LAX03FA232 · Sikorsky S-58ET
Sikorsky S-58ET · Accident: airframe, component or system failure while maneuvering
From Rancho P.Verdes, CA to Rancho P.Verdes, CA
Event
- NTSB case
- LAX03FA232
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Accident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 0 · all aircraft and ground
- Ground fatalities
- Unknown
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- General aviation
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Sikorsky S-58ET
- Aircraft type
- Sikorsky S-58
- Category
- Helicopter
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N15AH
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Rancho P.Verdes, CATo Rancho P.Verdes, CA
- Aircraft age
- Not recorded
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 133: Rotorcraft Ext. Load
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- Maneuvering
- First occurrenceThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Airframe, component or system failure
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Destroyed
Cause areas
- Rotor drive system, intermediate gearbox(42 deg) › Failure, total
- Rotor drive system, intermediate gearbox(42 deg) › Fatigue
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
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.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record LAX03FA232
- Event ID
- 20030718X01146
- Case number
- LAX03FA232
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: investigation status, coordinates. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: 5a4d28336c15097eb21360b58b4ef33706f929ce3bfd7eef08b0f592296eab3f; retrieved 2026-09-21T09:25:06.524Z.