LAX07LA020

During the takeoff climb the engine began to run rough, and was not producing enough power to sustain flight. The certified flight instructor (CFI) reported that there was no remaining runway when the engine began to lose power, and he made a forced landing in an open field. An annual inspection had been completed on the airplane 14 days prior to the accident, and this was the first flight since the inspection. During the annual inspection, the fuel system had been inspected. The inspection included de-fueling the fuel tanks to seal the wing leading edge rivets. The fuel tanks were serviced, and no leaks were observed. An inspection checklist for the fuel system identified various items for inspection at the 50 and 100-hour inspections. During the 50-hour inspection, the drain valves, vent lines and vents, filler cap, anti-siphoning valves, and fuel system placards are examined. In the 100-hour inspection, the internal tank inspection, gages, transmitters, fuel line fittings, vent lines, and vents, and the fuel vent line drain assembly beneath the fuselage is removed and cleaned. Following the annual inspection, the airplane sat on the ramp for 2 weeks before the accident flight. On the accident flight, the CFI stated that he and the owner/passenger did a thorough preflight with no discrepancies noted. According to the flight manual, during the preflight inspection, the pilot is to check that both the left and right wing fuel tank vents are unobstructed. The postaccident airframe inspection revealed that the left and right wings' fuel vent lines were clogged with dirt at each end, and their associated unions were also packed with dirt. The vent lines and unions were removed and shipped to the Safety Board's materials laboratory for further inspection. The fuel vent lines were found intermittently clogged with dirt at multiple locations along the length of the lines. The vent lines were cut open and the dirt removed for examination. Insect carcasses were found in the vent lines. According to the airframe manufacturer, there are three fuel vent lines; one at each wing, and one located on the belly of the airplane. If both the main fuel vent lines (left and right wings) become clogged, the belly fuel vent line would not be able to compensate for the clogged vent lines, and fuel flow to the engine would be restricted.

History of flight

On October 23, 2006, at 1500 Pacific daylight time, a single engine 1973 North American Rockwell Commander 112, N1022J, impacted flat terrain during the takeoff climb out, about 1/2-mile west of Chino Airport (CNO), Chino, California. The owner operated the airplane under the provisions of 14 Code of Federal Regulations (CFR) Part 91. The airplane was substantially damaged. The certified flight instructor (CFI) and the non-certificated owner/passenger were seriously injured. Visual meteorological conditions prevailed for the local area instructional flight, and no flight plan had been filed.

According to witnesses at the airport, after liftoff, the airplane continued on the upwind leg with the nose of the airplane increasing in pitch attitude until the left wing dropped and it impacted the ground.

The National Transportation Safety Board investigator-in-charge (IIC) interviewed the CFI. The CFI reported that the owner had recently purchased the airplane, and had taken it to Chino Aviation for repairs, where it had been for the past few months. The owner indicated to the CFI that he wanted to learn how to fly the airplane, and get his pilot's certificate.

The CFI reported that the flight was a demonstration flight for the owner. On the day of the accident, a thorough preflight was completed on the airplane, and 23 gallons of fuel was added which brought the total fuel amount to 30 gallons in each wing. The run-up was normal. The flight was cleared for takeoff and the CFI extended 10 degrees of flaps. Power was applied and after liftoff, the CFI retracted the landing gear, and then retracted the flaps. The CFI stated that they were not climbing as he would have expected and noted the vertical speed indicator showed a climb rate between 0 and 200 feet per minute with 2,600 rpm. As the airplane passed over power lines off the end of the runway, the CFI felt that the engine was not developing full power, and the airplane was starting to lose altitude. The CFI instructed the owner to continue to fly straight ahead, and he chose an open field to land in. The CFI stated that he remembered taking the flight controls from the owner, and then nothing of the last few seconds of the flight.

Recovery personnel reported a strong smell of fuel around the airplane. The right wing remained intact along with the fuel tank, but had separated at the airframe attach point. The left wing sustained impact damage and was removed by recovery personnel. The left wing fuel tank had been compromised by the impact. Recovery personnel separated the tail section and cut the flight control cables from the empennage to facilitate recovery of the airplane.

Aircraft information

The annual inspection was completed on October 9, 2006, by Chino Aviation, Chino, California. The entry in part states that the airplane was de-fueled, the fuel tanks were sealed at the wing leading edge rivets, and the fuel tanks were serviced with no leaks found, and that it had been inspected in accordance with an annual inspection. The accident flight was the first flight after the annual inspection.

The previous inspection was signed off on July 29, 2005; the entry in part stated, "Performed 100 hr and Annual inspection IAW Rockwell Commander 112 maintenance manual and 100 hr check list."

According to the airframe manufacturer's pilot operating handbook inspection checklist, as well as the Rockwell Commander Maintenance Manual (section 2 titled "SERVICING AND INSPECTION") at the 50-hour inspection the following items in the fuel system are identified to be inspected: drain valves, vent lines and vents, filler cap, anti-siphoning valves, and fuel system placards. At the 100-hour inspection the following items for the fuel system are identified to be inspected: an internal tank inspection, gage, transmitters, fuel line fittings, vent lines, and vents, and the fuel vent line drain assembly beneath the fuselage is removed and cleaned.

In the maintenance manual section 5 titled "FUEL SYSTEM," if fuel starvation is encountered after starting one of the probable causes could be plugged fuel vents. The remedy would be to pressure check the vent line, clean or replace the vent line.

According to the Federal Aviation Administration (FAA) Approved flight manual for the accident airplane, in section 2 titled PROCEDURES - NORMAL PROCEDURES, during the airplane inspection, the pilot is to check that both the left and right wing fuel tank vents are UNOBSTRUCTED.

Test and research

The airframe and engine inspections took place on October 25, 2006, at Aircraft Recovery Service, Littlerock, California. Investigators were able to establish flight control continuity from the tail to the cockpit via the control cables. The airframe manufacturer indicated that the separation points of both wings were consistent with impact damage.

An inspection of the fuel system revealed that both the left and right wings' fuel vent lines remained connected to their respective tanks. An external compressed air source was placed at each vent opening; however, no sound of air was heard passing into the fuel tanks. Both fuel vent lines were removed and investigators noted that debris was present at each of the openings for both fuel vent lines. An attempt was made to blow air through the left and right fuel vent line openings, but the lines remained clogged. Both the left and right fuel vent line unions were removed and were also clogged with foreign debris, similar in consistency as dirt. A third fuel vent line was located in the belly of the fuselage. The external compressed air source was connected to the vent line with no resistance encountered in the system. The fuel selector was removed and inspected; the selector was free of foreign debris and operated with no binding. Investigators placed the external compressed air source on each wing root fuel line, and were able to hear the hiss of air as it passed from the wing root line to the cockpit at the fuel selector location.

The left and right fuel vent lines as well as their respective unions were removed and sent to the Safety Board's materials laboratory in Washington, D.C. for an inspection. Materials laboratory personnel reported that the unions were packed solid with dirt and the vent lines were packed with dirt intermittently (multiple locations) throughout the entire length of the vent lines. In addition to the dirt, the vent lines contained small insect carcasses. The complete materials laboratory report is contained in the public docket for this accident.

According to the aircraft manufacturer's representative, if both the left and right fuel vent lines had become clogged, the alternate fuel vent line located on the belly of the fuselage would not be able to compensate for the clogged vents, thus restricting the fuel flow to the engine.

The visual inspection of the engine revealed a hole in the induction portion of the oil sump, and the crankshaft flange was bent. The engine remained attached and secured at its engine mounts, and all of the accessories remained attached and secured at their respective mounting pads/locations. The magnetos remained secured at their mounting pads, and magneto-to-engine timing was established as 25 degrees before top dead center (BTDC). Investigators noted that the fuel servo adapter plate attachment hardware was loose; upper left nut three-quarters of a turn, upper right nut one-half turn; lower left nut one-quarter turn, and the lower right nut one-quarter turn. An engine test run was attempted; the engine would start, but ran rough for a brief time. The engine was shipped to Textron Lycoming in Williamsport, Pennsylvania, for additional testing.

Under the auspices of the Safety Board, Lycoming personnel inspected the engine and then placed it in a test cell for an engine test run. They noted that there was no torque sealant o