Accident
On March 7, 2008, at about 1500 Pacific standard time, a Maule M-4 airplane, registration N51430, sustained substantial damage in an accident at Eastern Sierra Regional Airport, Bishop, California. The airplane was operated as a visual flight rules (VFR) cross-country flight under 14 CFR Part 91. The private pilot, who was also the registered owner/operator, and two passengers were not injured. Visual meteorological conditions prevailed, and no flight plan was filed. The pilot had departed at about 1455, with an intended destination of Columbia, California.
The airplane sustained substantial damage to the right horizontal stabilizer and right wing. Additionally, the right main landing gear collapsed during the event.
Flight and Maneuver
During a telephone conversation with the NTSB investigator-in-charge on March 10, the pilot reported that just after takeoff the engine began running rough. He returned to the airport for a landing on the departure runway. The airplane touched down long and overran the runway. To avoid a fence located beyond the overrun area, the pilot intentionally ground looped the airplane. During the ground loop, the right main landing gear collapsed.
Post-Accident Examination
Post-accident examination of the engine by an FAA inspector and an airframe and powerplant mechanic revealed that the alternate induction air valve (automatic air door) was separated from the induction bracket. A 2-inch-long AN3 bolt associated with the assembly was found lodged between the number six cylinder exhaust valve and exhaust port, holding the valve open. The corresponding door hardware—a spiral spring, washer, and cotter pin—were not found. The FAA inspector reported that the unfound hardware likely passed through the engine and exited via the exhaust.
Maintenance History
Maintenance logbook records indicated that an annual inspection of the engine was completed on December 28, 2007. No discrepancies or anomalies with the alternate air valve were noted during that inspection. The pilot reported that there were no discrepancies related to the alternate air system prior to the accident flight.