MISSOULA, MT, USA
N270BB
Mooney M20-M
While at cruise at flight level 250 (25,000 feet), the airplane experienced a total loss of engine power. While making an emergency descent in the direction of an alternate airport, the aircraft collided with mountainous terrain and was destroyed. Post-accident examination and testing of the airframe, engine and associated components revealed no evidence of a preexisting mechanical malfunction or failure.
HISTORY OF FLIGHT On December 12, 1999, about 1235 mountain standard time (MST), a Mooney M20-M, N270BB, was destroyed when it collided with mountainous terrain approximately nine miles northeast of Missoula, Montana. The airplane was registered to and operated by the pilot as an instrument flight rules (IFR) personal flight under the provisions of Title 14 CFR Part 91. The certified private pilot, the sole occupant of the aircraft, was fatally injured. Visual meteorological conditions prevailed at Missoula, and an instrument flight plan was activated. The flight originated from Felts Field, Spokane, Washington, approximately one hour prior to the accident. There was no fire and no report of ELT activation. Flight plan information obtained from Seattle Automated Flight Service Station (AFSS) indicated that the pilot's planned destination was Sioux Falls, South Dakota, (FSD) via Federal Airways (V-2) and direct routing. The flight plan indicated that the aircraft had 6 hours of fuel onboard and that the estimated time en route was 4 hours and 30 minutes. The flight plan also indicated that the pilot's planned altitude was 23,000 feet (FL230). At 1221, 48 minutes after departure, the pilot reported to Salt Lake Center, "... I have no manifold pressure [and] I need vectors to the closest airport." The Air Route Traffic Control Center (ARTCC) instructed the pilot to turn right to a heading of 270 degrees and advised him that the heading change will be a vector to Missoula. Prior to the reported loss of manifold pressure, the aircraft was in level flight at FL250. At 1935, the pilot advised ARTCC that he was entering instrument meteorological conditions (IMC) and that the aircraft's artificial horizon was inoperative. Approximately five minutes prior to this transmission (1930), the pilot advised ARTCC that he had "...feathered the prop". At 1236, radar and radio contact with the airplane was lost. The airplanes last known position was approximately 11 miles northeast of the Missoula International Airport. On the afternoon of December 12, 1999, Montana Department of Transportation and the Missoula County Sheriff's Department initiated a search for the missing aircraft. The wreckage was located the following day (December 13, 1999) approximately 9 miles northeast of Missoula, in the Rattle Snake Wilderness Area. PERSONNEL INFORMATION The pilot held a private pilot certificate with airplane single-engine land and instrument airplane ratings. The pilot held a third-class medical certificate issued on August 10, 1999. The pilot's flight logbook indicated that he had accumulated approximately 4,582 hours in single-engine airplanes. AIRCRAFT INFORMATION In November 1995, the airplane (1989 Mooney M20-M) was modified to an Air-Liquid Corporation, Liquid Rocket. Rocket Engineering of Spokane, Washington, performed the modification. The modification included replacement of the original 270 horsepower Textron-Lycoming TIO-540 engine with a factory new Teledyne Continental Motors TSIOL-550-A (liquid cooled) engine rated at 335-350 horsepower. The modification also included replacing the original propeller with a McCauley full-feathering propeller. On May 13, 1997, the aircraft was issued an experimental airworthiness certificate. At the time of issuance, the aircraft's total airframe time was 1,094.1 hours. At the completion of the modification and issuance of the experimental airworthiness certificate, Air-Liquid Corporation operated the airplane in experimental category for research and development purposes in pursuit of obtaining Supplemental Type Certificate (STC) approval from the Federal Aviation Administration. On December 1, 1999, after STC approval and a 100-hour maintenance inspection, the airplane was re-certificated in the standard category. The airplane's total time at re-certification was 1240.2 hours. At the accident site, the accident aircraft's Hobbs meter read 1241.8 hours. METEOROLOGICAL INFORMATION The 1245 METAR observation at Missoula, reported winds from 120 degrees at 8 knots; visibility 10 statute miles; few clouds at 4,000 feet AGL; scattered clouds at 4,900 feet; temperature 6 degrees C; dew point temperature 2 degrees C; altimeter setting 29.87 inches Hg. WRECKAGE AND IMPACT INFORMATION On June 27, 2000, investigators from the National Transportation Safety Board, Teledyne Continental Motors and a representative from Rocket Engineering examined the airplane wreckage. The wreckage was located in mountainous/forested terrain at an elevation of approximately 6,800 feet. The aircraft came to rest at 47 degrees, 1.33 minutes' north latitude, and 113 degrees 53.46 minutes' west longitude. The terrain angle measured approximately 35-40 degrees. A grouping of trees (approximately 140 feet in height) with broken tops and scarring was observed approximately 150 feet down slope from the main wreckage. The magnetic bearing from the group of trees to the main wreckage was approximately 315 degrees (Wreckage diagram attached). All aircraft components were located at the crash site. The main wreckage, consisting of the fuselage (from the engine compartment to the empennage) and the inboard sections of both wings were located at the northwest end of the wreckage distribution path. The forward section of the fuselage, the engine compartment and engine cowling were bent aft and upward. The propeller and propeller hub assembly separated as a unit from the crankshaft flange. All three propeller blades were attached to the propeller hub and two of the three blades were found in the feathered position. The aircraft's cockpit and cabin area was intact, but sustained significant impact damage. The flap switch and gear handle were observed in the up position. The throttle and propeller control handles were forward, and the mixture control was full aft in the idle cut-off position. The fuel selector was observed in the left tank position and the magneto switch was positioned in the "Both" position. The right horizontal and vertical stabilizers were intact, with the rudder and right elevator attached to their respective hinges. The left-side stabilizer was sheared off about mid-span, and the elevator was separated at the hinge attach points. Rearward crushing and leading edge deformity was noted to the left horizontal and vertical stabilizers. Control cable continuity was established from the empennage control surfaces forward to the cabin area. The remaining aircraft system components and sections of aircraft structure were located in the immediate area of the main wreckage. MEDICAL AND PATHOLOGICAL INFORMATION The State of Montana Medical Examiner, Missoula, Montana, performed a postmortem examination on the pilot on December 13, 2000. According to the postmortem report, the cause of death was "multiple blunt force injuries." The manner of death was listed as accidental. Toxicology samples from the pilot were sent to the Federal Aviation Administration, Civil Aeromedical Institute (CAMI), Oklahoma City, Oklahoma, for analysis. According to the postmortem report, results were negative for carbon monoxide, cyanide and ethanol. An unspecified amount of quinine was detected in the pilot's urine. No evidence of pilot impairment was found. ADDITIONAL INFORMATION The aircraft's engine was shipped to Teledyne Continental Motors, Mobile, Alabama, for teardown and inspection. A visual inspection of the engine noted impact damage to the frontal, lower and accessory areas of the engine. Rocker arm, valve train and accessory gear continuity was established by rotating the engine's crankshaft. Both crankcase halves and piston cylinders were intact. Portions of the exhaust tubing, intake tubing and balance tube were crushed and dented. The liquid cooling pump was broken away from its mounting pad. The engines oil sump was crushed rearward and aft. The engine oil pickup tube screen was clear. The turbo charger and turbo charger mounting bracket exhibited signs of impact damage, however, the intake was clear and the turbine rotated freely. One of the oil lines from the oil cooler to the turbo charger was loose, however, there was no evidence of a preexisting oil leak. The engine oil pump gears and their respective cavities exhibited normal operating signatures and no signs of hard partial passage were present. The propeller governor was sheared off, however, the base of the pump was still attached to its respective mounting pad. Disassembly and examination of the engine revealed no evidence of abnormal wear or failure of internal components. All cylinder overhead components were intact and appeared normal. The crankcase main bearings exhibited no evidence of bearing shift. The crankshaft main journals, crankpins and crankshaft counterweights were intact and movement was unrestricted. No lifter spalling or abnormal camshaft wear was noted. The fuel system components including the fuel pump, throttle/fuel metering unit and manifold valve were flow tested utilizing production test equipment. All three components functioned at or near factory recommended specifications without adjustment from the installed position (data from flow tests attached). Both magnetos and their respective ignition harnesses were bench tested. Electrical continuity was established for the two harnesses and both magnetos produced spark. Normal operating signatures were observed on the engine's spark plugs. Personnel from Arlin's Aircraft Services, Inc, Belgrade, Montana, retrieved the aircraft wreckage on June 27, 2000. On August 29, 2000, the airframe, engine and associated engine components were released to United States Aviation Underwriters, Incorporated, Seattle, Washington.
Engine failure for undetermined reasons. Factors include the lack of suitable terrain for an emergency landing, trees and mountainous terrain.
Source: NTSB Aviation Accident Database
Aviation Accidents App
In-Depth Access to Aviation Accident Reports
