Accident Overview
On September 8, 2013, about 1656 central daylight time, a Piper PA-32R-300, registration N8362C, operated by a private individual, was substantially damaged during a forced landing in a lake short of a runway at Guntersville Municipal Airport-Joe Starnes Field (8A1), Guntersville, Alabama. Visual meteorological conditions prevailed and no flight plan was filed for the personal flight under 14 CFR Part 91. The flight originated from Northeast Alabama Regional Airport (GAD), Gadsden, Alabama, at about 1609. The private pilot and one passenger sustained minor injuries.
Flight Sequence
The pilot reported a preflight inspection including fuel contamination checks with negative results. The aircraft departed with about 20 gallons of fuel in each wing tank and the fuel selector on the left tank. After flying over the passenger's house and north to Guntersville, the pilot decided to return to GAD due to haze. About 40–45 minutes into the flight, he switched the fuel selector to the right tank. Approximately 15 minutes later, the engine quit suddenly with no sputtering and the propeller continuing to rotate. At that moment, the aircraft was at 3,800 feet with engine settings at 2,250–2,300 rpm, manifold pressure 22–23 inches, mixture leaned 75° rich of peak, fuel consumption about 15 GPH, and fuel pressure in the normal range. The aircraft was 3–4 miles northeast of 8A1. The pilot turned right toward the airport, switched tanks, and turned on the auxiliary fuel pump, but power was not restored. He pitched for 120 mph and switched tanks three to four times without effect. Approaching 8A1, he announced an emergency landing on the common traffic advisory frequency. Winds favored runway 21. On approach with flaps retracted, the aircraft slowed such that the auto extend system deployed the landing gear. Unable to reach the runway, the pilot landed in water about 100 yards from shore. The airspeed at touchdown was 70 mph; the aircraft did not invert and came to rest in 3–4 feet of water. The left wing spars fractured, but the wing remained connected by flight control cables. The pilot believed that if the landing gear had not extended automatically, he could have reached land.
Engine and Fuel Examination
After recovery, an FAA inspector examined the aircraft and engine. The single drive dual magneto had separated from the engine accessory case but remained attached by the ignition harness. The lower magneto securing hardware was missing, with no damage to the stud threads. The upper magneto stud retained a portion of the magneto flange under a clamp secured by a flat washer, internal lock washer, and nut. The magneto was removed, air dried, and operated normally in testing. A portion of the magneto flange was fractured. The engine exhibited crankshaft, camshaft, and valve train continuity, and compression and suction in all cylinders. The fuel servo injector and manifold valve contained fuel; no other abnormalities were found. The magneto and upper hardware were sent to the NTSB Materials Laboratory. Examination revealed wear patterns on the lock washer, nut, and flat washer. The magneto clamp had pointed corners and no step feature. The gasket measured 0.034 inch thick, while the correct gasket should be 0.015 inch new and about 0.010 inch when clamped. The lower flange showed wear at the clamping face. The fractured flange had concentric crack arrest lines consistent with fatigue originating near the middle of the piece.
Fuel was present in both fuel cells. Compressed air confirmed continuity and normal function of the fuel system. An oil sheen was noted on the bottom fuselage skin. The GPS receiver data showed the aircraft's flight path. At 1652:33, the aircraft was about 3.2 nautical miles northeast of runway 21. Groundspeed slowed from 142 to 117 knots and altitude from 4,354 to 4,262 feet between 1652:33 and 1652:45. The aircraft maneuvered to a straight-in approach. From 1655:14 to 1655:47, groundspeed slowed from 86 to 68 knots on a southwesterly heading. The last data point placed the aircraft 754 feet at 023° from the approach end of runway 21.
Maintenance Records
The last annual inspection was signed off on February 18, 2011, with a total time of 5,156.49 hours. At the accident, total time was 5,176.26 hours. A review of 14 CFR Part 91.409 requires an annual inspection within the preceding 12 calendar months; the aircraft's inspection was overdue. Lycoming Service Instruction No. 1508C, dated February 10, 2011, describes mandatory magneto attachment procedures for Lycoming engines with dual magnetos, but compliance is not mandatory for Part 91 operators. The instruction states that failure to comply can cause loss of engine power. The correct parts include nut STD-1410, lock washer STD-475, clamp 66M19385, and gasket LW-12681. The manufacturer recommends compliance at the next oil change or magneto timing check, not to exceed 50 hours. The Pilot's Operating Handbook procedures for power-off landing with a backup gear extender instruct locking the emergency gear lever in override engaged before airspeed drops to 122 mph to prevent inadvertent gear extension. The best glide chart indicates a glide range of about 5 nautical miles from 4,240 feet pressure altitude to 600 feet elevation at the given conditions.