What happened
On November 14, 2009, a Beech A36, registration N17803, was involved in a fatal accident near San Gabriel, California. The flight departed from Brackett Field Airport (POC) in La Verne, California, at approximately 1600, destined for Van Nuys Airport (VNY). The aircraft was being operated under Part 91 for personal use.
About 15 minutes after takeoff, witnesses observed the aircraft on a shallow approach toward railroad tracks with the landing gear extended. Witnesses reported the engine was at idle power during this approach. The aircraft touched down on the railroad tracks, bounced several times, and traveled approximately 5 and 500 yards beyond the initial impact point before coming to rest against a concrete wall.
There were no reports of smoke or fire prior to the impact sequence, but a post-impact fire consumed much of the fuselage. The pilot, who was the sole occupant, sustained 1 fatal injury due to thermal injuries.
The investigation
Investigators examined the wreckage and the Lycoming TIO-540-J2BD engine. While the engine was found to be mechanically functional through manual rotation of the crankshaft, a specific failure was identified in the exhaust system.
An examination of the left exhaust system transition pipe revealed it had detached from the engine because the V-band clamp was not in place. A metallurgical analysis of the recovered V-band clamp showed that the clamp had fractured through the strap area. The fracture was consistent with a tensile overstress separation, and the strap had been weakened by localized oxidation (corrosion). Additionally, the T-bolt installed in the clamp was only 1.875 inches long, whereas the manufacturer specification for a -5 clamp requires a 3.0-inch bolt.
Post-impact examination of the airframe also revealed localized thermal damage on the upper left cowling that was not caused by the post-impact fire.