Beech A36 N17803 accident near San Gabriel, California

Probable cause

Failure of the exhaust band V-clamp during cruise flight, which resulted in an in-flight fire and a subsequent forced landing.

NTSB analysis

About 15 minutes after takeoff, witnesses observed the airplane make a forced landing adjacent to a railroad track. The airplane touched down partially on the track and bounced several times before coming to rest about 500 yards beyond the initial point of impact. The witnesses reported that the engine was at idle power during the shallow approach. The fuselage and engine area were thermally damaged and the pilot suffered fatal injuries due to a fire.

A postaccident examination revealed that a section of the upper left cowling had localized fire damage that was not attributed to the postimpact fire. The left cowling was placed in its normal position just forward of the airplane fuselage. A matching thermal pattern was noted in a small section of the airplane skin just aft of the firewall. Further examination revealed that the left exhaust system transition pipe and V-band clamp had separated from the engine and that the V-band clamp exhibited evidence of corrosion. A metallurgical examination of the V-band clamp revealed that it had fractured through the strap adjacent to a gap between the V-shaped clamping segments. The separation was a result of an overstress fracture of the strap, which was already weakened due to localized oxidation. It is likely that the failure of this clamp resulted in the initiation of an in-flight fire in the engine compartment area.

Text from the NTSB. Open the NTSB docket for WPR10FA056 for the full record.