N695HRRoscher Frederick THUNDER MUSTANG · 2011

On July 26, 2014, about 0842 Pacific daylight time, an experimental amateur-built Thunder Mustang, N695HR, was destroyed by fire following a forced landing on a road near Spanish Springs, Nevada. The builder/owner/pilot was uninjured, and the passenger received minor injuries. The personal flight was conducted under the provisions of Title 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no Federal Aviation Administration (FAA) flight plan was filed for the flight.

According to the pilot, he based the airplane at Nut Tree airport (VCB), Vacaville, California, and the day prior to the accident flight, he flew from VCB to Reno/Stead airport (RTS) Reno, Nevada. The plan was to leave with another airplane for the Oshkosh/EAA Airventure event on July 26, with a fuel stop at Rock Springs, Wyoming, and an overnight stop at Mitchell, South Dakota.

The two airplanes, each with two persons on board, departed RTS as a flight of two. The second person on the accident airplane was not a pilot. The airplanes were climbing through 10,000 feet, about 8 miles northeast of RTS, and were being switched over to Reno Approach control when the "engine died." The pilot described the engine failure as "immediate," without a gradual onset, or any prior symptoms. The propeller continued to windmill after the loss of power. The pilot manipulated various engine-related controls in an attempt to get the engine running again, but without success. He did not observe any indications that suggested the nature or cause of the engine failure.

The pilot recognized that he would not be able to return to RTS, or to glide to any other airport. He spotted a road that was suitable for landing, and set up for a landing to the north. Shortly after touchdown, the airplane struck a northbound pick-up truck. The airplane "spun around," the fuel tank was breached, and the left main landing gear collapsed. The airplane came to a stop, and after some difficulty with the canopy, both occupants egressed safely. About 15 seconds later a fire began, and destroyed the airplane.

The pilot held a private pilot certificate with airplane single-engine land and instrument airplane ratings. He reported that he had a total flight experience of approximately 2,200 hours, including about 200 hours in the accident airplane make and model. His most recent flight review was completed in May 2014, and his most recent FAA second-class medical certificate was issued in April 2014.

The airplane was a kit-built, scale version of the P-51 WWII fighter airplane. Construction of this airplane was completed in 2011.

The fuselage was primarily of composite construction. The conventional flight controls were actuated by pushrods directly linked to the cockpit controls for the elevator and ailerons, and by cables for the rudder. The landing gear was hydraulically operated. According to the pilot, the remainder of the airplane functions were essentially "completely electric." The 12 volt DC electrical system was powered by two independent power sources and electrical busses, referred to as the "Main" and "Aux" (auxiliary) systems. The Main system was powered by a 60 ampere (A) alternator, and the Aux system was powered by a 20A alternator. Each system had its own battery, each of the same type/model. The Main system utilized a separate, external voltage regulator, while the Aux system used a voltage regulator integral to its alternator.

The Main bus powered most of the airplane systems, including lights, trim, cooling doors, flaps, and landing gear control. The Aux bus powered many of the navigation and display electronic units, a custom computer, and (again) the landing gear control. Cockpit switches allowed an avionics bus to be powered by either the Main or Aux electrical system. The majority of the airplane avionics were powered by the avionics bus.

The airplane was equipped with a custom-designed, non-aviation V-12 engine based on the Chevrolet automotive engine. Most engine accessories were mounted on or near the aft face of the engine, and were driven by a pair of one inch wide serpentine belts. The engine was equipped with two MoTeC brand M-48 engine control units (ECUs). Each ECU could be powered by either or both of the Main and Aux busses, controllable by cockpit switches. Each ECU was dedicated to a single cylinder bank. Two separate "Ref[erence] sensors" detected crankshaft rotation position, and each sensor provided its signal to its ECU.

The engine was port injected, with a dedicated fuel injector for each cylinder. Operation of the six injectors for each cylinder bank was controlled by that cylinder bank's ECU. Unlike most aviation engines, each cylinder was equipped with a single spark plug. The engine was equipped with two separate ignition "coil packs," each of which provided ignition energy to its respective cylinder bank. Similar to the fuel injector control scheme, each ECU controlled the coil pack and ignition timing for its cylinder bank.

The fuel and ignition timing of each cylinder bank were controlled by the same ECU. The design independence of the cylinder bank fuel and ignition control provided a partial level of redundancy; according to airplane documentation, in the event of the failure of one ECU, "the engine will continue to run either the right or left cylinder bank independently, allowing for an emergency "limp home" mode."

The ECUs were mounted in the forward cockpit right sidewall. Two cockpit switches, one per electrical system, were available to connect or isolate the ECUs from the respective electrical system. The ECUs were individually isolatable. The pilot reported that he normally left the switches in the position which provided power from both electrical systems. During engine runup he would cycle the switches to ensure that the ECUs operated when powered independently by each electrical system. Two cockpit LEDs separately indicated the status of Main and Aux electrical power availability to the ECUs.

The airplane was equipped with a multitude of electronic devices that contained non-volatile memory (NVM). One of those devices had been custom designed and built by the pilot; he referred to it variously as the "telemetry/data recording computer," or as the "air data" or "flight" recorder. The device recorded data from both ECUs, the EI brand MVP-50 engine monitor, and several flight and navigation units. The device contained NVM, and was mounted aft of the rear passenger seat.

For additional details refer to the NTSB public docket for this accident

The 0855 automated weather observation at Reno International Airport (RNO), Reno, located about 12 miles south of the accident site, included calm winds, visibility 10 miles, few clouds at 15,000 feet, temperature 19 degrees C, dew point 3 degrees C, and an altimeter setting of 30.19 inches of mercury.

The airplane was a kit-built, scale version of the P-51 WWII fighter airplane. Construction of this airplane was completed in 2011.

The fuselage was primarily of composite construction. The conventional flight controls were actuated by pushrods directly linked to the cockpit controls for the elevator and ailerons, and by cables for the rudder. The landing gear was hydraulically operated. According to the pilot, the remainder of the airplane functions were essentially "completely electric." The 12 volt DC electrical system was powered by two independent power sources and electrical busses, referred to as the "Main" and "Aux" (auxiliary) systems. The Main system was powered by a 60 ampere (A) alternator, and the Aux system was powered by a 20A alternator. Each system had its own battery, each of the same type/model. The Main system utilized a separate, external voltage regulator, while the Aux system used a voltage regulator integral to its alternator.

The Main bus powered most of the airplane systems, including lights, trim, cooling doors, flaps, and landing gear control. The Aux bus powered many of the navigation and display electronic units, a custom computer, and (again) the landing gear control. Cockpit switches allowed an avionics bus to be powered by either the Main or Aux electrical system. The majority of the airplane avionics were powered by the avionics bus.

The airplane was equipped with a custom-designed, non-aviation V-12 engine based on the Chevrolet automotive engine. Most engine accessories were mounted on or near the aft face of the engine, and were driven by a pair of one inch wide serpentine belts. The engine was equipped with two MoTeC brand M-48 engine control units (ECUs). Each ECU could be powered by either or both of the Main and Aux busses, controllable by cockpit switches. Each ECU was dedicated to a single cylinder bank. Two separate "Ref[erence] sensors" detected crankshaft rotation position, and each sensor provided its signal to its ECU.

The engine was port injected, with a dedicated fuel injector for each cylinder. Operation of the six injectors for each cylinder bank was controlled by that cylinder bank's ECU. Unlike most aviation engines, each cylinder was equipped with a single spark plug. The engine was equipped with two separate ignition "coil packs," each of which provided ignition energy to its respective cylinder bank. Similar to the fuel injector control scheme, each ECU controlled the coil pack and ignition timing for its cylinder bank.

The fuel and ignition timing of each cylinder bank were controlled by the same ECU. The design independence of the cylinder bank fuel and ignition control provided a partial level of redundancy; according to airplane documentation, in the event of the failure of one ECU, "the engine will continue to run either the right or left cylinder bank independently, allowing for an emergency "limp home" mode."

The ECUs were mounted in the forward cockpit right sidewall. Two cockpit switches, one per electrical system, were available to connect or isolate the ECUs from the respective electrical system. The ECUs were individually isolatable. The pilot reported that he normally left the switches in the position which provided power from both electrical systems. During engine runup he would cycle the switches to ensure that the ECUs operated when powered independently by each electrical system. Two cockpit LEDs separately indicated the status of Main and Aux electrical power availability to the ECUs.

The airplane was equipped with a multitude of electronic devices that contained non-volatile memory (NVM). One of those devices had been custom designed and built by the pilot; he referred to it variously as the "telemetry/data recording computer," or as the "air data" or "flight" recorder. The device recorded data from both ECUs, the EI brand MVP-50 engine monitor, and several flight and navigation units. The device contained NVM, and was mounted aft of the rear passenger seat.

For additional details refer to the NTSB public docket for this accident

According to information provided by the FAA, the airplane landed on Nevada Highway 445, about 10 miles east-northeast of RTS, and about 6 miles north of Spanish Springs. The airplane came to rest upright, on the side of the road, facing south, with its landing gear collapsed. Fire consumed or severely damaged the airplane aft of the firewall, including the wings.

The wreckage was recovered to a secure location. Several fire-damaged electronic components were separated from the wreckage and visually examined for identification, and determination of their condition. Several could not be identified, and all were determined to be sufficiently thermally damaged that data recovery would be impossible. Despite that, the telemetry/data recording computer was sent to the NTSB Recorders Laboratory in Washington, DC, for a data recovery attempt. The laboratory personnel were unable to obtain any data from that device.

The engine and remaining airframe components were examined several months after the accident. The engine remained attached via all mounts to the airframe, and all engine accessories remained attached to their respective mounts. The engine exhibited extensive thermal damage, consistent with the post impact fire. The single main alternator belt and the two serpentine belts remained attached to the pulleys, but were partially consumed by fire. The two "ref sensor" wires remained intact.

The engine was able to be manually rotated about 1/4 turn before contact with undetermined mechanical blockages. That rotation enabled partial confirmation of engine drive- and valve-train continuity, including the crankshaft, camshaft, connecting rods, and valves. All rocker arms were found intact. The ignition harness remained attached to the spark plugs but exhibited thermal damage. All 12 spark plugs were present, and with the exception of contamination by oil, firefighting agent, and/or subsequent corrosion, appeared normal. All cylinders were examined internally using a lighted borescope; significant amounts of corrosion, and a substance consistent with fire suppressant, were observed within the cylinders. The engine-driven fuel pump was removed and disassembled. All internal components were unremarkable, with the exception of rust/corrosion throughout.

No evidence of any preexisting engine or airframe mechanical malfunction that would have precluded normal operation was observed. For additional details refer to the NTSB public docket for this accident.