LAX07LA122
LAX07LA122

On April 8, 2007, about 1645 Pacific daylight time, a Scottish American Bulldog 120, N706X, collided with a tree near South Lake Tahoe, California. The pilot/owner was operating the airplane under the provisions of 14 Code of Federal Regulations (CFR) Part 91. The private pilot was killed, and one passenger sustained serious injuries. The airplane sustained substantial damage to the wings and fuselage. The cross-country personal flight departed South Lake Tahoe about 1630 with a planned destination of Palo Alto, California. Visual meteorological conditions prevailed, and no flight plan had been filed.

Local authorities received reports of an emergency locator transmitter (ELT) signal. They began a search, and discovered the wreckage of the inverted airplane. They observed footprints in the snow leading away from the wreckage, and found a female survivor about 1 mile away.

The Federal Aviation Administration accident coordinator interviewed the survivor. She stated that they departed runway 18 at South Lake Tahoe airport (TVL) under visual flight rules to Palo Alto (PAO). Prior to departure, the pilot had the airplane fueled to capacity, 32 imperial gallons (38.4 us gallons). The pilot intended to follow highway 50 through the mountains; however, he experienced difficulty in climbing from Lake Tahoe. He elected to circle over Meyers, California, to gain sufficient altitude to pass over Echo Summit. During the circling climb, the pilot flew south of Meyers into even higher mountainous terrain. The passenger stated that the airplane was unable to climb or maintain altitude, and struck a tree with the right wing. The airplane came to rest inverted in a pasture.

The retriever cut all empennage control cables aft of the cabin during retrieval. The airplane had nosed over, the cabin had buckled, and the lower half of the fuselage separated at this point. All control cables were connected to their respective control surfaces. The elevators remained attached to the horizontal stabilizers; the rudder remained attached to the vertical stabilizer. The rudder and vertical stabilizer exhibited downward crush, and buckled at their midpoint.

Investigators from the National Transportation Safety Board and Textron Lycoming examined the wreckage at Plain Parts, Sacramento, California, on July 23, 2007.

Investigators removed the engine. They slung it from a hoist, and removed the top spark plugs. All spark plugs exhibited no mechanical deformation. The spark plug electrodes were oval. Spark plugs numbers one, two, and three were oily. All electrodes were gray, which corresponded to normal operation according to the Champion Aviation Check-A-Plug AV-27 Chart.

A borescope inspection revealed no mechanical deformation on the valves, cylinder walls, or internal cylinder head.

The oil sump screen was clean.

Investigators manually rotated the crankshaft with the propeller. The crankshaft rotated freely, and the valves moved approximately the same amount of lift in firing order. The gears in the accessory case turned freely, and the fuel pump plunger moved up and down. Investigators obtained thumb compression on all cylinders in firing order. The timing was at 20 degrees before top dead cylinder of the number one cylinder.

Investigators manually rotated the magnetos, and both magnetos produced spark at all posts.

The rubber diaphragm in the fuel distribution valve was unbroken, and investigators did not observe any contamination. The fuel nozzles were open. Investigators removed the fuel pump, and drained a clear blue fluid that smelled like aviation gasoline. They manually manipulated its operating arm, and it moved freely. They disassembled the pump, and the diaphragm was unremarkable.

The fuel selector valve was in the main position.

The right wing separated from the aileron outboard. The spar bent aft at the fracture surface, which was angular and irregular. The retriever cut the control cables. About 2 feet inboard of the wing tip, the leading edge had an 18-inch semicircular crush depression that went aft about 18 inches. The left wing separated at the front attachment point bolthole; the fitting bent aft, and the outboard section sheared along an angular plane. The retriever cut the wings off. Investigators moved the cut aileron and elevator control cables, and the control stick and control surfaces moved in the corresponding direction.

Both propeller blades bent aft about 20 degrees at midspan, and twisted toward the low pitch, high revolution per minute (rpm) position.

The FAA Forensic Toxicology Research Team, Oklahoma City, Oklahoma, performed toxicological testing of specimens of the pilot. Analysis of the specimens contained no findings for carbon monoxide, cyanide, volatiles, and tested drugs.

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