NTSB Factual Report

HISTORY OF FLIGHT

On February 3, 2004, about 1015, eastern standard time, a Mooney M-20K, N252WF, registered to and operated by a private individual as a Title 14 CFR Part 91 personal flight, made a forced landing in a potato field, about 7 miles east of Immokalee Airport, Immokalee, Florida. Visual meteorological conditions prevailed, and no flight plan was filed. The private-rated pilot and one passenger received minor injuries, and the airplane incurred substantial damage. The flight originated at Kendall-Tamiami Airport, Miami, Florida, the same day, about 0945.

The pilot stated that he was en route to Punta Gorda, Florida, to the Mooney maintenance facility where he has his airplane serviced, to have a 25-hr oil change performed. He further stated that the airplane was in cruise flight, at an altitude of 4,500 feet, when he detected a slight engine vibration. He noted that the fuel consumption had increased from the usual 12.5 gals/hr to 15.7 gals/hr, at 2,300 rpm and a manifold pressure of 30.00. He said that the characteristics he noted at that time were similar to those of a partially plugged fuel injector he had encountered in the past, and since he was half the distance to Punta Gorda, he elected to continue. Shortly thereafter he said the engine ceased operating. He said there were no sputtering or other noises, the engine just abruptly ceased operating, while the propeller continued to windmill. He said he established the proper glide attitude, while looking for a place to land. He said he switched fuel tanks, turned on the boost pump, and attempted to restart the engine, but it did not restart. At an altitude of about 3,000 feet, he said he noticed a field with long furrows, and after declaring an emergency and performing prelanding tasks, made a forced landing to the field. During the landing rollout the airplane incurred damage.

An FAA airframe and powerplant mechanic with an inspection authorization rating, who responded to the scene of the accident stated that he found the B-nut on the inlet side of the fuel flow divider loose, about one full turn. In addition he said he saw signatures consistent with a leak which originated at the B-nut and ran down the right front of the engine case.

On February 10, 2004, the NTSB conducted a follow-on examination of the accident airplane. Assisting the NTSB was a representative from Teledyne Continental Motors, as well as the airplane mechanic who had responded to the scene of the accident, and had witnessed the loose B-nut on the inlet side of the fuel flow divider. The examination revealed that the fuel manifold was properly positioned, and there were no anomalies noted with the unit. In addition, when the fuel manifold was opened, the screen was found to be clean and fuel was present. At the connection of the B-nut on the fuel inlet line to the manifold, torque putty was noted on the threaded connection on the manifold side, and no putty was observed on the B-nut. In addition, the engine was given an initial test run and no anomalies were noted. The B-nut was then placed in the position it was found at the accident scene, and the engine tested a second time, and during the test run, when the electric fuel boost pump turned on, fuel poured from around the B-nut.

TESTS AND RESEARCH

The accident airplane was equipped with a Teledyne Continental Motors TSIO-360-MB2B, 210 horsepower engine, serial number 279325-R. According to the airplane's engine log book, the engine had been rebuilt by Teledyne Continental Motors, and shipped to Mod Works Inc., Punta Gorda, Florida, who installed it in the accident airplane on March 03, 2003. According to the engine logbook, at the time of the accident the engine had accumulated a total time of 80 hours since installation, and had received two previous oil changes, all of which had been performed by Mod Works Inc.

NTSB Probable Cause

A loss of engine power due to the airplane mechanic's improper maintenance/installation and failure to ensure that the B-nut on the inlet side of the fuel manifold was properly tightened, which resulted in a fuel leak, and fuel starvation.