ASN Wikibase Occurrence # 365022
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| Date: | Monday 1 July 1991 |
| Time: | 15:00 LT |
| Type: |  Bell 412 |
| Owner/operator: | Air Methods Corporation |
| Registration: | N20703 |
| MSN: | 33017 |
| Year of manufacture: | 1981 |
| Engine model: | P&W PT6T-3B |
| Fatalities: | Fatalities: 0 / Occupants: 3 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Grand Junction, CO -
 United States of America
|
| Phase: | En route |
| Nature: | Ferry/positioning |
| Departure airport: | Grand Junction, CO |
| Monticello, UT (U43) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
DURING CRUISE FLIGHT, THE ENGINE TO TRANSMISSION DRIVE SHAFT FORWARD COUPLING OVERHEATED AND FAILED. THE PILOT EXECUTE AN AUTORATATION. DURING THE LANDING FLARE, THE PILOT DID NOT MAINTAIN ADEQUATE ROTOR RPM AND THE HELICOPTER LANDED HARD RESULTING IN SKID COLLAPSE. COMPANY MAINTENANCE PERSONNEL DISPATCHED THE HELICOPTER WITH A KNOWN DRIVE SHAFT COUPLING GREASE LEAK WHICH THEY HAD ATTEMPTED TO STOP BY USING AN UNAPPROVED SILICON SEALANT. THEY HAD REPACKED THE 500 PLUS HOUR COUPLING TWO TIMES PRIOR TO THE ACCIDENT. THE NORMAL REPACK INTERVAL WAS ONCE EVERY 600 HOURS. EXAMINATION OF THE FAILED DRIVE SHAFT DID NOT REVEAL ANY MISALIGNMENT, BUT DID ISOLATE HEAT RELATED FAILURE AREAS OF THE FORWARD COUPLING END.
Probable Cause: THE PILOT'S FAILURE TO MAINTAIN ADEQUATE MAIN ROTOR RPM PRIOR TO TOUCHDOWN. FACTORS WERE: THE DISCONNECTED ENGINE TO TRANSMISSION DRIVE SHAFT AND THE INADEQUATE INSPECTION BY COMPANY MAINTENANCE PERSONNEL.
Accident investigation:
 |
|
Sources:
NTSB DEN91LA095
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 19-Mar-2024 21:22 | ASN Update Bot | Added |
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