ASN Wikibase Occurrence # 367127
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| Date: | Wednesday 18 April 1990 |
| Time: | 09:30 LT |
| Type: |  Bell 47G-2 |
| Owner/operator: | Twin City Helicopters, Inc. |
| Registration: | N5120B |
| MSN: | 1941 |
| Total airframe hrs: | 4610 hours |
| Engine model: | LYCOMING VO-435-A1F |
| Fatalities: | Fatalities: 0 / Occupants: 1 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Oakdale, MN -
 United States of America
|
| Phase: | En route |
| Nature: | Agricultural |
| Departure airport: | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
WHILE FERRYING THE HELICOPTER TO CONDUCT AN AERIAL APPLICATION OPERATION, THE PLT SAID THAT THE ENGINE BEGAN TO OVERSPEED. THE PLT ENTERED AN AUTOROTATION TO REDUCE ENGINE RPM, BUT HAD TO CLEAR POWER LINES. USING THE ROTOR RPM TO CLEAR THE POWER LINES, THE ROTOR RPM DECAYED AND THE ACFT DROPPED IN FROM ABOUT 50 TO 75 FEET AGL. POST ACCIDENT INVESTIGATION REVEALED A MALFUNCTIONING MAIN TRANSMISSION CENTRIFUGAL CLUTCH. THE POWERPLANT TEST FAILED TO REVEAL ANY MALFUNCTION. AN ANNUAL INSPECTION HAD BEEN PERFORMED 6 DAYS AND 4 HOURS OF FLIGHT TIME PRIOR TO THE ACCIDENT.
Probable Cause: A SLIPPING ROTOR DRIVE CLUTCH ASSEMBLY DUE TO IMPROPER MAINTENANCE BY COMPANY PERSONNEL. CONTRIBUTING FACTORS WERE STATIC WIRES IN THE PATH.
Accident investigation:
 |
|
Sources:
NTSB MKC90LA088
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 22-Mar-2024 07:48 | ASN Update Bot | Added |
Corrections or additions? ... Edit this accident description
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