N7751YPiper PA-30 · 1965

On November 29, 2018, about 1421 eastern standard time, a Piper PA-30 (Twin Comanche) airplane, N7751Y, impacted terrain shortly after takeoff from Marion Municipal Airport, Marion, Indiana. The airline transport pilot sustained fatal injuries, and the airplane was destroyed. The airplane was registered to and operated by the pilot as a Title 14 Code of Federal Regulations Part 91 personal flight. Visual meteorological conditions prevailed at the time of the accident, and a flight plan was not filed for the local flight.

According to information from a sheriff's deputy, on the day before the accident, fixed-based operator employees observed the pilot performing ground engine runs outside of his hangar. According to family members, the pilot, who was also an airframe and powerplant mechanic, had been troubleshooting an unspecified fuel system problem with the left engine.

A family member described the accident flight as a "test flight."

Witnesses reported that, after departure, the airplane climbed to an altitude of about 500 ft above ground level and began a left turn. During the left turn, the airplane "nose-dived" in a downward spiral. The airplane then impacted terrain, and a post-impact fire ensued.

The pilot's logbook was not located during the investigation. An estimate of the pilot's flight time was determined based on his most recent airman medical application.

The airframe, engine, and propeller logbooks were not located during the investigation. The airplane was registered to the pilot on December 17, 2008.

During an examination of the pilot's hangar after the accident, an invoice, dated November 16, 2018, was located for the purchase of left and right fuel selector valves and miscellaneous installation hardware. A search of the hangar revealed an empty shipping box for the valves. In addition, a fuel selector access plate, a fuel valve protector cover, and fuel valve control handles for the airplane were found in the hangar. To complete the installation, these components would have been removed during the replacement of the fuel selector valves, and then reinstalled at the completion of the valve installation.

The Piper Twin Comanche Service Manual, section IX, Fuel System, provided the following system description:

The fuel system is contained in two independent units that allow each engine to have its own fuel supply. The systems are connected only by a crossfeed that will allow fuel to be drawn from one set of fuel cells to the engine of the opposite side, in the event of an emergency. For each engine, fuel is taken from each cell through a screen located in the cell outlet fitting and then on to a shut-off selector valve. From the selector valve, fuel is drawn through an electrically operated auxiliary fuel pump and on to an engine driven pump where it is pumped to the injector unit. The fuel valves are operated through controls located in a panel, just ahead of the main spar, between the pilot seats.

The Piper Twin Comanche Owner's Handbook, section II, Design Information, stated the following about the fuel system:

For emergency single engine operation, a crossfeed is provided to increase the range. When using fuel from cells on the opposite side of the operating engine, move the fuel selector for the inoperative engine to the main or auxiliary position; then move the fuel selector for the operating engine to the crossfeed position. For single engine landing, fuel must be pumped from the main cell on the same side as the operating engine.

Section II of the owner's handbook, stated the following about the propellers:

The propellers are...constant-speed, controllable, full-feathering units. These are controlled entirely by use of the propeller control levers located in the center of the power control quadrant. Feathering of the propellers is accomplished by moving the controls fully aft through the low RPM detent into the feathering position. Feathering takes place in approximately three seconds.

The airframe, engine, and propeller logbooks were not located during the investigation. The airplane was registered to the pilot on December 17, 2008.

During an examination of the pilot's hangar after the accident, an invoice, dated November 16, 2018, was located for the purchase of left and right fuel selector valves and miscellaneous installation hardware. A search of the hangar revealed an empty shipping box for the valves. In addition, a fuel selector access plate, a fuel valve protector cover, and fuel valve control handles for the airplane were found in the hangar. To complete the installation, these components would have been removed during the replacement of the fuel selector valves, and then reinstalled at the completion of the valve installation.

The Piper Twin Comanche Service Manual, section IX, Fuel System, provided the following system description:

The fuel system is contained in two independent units that allow each engine to have its own fuel supply. The systems are connected only by a crossfeed that will allow fuel to be drawn from one set of fuel cells to the engine of the opposite side, in the event of an emergency. For each engine, fuel is taken from each cell through a screen located in the cell outlet fitting and then on to a shut-off selector valve. From the selector valve, fuel is drawn through an electrically operated auxiliary fuel pump and on to an engine driven pump where it is pumped to the injector unit. The fuel valves are operated through controls located in a panel, just ahead of the main spar, between the pilot seats.

The Piper Twin Comanche Owner's Handbook, section II, Design Information, stated the following about the fuel system:

For emergency single engine operation, a crossfeed is provided to increase the range. When using fuel from cells on the opposite side of the operating engine, move the fuel selector for the inoperative engine to the main or auxiliary position; then move the fuel selector for the operating engine to the crossfeed position. For single engine landing, fuel must be pumped from the main cell on the same side as the operating engine.

Section II of the owner's handbook, stated the following about the propellers:

The propellers are...constant-speed, controllable, full-feathering units. These are controlled entirely by use of the propeller control levers located in the center of the power control quadrant. Feathering of the propellers is accomplished by moving the controls fully aft through the low RPM detent into the feathering position. Feathering takes place in approximately three seconds.

The airplane came to rest upright in a soft, wet field about 1/4 mile south of the departure runway. The accident site and the airplane wreckage are shown in the figure. Postaccident examination of the airplane showed that the fuselage, empennage, and inboard sections of both wings were consumed by post-impact fire. The instrument panel, instruments, and engine controls were destroyed by fire and impact. The front left seat remained attached to the cabin floor. (The right front seat was not installed and was found in the pilot's hangar.) The main cabin door was separated and came to rest about 15 ft forward of the main wreckage. The upper latch and side pin were found engaged, consistent with a closed or locked door position.

Figure. Accident Site

The left and right wings remained partially attached to the fuselage and displayed thermal, buckling, and leading edge damage. The left and right ailerons remained attached to the wing attach brackets and control pushrod. The left and right flaps remained attached to the wing structure and displayed thermal damage. The right outboard wing and wing tip were deformed aft. A ground scar, consistent with the right wing, was noted about 3 ft in front of the damaged right wing. The right flap control mechanism displayed thermal damaged and the control arm was found between the flaps 0° and slightly extended position. The landing gear retraction push-pull rod was found in the landing gear extended position.

The empennage was consumed by fire. The horizontal and vertical stabilizers and rudder were attached and displayed thermal damage. The rudder trim mechanism shaft position correlated to a neutral rudder trim setting.

Flight control continuity for the flight control surfaces could not be determined due to impact and thermal damage; but no mechanical anomalies were noted that would have precluded normal flight control operations.

The left engine and propeller assembly remained partially attached to the airframe. One propeller blade showed no damage, and one propeller blade was not twisted and bent aft. The right engine remained partially attached to the airframe, and the right propeller assembly was separated from the engine, aft of the crankshaft flange. The crankshaft fracture surface exhibited 45° shear lips. One propeller blade was twisted and bent forward, and one propeller blade was twisted and bent aft. Both the left and right propeller blades appeared to be in a low-pitch position.

After the on-scene examination, the airframe, engines, and systems were further examined at the recovery facility. The left fuel selector arm was found in the cross-feed position, and the right fuel selector arm was found in the right main fuel cell position. Thermal damage precluded movement of the left and right fuel selector arms to the different selector positions. The left and right main fuel cells, fuel outlet lines, and cross-feed fuel lines and fittings remained attached or partially attached to the fuel selectors and the "B" nuts were secure. The fuel lines displayed material loss and thermal damage. The left auxiliary fuel line and fitting were not located at the time of the examination, but a review of on-scene photographs showed the line and fitting partially in place on the fuel selector valve with only partial thread engagement. Magnified examination of the selector valve threads revealed the threads were undamaged.

Mechanical rotation determined left and right engine continuity to all pistons and the accessory gearboxes. Thumb compression was noted on all cylinders. The engines magnetos and accessories were thermally damaged and precluded functional testing of the components.

The Northeast Indiana Forensic Center, Fort Wayne, Indiana, performed an autopsy of the pilot. The pilot's cause of death was multiple blunt force injuries. Toxicology testing performed at the Federal Aviation Administration (FAA) Forensic Sciences Laboratory identified doxylamine (0.153 ug/mL, ug/g) in the pilot's liver specimens, but in the pilot's aortic blood specimens. The tests were negative for carbon monoxide and ethanol.

Doxylamine is a sedating antihistamine available over the counter to treat allergy symptoms or use as a sleep aid. Doxylamine undergoes postmortem distribution and central blood levels may be two to three times higher than peripheral blood levels.