LAX96LA196 · Ayres S2R-G6
Ayres S2R-G6 · Accident: total loss of engine power (mechanical failure) during takeoff
Event
- NTSB case
- LAX96LA196
- 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
Ayres S2R-G6
- 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
- N447AT
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From not recordedTo 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 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
- Takeoff · roll/run
- 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
- Total loss of engine power (mechanical 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
Cause areas
- Other maintenance personnel › Maintenance, overhaul, improper
- Pilot in command › Directional control, not maintained
- Pilot in command › Ground loop/swerve, not corrected
- Turbine assembly, air seal › Overtemperature
- Turbine assembly, turbine wheel › Disintegrated
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The pilot reported that as the aircraft reached the takeoff rotation point, the engine's turbine section disintegrated, throwing large chunks of turbine wheels and other debris through the top and side of the engine cowling. The pilot lost directional control while attempting to stop the aircraft on the 2,700 foot-long dirt runway and it veered off the right side of the airstrip, crossed a drainage canal, and collided with the opposite embankment. Engine disassembly revealed that the second stage turbine wheel rim separated over almost its entire circumference. Detailed examination of the hub's fracture found machining type scoring to a depth of about 0.1 inches on the forward face of the wheel, which reduced the strength in the wheel web until overload failure occurred. Inspection of the second stage turbine stator assembly found that the sheet metal support for the turbine wheel to stator air seal was separated from the stator and had shifted forward to contact the failed wheel. Twenty-two out of 31 cooling passages which pass through the stator vanes from the outside diameter of the stator to the seal support area were completely plugged by braze repair material. The braze material had flowed from the outside diameter toward the inside during an attempt to braze repair the sheet metal on the castings outside diameter. The seal support showed evidence of operation at a temperature a few hundred degrees hotter than normal. Allied Signal reported that this overtemp condition will cause the seal support to crack after a few hundred hours of operation. Review of the Allied Signal overhaul documents for the second stage stator assembly disclosed that a braze repair is only authorized for the rear air seal attachment to the casting, and not in the area of the cooling passages. The historical engine maintenance records disclosed that the second stage stator was overhauled on August 23, 1995, and installed in the engine on October 23, 1995, 207 hours and 230 cycles since overhaul.
Probable cause
The pilot's failure to maintain directional control during a rejected takeoff, and the catastrophic failure of the engine's turbine section due to an improper overhaul procedure. A factor in the accident was the close proximity of the drainage ditch to the edge of the private airstrip's runway.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record LAX96LA196
- Event ID
- 20001208X05810
- Case number
- LAX96LA196
- 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: ab933d7bc1095d5079d954a14567b95c38147cbadfd57a2da427e99383d5eb12; retrieved 2026-09-22T22:30:37.765Z.