MITCHELLVILLE, MD, USA
N7666P
MOONEY M20J
THE PILOT REPORTED THAT HE HAD COMPLETED HIS PRETAKEOFF CHECK AND RUN-UP, SUCCESSFULLY. HE STATED THAT DURING THE INITIAL CLIMB, AT ABOUT 400 FEET ABOVE THE GROUND, THE ENGINE LOST POWER. HE TRIED TO RESTART THE ENGINE, BUT WAS UNABLE. THE AIRPLANE IMPACTED IN A WOODED AREA ABOUT 1/2 MILE NORTH OF THE AIRPORT. THIS WAS THE SECOND FLIGHT WHILE IN MAINTENANCE TO DETERMINE TWO PRIOR PARTIAL POWER LOSSES DURING INITIAL CLIMB. THE AIRPLANE WAS REMOVED TO A HANGAR WHERE AN ENGINE RUN WAS ACCOMPLISHED AFTER A SUBSTITUTE PROPELLER WAS INSTALLED. THE ENGINE ATTAINED OVER 2675 RPM AND 26 INCHES OF MANIFOLD PRESSURE. EXAMINATION OF THE FUEL SERVO INLET SCREENS REVEALED EVIDENCE OF RUST AND CONTAMINATION. FURTHER TESTING OF THE SERVO INDICATED WATER AND CORROSION IN THE DIAPHRAGM ASSEMBLY.
HISTORY OF FLIGHT On Friday, September 3, 1993, at 1241 eastern daylight time, N7666P, a Mooney M20J, owned by Brian Poole of Arnold, Maryland, and piloted by Michael J Duncan of Fort Washington, Maryland, lost engine power and collided with a tree while on initial climb during a power-off forced landing 1/2 mile from Freeway Airport, Mitchellville, Maryland. Visual meteorological conditions prevailed and a flight plan was not filed. The certificated flight instructor was seriously injured while the passenger, a mechanic was not injured. The airplane was substantially damaged. The check flight was conducted under 14 CFR 91. According to the pilot, he had completed his pretakeoff check and run-up successfully. He stated that the magneto drop on the run-up check was not greater than 100 rpm. He stated that the takeoff was normal, all the engine instruments were in the green range, and the airplane was accelerated to climb speed. He stated that it was windy that day, and there was some turbulence during the initial climb; however, at about 400 feet above the ground the engine lost power. He stated that, "it was as if someone had turned off the magnetos." He stated that he tried to restart the engine which included pumping the throttle, but he was unsuccessful. The airplane impacted in a wooded area separating a 5 foot section of the right wing. According to the FAA, this was the third flight after its maintenance to determine the reason for the prior two partial power losses. A witness who was at the departure end of runway 18 stated that when the airplane passed overhead, it sounded normal. The accident occurred during the hours of daylight, at 38 degrees 56.42 minutes North and 76 degrees 46.31 minutes West. PERSONNEL INFORMATION The pilot held a flight instructor certificate with single and multiengine land ratings. He reported over 2400 hours of total flight time including 150 hours in type. AIRCRAFT INFORMATION The 1988 year model Mooney M20J airplane, serial no. 24-1673 was equipped with a Lycoming IO-360-A3B6D, serial no. L24812-51A. According to the engine log book, the airplane had accumulated over 315 hours of total flight time including 34 hours since the last annual inspection that was completed on March 1, 1993. METEOROLOGICAL INFORMATION The 1255 surface weather observation for Andrews Airforce Base Airport, about 10 miles south of the accident site was as follows: Sky condition, 3000 feet scattered; visibility, 7 miles; temperature, 93 degrees (F); dew point, 69 degrees (F); wind condition, 220 degrees at 16 knots; and altimeter, 29.99 inches. WRECKAGE AND IMPACT INFORMATION The airplane collided with a tree separating a five foot section of the right wing. Examination of the accident site revealed the wreckage was confined within the dimensions of the airplane. The airplane was oriented on a 170 degree magnetic bearing. The airplane remained intact except the right aileron that separated with the 5 foot section of right wing. This section separated during the impact sequence and was located about 5 feet from the main wreckage. Both wings remained intact and contained a total of about 60 gallons. The empennage was intact. Flight control cable continuity was established to the left aileron in the left wing; however, control continuity was not established to the right aileron as it had separated during the impact sequence. Continuity was also established to the rudder and elevator. The landing gear and flaps were found in the retracted position. Examination of the engine revealed it remained intact. The engine was removed to Alphin Aircraft in Hagerstown, Maryland, on September 14, 1993 where an engine test run was completed under the supervision of the NTSB. Visual inspection of the engine did not disclose evidence of engine damage. The airplane's ram air to the fuel servo was replaced with an air filter 31 hours prior to the accident. Examination of the filter and the induction system revealed metal chips, dirt and a twig about one and one half inches long in front of the fuel servo. The air induction was intact. The propeller was bent during the impact sequence so a substitute propeller was used. The engine started after two attempts, and a manifold pressure of 26 inches and 2675 rpm was attained with the throttle set to the full forward position. The magnetos was selected to left, right and both positions, and no evidence of malfunction was noted. After the engine run, the fuel servo was removed for further examination. Visual examination of the fuel servo inlet screens revealed evidence of rust and corrosion on the spring, the threads of screen retaining plug and the opposite end of the spring around the "O" ring (see photos). The fuel servo was sent to Precision Air Incorporated in Miami, Florida, on September 30, 1993 for further examination under the supervision of the FAA. The examination disclosed evidence of corrosion and water in the diaphragm assembly. Details of the fuel servo examination is attached to this report. ADDITIONAL INFORMATION The wreckage was released to the owner's insurance representative on September 27, 1993.
CORROSION IN THE FUEL CONTROL UNIT, WHICH RESULTED IN FUEL STARVATION AND LOSS OF ENGINE POWER. RELATED FACTORS WERE: INADEQUATE MAINTENANCE, AND THE LACK OF SUITABLE TERRAIN FOR AN EMERGENCY LANDING.
Source: NTSB Aviation Accident Database
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