Canton, MA, USA
N4126H
Mooney M20J
The private pilot had owned the airplane and flew it in actual instrument meteorological conditions for many years. The pilot successfully flew a localizer approach, and descended through a cloud layer into visual conditions about 500 feet above ground level. She was in radio contact with air traffic control when the airplane pitched up, then down, and descended rapidly into swampy terrain. During an approximately 45-day period prior to the accident flight, the pilot had experienced problems with the manual and electric pitch trim sticking or exhibiting stiffness when she attempted to move the trim toward the nose up position. The problem was addressed twice by a maintenance repair facility at the pilot's home airport, and once by an avionics repair facility; however, the pilot continued to report problems of trim stiffness. The pilot's husband, who was also a certificated pilot, did not notice any trim problems on a recent long cross-country flight. An examination of the wreckage, including the pitch trim system, did not reveal any preimpact mechanical malfunctions. While the aft pitch trim jackscrew required slightly more force to turn toward the nose up position, verses the nose down position, the aft pitch trim jackscrew moved freely by hand in both directions. In addition, fresh grease was observed on both the forward and aft pitch trim jackscrews. The flaps were found fully extended, and the pitch trim was found in a nose up position, consistent with a normal approach and landing descent.
HISTORY OF FLIGHT On June 4, 2007, at 1011 eastern daylight time, a Mooney M20J, N4126H, was substantially damaged when it impacted terrain in Canton, Massachusetts, while on an approach to Norwood Memorial Airport (OWD), Norwood, Massachusetts. The certificated private pilot was fatally injured. Instrument meteorological conditions prevailed for the flight that departed Sky Manor Airport (N40), Pittstown, New Jersey, about 0800. An instrument flight rules (IFR) flight plan was filed for the personal flight conducted under 14 Code of Federal Regulations Part 91. According to data from the Federal Aviation Administration (FAA), the pilot received a weather briefing and filed an IFR flight plan via Data User Access Terminal (DUATs). The flight proceeded uneventfully to the Norwood, Massachusetts, area. The pilot was in radio contact with Boston Terminal Radar Approach Control (TRACON), and then the Norwood air traffic control tower. At 0954, the Boston TRACON controller told the pilot to expect the localizer runway 35 approach, with a circle to land on runway 10 at OWD. The pilot acknowledged the transmission, and subsequently advised the controller that she had the current automated terminal information system (ATIS) information, "Lima." At 1006, the TRACON controller provided a vector of 230 degrees, advised that the airplane was 4 miles from STOGE intersection, instructed the pilot to maintain an altitude of 2,000 feet mean sea level (msl), and issued a clearance for the localizer runway 35 approach, circle to land on runway 10. The pilot acknowledged the clearance. At 1008, the TRACON controller advised the pilot to contact the OWD control tower. The pilot acknowledged the instructions and complied. At 1009, the pilot radioed the OWD control tower, provided a position report of 1 mile from STOGE, and requested wind information. The OWD tower controller stated that the winds were from 110 degrees at 12 knots. The controller also told the pilot that runway 35 was available (if she didn't want to perform the circling approach to runway 10). The pilot opted for runway 35, and was cleared to land. The pilot then provided another position report over STOGE. At 1011, the controller observed the accident airplane descend from a cloud layer. The controller asked the pilot if she had the airport in sight, and the pilot replied that she did. The controller then repeated the landing clearance and provided wind information of 110 degrees at 12 knots. The pilot began to read back the wind information and had stated, "one one zero," when the transmission ceased. No further transmissions were received from the airplane. The controller observed the nose of the airplane pitch up and then down, followed by a rapid descent into terrain. A review of radar data from Boston TRACON and Providence TRACON revealed that the accident airplane approached OWD from the west. The airplane flew through the localizer course for runway 35, but then corrected and intercepted the localizer course near STOGE. The airplane descended on course, slightly to the left, until the last target was recorded about 2.5 miles from the runway 35 threshold. There was limited or no radar contact with the accident airplane during the last few moments of flight. A witness was driving on Route 95 South in the area of Norwood, Massachusetts. He lived near the airport, and was familiar with approaching aircraft. The witness observed the accident airplane in level flight, and thought it was very low. He estimated the height of the airplane was between 250 to 300 feet above ground level (agl). The windows in his vehicle were up due to rain, and the witness did not hear any sounds associated with the airplane. The witness further stated that the right wing tipped up, the nose tipped down, and the airplane descended rapidly into a swampy area. The airplane impacted terrain about one-third mile prior to the runway 35 threshold, and approximately 200 feet right of the extended runway centerline. PERSONNEL INFORMATION The pilot, age 57, held a private pilot certificate, with ratings for airplane single engine land and instrument airplane. Her most recent FAA third class medical certificate was issued on October 2, 2006. At that time, she reported a total flight experience of 1,590 hours. The pilot's husband stated that she had owned the accident airplane for approximately 12 years, and had received her instrument rating prior to purchasing it. The pilot's husband also noted that she frequently flew the accident airplane in actual instrument meteorological conditions (IMC). The pilot kept an electronic flight log on her computer. According to the log, she had accumulated 1,670.2 total hours of flight experience, of which, 27.9 and 38.7 hours were accumulated during the 30 days and 90 days preceding the accident. Of the total flight experience, about 1,342 hours were in the accident airplane, and 158 hours were in IMC. The pilot had flown 6 hours and 9 hours in IMC during the 30 days and 90 days preceding the accident. AIRCRAFT INFORMATION The airplane was manufactured in 1979. A review of the airplane's logbooks, maintenance invoices, and correspondence between the pilot and a maintenance facility at OWD, her home base, revealed that the airplane's most recent annual inspection was completed on April 5, 2007. At that time, the airplane had accumulated 2,205.5 total hours of operation, and the engine had accumulated 1,799.1 hours of operation since new. The airplane flew about 40 hours from the time of the most recent annual inspection until the accident. A review of the invoice for the annual inspection revealed, "Elevator Trim Chain Appears Loose. Adjusted Chain As Required IAW The Mooney Maintenance Manual. Operations Checked OK." Shortly after the annual inspection, the pilot experienced a problem with the electric pitch trim. Specifically, it did not work on one occasion at the end of a flight, and on other occasions, it seemed to have difficulty traveling toward the nose up position. On April 26, 2007, the maintenance facility at her home base diagnosed the problem as a "...Bad Connection At Connector On Wire Harness Side & Adjustment of Clutch On Trim Servo...," and the pilot took the airplane to an avionics repair facility. On May 2, 2007, the avionics repair facility noted: "Autopilot Auto And Manual Electric Pitch Trim INOP In Up Direction. Ground tested A/P and trim system. Verified squawk. Found manual trim very stiff in up direction. Gained access to trim servo located in tail. Removed trim servo to shop and bench tested. No trouble found. Motor runs good and slip clutch is set correctly. Found trim system stiffness in up direction to be at fault. Gained access to trim jack screw in tail. Lubed jack screw. No improvement. Customer will have mechanic at home base fix trim stiffness. Closed up access and secured aircraft for flight." On May 9, 2007, the maintenance facility at the pilot's home base noted: "Troubleshoot Electric Trim Stiff. Troubleshoot, Check Electric Trim. Lubed Jack Screw And Lubed All Bearings. Operations Checked OK." From May 9 through May 21, the pilot and her husband flew the accident airplane from Massachusetts, to New Mexico, and back to Massachusetts. The pilot had reported intermittent sticking of the pitch trim during that trip. Her husband was also a certificated pilot, and did not notice any trim problems during that trip. METEOROLOGICAL INFORMATION The reported weather at OWD, at 0953, was: wind 100 degrees at 11 knots; visibility 2 miles in mist; overcast ceiling at 500 feet; temperature 17 degrees Celsius (C); dew point 61 degrees C; altimeter 29.58 inches of mercury. Review of a current approach chart for the localizer runway 35 approach at OWD revealed that the minimum descent altitude for a straight-in approach was 580 feet msl (531 feet agl). The minimum visibility requirement was 3/4-mile. For a circling approach, the minimum descent altitude was 600 feet msl (550 feet agl). The minimum visibility requirement was 1 mile. Review of a current approach chart for the RNAV (GPS) runway 35 approach at OWD revealed that the descent altitude for a localizer with vertical guidance (LPV) approach was 344 feet msl (295 feet agl). The minimum visibility requirement was 1 mile. For a circling approach, the minimum descent altitude was 600 feet msl (550 feet agl). The minimum visibility requirement was 2 miles. WRECKAGE AND IMPACT INFORMATION The wreckage was examined at the accident site on June 5, 2007. All major components of the airplane were accounted for at the scene, and no debris path was noted. The wreckage was resting in a wooded swamp area, at an approximate 30-degree nose down angle. The engine, wings, and empennage remained attached to the fuselage. The right wing exhibited compression damage on the underside, and impact damage at the leading edge. The approximate one-quarter outboard section of the right wing, including the wingtip, was bent upward. The right fuel tank was compromised. The right aileron was in the approximate neutral position, and sustained impact damage. The left wing also exhibited compression damage, and the approximate one-third outboard section of the left wing was bent upward. The left fuel tank remained intact, and contained approximately 15 gallons of 100LL aviation gasoline. The left aileron was also in the approximate neutral position. The empennage was canted approximately 30 degrees upward, and resting against trees. The elevator and rudder remained attached to the empennage. Approximately 11 threads were measured on the horizontal stabilizer trim jackscrew. According to a representative of the airplane manufacturer, the measurement corresponded to a nose-up trim position, consistent with a setting used during a low engine power descent. The representative further stated that 16 threads corresponded to full nose-up pitch trim. The cockpit and cabin areas were crushed inward at the roof and firewall area. The flap switch was in the neutral/off position, and the landing gear selector was in the UP position. The throttle, mixture, and propeller controls were in the full forward position. The engine remained attached to the airframe, and was separated during recovery. Both propeller blades remained attached to the hub. One propeller blade exhibited s-bending, and the other was not damaged. Several tree branches, ranging in diameter from 1 to 6 inches, were cut at approximate 90-degree angles and exhibited black paint transfer. The valve covers were removed, and oil was noted throughout the engine. The top spark plugs were removed from the engine for inspection. Their electrodes were intact and light gray in color, except for the number one spark plug, which was oil soaked. The single drive dual magneto unit was removed from the engine. Due to impact damage, the magneto could not be tested. The oil filter was removed and the oil filter screen was absent of metallic contamination. The oil suction screen was also free of metallic contamination. The engine driven fuel pump remained intact, and discharged fuel when activated by hand. The fuel servo and fuel manifold also contained fuel, and the fuel servo screen was absent of debris. The fuel lines contained fuel, and the fuel nozzles were clear. When the propeller was rotated by hand, camshaft, crankshaft, and valve train continuity was confirmed. Thumb compression was attained on all cylinders. The wreckage was re-examined on July 17, 2007, at a recovery facility. Left and right aileron control continuity were confirmed from the ailerons to their respective bellcranks, and then from the bellcranks through the center wing sections, which were cut during recovery, to the wing roots. Continuity was confirmed from the elevator and rudder, via their respective push pull tubes, to the center tailcone section, which had been cut during recovery. Continuity then continued from the center tailcone section, through the aft cabin area, and to the cockpit floor. Pitch trim continuity was confirmed from the horizontal stabilizer trim jackscrew, via a torque tube, to the electric trim servo at the center tailcone section, and to the manual trim wheel assembly in the cockpit. The bicycle chain for the electric pitch trim was separated from the sprocket, consistent with impact damage. The forward pitch trim jackscrew, located under the cockpit floor, measured approximately 1 3/8 inches from the aft end of the moving lug, to the stop nuts on the aft end of the jackscrew, consistent with a nose up position. The bicycle chain for the forward pitch trim jackscrew remained on its sprocket. According to a representative from the airplane manufacturer, a full nose up position would have been approximately 2 inches from the aft end of the moving lug, to the stop nuts on the aft end of the forward pitch trim jackscrew. Full nose down would have been approximately 3/4 inch from the aft end of the moving lug, to the stop nuts on the aft end of the forward pitch trim jackscrew. The aft pitch trim jackscrew required slightly more force to turn toward the nose up position, verses the nose down position; however, the aft pitch trim jackscrew moved freely by hand in both directions. Some dirt was noted on the aft pitch trim jackscrew, consistent with impact and aircraft recovery. Fresh grease was observed on both the forward and aft pitch trim jackscrews. The landing gear was extended, and the landing gear actuator rod was in a retracted position, consistent with gear extension. Approximately 1/2 inch of threads were observed on the flap actuator jackscrew, consistent with full flap extension. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy was performed on the pilot by the Commonwealth of Massachusetts, Office of the Chief Medical Examiner, Boston, Massachusetts. The autopsy report revealed the cause of death as "blunt trauma." Toxicological testing was conducted on the pilot at the FAA Toxicology Accident Research Laboratory, Oklahoma City, Oklahoma, with no anomalies noted. TESTS AND RESEARCH During the wreckage re-examination, a portion of the right aileron control tube was found separated, and forwarded to the Safety Board's Materials Laboratory, Washington, D.C. An examination of the tube revealed that all fractures were consistent with overstress. An audio copy of the pilot's radio transmissions to the Norwood Tower was forwarded to the Safety Board's Vehicle Recorders Laboratory, Washington, D.C. A sound spectrum study was conducted to identify any background sound signatures that could be associated with airplane's propeller. Propeller sound signatures were then converted to propeller rpm: pilot radios Norwood Tower, 2310 rpm pilot advises controller her approach clearance, 2355 rpm pilot accepts runway 25 option, 2520 rpm pilot acknowledges landing clearance, 2520 rpm pilot reports airport in sight, 2385 rpm final transmission, pilot repeats wind information, 2610 rpm
The pilot's failure to maintain airspeed, which resulted in an inadvertent stall and subsequent impact with terrain.
Source: NTSB Aviation Accident Database
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