N6627G

On December 25, 2017, about 1325 Pacific standard time, a Cessna 150 airplane, N6627G, was substantially damaged when it was involved in an accident near Perris, California. The private pilot and passenger were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.

The pilot stated that he departed San Gabriel Valley Airport (EMT), El Monte, California, with about 22 gallons of fuel onboard. About halfway through the flight, the engine experienced a total loss of engine power. He described the power loss as "smooth, but very fast." His subsequent attempts to restart the engine by pumping both the throttle and mixture and actuating the carburetor heat were unsuccessful. After he selected a forced landing site, the pilot circled the site while he configured the airplane to land. The airplane touched down in a soft field and, after the nose landing gear contacted the ground, the airplane nosed over and came to rest inverted.

The airplane's GPS track showed that the airplane reached a cruise altitude of about 5,400 ft about 16 nautical miles (nm) from EMT and maintained this altitude for the duration of the flight. At 1319, the airplane turned to a northeast heading and began a slow descent at a rate of about 1,000 ft per minute. Two minutes later, the airplane turned to the southeast for several seconds before making a momentary turn to the north. The radar track ended seconds later after the airplane made a 180° turn to the south.

A postaccident examination of the airplane by the Federal Aviation Administration (FAA) revealed substantial damage to the engine firewall, engine mounts, and empennage. Additionally, the lower engine cowling was crushed vertically.

According to FAA records, the airplane was manufactured in 1970 and registered to the pilot on June 30, 2014. Maintenance records indicated that the most recent annual inspection was completed on May 3, 2017, at a total time of 4,981 flight hours, and a tachometer time of 2,984 flight hours. At that time, the engine had accrued a total of 623 flight hours since its most recent engine overhaul, which was completed on August 1, 1994. According to the airplane's tachometer, at the time of the accident, the airplane had amassed a total of 3,031 flight hours. The logbooks did not contain any records to indicate that the carburetor had been overhauled or inspected in its service history.

The logbooks showed that the airplane accumulated about 166 flight hours between February 2015 and the date of the accident. The airplane had accrued a total of 8 flight hours in 8 years since it was registered to the pilot. While an entry from February 1, 2015, showed that the carburetor screen was checked, the logbooks did not provide any indication that the fuel strainer had been inspected.

Flight control continuity was traced from the cockpit to the elevator, rudder, and ailerons. The left aileron cable and through cable were both fractured in tensile overload at the aileron-flap junction. The elevator trim actuator was extended about 1.4 inches, consistent with a takeoff position; the wing flap position could not be determined.

Fuel line continuity was confirmed from both wing tanks to the engine. The fuel tanks were not breached, and the tank filters were free of debris. The fuel strainer expelled fuel when the drain valve was opened, and fuel flow ceased when the drain valve was closed. Trace amounts of fuel that resembled 100 low lead aviation grade gasoline and some debris were expelled from the fuel strainer. A large amount of corrosion was observed in the fuel strainer bowl, along with some debris. The right fuel tank displayed a significant amount of rust around the filler neck and on the fuel tank cap.

Continuity of the mixture and throttle controls was confirmed.

Several ounces of fuel that resembled 100 low lead aviation grade gasoline were drained through the fuel strainer, which did not present any contamination or debris. Fuel line continuity was confirmed from the door posts to the fuel selector valve, which moved normally through each of its detents.

The top spark plugs were removed, and thumb compression and suction were obtained for all four cylinders and in the proper firing order. Mechanical continuity was established throughout the rotating group, valve train and accessory section as the engine was manually rotated at the propeller.

The engine spark plugs were gray in appearance with light colored combustion deposits, consistent with normal wear when compared to the Champion Aerospace Aviation Service Manual. Both magnetos remained attached to the engine accessory case, the impulse coupling engagement was heard, and all 8-ignition harness leads exhibited sparks when the propeller was rotated by hand.

Carburetor Examination

The carburetor had separated from the induction risers at the mounting flange but remained partially attached to the engine by the throttle and mixture control cables. Full travel was achieved for both linkages when the levers were moved. The carburetor fuel inlet screen was free of obstructions. Partial disassembly of the unit revealed no anomalies with the carburetor floats, needle valve, and venturi. The accelerator pump nozzle was covered in corrosion.

An examination of the carburetor was performed by the manufacturer with oversight from an FAA representative. The accelerator pump control, throttle, and mixture controls on the carburetor did not show any resistance when moved by hand. The unit failed the manufacturer flow test, as the accelerator pump did not deliver any fuel to the throat of the throttle body. Debris was observed in the carburetor float bowl, the accelerator pump check valve was blocked, and additional contamination was found in the output of the venturi airflow.

According to a representative of the carburetor manufacturer, fuel enters the fuel bowl from the carburetor's fuel input line and is directed to the throat through a pickup tube downstream through a fuel pickup tube at the bottom of the bowl. The pickup tube is a small orifice about the size of a pencil eraser adjacent to a fuel drain plug. A photograph from the examination showed that the fuel drain plug was fully obstructed. (see figure.) The representative noted that the float bowl is a sealed container and not normally susceptible to ingesting debris unless the bowl is breached. The bowl was not breached during the accident sequence.

Figure. Fuel Drain Plug