ASN Wikibase Occurrence # 217251
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| Date: | Saturday 20 November 1993 |
| Time: | 08:45 |
| Type: | Hiller UH-12E Soloy |
| Owner/operator: | R AND B HELICOPTERS INC. |
| Registration: | N161HA |
| MSN: | HA-3061 |
| Total airframe hrs: | 7725 hours |
| Engine model: | ALLISON 250-C20 |
| Fatalities: | Fatalities: 0 / Occupants: 1 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | Salinas, CA -
 United States of America
|
| Phase: | Landing |
| Nature: | Agricultural |
| Departure airport: | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
DURING A SWATH RUN TO APPLY A MIXTURE OF PESTICIDES, THE PILOT HEARD A LOUD 'POP'. THE HELICOPTER'S COLLECTIVE CONTROL BEGAN TO OSCILLATE AND THE AIRCRAFT EXPERIENCED A SEVERE VIBRATION. THE HELICOPTER ALSO BEGAN TO OSCILLATE AND THE PILOT SLOWED TO ABOUT 15 KNOTS AND ATTEMPTED TO LAND. A SPRAY BOOM ATTACHED TO THE HELICOPTER CONTACTED THE GROUND AND THE HELICOPTER ROLLED ON ITS LEFT SIDE. EXAMINATION REVEALED THE PRESENCE OF FRETTING CORROSION AND A FATIGUE FAILURE OF THE TENSION-TORSION BAR PIN, INTO WHICH THE MAIN ROTOR BLADE DRAG BRACE IS ATTACHED. A SECOND TENSION-TORSION PIN FROM A SISTER HELICOPTER WAS DISCOVERED TO ALSO HAVE CORROSION AND A FATIGUE CRACK. PINS FAILED AT 369.5 HOURS AND 489.4 HOURS RESPECTIVELY. THE RETIREMENT LIFE OF THE PIN IS 643 HOURS.
Probable Cause: a fatigue failure of the torsion-tension bar pin due to fretting corrosion. A factor in this accident was an inadequate quality of material utilized in the manufacture of the pin.
Accident investigation:
 |
|
Sources:
NTSB: https://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20001211X13762&key=1
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 04-Nov-2018 08:43 | ASN Update Bot | Added |
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