N656MACessna 172R

On June 11, 2024, about 2045 central daylight time, a Cessna 172R airplane, N656MA, was substantially damaged when it was involved in an accident near Gainesville, Texas. The flight instructor was fatally injured, and the student pilot was seriously injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 instructional flight.

Airport video surveillance showed a fuel truck fueling the airplane about 0625 on the day of the accident. Fuel records indicated that the airplane was filled with 32.4 gallons of fuel. Flight logs indicated that the airplane only flew once (the accident flight) on the day of the accident. Airport surveillance video showed the flight instructor and student pilot visually inspecting the fuel tanks on each wing during the preflight check about 1912.

ADS-B data indicated that the airplane departed Denton Enterprise Airport (DTO), Denton, Texas, about 1948. The flight instructor and student pilot departed to the northwest of DTO, maneuvered, flew to Gainesville Municipal Airport (GLE), Gainesville, Texas, and made multiple takeoffs and landings at GLE.

According to the student pilot, he and his flight instructor were practicing takeoffs and landings at GLE. On the third takeoff, his flight instructor stated that they were too low and not climbing, so the flight instructor tried to add more power. Then the engine stopped, and the propeller windmilled. The student pilot stated that they were about 100 ft above ground level when the engine stopped. They glided the airplane to a field and hit the ground hard, bounced, and hit the ground harder.

A review of maintenance logbooks revealed that the airplane had a 100-hour inspection on May 14, 2024. The airplane’s engine was overhauled in May 2019, and the company that performed the overhaul installed a new Tempest engine-driven fuel pump (part number AF15473, serial number 066J15) at that time. The engine overhaul company purchased the fuel pump in April 2019 directly from the fuel pump manufacturer. According to the fuel pump manufacturer, the fuel pump was not a field-serviceable unit, so if the fuel pump needed to be serviced, it would need to go back to the manufacturer for servicing. A review of maintenance logbooks did not indicate that the fuel pump was removed or serviced once it left the engine overhaul facility in May 2019.

A review of maintenance logbooks revealed that the airplane had a 100-hour inspection on May 14, 2024. The airplane’s engine was overhauled in May 2019, and the company that performed the overhaul installed a new Tempest engine-driven fuel pump (part number AF15473, serial number 066J15) at that time. The engine overhaul company purchased the fuel pump in April 2019 directly from the fuel pump manufacturer. According to the fuel pump manufacturer, the fuel pump was not a field-serviceable unit, so if the fuel pump needed to be serviced, it would need to go back to the manufacturer for servicing. A review of maintenance logbooks did not indicate that the fuel pump was removed or serviced once it left the engine overhaul facility in May 2019.

The airplane impacted a grassy cow pasture about 0.5 mile northwest of the departure end of runway 36 at GLE. The left wing tip struck the ground first about 95 ft south of telephone wires that ran east to west along the field. About 32 ft south of the left wing tip impact location, the propeller, still attached at the flange, was found partially embedded in the dirt. One blade was buried about 8 inches deep, and the other blade was resting on the ground. A single propeller strike, about 5 inches deep, preceded the propeller assembly. Lying next to the propeller was the starter gear ring. Lying about 18 ft south of the propeller was the bottom part of the cowling. The main wreckage was found about 39 ft south of where the bottom part of the cowling was located.

The distance from the left wing tip strike to the main wreckage was about 89 ft along a heading of about 180°. The main wreckage came to rest on a heading of about 055°. The debris field contained pieces of broken windshield, a small piece of the outboard side of the left aileron, and the left door. Both wings and the empennage were still attached to the fuselage. The engine was still attached at the firewall.

The master switch (battery and alternator) was found in the On position. The ignition was in the Both position. The throttle and mixture controls were in the full forward position.

The left wing fuel tank was breached; the right wing fuel tank was not breached. A strong smell consistent with 100LL aviation fuel was present, and fuel blight could be seen on the grass underneath the wings. About 40 ounces of fuel was removed from the left wing fuel tank, and 56 ounces of fuel was removed from the right wing fuel tank. The fuel line between the fuel shutoff valve and the fuel strainer bowl was found separated. The fuel strainer bowl had fuel in it. The fuel selector handle was found just to the right of the Both detent position. The fuel header tank was removed, and the tank was intact and contained fuel. The fuel in the header tank was tested for water with water-finding paste, and no water was detected.

During the on-scene examination, the engine-driven fuel pump was found tightly installed to the accessory section of the engine. The pump was removed along with its inlet and outlet hoses. The hose from the fuel pump to the fuel servo had about 1 ounce of fuel in it. The line from the outlet of the fuel servo to the fuel manifold had trace amounts of fuel, and a trace amount of fuel was found within the fuel manifold. There was no fuel in any of the 4 injector fuel lines.

The top 5 screws on the engine-driven fuel pump were loose. Two fingers on a screwdriver were enough to turn each screw. According to the fuel pump manufacturer, the screws on the fuel pump should be torqued to 30 to 45 inch-pounds, and if the screws are not properly torqued, the clamping force on the top 2 diaphragms could be compromised, which could lead to the fuel pump ingesting air and not operating properly. The manufacturer also stated that before the fuel pumps are stocked or shipped from their facility, they are visually inspected, at which time torque striping is applied to at least 2 of the screws. The fuel pump on the accident airplane had a torque stripe on one of the top screws and 2 of the bottom screws. All 3 torque stripes were aligned and unbroken.

The fuel pump was placed in a vice and actuated by hand. Air bubbles and oil were observed along the split line of the top cap. All diaphragms were found intact with no damage or debris.

An autopsy was conducted on the flight instructor by the Southwestern Institute of Forensic Sciences at Dallas – Office of the Medical Examiner. The cause of death was “multiple injuries.” Toxicological testing of the flight instructor’s specimens was conducted by the Federal Aviation Administration Office of Forensic Sciences, Oklahoma City, Oklahoma. Diphenhydramine was detected in cavity blood (100 ng/mL) and urine (detected only – no amount).

Diphenhydramine is a sedating antihistamine medication widely available over the counter in multiple sleep aids and cold and allergy products. Diphenhydramine can cause cognitive and psychomotor slowing and drowsiness and often carries a warning about driving and operating machinery.