Accident Overview
On July 28, 2011, at approximately 1200 eastern daylight time, a Cessna 172M (registration N1443U) was substantially damaged during a forced landing in Lake Okeechobee near Pahokee, Florida. The aircraft was on an instructional flight under Part 91 operating rules. Visual meteorological conditions prevailed, and no flight plan had been filed. The flight was between Palm Beach County Glades Airport (PHK) in Pahokee and Fort Lauderdale Executive Airport (FXE).
Pilot Accounts
The certificated flight instructor reported that the accident flight was part of a series of cross-country and student solo flights that day. After arriving at PHK, three practice landings were performed before a full-stop landing. During a subsequent takeoff from runway 17 (with winds from 100 degrees magnetic at 10 knots), the student pilot was at the controls. All engine gauges were within normal ranges, and the fuel tanks were half full.
As the airplane reached 500 feet during a straight-out departure, the engine began shaking, sputtering, and producing alarming noises. The flight instructor immediately took control, quickly checked the mixture, fuel selectors, engine instruments, and fuel, finding nothing abnormal. She then turned the airplane back toward runway 35 and radioed an engine failure. Although the engine did not completely stop, it was not producing thrust, and the airplane could not maintain altitude.
After turning toward runway 35, the instructor realized the airplane was too high and too fast. She pulled out the throttle but did not use flaps or attempt a slip. The airplane overflew the entire runway length, forcing the instructor to consider alternatives: a house ahead, a road with power lines to the right, and the lake to the left. She turned toward the lake, extended the glide as long as possible, and the airplane touched down and nosed over. Both occupants exited and waited on the inverted fuselage until rescued.
Engine Examination
After recovery from the lake, Federal Aviation Administration (FAA) inspectors and flight school maintenance personnel examined the Lycoming O-320-E2D engine. They discovered that the No. 3 cylinder exhaust valve head had sheared off the stem. The stem, spring, and rocker arm remained intact. The No. 3 piston showed signs of mechanical damage from the detached head inside the combustion chamber.
The engine had last undergone a 100-hour inspection on July 21, 2011, at which time it had accrued 2,211.8 hours since major overhaul. At the accident, total hours since major overhaul were 2,229.5. Notably, Lycoming Service Instruction 1009AU (dated November 18, 2009) recommends a time-between-overhauls of 2,000 hours for the O-320-E engine.
Damage
The aircraft sustained substantial damage as a result of the forced landing and subsequent submersion.