20150903020689A

On September 3, 2015, at 1635 EDT, a Cessna R172K, s/n R1723011 registered to black sheep aviation LLC suffered a total engine failure while in cruise flight. The weather was visual meteorological conditions and no flight plan had been filed. The aircraft was extensively damaged upon impacting the ground and both persons on board suffered serious injuries. The pilot holds a private pilot certificate and was appropriately rated and was current and qualified for the subject flight.

N758DK departed lincoln park airport, lincoln park, NJ (N07) at approximately 1430 EDT and proceeded to republic airport, farmingdale, NY (frg). After an uneventful landing at frg the pilot picked up a passenger. They then proceeded to fly along the hudson river at 2000 feet AGL for approximately 2.5 hours making total flight time approximately 3.5 hours. According to the pilot, at approximately 1635 EDT the engine began to make a ?grumbling? Sound and then completely shut down with the propeller in a fixed position. After several restart attempts which were unsuccessful, the passenger radioed an emergency call at which time the aircraft was in a steep descent and, during an emergency landing attempt, proceeded to impact a wooded area adjacent to a soccer field in Cresskill, NJ. The aircraft tach time at the accident was 2146.2 hours. It received its last annual inspection on July 17, 2015 at tach time of 2094.0 hours. The aircraft met all other applicable airworthiness requirements for the subject flight.

After aircraft recovery operations were completed, the engine was removed and shipped to the engine manufacturer, Continental motor corporation, mobile, Alabama. A teardown inspection was accomplished which was observed by an FAA inspector. During the teardown inspection it was noted that the #2 and #3 cylinder through bolt nut and perimeter nut torques were below factory specifications, allowing for a loss of bearing pinch of the #2 main bearing. The #2 main bearing shifted forward contacting the crankshaft. The crankshaft broke through the #4 throw.

Review of engine maintenance records revealed the #2 & #4 cylinders had been removed and reinstalled locally for maintenance on may 11, 2012 at 1914.7 hours. This was 231.5 hours of operation prior to failure. This operation required torqueing of the shared #2 and #3 cylinder through bolts. The evidence suggests that the nuts were improperly torqued. During a telephone conversation, the mechanic that replaced the cylinders stated that he had properly torqued the nuts, used a calibrated torque wrench and the most current manufacturer?s technical data to perform the task. He also said that the company where he performed the work was out of business and all records, technical data and tooling were discarded. The torque wrench he used is no longer available for inspection by the FAA. As there was no way to prove conclusively that this mechanic improperly torqued the nuts, a compliance action consisting of counseling has been completed with the mechanic and documented accordingly.

The engine was last overhauled February 8, 2000 at a time since new of 2616.8 hours. At the time of the accident, it had accumulated 1114.0 hours since major overhaul. The engine manufacturer recommends 2000 hours or 12 years between overhauls.

If any additional information becomes available this report will be amended as necessary.