Hughes 369D N1091S

Summary

On 21 July 2003 at about 17:00 local time, a Hughes 369D registered N1091S was involved in an accident near Ketchikan, Alaska, United States. 3 people were on board and one had minor injuries. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

21 July 2003 at 17:00

Classification

Accident

Location

Ketchikan, Alaska, United States

Coordinates

55.8694, -131.4656

Aircraft

Hughes 369D

Registration

N1091S

Category

Helicopter

Engines

1

Operator

Not recorded

Operating rule

Part 135: Air Taxi & Commuter

Phase of flight

Not recorded

Route

Ketchikan → Ketchikan

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

ANC03LA082

1 person had minor injuries.

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.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

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.

Quoted verbatim from the NTSB record.