ASN Wikibase Occurrence # 75579
This information is added by users of ASN. Neither ASN nor the Flight Safety Foundation are responsible for the completeness or correctness of this information.
If you feel this information is incomplete or incorrect, you can submit corrected information.
| Date: | Saturday 12 July 2003 |
| Time: | 10:28 |
| Type: |  Sikorsky S-58ET |
| Owner/operator: | Aris Helicopters, Ltd. |
| Registration: | N15AH |
| MSN: | 58-1563 |
| Total airframe hrs: | 7879 hours |
| Engine model: | Pratt & Whitney PT6T-6 |
| Fatalities: | Fatalities: 0 / Occupants: 1 |
| Aircraft damage: | Destroyed |
| Category: | Accident |
| Location: | Rancho Palos Verdes, CA -
 United States of America
|
| Phase: | Manoeuvring (airshow, firefighting, ag.ops.) |
| Nature: | External load operation |
| Departure airport: | Rancho P.Verdes, CA |
| Rancho P.Verdes, CA | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The helicopter experienced a loss of tail rotor drive while maneuvering during a Federal Aviation Administration authorized low altitude external long line host operation, and collided with the ground in the subsequent descent. At the time, the operation was being performed in an area of the height-velocity curve that did not allow for a successful autorotative landing. Witnesses reported that minutes prior to the accident the pilot had made a precautionary landing due to illumination of the intermediate gearbox (IGB) chip light. The pilot removed, inspected, and cleaned the chip plug that contained metallic-like particles. During this action, the pilot was overheard to express concern to a ground crewmember by stating "this can be a problem." The pilot elected to continue flight operations. About 13 minutes later, within 200 feet above ground level while lifting an air conditioner (AC) unit from a school building, the pinion gear (part number S1635-64114-101) going into the drive side of the helicopter's intermediate gearbox (IGB) failed. This resulted in a total loss of antitorque control, and the helicopter yawed and spun in a clockwise direction while descending, and the helicopter impacted the unoccupied schoolyard. The pinion gear for the intermediate gearbox was examined. The laboratory reported that the initiating failure event had resulted from a fatigued gear tooth. The failure occurred about 175 hours prior to the part reaching its 2,000-hour life limit. The external long line was still connected to the cargo hook. Examination of the cockpit disclosed that the electrical cargo release switch was not armed. Post accident tests established that both the electrical release and manual backup cargo release mechanisms functioned.
Probable Cause: A total loss of antitorque control, due to the fatigue-induced failure of a gear within the drive shaft's intermediate gear box (IGB). Contributing factors were the pilot's improper on-ground decision to continue flight operations following discovery of material on the IGB's chip plug, and his failure to immediately jettison the external load.
Accident investigation:
 |
|
Sources:
NTSB: https://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20030718X01146&key=1
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 12-Jul-2010 00:19 | TB | Added |
| 21-Dec-2016 19:25 | ASN Update Bot | Updated [Time, Damage, Category, Investigating agency] |
| 08-Dec-2017 18:57 | ASN Update Bot | Updated [Operator, Nature, Departure airport, Destination airport, Source, Narrative] |
Corrections or additions? ... Edit this accident description
The Aviation Safety Network is an exclusive service provided by:
Quick Links:
| ASN Home | Send Correction / Feedback |
| FSF Home | Disclaimer | Copyright |
| Contact Us | Privacy Policy |
| Press / Media |
CONNECT WITH US:
©2024 Flight Safety Foundation