N29225Cessna TU206C · 1968

On August 13, 2016, about 1100 central standard time, a Cessna TU206B airdrop configured airplane, N29225, registered to the pilot and operated by Gypsy Moth Skydive LLC of Benton, Kansas, sustained substantial damage during a forced landing after a loss of engine power while maneuvering in the vicinity of Skiatook, Oklahoma. All seven occupants, the private pilot and six passengers (parachutists), sustained minor injuries. The local flight was being operated under the provisions of Federal Code of Regulations Part 91 and the intent was to climb to altitude and dispatch the 6 parachutists. Visual meteorological conditions prevailed and a flight plan was not filed. The flight originated from the Skiatook Municipal Airport (2F6), Skiatook, Oklahoma, about 1030.

According to the pilot, he had topped off the fuel tanks the night before. He was planning to sell the airplane and was giving some demo flights. On the morning of the accident, the preflight was normal. He conducted a flight for about 20-minutes and reported that the engine was running strong. After returning to 2F6, the airplane was shut down for 5-10 minutes. He loaded his air drop passengers and performed normal ground checks of the flight controls and engine. After takeoff, the climbout was about 85 knots and 500 feet per minute rate of climb. About 900-1,000 feet AGL, the engine lost complete power. He immediately nosed over, scanned landing options, and put in 10 degrees of flaps. He committed toward a field near a rural house and set the flaps committed towards field in front of a house, nosed further, set the flaps to 30-degrees a few seconds prior to impact with the ground. The airplane slid to a stop and everyone exited through the aft cargo door.

The initial examination of the wreckage was conducted under the supervision of the FAA. The airplane was resting in a grassy field near a house. The nose landing gear was separated from the firewall mounts and the right main landing gear was separated from the fuselage. the propeller was bent and the engine was separated from the firewall. The front portion of the fuselage was damaged and the forward section of the empennage was buckled. The airplane's wings were removed and the wreckage transported to a secure facility (Dawson Aviation, Clinton, Arkansas) for further examination. About 5 gallons of fuel was removed from the airplane prior to transport to Dawson.

The wreckage was further examined on August 18, 2013, at Dawson Aviation. The inspection was conducted under the supervision of the FAA. Flight control cable continuity was established from the cockpit to all control surfaces. The fuel selector valve was observed between the right tank and off position. The valve was placed in the right tank position and air was passed from the wing tank outlet to the fuel boost pump. The valve was placed in the off position and no air passed through the valve. The fuel strainer was removed and a small amount of fuel was observed. It was tested with water finding paste and the results were negative for water. There was a significant amount of debris observed in the fuel strainer and the strainer bowl. The debris was similar to caulking along with some rust particles. The aircraft was equipped with Monarch Air fuel caps.

There were no seats in the rear of the aircraft. The aircraft was configured for air drop operations and had a bench seat in the passenger compartment. The passengers restraint system appeared to be homemade with the belts attached at the floor attachment location with aluminum snap hooks. Other than the fuel selector valve, and the debris in the fuel strainer bowl, no other anomalies were found with the airframe.

The propeller remained attached to the engine and no damage was observed to the spinner. One propeller blade was not damaged. The second blade exhibited a bend towards the flat side of the blade, about 5-inches in from the blade tip. The third blade was bent toward the flat side of the blade and was curled under the lower area of the engine cowling. The crankshaft of the engine was rotated by hand. There was continuity and air was expelled from all cylinders with thumb compression. Both magnetos produced sparks on the top spark plugs. A "B-Nut" was observed loose on the right side upper deck pressure line. The engine appeared in a condition to perform a test run and was shipped to Continental Motors, Mobile, Alabama.

On March 22, 2017, the engine was prepared for a test run at Continental Motors, Mobile, Alabama, under the supervision of the NTSB IIC. Initial inspection of the engine did not reveal any pre-impact anomalies. The cylinders were borescoped and all intake and exhaust valves were intact. The piston domes and valve faces exhibited normal combustion signatures. After test cell safety preparations, the engine was placed in the test cell for a run. Since the B-nut to the upper deck pressure was found in a loose condition at the accident site, prior to the initial engine test run, the B-nut was tightened. After the initial test run, the B-nut was loosened and the engine was run a second time with the B-nut loose as it was initially found.

During the initial test run and the second test run, the engine accelerated normally throughout various RPM ranges.