Accident Details
On July 3, 2009, at about 0914 mountain standard time, a Piper PA-30 twin-engine airplane, registration N7657Y, was substantially damaged when it impacted terrain following a partial loss of engine power during takeoff from Tucson International Airport (TUS), Tucson, Arizona. The airplane was operated by the pilot under Part 91. The commercial pilot and three passengers sustained minor injuries. Visual meteorological conditions prevailed; no flight plan was filed for the personal cross-country flight to Show Low, Arizona.
Pilot Report
The pilot reported that after being cleared for takeoff on runway 11L, he advanced mixture controls, turned on boost pumps, and advanced throttles. Power came up normally in both engines, with manifold pressure gauges in the mid-20s and tachometers just over 2,500 rpm. The left engine fuel flow was 16 GPM, which the pilot described as excessive compared to the right engine's 12 GPM. The airplane lifted off at about 80 mph, and the pilot intended to remain close to the runway until accelerating beyond 90 mph. At about 10 to 20 feet above ground level, the airplane began to veer left, and despite control inputs, the left wing continued to drop, leading to ground impact. The pilot stated that the left engine did not seize or stop turning before impact. Local law enforcement reported that the pilot later stated he lost power to the left engine at about 30 feet and could not stabilize the aircraft.
Post-Accident Examination
The airplane came to rest between taxiway Alpha 7 and Tango, about 332 feet left of runway 11 centerline. The left and right engines were mostly separated from their mounts; the forward fuselage was crushed aft. First responders turned both fuel selectors from MAIN to OFF after the accident. Flight control continuity was confirmed from cockpit to all primary surfaces. Both engines and empennage were separated during recovery.
The left engine (Lycoming IO-320-B1A, serial L-1582-55A) remained intact but its throttle body fuel control unit was separated. Manual rotation established continuity and thumb compression on all cylinders. The propeller flange and crankshaft appeared slightly bent. The fuel servo was free-moving and its screen had no debris. Spark plugs showed worn/normal wear; some had black deposits. Oil soaking was noted on bottom plugs of cylinders one and two. The left propeller assembly had blades loose in the hub, with one blade curled 180 degrees opposite rotation and both exhibiting gouging and scratching.
The right engine (Lycoming IO-320-B1A, serial L-1591-55A) was intact but its starter, alternator, and fuel servo were displaced. Manual rotation established continuity and thumb compression. Spark plugs showed normal wear with light gray deposits, except bottom cylinder two showing worn-severe. The right propeller assembly had both blades attached, with twisting opposite rotation and chordwise scratching.
Engine Component Findings
The left engine fuel control servo, fuel flow divider, and injector nozzles were examined at Precision Airmotive LLC. The servo's fuel rate exceeded factory limits on three of nine tests; at takeoff power, it was 8.2 pounds/hour over the in-service limit. The fuel flow divider had seized fittings but airflow was verified. Fuel nozzles tested below specifications at low pressure (12 PSI) for cylinders one, three, and four, and below specifications at both pressures for cylinder two.
The right engine fuel control servo was within factory limits on eight of nine tests, including at takeoff power.
Probable Cause
No probable cause was stated in the source.