CEN24LA141 · Cozy Mark IV
Cozy Mark IV · Accident: loss of engine power (total) en route
From Stinson Municipal Airport (SSF) to Ellington Airport (EFD)
Event
- NTSB case
- CEN24LA141
- 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
- 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
Cozy Mark IV
- Aircraft type
- Cozy MARK
- 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
- N20MN
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Stinson Municipal Airport (SSF), San Antonio, TXTo Ellington Airport (EFD), Houston, TX
- Aircraft age
- About 25 years (built 1999)
- 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
- Defining eventThe 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 (total)
- 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
- Aircraft › Aircraft power plant
- Personnel issues › Task performance
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
While enroute, at 9,500 ft above mean sea level (msl), the engine lost all power. After multiple attempts to restart the engine, the pilot executed a forced landing to a nearby airport. The airplane landed short of the runway threshold and its nose landing gear separated as the airplane transitioned onto the asphalt runway. The left wing and left canard sustained substantial damage. Postaccident examination of the engine revealed that the left crankshaft idler gear shaft separated from its attach points, which prevented the crankshaft idler gear from engaging its corresponding crankshaft and camshaft gears. The disengagement prevented camshaft rotation and valvetrain timing to the crankshaft. The left crankshaft idler gear’s attachment hardware were both separated into two sections from abrasion. The capscrew was lockwired to the idler shaft but no lockwire was observed through the stud and slotted shear nut. It is likely that maintenance personnel did not follow the engine manufacturer’s service instructions and undertorqued the fasteners during installation, resulting in insufficient clamping force. Additionally, the absence of lockwire likely permitted the shear nut to back off during engine operation. Because the airplane’s maintenance records were not available for review, the investigation was not able to identify when the crankshaft idler gear was last serviced.
Probable cause
Maintenance personnel’s failure to properly torque the crankshaft idler gear hardware according to the engine manufacturer’s service instructions, which resulted in separation of the crankshaft idler gear’s fasteners and disengagement of the camshaft, crankshaft, and crankshaft idler gear and a subsequent total loss of engine power.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CEN24LA141
- Event ID
- 20240326193992
- Case number
- CEN24LA141
- Dataset
- full-current
- Source SHA-256
- 5cf380f0061817c0331a6b2d8cc7e0ee3a79bea469a1001dc5c10e56f35f5ab3
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, cause areas. 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: 48a0741b6280c26b193215fe030d4ae064ae7e6f5b45df8dfd1d1402f6882b0c; retrieved 2026-09-16T18:37:35.345Z.