CEN11LA404 · Ayres Corporation S2R-T34
Swan Lake Flying Services Ayres Corporation S2R-T34 · Accident: powerplant system/component malfunction/failure while maneuvering
From Athleimer, AR (no airport) to Athleimer, AR
Narrative check · The NTSB narrative appears to contradict this record's location, departure or destination and damage. Values are shown as recorded, not corrected; compare with the narrative.
Event
- NTSB case
- CEN11LA404
- 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
Ayres Corporation S2R-T34
- Aircraft type
- Ayres S2
- 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
- N30902
- Operator
- Swan Lake Flying Services
- Onboard fatalities
- Unknown
- Route Narrative disagrees
- From Athleimer, AR (no airport)To Athleimer, AR
- 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 137: Agricultural
- 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
- 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
- Powerplant system/component malfunction/failure
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Substantial Possible conflict
Cause areas
- Aircraft › Aircraft power plant
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The pilot had just started his first pass spraying fertilizer when the turboprop engine “exploded” and the propeller suddenly stopped. He saw flames around the cowling and soot and pieces of metal were exiting the exhaust stack. The pilot made a forced landing to a field, which resulted in the landing gear being torn from the airplane. The pilot was able to exit before the airplane was completely consumed by fire. A teardown examination of the engine revealed a failure in the first stage planetary gearset of the propeller reduction gearbox. All the gear teeth of the sun gear were ground down as far as the gear tooth roots, and the three meshing planetary gear teeth were battered and mutilated with only about 2/3 of the gear teeth height remaining. Review of the documentation of the last repair revealed that the gearset was a used replacement from another engine, contrary to manufacturer guidance, which states that first stage planetary gears should be replaced with a new gearset. The shop that sold the used gearset had misrepresented it as being zero-timed. The hours accumulated on the used gearset were beyond the manufacturer’s recommended time between overhaul.
Probable cause
Failure of the first stage planetary gearset in the propeller reduction gearbox, which resulted in catastrophic engine failure. Contributing to the failure was the misrepresentation of the gearset being zero-timed by the company that sold the gearset to the operator. Also contributing was the total accumulated hours on the used gearset, which were beyond the manufacturer's recommended time between overhaul.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CEN11LA404
- Event ID
- 20110620X20126
- Case number
- CEN11LA404
- 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. 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: 726a37f97729994727fd14b31872887b080c98a1bdb360e7c941a2c0089345a2; retrieved 2026-09-15T16:18:58.670Z.