Incident Overview
On July 3, 2019, at 1035 Hawaii-Aleutian standard time, a Cessna TU206F (registration N150SC) was substantially damaged in an accident near Waikoloa Village, Hawaii. The commercial pilot and a passenger were not injured. The aircraft was operating as a Title 14 Code of Federal Regulations Part 91 aerial observation flight.
Sequence of Events
The pilot reported that the flight was destined for Kona, Hawaii, to conduct aerial survey work. After about three hours of flight, the pilot noticed a low oil pressure indication in the cockpit. He prepared for a landing at Ellison Onizuka Kona International Airport (PHKO), Kona, Hawaii. During this approach, he heard a “bang” and the airplane began to shake. The pilot pitched the airplane to maintain best glide speed and observed that the engine had lost all oil pressure. Although the engine continued to run at an idle setting, the pilot had no throttle authority. He initiated a forced landing to a road; during the landing, the right wing struck a road sign, and the airplane came to rest in a ditch.
Engine Examination
A Federal Aviation Administration inspector examined the engine. The examination revealed that the No. 4 connecting rod crankshaft end and cap had separated from the rod, and the bolts were sheared. One of the nuts for the connecting rod cap bolts was split, and both pieces were recovered. The inspector also noted indications of high heat on the piston end of all the connecting rods, with darkening on the crankshaft end of the No. 5 connecting rod. Numerous large pieces of the connecting rod cap and pistons had migrated through the engine case, resulting in further damage to several other cylinders and pistons. Cracks were observed on at least two other pistons, and damage was noted to the cylinder mounting flanges on at least three cylinders.