Accident Overview
On June 25, 2023, at 0900 Pacific daylight time, a Piper PA-24-250, registration N6430P, was substantially damaged during a forced landing near Alturas, California. The pilot sustained minor injuries. The aircraft was operated as a personal flight under Title 14 Code of Federal Regulations Part 91.
Pilot's Account
The pilot reported that after departing Alturas Municipal Airport (AAT) with two passengers, the engine began to miss and run rough. He returned to the airport, landed uneventfully, parked, and exited the airplane. He stated that he performed a full preflight inspection, including sampling fuel from all four fuel tanks and checking for loose spark plugs and magnetos. All engine components appeared satisfactory. He then decided to conduct an engine run-up and test flight without passengers before continuing to the intended destination.
During the pre-takeoff engine run-up, the pilot reported normal operation, and he departed from runway 21. After climbing a couple hundred feet, the engine began to violently shake. The pilot initiated a left turn back to the airport, and the engine lost all power. The airplane descended, landed hard, and came to rest upright in the grass adjacent to the runway.
Examination Findings
On-site examination revealed the airplane remained upright and intact, with substantial damage to the fuselage, both wings, and the right horizontal stabilizer. Postaccident examination of the airframe found no preimpact mechanical malfunctions that would have precluded normal operation. Examination of the engine revealed several pin holes in the exhaust tube surrounding the exhaust gas temperature (EGT) probe hole.
Mechanical and valvetrain continuity was established by manual rotation of the propeller. However, when the propeller was rotated, spark from the ignition harness No. 5 top lead was absent. Both magnetos were intact and secure at their mounting pads. The right magneto was removed and a functional test produced intermittent spark. The left magneto was removed and functionally checked with no discrepancies. Both magnetos were shipped to Continental Aerospace Technologies, where bench testing revealed no discrepancies. The right magneto was disassembled, and about one-quarter of its distributor gear teeth were found separated from the distributor gear. No evidence of additional mechanical anomalies was observed with either magneto. No maintenance records for the magnetos, engine, or airframe were made available during the investigation.