LAX98FA236 · Sikorsky CH-54A
Sikorsky CH-54A · Accident: rotor failure/malfunction en route
From Blythe Airport (BLH) to Apple Valley Airport (APV)
Event
- NTSB case
- LAX98FA236
- 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
- 3 · all aircraft and ground
- Ground fatalities
- 0
- 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 CH-54A
- Aircraft type
- Sikorsky CH-54
- 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
- N64KL
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Blythe Airport (BLH), Blythe, CATo Apple Valley Airport (APV), Apple Valley, 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 91: General Aviation
- 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
- En route · cruise
- 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
- Rotor failure/malfunction
- 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
- Pilot in command › Maintenance, compliance with ad, disregarded
- Rotor system, main rotor blade spar › Separation
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
While in cruise flight, a main rotor blade separated. The helicopter exploded in flames and crashed. The green blade had failed an AD directed BIM check the evening prior to the accident. The crew chief recharged the blade with nitrogen and allowed the helicopter to remain parked overnight. The next morning he checked the BIM and found it had retained its charge. The crew of the accident aircraft, who were accompanied by the company's chief pilot in a second aircraft, made the decision to continue to fly the helicopter to its destination. There were several cellular calls both to and from the operator on the evening before the accident. A new exclusive-use contract for both aircraft was already in effect. The maintenance history of the green blade contained an unspecified minor repair after a reported overhaul. The operator stated that, at no time, had it performed any maintenance or repair to the blade. After the blade's mating fracture surfaces were examined, it was found that a hole had been drilled from the underside into the spar. The hole terminated at a conical point that is consistent with a drill bit. Fatigue banding could be seen in the immediate vicinity of the hole. Striations near the conical point, typical of fatigue, were seen with a SEM. The drill hole was under a blade pocket and had not been visible during previous inspections. There is no prescribed inspection/maintenance procedure short of removing the blade pockets that would have revealed the hole. Blade pockets are condition items. Stop-drilling cracks in blade pockets to prevent crack propagation is an authorized military maintenance procedure. Drilling into the spar as part of the process is not authorized.
Probable cause
An in-flight main rotor blade spar separation as a result of the pilot-in-command's decision to continue to fly the aircraft after it had failed an AD directed BIM check. Factors were the failure of the operator's chief pilot to maintain proper supervision over the operation of a company aircraft with a known grounding deficiency and the improper repair to the main rotor blade by unknown persons, which damaged the blade's spar.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record LAX98FA236
- Event ID
- 20001211X10621
- Case number
- LAX98FA236
- 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. 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: 52993cfed73a0becd5e2079005a7dcf59ead4781d70e527e109eaf66083238e2; retrieved 2026-09-20T22:30:04.778Z.