Kaman HH-43 B/F N4069R

Summary

On 23 September 1996 at about 23:00 local time, a Kaman HH-43 B/F registered N4069R, operated by Skyline Helicopters, was involved in an accident near Troy, Montana, United States. 6 people were on board and 2 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

23 September 1996 at 23:00

Classification

Accident

Location

Troy, Montana, United States

Coordinates

48.7194, -115.7405

Aircraft

Kaman HH-43 B/F

Registration

N4069R

Category

Helicopter

Engines

1

Operator

Skyline Helicopters

Operating rule

Part 91: General Aviation

Purpose of flight

Positioning

Phase of flight

Not recorded

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

SEA96LA219

2 people had minor injuries.

failure of the freewheeling sprag unit bearings for undetermined reasons.

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

Read the full NTSB narrative

The pilot reported that while in cruise flight, the internal autorotation cockpit gauge needles split, and the helicopter lost altitude. The rotor rpm was decreasing, and the pilot initiated an autorotation. During the descent, the pilot noted that the N1 gauge indicated that the engine was running, but there was no power to the rotor. The helicopter landed hard, which drove the landing gear through the belly and separated the tail boom. A postaccident investigation revealed that bearings in the one-way freewheeling sprag clutch had failed. The one-way clutch was not a time-retireable item, and determining total time of the assembly from the maintenance records was not possible.

Quoted verbatim from the NTSB record.