LAX97FA291 · Hefner Pitts S1S
Hefner Pitts S1S · Accident: propeller failure/malfunction en route
From Van Nuys Airport (KVNY) to an unrecorded destination
Event
- NTSB case
- LAX97FA291
- 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
- 1 · 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
Hefner Pitts S1S
- Aircraft type
- Hefner Pitts S1
- Category
- Airplane
- 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
- N10HJ
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Van Nuys Airport (KVNY), CATo not recorded
- 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 · climb to 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
- Propeller 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
- Other maintenance personnel › Procedures/directives, not followed
- Propeller system/accessories, blade › Failure, total
- Propeller system/accessories, blade › Fatigue
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The pilot departed and requested a right-hand departure to the practice area. During the downwind departure he declared an emergency and witnesses observed the aircraft spiraling downward at a 45-degree angle into a residential street. Parts from the aircraft were found some distance from the accident site. The propeller along with the severed crankshaft flange were found still bolted together less part of one propeller blade. Metallurgical examination revealed that a blade had failed midspan due to fatigue. The propeller was being operated above the design rpm red line of 2,700. Additionally, the propeller was being subjected to gyroscopic aerobatic loads. An rpm restriction for the propeller mandated by an airworthiness directive was not placarded on the instrument panel per the AD. The engine was designed for a type certificated helicopter application and was approved for a 3,200 rpm red line.
Probable cause
the operation of the propeller beyond the design rpm limitations and the resultant gyroscopic loads from aerobatics. Contributing to the accident was the lack of a required instrument panel rpm restriction for the propeller mandated by an airworthiness directive.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record LAX97FA291
- Event ID
- 20001208X08663
- Case number
- LAX97FA291
- 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: 4cd9427d528246aff2e37d0cccc7a1c3378442318d02f41515a61708a567867c; retrieved 2026-09-20T22:51:17.087Z.