CEN22LA227

While in cruise flight, the pilot observed the manifold pressure drop, followed by a loud rattling engine noise with strong vibrations. The pilot shut down the engine and diverted toward a nearby airport. The pilot reported that he thought the airplane was too high on the downwind leg; however, after he turned the airplane onto the final leg, he realized that the headwind would prevent him from making it to the runway. The pilot performed a forced landing into rough terrain short of the runway, which resulted in substantial damage to the right wing. Postaccident examination of the No. 3 cylinder revealed the cylinder barrel was fractured between the cooling fins and the threaded section used for mounting the cylinder head. A metallurgical examination revealed a fatigue crack that originated at a corrosion pit on the outer diameter surface of the cylinder barrel. The inboard-facing side of the first cylinder cooling fin was tinted black for a 180° arc, with the center of the arc in line with the fatigue crack. Manufacturer guidance includes inspection of cylinder fins for any signs of oil or soot leakage that might indicate a cylinder or head-to-barrel junction structural integrity breach. The engine was operated about 30 hours since the last annual inspection.

On May 29, 2022, about 1527 mountain daylight time, a Piper PA-28RT-201T, N2148J, was substantially damaged when it was involved in an accident near Morgan, Texas. The pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that, while in cruise flight at 9,500 ft mean sea level (msl), he observed the throttle lever creep back and a drop in manifold pressure. The pilot descended to about 5,500 ft msl and then observed a loud rattling engine noise with strong vibrations. The pilot shut down the engine, located a nearby airport, and executed a forced landing to runway 17 at W4 Ranch Airport, Morgan, Texas. The pilot reported that he thought the airplane was too high on the downwind leg; however, after turning onto the final leg, he realized that the headwind was going to prevent him from making it to the runway. During landing, the airplane touched down short of the runway in an area of rough terrain, which resulted in substantial damage to the right wing. Examination of the No. 3 cylinder at the National Transportation Safety Board Materials Laboratory revealed the cylinder barrel had fractured in the smooth-walled region located between the cooling fins and the threaded section used for mounting the cylinder head. The fracture surface was examined with the aid of a stereomicroscope. Features were consistent with a fatigue crack that originated along the outer diameter surface of the barrel at a corrosion pit. The fracture surface near the pit exhibited radial lines and flat feathery features that were consistent with crack initiation and progression due to cyclic fatigue. The inboard-facing side of the first cylinder cooling fin and adjoining material was tinted black for about a 180° arc. The fatigue crack was in line with the center of the black tinted arc. The Continental Engine Standard Maintenance Practice Manual, Section 6-4.11.1, includes the following information for a cylinder visual inspection: Inspect the external surfaces of the cylinder head including the fins, intake and exhaust ports, top and bottom spark plug bosses and fuel nozzle bosses for cracks, exhaust flange leakage or any signs of oil, fuel, or soot leakage indicating cylinder or the head-to-barrel junction structural integrity breach. A review of maintenance records revealed the compression checks of the No. 3 cylinder were lower than the other cylinders during the last 3 annual inspections. The engine was operated about 30 hours since the last annual inspection which was performed on July 19, 2021. The mechanic did not respond to requests for an interview regarding the recent maintenance of the engine.