ERA15LA092

The pilot reported that, during initial climb, he heard a big "bang," which was followed by a total loss of engine power. He subsequently performed a forced landing straight ahead into trees. Teardown examination of the engine revealed that the lower rear crankshaft counterweight had separated. During a subsequent examination, all four snap rings from the lower rear crankshaft counterweight were found loose in the engine, and one of the rings was found broken in half. Three of the lower rear counterweight retaining plates were found, but the fourth retaining plate was not recovered. Two snap rings that were still in place on the upper rear crankshaft counterweight were examined. The examination revealed that the width between the snap ring ears on one of the snap rings did not meet the manufacturer-prescribed width, indicating that the snap ring was not properly seated. After that snap ring was removed and its groove was cleaned of deposits with a wire brush, it seated properly when reinstalled. A review of maintenance records revealed that, about 16 years before the accident, the engine had been rebuilt and had accumulated about 1,600 hours since it was rebuilt and that, about 8 years before the accident, a top overhaul was performed on the engine. The crankshaft was inspected about 6 months after the factory rebuild in accordance with an airworthiness directive (AD); however, there likely would have been little to no deposits in the crankshaft so soon after the factory rebuild. Before the issuance of the AD, the engine manufacturer had issued a mandatory service bulletin, which included a warning that the "failure to properly install counterweight retaining plates and snap rings may result in engine damage and possible failure." It is likely that the lower rear crankshaft counterweight snap rings were not properly installed; however, it could not be determined when or by whom they were improperly installed.

On January 6, 2015, about 1710 eastern standard time, a Beech V35B, N246JT, operated by a private individual, was substantially damaged during a forced landing into trees in Long View, North Carolina, following a total loss of engine power during initial climb from Hickory Regional Airport (HKY), Hickory, North Carolina. The commercial pilot was seriously injured and the three passengers incurred minor injuries. The personal flight was conducted under the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed and no flight plan was filed for the planned flight to Pitt-Greenville Airport (PGV), Greenville, North Carolina.The pilot stated that during initial climb, about 300 feet above ground level, he heard a loud bang followed by a total loss of engine power. He subsequently performed a forced landing straight ahead into trees. Examination of the wreckage by a Federal Aviation Administration inspector revealed substantial damage to the fuselage. The inspector also noted a hole in the engine case near the No. 2 cylinder. A teardown examination of the engine was performed at a recovery facility, under the supervision of an NTSB investigator. The examination revealed that the lower rear crankshaft counterweight had separated and the No. 1 connecting rod separated. Oil was present throughout the engine and there was no evidence of lack of lubrication. The No. 2 cylinder, crankshaft, and camshaft could not be separated from the engine case half for examination due to rotational damage that occurred following the separation of the crankshaft counterweight. Those components were then forwarded to the manufacturer's facility for further examination as the teardown examination could not be completed at the recovery facility. The subsequent examination at the manufacturer's facility was also performed under the supervision of an NTSB investigator. The examination revealed that all four snap rings from the lower rear crankshaft counterweight were found loose in the engine, and one of the rings had separated in half. Three of the lower rear counterweight retaining plates were found, but the fourth was not recovered. For comparison purposes, two snap rings were examined on the upper rear crankshaft counterweight. According to the manufacturer's mandatary service bulletin (MSB 99-3C), the minimum width between the snap ring ears must be 0.179 inch or more; a smaller width was indicative of a snap ring that was not properly seated in its groove. For one of the two upper rear counterweight snap rings, a 0.179 inch gap gauge could not be inserted as there was less than the prescribed space between the snap ring ears. However, when that snap ring was removed and its groove was cleaned of deposits by a wire brush, the snap ring then seated properly when reinstalled. Subsequently, the 0.179 inch gap gauge fit between the ears of the reinstalled snap ring. Review of maintenance records revealed that the airplane's mostrecent annual inspection was completed on July 16, 2014. At that time, the airframe had accumulated 3,394 total hours of operation. The engine was a factory rebuild in 1998 and had accumulated 1,561 total hours at the time of the annual inspection. The airplane flew about 46 hours from the time of the inspection, until the accident. Maintenance records show the engine received a top overhaul in 2006. The maintenance records also revealed that the crankshaft was inspection in June, 1999 in accordance with airworthiness directive 99-09-17. Continental Engines Service Bulletin MSB 99-3C states, "WARNING Do not use plates that have a loose fit. Failure to properly install counterweight retaining plates and snap rings may result in engine damage and possible failure."