Augusta, GA, USA
N777CV
MOONEY AIRCRAFT CORP. M20K
Maintenance personnel reported that, 2 days before the accident, they were hired by the pilot to prepare the airplane for a maintenance ferry flight following a gear-up landing. While inspecting the airplane, the mechanic noted that the three-blade propeller was bent, so he removed it. Subsequently, the pilot provided maintenance personnel with a two-blade propeller, which they installed. However, when the mechanic attempted to replace the spinner, it would not fit properly. Therefore, he did not sign off the logbooks and advised the pilot that the airplane should not be flown. Review of the airplane's records revealed that the airplane had a supplemental type certificate for an engine conversion kit that required a three-blade propeller. On the day of the accident, another mechanic conducted a run-up of the engine and noted that the propeller was not working correctly. The supplier of the two-blade propeller advised the mechanic that the airplane should not be flown in that condition. The mechanic discussed the anomaly with the pilot and advised him not to fly the airplane until the issue was resolved. The pilot acknowledged the discrepancy but chose to fly the airplane. Shortly after takeoff, witnesses observed the propeller separate from the airplane. Subsequently, the airplane spiraled to the ground in a nose-down attitude. Examinations revealed that the propeller attachment bolts had failed, which resulted in the separation of the propeller from the airplane. Five of the six propeller mounting studs exhibited evidence of high-stress fatigue cracking, which indicates that a severe spectrum of cyclic loading in the propeller/engine system occurred, likely as the result of using an unapproved propeller on the airplane.
HISTORY OF FLIGHT On July 18, 2011, about 1225 eastern daylight time, a Mooney M20K, N777CV, collided with the ground shortly after takeoff from Augusta Regional Airport (AGS), Augusta, Georgia. The private pilot was fatally injured. The airplane came to rest on the airport's property and was substantially damaged when it impacted the terrain. The airplane was registered to and operated by a private individual under the provisions of 14 Code of Federal Regulations Part 91 as a maintenance test flight. Visual meteorological conditions prevailed, and no flight plan was filed. The flight was originating at the time of the accident. A pilot who taxied out behind the accident airplane watched the airplane on climb out. He heard someone yell over the radio that an airplane had crashed. He looked across the runway,and saw fire and black smoke, and realized that it was the pilot who had just departed. According to witnesses, they observed the airplane on initial climb and the engine sounded extremely loud. The airplane climbed slowly before making a sharp left turn. The sound of the engine increased followed by a loud "bang." One witness stated the propeller separated from the airplane and fell to the ground, the airplane spiraledto the ground in a nose down attitude, and a post crash fire ensued. PERSONNEL INFORMATION The pilot, age 58, held a private pilot certificate with ratings for airplane single-engine land and sea, multi-engine land with instrument airplane. He held a third-class airman medical certificate issued on September 9, 2010, with limitations for corrective lenses. The pilot's logbook was not recovered for review. The pilot's September 9, 2010 application for his medical certificate indicated he had 8,000 total civilian flight hours. A review of the pilot's application for insurance revealed that in July of 2011, the pilot reported on an updated application that he had 8,400 total hours with 3,237 in multi-engine and 3,000 in make and model. It also indicated that his last biannual flight review was completed on April 25, 2011. AIRCRAFT INFORMATION The three-seat, low-wing, retractable-gear airplane, serial number 25-0149, was manufactured in 1979. It was delivered with a Continental TSIO-360-GB, 210 hp engine, which was equipped with a McCauley two blade propeller. In 1995 a Rocket Engineering engine conversion kit was installed under supplemental type certificate SE00223SE. The kit is called the 305 Rocket and is powered by a Continental TSIO-520-NB engine and equipped with a McCauley three blade propeller. Review of copies of maintenance logbook records obtained from Race City Aviation showed an annual condition inspection in accordance with Appendix D, Part 43 was completed November 26, 2011, at a recorded tachometer reading of 2614.5 hours. The airplane's logbooks were destroyed by fire in the wreckage. The tachometer was destroyed and the total airframe hours, time flown since the last annual inspection, total engine hours and total hours since the engine was last overhauled could not be determined. The airplane was fueled with a total of 40 gallons of aviation gasoline prior to takeoff. According to information obtained from the Federal Aviation Administration (FAA), the pilot was involved in a previous gear-up landing accident with the same airplane at AGS on April 11, 2011. During that accident, the airplane sustained substantial damaged to the propeller and the fuselage. Maintenance personnel who worked on the airplane two days before the accident stated, they prepped the airplane for a ferry flight back to Lake Norman Airpark (14A), Mooresville, North Carolina. On an initial walk around inspection, a mechanic noted the landing gear was not down and locked and the three bladed propeller was bent. The mechanic secured the landing gear and removed the three blade propeller. A two bladed McCauley propeller supplied by the pilot was installed on the airplane in accordance with the Mooney M20K Maintenance Manual section 61-00-10. When the mechanic attempted to replace the spinner it would not fit without cowling interference. The mechanic called his shop and was advised that that Aero Engines of Winchester, Virginia had supplied the propeller. The mechanic did not sign off the logbook or the ferry permit. Further investigation revealed the FAA airworthiness certificate application for the ferry permit indicated the shop owner had signed off as the work had been completed. On July 15, 2011, another mechanic accompanied the pilot to AGS to reconnect the battery and conduct a run up of the engine. During the run up, the mechanic noticed that with the two blade propeller; the propeller control operated in reverse. He said that when the propeller lever was advanced, the RPM would decrease, and when the propeller lever was retarded, the RPM would increase. The mechanic stated that the personnel at Aero Engines advised him that although the propeller lever controlled the propeller, he would not advise anyone to fly the airplane that way. The mechanic discussed the anomaly with the pilot and advised him not fly the airplane until the issues were resolved. METEOROLOGICAL INFORMATION A review of recorded weather data at AGS, revealed that at 1255 conditions were winds 270 degrees at 6 knots, visibility of 10 miles, cloud conditions scattered at 7,500 feet above ground level, temperature 23 degrees Celsius, dew point temperature 6 degrees Celsius, and altimeter 30.06 inches of mercury. WRECKAGE AND IMPACT INFORMATION The wreckage was located on the airfield approximately 50 feet to the left of runway 26. The airplane came to rest on a heading 180 degrees. The airframe was consumed by fire and crushed upward; all flight control surfaces were accounted for at the accident site. Examination of the wreckage revealed that the two bladed propeller assembly was separated from the engine flange and located approximately 1,000 feet forward of the main wreckage site. The propeller was recovered and sent to the National Transportation Safety Board's Material Laboratory for examination. The upper and lower cowlings were fire damaged and located forward of the wreckage. The engine was displaced aft towards the firewall and downward into the ground. The engine displayed external fire damaged, and the magnetos were broken away from the accessory section. The vacuum pump was broken away from the accessory section and fire damaged. The nose wheel assembly remained attached to the nose gear trunnion and was in the retracted position. The cabin area from the engine firewall extending aft to the empennage was consumed by fire from the floor upwards. The instrument panel and all instrument components were consumed by fire. Continuity of the flight control system was confirmed from the control yoke aft to all flight control surfaces. The right wing was partially consumed by fire throughout the wing span from the wing root to the wing tip. The right wing remained attached to the main spar. The aileron remained attached to the wing and connected to the control tube. The right main fuel tank was ruptured and no signs of fuel were noted. The fuel cap was secured with a tight seal and fire damaged. The right flap was fire damaged, and separated from the wing. The right main landing gear assembly was fire damaged. The empennage was intact and connected to the main fuselage and fire damaged. The control tubes for the rudder and elevators were still attached. The rudder was attached to the vertical stabilizer at the attachment hinges. The elevators were attached to the horizontal stabilizers at the attachment hinges. The left wing was crushed upwards from the underside of the wing. The left main fuel tank was ruptured and no signs of fuel were noted. The fuel cap was secured with a tight seal. The left flap was partially broken away from the hinge attachment hinge points. The left aileron was attached at the hinge points. The left main landing gear assembly was in the retracted position. Examination of the airframe and flight control system components did not reveal any preimpact mechanical malfunctions or failures that would have precluded normal operation. The engine remained attached to the engine mounts. The engine exhibited an extensive amount of fire damage. The left and right exhaust pipes and muffler were crushed upwards. The oil sump was ruptured and crushed upwards towards the engine casing. A small amount of oil was observed in the oil sump. The cylinders were borescoped and were free from debris. The crankshaft was rotated by hand and all pistons were observed moving. Compression and valve train continuity was established to each cylinder during the rotation of the crankshaft. The top sparkplugs were removed and examined and the lower spark plugs were examined during the borescope examination. All spark plugs revealed normal wear when compared to the Champion Check- A- Plug chart. Examination of the fueling system revealed that the fuel lines and the fuel pump were fire damaged. The drive coupling was intact and not damaged. The drive shaft was free to rotate and no fuel was observed in the inlet line. The fuel manifold was disassembled and the fuel screen was clean and free of debris. A small amount of fuel was observed in the manifold. Examination of the engine and its components did not reveal any preimpact mechanical malfunctions or failures that would have precluded normal operation. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy was performed on the pilot on July 19, 2011, by the Division of Forensic Sciences, Georgia Bureau of Investigation, Georgia, as authorized by the State of Georgia. The autopsy findings included "multiple blunt force injuries," and the report listed the specific injuries. Forensic toxicology was performed on specimens from the pilot by the Federal Aviation Administration Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma. The toxicology report stated that no ethanol was detected in the liver or the muscle, and no drugs were detected in the liver. TESTING AND RESEARCH Examination of the propeller was conducted by the NTSB Materials Laboratory, Washington, D.C. The examination revealed that there were five bolt studs remaining in the hub along with two locating dowel pins. One bolt stud was missing from the hub and the remaining five bolt studs and both dowels were fractured near the face of the hub. The bolt stud locations were numbered S1 thru S6 with the #1 bolt stud on the serial number side of the hub. A separated bolt and nut were located and were determined to be the missing #6 bolt stud and nut. Microscopic examinations of the bolt stud fractures revealed features and fracture markings indicative of high stress fatigue propagation in five of the six bolt studs. All fatigue areas initiated in the roots of the first and second engaged thread in the hub. The S1 bolt stud fracture was entirely overstress accompanied by bending deformation. The S2 bolt stud showed high stress fatigue from one side through about 70% of the cross section. The remaining overstress area showed twisting deformation. The S3 bolt stud had two opposed regions of fatigue that penetrated about 60% of the bolt stud's cross section. The S4 bolt stud also showed two fatigue regions from adjacent thread roots. Total fatigue penetration was approximately 40%. The S5 bolt stud had a single fatigue region penetrating through about 40% cross section. The nut side piece of the S6 bolt stud had only about 10% fatigue from one side. The remaining overstress region showed bending and twisting deformation. The unthreaded grip area on the S6 bolt stud was polished in local areas and the exposed nut side threads were flattened and polished consistent with contact by the bores of the crankshaft mounting hole. Both locating dowels were fractured approximately flush with the mounting surface of the hub. Both dowel fractures showed post fracture damage and fracture features indicative of overstress separations. The mounting face of the hub had areas of light fretting with localized areas of polishing.
The pilot’s decision to fly the airplane after maintenance personnel advised him that the airplane should not be flown because the pilot provided an incorrect propeller for installation and the subsequent failure of the propeller attachment bolts and the separation of the propeller.
Source: NTSB Aviation Accident Database
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