ASN Wikibase Occurrence # 30813
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| Date: | Monday 14 December 1998 |
| Time: | 18:44 LT |
| Type: |  Bell 47G-5 |
| Owner/operator: | Ronald R. Lamell |
| Registration: | N8103J |
| MSN: | 25001 |
| Year of manufacture: | 1970 |
| Total airframe hrs: | 6143 hours |
| Engine model: | Lycoming VO-435-B1A |
| Fatalities: | Fatalities: 0 / Occupants: 2 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Essex Junction, Vermont -
 United States of America
|
| Phase: | Approach |
| Nature: | Private |
| Departure airport: | (NONE) |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
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.'
Probable Cause: 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.
Accident investigation:
 |
|
Sources:
NTSB IAD99LA024
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 27-Sep-2008 01:00 | ASN archive | Added |
| 20-Oct-2011 12:32 | Dr. John Smith | Updated [Time, Operator, Total fatalities, Total occupants, Other fatalities, Location, Country, Phase, Nature, Departure airport, Destination airport, Source, Damage, Narrative] |
| 04-Apr-2024 11:58 | ASN Update Bot | Updated [Time, Operator, Other fatalities, Phase, Nature, Departure airport, Destination airport, Source, Damage, Narrative, Accident report] |
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