Accident Details
On June 29, 2018, at about 1307 Alaska daylight time, a float-equipped Piper PA-18 airplane, registration N7675D, sustained substantial damage in an accident at Lake Hood Seaplane Base (LHD), Anchorage, Alaska. The pilot sustained minor injuries, and the passenger was uninjured. The flight was conducted as a personal flight under Title 14 Code of Federal Regulations Part 91.
The pilot reported that he and the pilot-rated passenger fueled the airplane before departure using a private fuel tank at the floatplane slip. The preflight inspection and engine run-up were normal. The pilot was conducting the takeoff from the rear seat. During the initial climb from the north water lane, at an altitude between about 100 and 200 feet above ground level, the engine began to sputter and lose power. Realizing that a water landing was not possible, the pilot turned toward a nearby gravel runway and asked the passenger to verify that the fuel selector valve was in the "on" position, which the passenger confirmed. The pilot pumped the throttle in an attempt to restore power, but the engine did not respond. The airplane subsequently impacted the grassy area between the runway and a taxiway.
The passenger corroborated the pilot's account and added that the airplane landed with a nose-high attitude and then banked right. After touchdown, the airplane slid across a taxiway and another grassy area, coming to rest on a heading of about 070°. Substantial damage was sustained to the fuselage and wings.
Examination Findings
At the accident site, a large amount of fuel was observed leaking from the left wing root. Examination of the pilot's private fuel tank and fueling system revealed debris in the fuel nozzle, but a fuel sample taken from the nozzle contained no water or debris.
A postaccident examination of the engine and fuel system was conducted two months after the accident. During that interval, the engine cowling was removed, and the wreckage and engine were exposed to rain. The engine remained attached to the airframe and was intact; all fuel and oil lines were secure. The fuel selector was found positioned to "left fuel on." The propeller assembly was connected to the engine crankshaft and could be rotated by hand. One propeller blade exhibited a rearward curl and a slight S-bend at the outer 8 inches, along with leading edge impact damage and scrapes. The other blade was straight, with extensive trailing edge impact damage and dirt and grass dried onto the cambered face.
Corrosion and carbon deposits were found around the spark plug threads, gasket, and neck. No spark could be produced at the leads when the propeller was rotated. The magnetos were bench-tested and no anomalies were noted. The propeller and crankshaft could be manually rotated, and crankcase and valve train continuity was established. The fuel strainer was full of fuel and contained minimal debris. The fuel line from the strainer to the engine and the carburetor contained no fuel, and no blockages were found. All fuel samples taken from the system and all system filters were clear of sizeable debris, consistent with avgas, and no water was detected.
No evidence of any preaccident mechanical malfunctions or failures that would have precluded normal engine operation was discovered.