Bell 47-G5 N8103J

Summary

On 14 December 1998 at about 21:44 local time, a Bell 47-G5 registered N8103J was involved in an accident near Essex Junction, Vermont, United States. 2 people were on board and 2 were seriously injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

14 December 1998 at 21:44

Classification

Accident

Location

Essex Junction, Vermont, United States

Coordinates

Not recorded

Aircraft

Bell 47-G5

Registration

N8103J

Category

Helicopter

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Aircraft damage

Substantial

Weather

VMC

Light

Dusk

NTSB number

IAD99LA024

2 people were seriously injured.

the pilot's improper entry into the autorotation, which resulted in the loss of power and a low rotor rpm condition. Also causal was the pilot's improper execution of the autorotation which resulted in the hard landing. Factors in the accident were the performance of the autorotation at dusk over rough terrain.

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

Read the full NTSB narrative

The pilot and mechanic departed on a maintenance test flight after completing the installation of an overhauled engine. They performed ground engine runs and two short legs of the test flight. After each leg, the helicopter was shut down and the engine was checked for leaks. The pilot departed on the third leg after official sunset, and after climbing to approximately 1,700 feet, the pilot closed the throttle, then entered autorotation. The mechanic said the engine and rotor rpm decayed simultaneously and then the engine stopped running. During descent, the pilot attempted to restart the engine without success. The autorotation was terminated with a hard landing. Examination of the engine revealed no anomalies and it ran to rated power in a test cell. While operating at full rpm, the throttle was moved rapidly to the flight idle position. The engine exhibited a smooth reduction in rpm to the idle power setting with no interruption. An FAA Helicopter Handbook stated to begin an autorotation, the collective should be placed full down maintain cruise RPM with the throttle. Then decrease the throttle and adjust it to keep the engine RPM 'well above normal idling speed.'

Quoted verbatim from the NTSB record.