History of Flight
On April 3, 2011, about 1537 Pacific standard time, a North American Navion A, registration N91472, collided with the ground while maneuvering after takeoff near Alameda, California. The certificated private pilot, the sole occupant, was fatally injured. The airplane was operated as a personal flight under 14 CFR Part 91. Visual meteorological conditions prevailed, and no flight plan was filed for the local flight that originated from Metropolitan Oakland International Airport (OAK) about 1536.
A pilot-rated witness reported that the airplane's initial climb was normal and the engine sounded good. Shortly thereafter, at about 200 feet above ground level, the engine shutdown as if the throttle had been retarded or the mixture control pulled to idle cutoff. The airplane began a descending left turn and continued beyond the witness's view. Other witnesses reported hearing “emergency emergency” transmitted on the Oakland tower frequency shortly after the accident airplane was cleared for takeoff from runway 33. No further radio communications were received from the pilot.
Aircraft Information
The airplane, a Navion A model, serial number NAV-4-279, was manufactured in 1946 and powered by a Continental IO-470 engine. It was equipped with a constant speed propeller and Osborne 20-gallon wing tip fuel tanks. Maintenance records indicated the most recent annual inspection was completed on August 5, 2010, at which the airframe total time was 2,676 hours and the engine total time was 2,023 hours (938 hours since major overhaul). The airplane was retrofitted with an American Navion Society ANS3 fuel selector valve concurrent with that annual inspection.
Wreckage and Impact
An FAA airworthiness inspector reported that the airplane came to rest in a tidal estuary about 0.5 miles northwest of the departure runway, partially buried in mud and water. The fuselage and wings sustained extensive structural damage. Both main wing fuel tanks were breached and leaked unknown amounts of fuel. The auxiliary fuel tank under the aft seat was intact and contained fuel. Both wing tip fuel tanks separated from the wings and were embedded in mud; they contained undetermined amounts of fuel upon recovery.
Examination
Postaccident examination at a storage facility revealed extensive impact damage. The engine compartment and forward fuselage were fragmented with aft crushing. Cockpit controls and instrumentation were fragmented and deformed. Flight control surfaces remained attached, and continuity was confirmed via control cables. The fuel selector, a five-point positive lock valve, was found in the right tip tank position. It moved freely and flow continuity was confirmed for each position.
The engine was examined; spark plugs were removed and cylinders borescoped. Combustion chambers and piston heads were undamaged but contained mud and debris. The crankshaft was rotated and compression was obtained in cylinders 2, 3, 4, 5, and 6. The oil sump was removed; camshaft and lifters were undamaged. Magnetos were water-soaked and produced no spark, but no preaccident mechanical malfunctions or failures that would have precluded engine operations were found.
Additional Information
The Osborne Airplane Flight Manual Supplement stated that auxiliary tip tank fuel should only be used in level flight to prevent overflowing the main tank due to excessive fuel return. The fuel selector valve in the accident airplane was not placarded with these procedures. The source did not determine whether the position of the fuel selector valve contributed to the in-flight emergency and accident sequence.