Beechcraft A36 N700TT

Summary

On 16 October 2003 at about 22:30 local time, a Beechcraft A36 registered N700TT was involved in an accident near Lancaster, California, United States. One person was on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

16 October 2003 at 22:30

Classification

Accident

Location

Lancaster, California, United States

Nearest airport

General Wm J Fox Airfield (WJF)

Coordinates

34.7867, -118.2903

Aircraft

Beechcraft A36

Registration

N700TT

Category

Airplane

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

Fullerton → Fresno

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

LAX04LA016

Nobody was injured.

A loss of engine power due to thermal fatigue failure of the first stage turbine wheel resulting in release of a section of its rim. The thermal fatigue was due to the engine exceeding its temperature limits during one or more start cycles.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

The airplane collided with power lines during an off-airport forced landing following a loss of engine power. While in cruise at 10,500 feet, the pilot heard a bang, and the engine lost power. He declared an emergency, and attempted to glide to a nearby airport; however, he was unable to make it to the runway. The airplane collided with power lines and fell to the ground about 4 miles west of the airport. The N1 and N2 shafting systems were bound up and would not move. The upper magnetic chip detector was free of metal, but it did contain coke. There was slight varnishing of the anode and cathode. The lower magnetic chip detector contained a substantial amount of metallic particles, subsequently identified as material from the No. 5 bearing. The particles did bridge the gap from anode to cathode. A detailed examination of the engine determined that three sections of the first stage turbine wheel separated. The stub shaft also fractured and separated, and a portion of the fractured tie bolt remained in the wheel. Metallurgical examination of the first and second stage turbine wheels found evidence of gamma prime solutioning and localized melting of the second stage turbine wheel airfoil tips, indicating temperature exposures above 2,100 degrees Farenheit, a temperature range outside the normal operating envelope of these wheels. This exposure to elevated temperatures resulted in rim separation due to thermal fatigue initiating at the rim followed by accelerated interdendritic creep crack growth. No evidence of an oil fire was associated with the first stage wheel separation. The composition, hardness, and microstructure of the first stage turbine wheel were as required by the engineering drawing. The No. 5 bearing exhibited heat distress, but the cause of this could not be conclusively determined. According to Rolls-Royce Allison, the internal evidence of excessive thermal damage to the first and second stage turbine wheels was consistent with prior examples of known hot starts.

Quoted verbatim from the NTSB record.