ASN Wikibase Occurrence # 365607
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| Date: | Tuesday 12 March 1991 |
| Time: | 10:00 LT |
| Type: |  Bell UH-1B |
| Owner/operator: | Colony Services, Inc. |
| Registration: | N9687R |
| MSN: | 62-12529 |
| Total airframe hrs: | 7047 hours |
| Engine model: | LYCOMING T53L11D |
| Fatalities: | Fatalities: 0 / Occupants: 1 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Vero Beach, FL -
 United States of America
|
| Phase: | Initial climb |
| Nature: | Agricultural |
| Departure airport: | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
SHORTLY AFTER TAKEOFF AT 40 FT AGL, THE PLT STATED THAT HE OBSERVED THE HIGH/LOW ROTOR/ENG WARNING LIGHT WAS ILLUMINATED & THE HELICOPTER ENTERED AN UNCOMMANDED RT YAW. HE ENTERED AN AUTOROTATION & WHILE DESCENDING, THE MAIN ROTOR BLADES CONTACTED TREES. HE PULLED COLLECTIVE PITCH BEFORE IMPACT WITH TERRAIN. EXAM OF THE HELICOPTER REVEALED THAT THE UPPER RT TAILBOOM ATTACH BOLT WAS STRIPPED WHICH ALLOWED THE TAILBOOM TO SHIFT RESULTING IN THE SEPARATION OF THE NOS. 1 & 2 TAIL ROTOR DRIVE SHAFT SECTIONS AT THE COUPLING. EXAM OF THE STRIPPED BOLT BY A QUALIFIED INDIVIDUAL REVEALED THAT IT FAILED DUE TO BEING OVERTORQUED. THE COMPANY MECHANIC STATED THAT THE TAILBOOM ATTACH BOLTS ARE CHECKED FOR PROPER TORQUE EVERY 100 HRS & WAS LAST ACCOMPLISHED ABOUT 55 HRS EARLIER.
Probable Cause: IMPROPER MAINTENANCE ADJUSTMENT BY COMPANY MAINTENANCE PERSONNEL RESULTING IN OVERTORQUE OF A TAILBOOM ATTACH BOLT WHICH ALLOWED THE TAILBOOM TO SHIFT. THIS DISENGAGED THE TAIL ROTOR DRIVE SHAFT AT A COUPLING RESULTING IN THE LOSS OF TAIL ROTOR DRIVE.
Accident investigation:
 |
|
Sources:
NTSB MIA91LA113
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 20-Mar-2024 11:55 | ASN Update Bot | Added |
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