bellcrank and governor input arm, engine power increases or decreases. The bolt is normally retained by a castellated nut, and then secured in-place by a cotter pin. Company personnel returned to the accident scene and located the missing bolt and nut lying on the ground, under the location where the engine access doors were opened during an inspection of the engine, before the helicopter was removed from the accident scene. Also found was a cotter pin with one broken side, but it could not be determined if the broken cotter pin was the missing pin from the bolt. The most recent inspection of the helicopter was a 100 hour inspection, conducted by company personnel, 51.8 service hours before the accident. Numerous company pilots had flown the helicopter before the accident. In addition, each pilot conducted an inspection of the helicopter before beginning flight operations. On the day of the accident, the helicopter had flown about 2.5 hours before the accident.
Probable Cause: The improper installation of a bolt in the gas generator governor linkage by company maintenance personnel, which resulted in a loss of the bolt, a loss of engine power while maneuvering, and subsequent forced landing and collision with trees. Factors contributing to the accident were an inadequate preflight inspection by the pilot, and an uncommanded surge in engine power.
Accident investigation:
 |
|
Sources:
NTSB ANC03LA082
History of this aircraft
Other occurrences involving this aircraft
| 13 September 1983 | N1091S | Temsco Helicopters | 0 | Wrangell, AK | |
w/o |
| 13 September 1983 | N10915 | Temsco Helicopters | 0 | Wrangell, AK | |
w/o |
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 13-Oct-2022 09:08 | ASN Update Bot | Added |
Corrections or additions? ... Edit this accident description
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