WPR09LA324
WPR09LA324

On July 3, 2009, about 0914 mountain standard time, a Piper PA-30 twin-engine airplane, N7657Y, was substantially damaged when it impacted terrain following a partial loss of engine power during takeoff from the Tucson International Airport (TUS), Tucson, Arizona. The airplane was registered to and operated by the pilot under the provisions of Title 14 Code of Federal Regulations Part 91. The commercial pilot and his three passengers sustained minor injuries. Visual meteorological conditions prevailed and no flight plan was filed for the personal flight. The cross-country flight was originating at the time of the accident with an intended destination of Show Low, Arizona.

In a written statement, the pilot reported that after being cleared for takeoff on runway 11L, he "advanced the mixture controls, turned on the boost pumps, and advanced the throttles." The pilot noticed that the power "came up normally in both engines" as he observed the manifold pressure gauges indicating within the "mid 20’s" and the "tach gauges showed just over 2500 rpm." The pilot stated that the left engine fuel flow "was a bit excessive" as the "right engine showed 12 GPM which is normal and the left engine showed 16 GPM."

The pilot further reported that the airplane lifted off the ground around 80 miles per hour and he intended on remaining close to the runway until accelerating beyond 90 miles per hour. As the airplane was about 10 to 20 feet above ground level (agl), the airplane started to veer to the left. Despite the pilot's control inputs, the airplane continued to veer to the left as the "left wing continued to drop." Subsequently, the airplane impacted the ground. The pilot added that “the left engine did not seize or stop turning at any time prior to contacting the ground.”

Local law enforcement reported that following the accident, the pilot stated that as the airplane was about 30 feet above the ground, “he lost power to the left engine” and was “unable to stabilize the aircraft.”

Examination of the airplane by a Federal Aviation Administration (FAA) inspector revealed that the airplane came to rest between taxiway Alpha 7 and Tango, about 332 feet left of the centerline for runway 11. The left and right engines were mostly separated from their mounts. The forward part of the fuselage was crushed aft. The inspector stated that first responders turned the left and right fuel selectors from the "MAIN" position to the "OFF' position shortly after the accident.

According to the airframe manufacturer's approved flight manual, the published minimum control airspeed for single-engine operations is 90 miles per hour.

Examination of the recovered airframe revealed flight control continuity from the cockpit controls to all primary flight control surfaces. Both left and right engines and empennage were separated from the airframe by wreckage recovery personnel to facilitate wreckage recovery.

The left engine, a Lycoming IO-320-B1A, serial number L-1582-55A, remained intact. The throttle body fuel control unit was separated from the engine. The top spark plugs were removed and the crankshaft was manually rotated by hand using a hand tool attached to the crankshaft propeller flange. Rotational continuity was established throughout the engine and valve train. Thumb compression was noted on all four cylinders. The propeller flange and crankshaft appeared to be slightly bent.

The fuel servo was separated from the engine at its respective mount. The throttle and mixture control levers moved from stop to stop freely by hand. The fuel servo screen was removed and no debris was noted.

The top cylinder one, two, three, and four spark plugs exhibited worn/normal wear when compared to the Champion AV-27 check-a-plug comparison chart. Black deposits were observed within the electrode area on all of the top spark plugs. The bottom cylinder one, two, three, and four spark plugs exhibited signatures consistent with worn/normal wear. The bottom cylinder one and two spark plugs were oil soaked. The number three and four cylinder spark plugs exhibited black deposits within the electrode area.

The left engine fuel control servo, fuel flow divider, and fuel injector nozzles were removed and sent to Precision Airmotive LLC for further examination.

The left propeller assembly was separated from the engine by wreckage recovery personnel. Both propeller blades were loose within the propeller hub. One blade was curled about 180 degrees opposite the direction of rotation about 10 inches inboard from the blade tip. The blade exhibited leading edge gouging and chordwise scratching on the blade face from about 12 inches inboard to the blade tip. The other blade was twisted opposite the direction of rotation along with a slight aft bend about 8 inches outboard of the propeller hub. The blade exhibited chordwise scratching and polishing on the blade face near the outboard 10 inches of the propeller blade.

The right engine, a Lycoming IO-320-B1A, serial number L-1591-55A, was intact. The starter, alternator, and throttle body fuel servo unit were displaced from the engine. The top spark plugs were removed and the crankshaft was manually rotated by hand using a hand tool attached to the crankshaft propeller flange. Rotational continuity was established throughout the engine and valve train. Thumb compression was noted on all four cylinders. The throttle and mixture control levers moved from stop to stop freely by hand.

The top cylinder one, two, three, and four spark plugs exhibited worn/normal wear when compared to the Champion AV-27 check-a-plug comparison chart. Light gray deposits were observed within the electrode area. The bottom number one, three, and four spark plugs exhibited normal wear signatures when compared to the Champion AV-27 check-a-plug comparison chart. The number two bottom spark plug exhibited worn-severe signatures. The bottom number one cylinder spark plug was oil soaked. The number two, three, and four cylinder bottom spark plugs exhibited light gray deposits within the electrode area.

The right engine fuel control servo was removed and sent to Precision Airmotive LLC for further examination.

The right propeller assembly was separated from the engine by wreckage recovery personnel. Both propeller blades remained attached to the propeller hub. One blade was twisted opposite the direction of rotation from about mid-span of the blade. Chordwise scratches were observed on the propeller blade face and leading edge from the blade tip to about 8 - 10 inches outboard of the blade root. Leading edge gouges were observed on the outboard 6 inches of the propeller blade. The other blade was twisted opposite the direction of rotation from about mid-span. Chordwise scratching and blade polishing was observed on the outboard 10 inches of the propeller blade face and outboard 15 inches of the leading edge.

The left engine fuel control servo, fuel flow divider, and fuel injector nozzles were examined at the facilities of Precision Airmotive LLC., Marysville, Washington. The fuel servo was installed on a test bench and functionally tested. The observed fuel rate (pounds/hour) exceeded the recommended factory limits on three of the nine flow tests conducted. When tested at a level consistent with takeoff, the fuel flow rate observed was 8.2 pounds/hour over the factory in-service limitations. Examination of the fuel flow divider revealed that all fittings were seized within the divider body and could not be removed. Air pressure was applied to the flow divider and air flow throughout all ports was verified. The fuel nozzles were placed on a test bench and flow tested. The number one, three, and four fuel nozzles test results were below the factory specifications during the low pressure (12 PSI) flow test and within the factory specifications during the high pressure (36 PSI) flow test. The number two fuel nozzle tested below factory specifications on both the 12 PSI and 36 PSI tests.

The right engine fuel control servo was installed on a test bench and functionally tested. The observed fuel rate (pounds/hour) was found within factory specifications on eight of the nine tests. When tested at a level consistent with takeoff, the fuel flow rate observed was within factory in-service limitations.

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