NTSB Factual Report

On December 15, 2015, at 1050 eastern standard time, a Piper PA-32-300, N8675N, made a forced landing about .1-mile north of Malcolm McKinnon Airport (SSI), Brunswick, Georgia, after a catastrophic engine failure. The pilot and the passenger sustained minor injuries. The airplane landed on the roof of a home and collided with trees which resulted in substantial damage to the fuselage and wings. The airplane was registered to a private company and operated as a 14 Code of Federal Regulations (CFR) Part 91 personal flight. Visual flight rules conditions existed near the accident site at the time of the accident. No flight plan was filed for the flight that originated from Jacksonville Executive at Craig Airport (CRG), Jacksonville, Florida, about 1020 and was destined for the Rock Hill/York County/Bryant Field (UZA), Rock Hill, South Carolina.

The pilot stated that he was in cruise flight at 7,500 ft mean sea level (msl) when, without any warning, there was a loud explosion from the engine and an immediate loss of engine power. The explosion caused the oil filler door to open and it partially pushed the Garmin 430 out of the dashboard. Oil spewed all over the windshield and smoke filled the cockpit. The pilot declared an emergency and attempted to glide to St. Simons Airport, St. Simons, Georgia; however, he landed on a rooftop a few hundred yards short of the runway. There was no post-impact fire.

An examination of the engine was conducted on January 26, 2016, by the National Transportation Safety Board (NTSB). The examination revealed the No. 4 cylinder had separated from the engine case. The cylinder skirt was split in several areas consistent with the piston making contact with the cylinder after it separated from the case. Groove marks etched on the top of the piston were consistent with it striking the cylinder skirt. All of the No.4 cylinders mounting stubs and thru-bolts were fractured except for the bottom forward stud. The piston and corresponding connecting rod for the No. 4 cylinder were found in the bottom of the engine cowling. The other engine components appeared unremarkable. The engine was completely disassembled and the No. 4 crank-journal showed no signs of bearing migration or excessive heat. However, there were numerous gouges and scratches throughout the inside of the engine from debris after the cylinder separated.

A review of the engine logbook revealed the engine was overhauled in February 2007 and installed on the airplane on March 16, 2007. The last engine inspection was completed on November 17, 2015, at total time of 1,005.0 hours since overhaul. A review of the engine's maintenance history since it was overhauled revealed no maintenance had been done to the No. 4 cylinder.

NTSB Probable Cause

Maintenance personnel's failure to properly torque a No. 4 cylinder hold-down nut during engine overhaul, which resulted in the loosening of the nut and the subsequent failure of the studs and through bolts and separation of the cylinder.