What happened
On October 31, 2024, a PIPER PA-32-300, registration N154DC, was involved in an accident near Prescott Valley, Arizona. The pilot was conducting a local flight to investigate a fuel mixture discrepancy experienced during a previous flight. During the takeoff climb, the pilot noted unusual exhaust gas temperature (EGT) and fuel flow readings and decided to return to the airport for maintenance inspection.
While returning to the airport, the pilot heard two loud bangs followed by a total loss of engine power. Shortly after, smoke and flames appeared inside the cabin near the forward right-side floorboard. The pilot used an onboard fire extinguisher to put out the fire and performed a forced landing in an open field. The pilot was not injured, though the aircraft sustained substantial damage.
The investigation
Post-accident examination of the wreckage revealed that the No. 3 cylinder had separated from the engine case. The impact of the separated cylinder caused outward deformation of both the upper and lower right engine cowlings. Thermal damage was found on the lower right engine cowling and the forward fuselage.
Mechanical analysis of the engine showed that the No. 3 connecting rod had fractured, with subsequent damage found to the engine case, camshaft, and crankshaft. Investigators found that five of the eight base nuts for the No. 3 cylinder were missing. Evidence of fretting was present at the engine case mating surfaces and on all six cylinder hold-down plates, which is consistent with reduced torque of the engine case nuts, bolts, and cylinder base nuts.
Records indicated the engine had 1,168.83 hours since its last overhaul, which occurred in 1997. The most recent annual inspection was completed approximately 72 operating hours before the accident.