ASN Wikibase Occurrence # 358253
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| Date: | Wednesday 20 September 1995 |
| Time: | 12:30 LT |
| Type: | Texas Helicopter M74 Wasp (Bell OH-13E) |
| Owner/operator: | Heli Flight Ag Service, Inc. |
| Registration: | N38115 |
| MSN: | 77-011 |
| Total airframe hrs: | 4196 hours |
| Engine model: | LYCOMING VO-435-A1F |
| Fatalities: | Fatalities: 0 / Occupants: 1 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Yakima, WA -
 United States of America
|
| Phase: | Manoeuvring (airshow, firefighting, ag.ops.) |
| Nature: | Agricultural |
| Departure airport: | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
IMMEDIATELY AFTER LIFTING OFF AND REACHING TRANSLATIONAL LIFT, THE PILOT LOST COLLECTIVE PITCH CONTROL AND ROTOR RPM BEGAN TO DECREASE. THE HELICOPTER BEGAN AN UNCONTROLLED DESCENT AND IMPACTED WITH A POND. EXAMINATION REVEALED THAT AN ATTACHMENT BOLT IN THE SCISSOR ARM ASSEMBLY OF THE PITCH CONTROL SUPPORT ASSEMBLY HAD FAILED. EXAMINATION OF THE FRACTURE SURFACE REVEALED THAT THE BOLT HAD FAILED IN FATIGUE, WITH MULTIPLE CRACKING ORIGINS EMANATING FROM THE THREADS OF THE BOLT.
Probable Cause: FATIGUE FAILURE OF THE BOLT ATTACHING THE SCISSOR ARM ASSEMBLY TO THE PITCH CONTROL SUPPORT ASSEMBLY. THE FAILURE OF THE BOLT LED TO A LOSS OF COLLECTIVE PITCH CONTROL AND REDUCED ROTOR RPM.
Accident investigation:
 |
|
Sources:
NTSB SEA95LA227
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 14-Mar-2024 11:28 | ASN Update Bot | Added |
Corrections or additions? ... Edit this accident description
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