Accident Overview
On August 2, 2010, about 1205 eastern daylight time, a Cessna 177B, registered as N925KM to Rocky Wings, Inc., sustained substantial damage during a ditching near the southern coastline of Mashpee, Massachusetts. The aircraft had experienced a loss of engine power. Visual meteorological conditions prevailed, and no flight plan was filed for the personal flight conducted under 14 CFR Part 91. The private pilot and one passenger were not injured. The flight originated from Fairmouth Airpark, Fairmouth, Massachusetts, about 1000.
Pilot's Account
The pilot reported conducting a thorough preflight inspection and engine run-up before departure, with no discrepancies noted. The flight departed with full fuel tanks and flew locally at 1,000 feet, with power set to 20 inches manifold pressure and 2,300 rpm for most of the flight. While south of Mashpee and preparing to return to the departure airpark, the pilot moved the propeller control to the low pitch position and applied carburetor heat, after which the engine lost power. He immediately removed carburetor heat, but engine power was not restored. He trimmed to maintain 70 knots while attempting to restore power by reapplying carburetor heat and switching the fuel selector between left and right positions. The engine responded briefly but then lost power again. The pilot then focused on flying the airplane and elected to ditch away from the beach area. The airplane remained upright after water contact, and both occupants exited through the co-pilot's door and swam to shore.
Investigation Findings
Examination of the engine by a Federal Aviation Administration (FAA) airworthiness inspector revealed crankshaft, camshaft, and valve train continuity. Inspection of ignition system components—including magnetos, spark plugs, and ignition leads—showed no evidence of preaccident failures or malfunctions. The air induction and exhaust systems exhibited some impact damage but no preaccident anomalies. The oil filter contained no ferrous contamination, and fuel system components (carburetor, engine-driven fuel pump, auxiliary fuel pump, and flexible fuel lines) were free of preaccident failures or malfunctions. No mechanical reasons for the reported loss of engine power could be determined.
Review of FAA Special Airworthiness Information Bulletin CE-09-35, titled "Carburetor Icing Prevention," noted that based on the temperature and dew point at the time (75°F and 52°F, respectively), atmospheric conditions were favorable for serious icing at glide power.