On June 16, 2002, a Cessna 175 (registration N7338M) operated by Brent A. Carlson was involved in an aviation accident near Salt Lake City, UT. Investigators recorded the probable cause as: total mechanical loss of engine power for reasons undetermined. Contributing factors were the lack of an annual inspection and the (forced landing in) salt water. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During cruise at 5,600 ft MSL, the tachometer showed a 100-200 rpm drop, oil temperature pegged high, engine vibrated, upper cowling broke off revealing a casing breach, white smoke filled cockpit, engine seized, propeller stopped vertical, forced landing in salt water ensued. Last annual inspection was 9 years prior.
Accident Narrative
While in cruise flight at 5,600 feet mean sea level (MSL), the tachometer indicated the engine had lost 100 to 200 revolutions per minute (rpm). Shortly thereafter, the oil temperature gauge pegged high, while oil pressure remained steady at 25 psi. The engine began to vibrate, and the upper cowling broke off, exposing a breach in the top of the casing aft of number 3 cylinder. White smoke filled the cockpit, the engine seized, and the propeller stopped in the vertical position. A forced landing in salt water ensued.
Maintenance History
The last annual inspection on the airplane had been performed 9 years before the accident.