ATL04LA029 · Yakovlev YAK55M
Yakovlev YAK55M · Accident: loss of engine power en route
From Tallahassee International Airport (TLH) to Montgomery Regional (Dannelly Field) Airport (MGM)
Event
- NTSB case
- ATL04LA029
- 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
Yakovlev YAK55M
- Aircraft type
- Yakovlev YAK55
- 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
- N55YA
- Operator
- Peter K. Herzig · private individual
- Onboard fatalities
- Unknown
- Route
- From Tallahassee International Airport (TLH), Tallahassee, FLTo Montgomery Regional (Dannelly Field) Airport (MGM), Montgomery, AL
- 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
- Loss of engine power
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Substantial
Cause areas
No findings designated as a cause are recorded in the NTSB data yet.
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
The pilot stated he was at 3,000 feet in cruise flight, when he felt an instantaneous onset of a severe vibration. He reduced power and looked at the instrument panel. He did not observe an illumination of the engine chip detector light. He increased power to see what manifold pressure that he could maintain. The airplane would not maintain cruise flight. He observed a field to his front and initiated a forced landing to the field. He completed an engine shut down and started slipping the airplane to the harvested cornfield. The airplane touched down, rolled about 200 feet, and collided with a berm. Examination of the airplane revealed the propeller would continue to turn without the engine running. The propeller assembly was disassembled and the propeller shaft was fractured. Disassembly of the engine revealed all 9 connecting rods were fractured. The propeller shaft and connecting rods were examined by the NTSB Materials Laboratory. Post separation damage of the connecting rods had totally obliterated the fracture surfaces of the connecting rods making the determination of the failure modes impossible.
Probable cause
A loss of engine power due to a fractured connecting rod for undetermined reasons.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record ATL04LA029
- Event ID
- 20031031X01844
- Case number
- ATL04LA029
- 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: 52350b67c7b50afad315d4222fff5e765b923a2c10b356517c892b99106ec0dc; retrieved 2026-09-22T08:20:38.015Z.