ASN Wikibase Occurrence # 357123
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| Date: | Wednesday 3 July 1996 |
| Time: | 21:15 LT |
| Type: |  Hiller OH-23C |
| Owner/operator: | Private |
| Registration: | N301CH |
| MSN: | 56-2252 |
| Total airframe hrs: | 5222 hours |
| Engine model: | Franklin 6V-335B |
| Fatalities: | Fatalities: 0 / Occupants: 2 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Marathon, FL -
 United States of America
|
| Phase: | Landing |
| Nature: | Unknown |
| Departure airport: | (KMTH) |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
During a previous flight, the helicopter was reported to have excessive vertical vibration and to require excessive collective forces during flight. Mechanics worked on the main rotor blades to correct the problem, then the helicopter was flown on a maintenance test flight. During the test flight, the pilot noted that the vertical vibration had 'gone away,' but before landing, the vertical vibration returned. Shortly thereafter, the pilot heard a loud 'pop'. As he flared for landing, the blue main rotor blade separated and the helicopter crashed. Examination of the separated blade showed the wood in the area of the blade grip had failed, allowing the blade to separate. Evidence of a previous repair was present in this area, which lacked adequate adhesive between some of the mating surfaces. Also, an unapproved sealant had been used over the repaired area, and oil had contaminated the wood in this area. There was no evidence of dry rot in the failed area. The logbook records did not show the previous blade repair.
Probable Cause: Improper repair of a previous crack in the blue main rotor blade by unknown persons; improper inspection of the main rotor blades by maintenance personnel, following a reported vibration problem; and subsequent failure of the main rotor blade, which resulted in an uncontrolled collision with the terrain.
Accident investigation:
 |
|
Sources:
NTSB MIA96LA176
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 13-Mar-2024 14:25 | ASN Update Bot | Added |
Corrections or additions? ... Edit this accident description
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