NTSB Identification: CEN16LA134
On March 26, 2016, about 1115 central daylight time, a Grumman American Aviation Corp. AA 1B airplane, N8883L, impacted terrain during a forced landing near Stephenville, Texas, following a loss of engine power. The pilot and his passenger sustained serious injuries. The airplane was substantially damaged during the forced landing. The airplane was registered to and operated by the pilot as a 14 Code of Federal Regulations 91 personal flight. Day visual meteorological conditions prevailed along the route of flight about the time of the accident, and the flight was not operating on a flight plan. The flight originated from the Dallas Executive Airport (RBD), near Dallas, Texas, about 0958 and was destined for the Stephenville Clark Regional Airport (SEP), near Stephenville, Texas.
According to the pilot's accident report, a full preflight, to include a fuel check, was completed. He indicated that the flight departed from RBD and when the flight was about 20 miles east of SEP, he cancelled flight following when he had the destination airfield in sight. Approximately 18 miles out, the engine lost power while the airplane was at 4,500 feet above mean sea level while the left wing fuel tank was selected. After going through emergency procedures and turning the auxiliary fuel pump on, the pilot selected the right fuel tank and a restart was successful. The pilot indicated that he was not sure why the engine lost power. He pitched down and did a 300-foot descent at full power to regain airspeed in order to get to the airfield faster. Approximately four miles east of airport, the engine lost power again. He again went through emergency procedures, attempted a restart several times, but he could not get a restart. The pilot prepared the plane for an off-field landing on Highway 377 but saw oncoming traffic. He saw an open field and began to guide the plane to the open field. He leveled the wings and maintained airspeed to get to the open field. The airplane impacted the top of a horse trailer and the pilot was ejected from the airplane. The pilot and passenger were subsequently transported to a hospital.
The pilot held a Federal Aviation Administration (FAA) private pilot certificate with an airplane single engine land rating. The pilot held a FAA third-class medical certificate that was issued in January of 2016. He reported that he had accumulated 131.9 hours of total flight time and 14.1 hours of total time in the accident airplane model.
N8883L was a 1974 model Grumman American Aviation Corp. AA 1B, low-wing, fixed-tricycle landing gear, two-place monoplane with serial number AA1B-0383. The airplane was powered by a 108-horsepower Lycoming O-235-C2C engine with serial number L-11776-15. The airplane's fuel system utilized a tubular main wing spar comprised of a two-cell fuel tank (one cell in each wing). Each fuel cell held 12 gallons of fuel, of which, 11 gallons were considered usable. Fuel quantity was indicated by vertical sight gauges on the left and right cabin walls, each sight gauge corresponded to the respective side fuel cell. According to fueling records, the airplane was serviced with 4.02 gallons of 100 low lead aviation gasoline (avgas) on March 24, 2016.
At 1115, the recorded weather at SEP was: Wind from 190 degrees at 8 knots: visibility 10 statute miles; sky condition clear; temperature 18 degrees C; dew point 9 degrees C; altimeter 29.95 inches of mercury.
The airplane wreckage and accident site was examined and documented by a Federal Aviation Administration inspector. Review of the inspector's photograph did not reveal any leaks or discoloration consistent with a fuel leak. The airplane had a nose down left wing low attitude. The fuel tank selector was found positioned near the right tank position. A liquid was observed in the right fuel gauge. However, no fuel was recovered when the airplane was disassembled by a recovery company for relocation.
In the pilot's accident report, he indicated that a mechanical malfunction occurred which caused the engine to stop producing power and that he could not get the engine restarted.
The airplane was relocated to a recovery yard where it was examined by an inspector from the FAA, an air safety investigator from the engine manufacturer, and by the National Transportation Safety Board (NTSB) investigator in charge. The engine's spark plugs were removed and the top plugs revealed a normal color when compared to a Champion Check-A-Plug chart. The carburetor was found separated from its intake mounting flange. Disassembly of the carburetor revealed its bowl contained a liquid that was subsequently collected. The liquid contained debris. The liquid did not contain water when tested with a water disclosing paste. An examination of the carburetor's fuel screen did not reveal any debris. The electric fuel pump screen contained debris. The electric fuel pump cap had debris adhering to its internal surface. Disassembly of the engine driven fuel pump did not reveal any anomalies. The tachometer indicated 4,338.53 hours. The engine produced a thumb compression when the propeller was rotated by hand. Spark was observed at the end of ignition leads when the propeller was turned by hand. Pressurized air was applied to each fuel line going the fuel tank selector and air exited the fuel line going to the carburetor when the respective side was selected. Each fuel tank was pressurized and no leaks were observed. The electric fuel pump screen, electric fuel pump cap, and collected liquid from the carburetor bowl were retained for examination. No anomalies were detected that would have precluded normal engine operations.
The liquid sample was sent to Core Laboratories/Saybolt for analysis. The liquid was found to be consistent with avgas.
The fuel screen, fuel pump cap, and particles found in the avgas in the carburetor bowl were sent to the NTSB Materials Laboratory. These samples were examined using a Fourier Transform Infrared (FTIR) spectrometer with a diamond attenuated total reflectance (ATR) accessory in accordance to ASTM E1252-98 and ASTM E334-01 (American Society for Testing Materials E1252-98: Standard Practice for General Techniques for Obtaining Infrared Spectra for Qualitative Analysis and American Society for Testing Materials). The spectrometer was used to collect and process infrared wavelength absorbance spectra of the unknown material.
A comparison search was performed using a spectral library database for the spectra from each sample. The search did not find a strong spectral match for either a single material or a mixture; however, there were similarities to the spectra of several surfactants, which is a byproduct of the fuel refining processes as well as a common additive in aviation fuel.
The particulate material was then analyzed using X-ray fluorescence (XRF) to determine the elemental composition of the particulate material. The composition of the material consisted mainly of aluminum, iron, lead, zinc, copper, and chromium. These metals are commonly found in aircraft fuel systems and fuel.
A GoPro Hero HD camera was found in the area of the wreckage and was shipped, along with a Magellan GPS 315 device, to the NTSB Vehicle Recorders Laboratory for downloading and decoding. The GPS unit does not appear to have the capability to store tracks in non-volatile memory. However, video data from the camera revealed that it was mounted in the airplane between the pilot and passenger. The GoPro captured the front seat occupants, a portion of the instrument panel, engine controls, and a view outside of the windscreen. The study, in part, indicated that during the accident flight, the video showed the pilot's fuel management included switching fuel tanks and using fuel pumps. About 1104, the fuel pressure gauge indication dropped to near zero from about five psi. The engine exhibited sounds consistent with losing power. The pilot switched the fuel tank selector from the right tank to the left tank and turned the fuel pump on. The fuel pressure gauge returned to about five psi. About 1111, the fuel pressure gauge indication dropped to near zero again. The engine exhibited reduced RPMs consistent with a power loss. The engine surged during the descent and the vertical speed indicator showed a value near 800 feet per minute. The airspeed indicator showed a value near 80 mph. The stall warning horn was heard intermittently while the airplane was maneuvered toward a landing area during the descent. Trailers and vehicles can be seen while the airplane pitched up. The video showed the airplane impacted a trailer and the airplane then rolled to the right. The camera became liberated from its mount and it came to rest in nearby grass. The camera subsequently recorded the pilot walking in front of the camera. The recording, in part, contained the pilot's conversation when he stated that the "airplane's new to me" and that he "just run it out of fuel." The NTSB Vehicle Recorder Laboratory onboard image recorder study is appended to the docket associated with this investigation.