Accident Overview
On June 8, 2015, at approximately 1600 Pacific daylight time, a Mooney M20C, registration N7887V, was destroyed during an off-airport landing following an in-flight fire. The accident occurred while the airplane was in the airport traffic pattern at Reno-Stead Airport (RTS), Reno, Nevada. The airplane was registered to and operated by the pilot under Title 14 Code of Federal Regulations Part 91. The airline transport pilot and an airline transport pilot rated passenger were not injured. Visual meteorological conditions prevailed, and no flight plan was filed for the personal flight. The local flight originated from RTS about one hour prior to the accident.
Flight History
The pilot reported that they departed Runway 8 and performed a series of touch-and-go takeoffs and landings, which included three go-arounds. While on downwind for the fourth landing, they noticed smoke inside the cockpit. The pilot initiated a forced landing to a dirt road approximately one mile north of the airport. When the pilot and passenger exited the airplane, they observed flames originating from the lower cowling area near the air intake.
Wreckage Examination
Examination of the airplane by a Federal Aviation Administration inspector revealed that the fuselage and inboard portion of both wings were mostly consumed by fire. The wreckage was recovered to a secure location for further examination.
On July 29, 2015, examination of the recovered wreckage revealed that it was mostly consumed by fire. The engine remained attached to the engine mounts. All fuel lines and oil lines appeared to be intact and secured to their respective fittings, with the exception of the number two oil return line from the rocker box to the crankcase, which was found disconnected from the rubber sleeve and clamped at the crankcase. In addition, the tube from the turbocharger waste gate to the exhaust was separated into two pieces throughout the entire area of a weld seam at the exhaust side of the tube. A heavy amount of oil residue was observed within the area surrounding the separated tube. A portion of the separated exhaust was removed and sent to the National Transportation Safety Board Materials Laboratory for further examination.
Laboratory Examination
Further examination of the two portions of the exhaust tubing revealed that both portions of the exhaust manifold internal and external surfaces exhibited an oxidized appearance. Both halves of the separation between the two portions exhibited similar levels of oxidation. Neither portion exhibited any deformations or dents. The clamp assembly appeared oxidized but did not exhibit any damage.
Examination of portion number one, which contained the remaining weld bead, revealed that an approximate 2-inch crack had formed between portion number one and the bead. The base material in the vicinity of the crack was oxidized and appeared to have been eroded.
Examination of portion number two revealed thinning of the tube wall near the area of separation. Wall thickness measurements on the opposite side of the separation area indicated a thickness of approximately 0.042 inch, while wall thickness measurements near the separation were as low as 0.021 inch.