Incident Overview
The aircraft, with three USAF officer pilots aboard, experienced engine trouble shortly after takeoff. While en route to a local practice area over a canyon at 4,500 feet, the pilots observed the engine running slightly rough with a steady decrease in RPM. The engine RPM eventually dropped to 1,800, and all attempts to restore power were unsuccessful.
Descent and Landing
Unable to maintain level flight, the aircraft descended below the tops of surrounding ridges. The pilots determined that the only viable option was to contact the hillside in a controlled manner. They stalled the aircraft into the thick brush-covered hillside.
Post-Crash Examination
The crash site was inaccessible, preventing determination of fuel system continuity or fuel supply quality. The carburetor, gascolator, and ignition leads were destroyed in the crash. Detailed examination of the engine revealed heavy sooting of the #1 top spark plug and moderate erosion and gas blow-by of the pistons. Compression tests during the last 100-hour inspection had shown three cylinders below 60 PSI. The last major overhaul of the engine was 25 years and 2,221 hours prior to the accident, while the engine manufacturer recommends a major overhaul every 2,000 hours or five years.