CEN18LA276

The private pilot reported that, as he approached the destination airport, he noted "a sudden and severe noise and vibration" and "a…stream of gray smoke from under the right side of the [engine] cowling," followed by a loss of engine power. The pilot subsequently conducted a forced landing, during which the airplane sustained substantial damage to the fuselage and right wing. Postaccident engine examination revealed two holes in the top of the crankcase near the Nos. 3 and 4 cylinders. A teardown examination of the engine revealed that the No. 4 connecting rod had failed due to oil starvation, which resulted in a catastrophic engine failure. Foreign debris, which was similar to a paper towel, was recovered from the engine oil sump and the oil pickup screen. Most of the screen area was obstructed by the debris, which had interrupted the oil flow from the sump to the engine. The airplane maintenance records noted that the alternator and alternator drive gear were replaced about 8 weeks before the accident. The engine had been operated about 24 hours since the alternator replacement. The starter and starter adapter were replaced the day before the accident flight. The engine had been operated about 15 minutes since the most recent maintenance work was performed. It is likely that maintenance personnel left the paper towel in the engine during the recent maintenance work, which resulted in oil starvation, the failure of the connecting rod, and the catastrophic engine failure and subsequent total loss of engine power.

On July 17, 2018, about 0830 central daylight time, a Beech V35 airplane, N228Q, was substantially damaged during a forced landing following a loss of engine power near Katy, Texas. The pilot was not injured. The airplane was registered to Pivot Group LLC and operated by the pilot as a Title 14 Code of Federal Regulations Part 91 personal flight. Day visual meteorological conditions prevailed. The flight was not operated on a flight plan. The flight originated from the Fair Weather Field Airport (TX42), Monaville, Texas, about 0820 and was destined for the West Houston Airport (IWS), Houston, Texas.The pilot reported that "a sudden and severe noise and vibration" and "a brief stream of gray smoke from under the right side of the [engine] cowling" preceded a loss of engine power as he approached the destination airport. He subsequently executed a forced landing to a residential development under construction. The airplane "bounced and skidded" before coming to rest upright. The airplane sustained substantial damage to the fuselage and right wing. A postrecovery engine examination was conducted under oversight of the National Transportation Safety Board (NTSB) investigator-in-charge. A visual examination revealed two holes in the top of the crankcase near the No. 3 and No. 4 cylinders. The crankcase appeared to be otherwise intact. A teardown examination determined that the No. 4 connecting rod had separated from crankshaft journal. The connecting rod remained attached to the piston. The end of the connecting rod common to the crankshaft was deformed consistent with secondary mechanical damage. The No. 4 crankshaft journal was discolored consistent with oil starvation. The No. 4 piston was wedged in the cylinder and portions of the piston skirt had separated. The oil sump contained foreign debris that appeared to be a paper-based shop towel. The oil pickup screen was obstructed by similar debris. Approximately 7 quarts of oil were recovered from the sump in addition to the debris. At the time of the examination, the hour (Hobbs) meter and tachometer indicated 1,414.3 hours and 5,959.54 hours, respectively. The debris recovered from the oil sump and the pickup screen was forwarded to the NTSB materials lab. Microscopic examination revealed that the debris consisted of a fibrous material with the appearance of a textured paper product similar to paper towels. A sample was washed with acetone to remove the engine oil and analyzed using a spectrometer. The cleaned sample displayed a spectrum with a strong match to cellulose, which is found in natural plant fibers such as cotton and wood. Paper products are manufactured with cellulosic material. A review of the airplane maintenance records revealed that the most recent annual inspection was completed on September 22, 2017, at 5,815.4 hours tachometer time. On June 6, 2018, the alternator and alternator drive gear were replaced. The corresponding hour meter and tachometer times were 1,390.3 and 5,935.7hours, respectively. On July 16, 2018, the starter and starter adapter were replaced. The corresponding hour meter and tachometer times were 5,959.33 hours and 1,414.0 hours, respectively. The records contained no subsequent entries.