Adrian, MI, USA
N411JL
MOONEY AIRPLANE COMPANY, INC. M20TN
The pilot reported that the airplane, with its autopilot engaged, experienced a "violent pitch-up" without warning while it was climbing through about flight level 180. Extreme forward yoke pressure (the pilot estimated between 100 and 150 pounds force) was required to keep the airplane from pitching up and stalling, so the pilot kept both hands on the yoke. The Airplane Flight Manual contains emergency procedures for use in the event of an autopilot out-of-trim event; the third item on the checklist directs pilots to re-trim the pitch, if necessary, using the trim wheel. The pilot noted that he did not attempt to use the manual trim wheel to change the airplane's pitch attitude because that would have required him to release hand pressure on the control yoke. He was uncertain when or how the autopilot was disengaged. He declared an emergency and made a spiraling descent to lose altitude. He reported that he encountered multiple violent pitch up and down oscillations near the bottom of the descent; the pilot's seat was broken during one of the oscillations, which allowed the pilot to use his knees to apply forward yoke pressure. He stated that by using his knees to control the yoke, the airplane was "quasi-stable," pitch oscillations still occurred due to the lack of precise pitch control. While still having difficulty controlling the airplane's pitch with the electric nose pitch trim in the full up position, he prepared for an emergency landing. The pilot used his knees to provide forward yoke pressure as he landed the airplane about 450 feet short of the runway. The airplane's nose gear collapsed, the main landing gear were sheared off, and the airplane skidded about 900 feet before coming to rest to the left of the runway. The duration of the flight from the initial pitch up event to landing was about 27 minutes. Three separate examinations of the airplane's flight controls and autopilot system found no anomalies with the autopilot system or an explanation for the violent nose-pitch-up event. The Emergency Section of the Airplane Flight Manual (AFM) supplement for the autopilot stated that for an Autopilot Out of Trim emergency the pilot should: 1) disengage the autopilot 2) maintain/regain aircraft control, and 3) pitch trim...re-trim if necessary using the trim wheel.
HISTORY OF FLIGHT On July 27, 2012, about 0846 eastern daylight time (all times edt), a Mooney M20TN, N411JL, experienced a severe nose pitch-up while climbing through flight level (FL) 180 to FL230. The private pilot, the sole occupant, initiated an emergency descent. During the attempted landing at the Lenawee County Airport (ADG), Adrian, Michigan, the airplane landed short of the Runway 23. The nose gear collapsed and the main landing gear separated from the airplane which resulted in substantial damage to the airplane. The pilot was not injured. The airplane was registered to and operated by 4thWave, Inc., under the provisions of the 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed at the time of the accident. The flight departed from the Wittman Regional Airport, Oshkosh, Wisconsin, about 0732 on an instrument flight rules (IFR) flight plan with the Manassas Regional Airport (HEF), Manassas, Virginia, as the intended destination. The pilot reported that he departed Oshkosh under visual flight rules (VFR) and hand flew the airplane for about 20 minutes, and then he turned the airplane's autopilot on. Passing Muskegon, Michigan, he activated his IFR flight plan and received an air traffic control (ATC) clearance to climb to 17,000 feet above mean sea level (msl). The pilot reported that while in the climb, his backup oxygen system which he was using was not working. He descended to 15,000 feet msl in order to change his mask to the Mooney built in oxygen system. Once he confirmed that the airplane's oxygen mask was working properly, he resumed the climb to 17,000 feet msl. At 0843:12, ATC instructed the pilot to climb to FL 230, which the pilot acknowledged. The pilot reported that during the climb, the airplane experienced a "violent pitch up." (The ATC transcript and radar data indicated that the pitch up occurred when the airplane was climbing approximately through FL180) The pilot stated that it was a rapid pitch up with no warning signs, and extreme forward yoke pressure was required to keep the airplane from pitching up to avoid a possible aerodynamic stall. He estimated that it took 100 to 150 pounds of force, with both hands on the yoke, to keep the airplane from pitching up. The ATC transcript indicated that at 0846:43, the ATC controller asked the pilot if he had copied the routing instructions. The pilot responded, "Negative. I've got an issue right now. I'll get back to you." The radar returns indicated that the airplane was leveling at FL190. At 0848:42, the pilot stated, "I have to descend. I can't seem to control the airplane. It wants to keep climbing. I have to descend." The ATC controller issued a descent to 14,000 feet msl, and subsequently, asked the pilot if he was declaring an emergency. The pilot responded, "Negative. I think I have it under control. It's going to be a struggle." The airplane's heading changed to a more southerly heading. At 0850:59, the airplane had descended to 11,000 feet msl. ATC told the pilot to state his intentions, and the pilot responded, "Going to have to declare an emergency; can't hold the plane." At 0851:29, another aircraft on the radio frequency stated that the accident pilot sounded hypoxic and needed to get his oxygen mask on. The ATC transcript shows that another aircraft made an unintelligible transmission. The pilot stated that he had his oxygen mask on and he was not hypoxic. However, the task of maintaining control of the airplane was taking his focused attention, and the stressful situation resulted in his radio calls being sporadic and less clear than typical. The pilot reported that his major concern was to avoid stalling and spinning the airplane. He therefore kept both hands on the yoke to keep the airplane from pitching up. He did not attempt to use the manual trim wheel to change the airplane's pitch attitude, because that would have required him to release hand pressure on the control yoke. He was uncertain when or how the autopilot was disengaged. He did not attempt to push the autopilot power switch located on the instrument panel, which works as the autopilot's system's circuit breaker, or pull any of the other circuit breakers. After the pitch up occurred, he tried using the manual electric trim split switch located on the yoke, but it had no effect. He stated that the airplane "would continually go into a stall condition, and this reinforced actions to keep [the] nose down, which required the greatest yoke pressure." He made no rudder application during the entire incident because he was concerned that it might cause an incipient spin. At 0852:07, the pilot stated to ATC, "I just got to descend. I can't keep airplane down to descend." In order to lose altitude, the pilot reported that he "achieved a quasi-stable descent with a rapid spiral descent." The ATC radar returns indicated that the airplane appeared to be in a spiral descent. At 0901:59, ATC stated, "Say altitude." The pilot responded, "10,000…I just want to get on the ground. I'm having trouble controlling the airplane. It continues to want to stall." The pilot reported that he encountered multiple violent pitch up and down oscillations near the bottom of the descent. The pilot seat was broken during one of the oscillations, which allowed the pilot to use his knees to apply forward pressure to the yoke. He stated that by using his knees to control the yoke, the airplane was "quasi-stable," but there were still pitch oscillations due to the lack of precise pitch control. At 0906:18, the pilot stated, "I finally got the airplane under control. I'm at 3,000 feet. I might be able to take it down." The ATC controller stated, "Roger, what type of airport to you need?" The pilot responded, "I'll take anything. I might have to land in a field. Having a devil of a time controlling the plane. What's close by?" About 0909, ATC reported that they lost radar contact with the airplane due to the airplane descending below radar coverage. The airplane continued heading southwest for about 8 nautical miles after descending below radar coverage. By referencing the airplane's moving map, the pilot decided to try to land at ADG. While still having difficulty controlling the airplane's pitch, he prepared for an emergency landing. The pilot used his knees to provide forward pressure to the control yoke as he flew the approach to ADG, which ended in a hard landing in the grass short of runway 23. PERSONNEL INFORMATION The 68-year-old private pilot held a private pilot's certificate with single-engine land, glider, and instrument airplane ratings. He held a third class medical certificate that was issued on January 3, 2011, with the limitation of wearing corrective lenses. He had a total flight time of 917 hours with 346 hours in the accident airplane. AIRCRAFT INFORMATION The airplane was a single-engine Mooney M20TN, serial number 31-0096, manufactured in 2008, and powered by a 280 horsepower Lycoming TSIO-550-G1 engine. The last annual maintenance inspection was completed on December 2, 2011, and the total time on the airframe, engine, and propeller at the time of inspection was 410.5 hours. The total time at the time of the accident was 594 hours. The airplane was equipped with the Garmin G1000 Integrated Avionics System which consisted of a primary flight display (PFD), a multi-function display (MFD), an audio panel, and attitude and heading reference system (AHRS), an air data computer (ADC), and the sensors and computers to process flight and engine information for display to the pilot. The G1000 also interfaced to the S-TEC55x autopilot and repeated the autopilot mode annunciations on the G1000 PFD. The airplane was also equipped with the Garmin GFC 700 Automatic Flight Control System (AFCS) which was a 2 axis autopilot and flight director system. The system consisted of autopilot controls on the MFD, servos with autopilot processing logic, flight director processing logic in the Garmin integrated avionics (GIAs), a control wheel-mounted elevator trim switch, a control wheel-mounted trim interrupt and autopilot disconnect (A/P DISC/TRIM INTER) switch, a control wheel-mounted control wheel steering (CWS) switch, a remote-mounted go-around switch, and PFD/MFD-mounted altitude preselect, heading, and course knobs. The GFC 700 autopilot contained an electric pitch trim system which is used by the autopilot for automatic pitch trim during autopilot operation and by the pilot for manual electric pitch trim when the autopilot is not engaged. The manual electric pitch trim system was operated by a split switch on the pilot's control wheel. The GFC 700 autopilot and manual electric trim will not operate until the system has satisfactorily completed a preflight test. The preflight test begins automatically with the initial power application to the aircraft and the A/P POWER switch set to the ON position. Use of the autopilot or manual electric trim system is prohibited if the preflight test is not satisfactorily completed. The Emergency Procedures section of the Mooney Airplane Flight Manual (AFM) Supplement for the Garmin GFC 700 autopilot system provided the emergency procedures to use in the event of an AUTOPILOT OUT OF TRIM. The emergency procedure was: 1) A/P DISC/TRIM INTER Switch---DEPRESS AND HOLD---while grasping control wheel firmly 2) Aircraft Attitude---MAINTAIN/REGAIN AIRCRAFT CONTROL ---using standby attitude indicator if necessary 3) Pitch Trim---RE-TRIM if necessary, using the trim wheel 4) A/P POWER SWITCH---OFF 5) A/P DISC/TRIM INTER button---RELEASE -WARNING- FOLLOWING AN AUTOPILOT, AUTOTRIM OR MANUAL ELECTRIC TRIM SYSTEM MALFUNCTION, DO NOT ENGAGE THE AUTOPILOT OR OPERATE THE MANUAL ELECTRIC TRIM UNTIL THE CAUSE OF THE MALFUNCTION HAS BEEN CORRECTED. -WARNING- DO NOT ATTEMPT TO OVERPOWER THE AUTOPILOT IN THE EVENT OF A PITCH MISTRIM. THE AUTOPILOT SERVOS WILL OPPOSE THE PILOT INPUT AND WILL CAUSE PITCH TRIM TO RUN OPPOSITE THE DIRECTION OF PILOT INPUT. THIS WILL LEAD TO A SIGNIFICANT OUT-OF-TRIM CONDITION RESULTING IN LARGE CONTROL WHEEL FORCE WHEN DISENGAGING THE AUTOPILOT The Emergency Section of the AFM Supplement contains this warning in the AFTER TAKEOFF section. It reads in part: -WARNING- ...DO NOT ATTEMPT TO MANUALLY FLY THE AIRPLANE WITH THE AUTOPILOT ENGAGED. THE AUTOPILOT SERVOS WILL OPPOSE THE PILOT INPUT AND WILL TRIM OPPOSITE THE DIRECTION OF PILOT INPUT (PITCH AXIS ONLY). THIS COULD LEAD TO A SIGNIFICANT OUT-OF-TRIM CONDITION. DISCONNECT THE AUTOPILOT IF MANUAL CONTROL IS DESIRED... METEOROLOGICAL INFORMATION At 0853, the surface weather observation at ADG was: wind light and variable, sky clear, visibility 10 miles, temperature 24 degrees Celsius (C), dew point 19 degrees C, and altimeter 29.85 inches of mercury. WRECKAGE AND IMPACT INFORMATION A Federal Aviation Administration avionics inspector examined the airplane at the accident site and after the airplane was moved into a hangar at ADG. The examination of the accident site revealed that the airplane impacted the terrain about 450 feet short of runway 23. The main landing gear and doors sheared off, the nose gear collapsed into the wheel well, the propeller blades were bent back as the airplane skidded though the grass, across the asphalt threshold, and into the grass for another 450 feet before it came to rest. The empennage and fuselage were twisted at the empennage attach points, the left wing was bent at the outboard section of the wing, and all flight control surfaces were damaged. The landing gear handle was in the down position, the flaps were up, and no burnt odors were noticed in the cockpit area. The following items were found in the front cockpit seats: back up oxygen bottle and mask; 2 oxygen masks with boom mikes; CO2 detector; blood oxygen monitor; 2 headsets, and a flight bag with flight related items. The examination of the flight controls revealed the following: 1) The tail stabilator was in the full down position. 2) The pitch trim was 2 wheel notches from nose full up (manual pitch trim setting). 3) The pitch trim continuity was verified; however, the trim travel was limited to full nose up to neutral due to the tail damage that limited trim travel. 4) The pitch electrical trim was operative and indication was verified on the Garmin MFD; however, the trim travel was limited to full nose up to neutral due to the tail damage that limited trim travel. 5) The elevator control continuity was verified; however, the control travel was not verified due to tail damage. 6) Yaw control continuity was verified; however, the control travel was not verified due to tail damage. 7) The rudder electric trim was verified as operative. 8) The roll control continuity was verified; however, the control travel was not verified due to wing and aileron damage. 9) The speed brakes did deploy and retract when operated. TESTS AND RESEARCH Flight Controls and Autopilot The airplane's flight controls and autopilot system were examined again on August 21, 2012, with National Transportation Safety Board (NTSB) oversight. The autopilot and flight controls were examined with the following results: 1) The pitch trim wheel was manually operated. The trim could be moved to the nose up stop, but only to approximately mid-range in the nose down direction due to the damage to the tail section and empennage of the airplane. 2) The Garmin PFD and MFD started up normally. The autopilot automated preflight test began and completed successfully. 3) Using the pilot's control wheel switches, the electric pitch trim moved nose up and nose down accordingly. The pilot's control wheel AP disconnect/Trim Interrupt switch interrupted the electric pitch trim when the switch was pushed and held. 4) The split trim switch operated normally. The test verified that the electric pitch trim did not move when each half was actuated individually. 5) The autopilot operated normally in the HDG (heading) and PIT (pitch attitude hold) modes. 6) The autopilot Nose UP and Nose DN buttons on the MFD operated correctly, with associated elevator movement. 7) Used the autopilot Nose UP button on the MFD and restrained the control wheel movement. The test verified nose up electric auto pitch trim response. 8) Used the autopilot Nose DN button on the MFD and restrained the control wheel movement. The test verified nose down electric auto pitch trim response. The examination of the airplane on August 21, 2014, revealed no evidence of an electrical fire or a short. There was no burnt smell from the avionics equipment or cockpit displays. On September 24, 2012, a third examination of the flight controls and autopilot system was conducted by an avionics service facility with FAA oversight. The autopilot preflight tests were conducted and no error messages were noted. Tests of the autopilot in the normal operating mode revealed no defects. Operational tests of the autopilot in all modes were performed. The roll mode followed heading commands and course changes. The pitch mode functioned normally including auto trim functions. All disconnect functioned normally, and the manual electric trim functioned normally. The two integrated Garmin GIAs that control the Garmin 700 autopilot system were put into the maintenance mode to access the maintenance logs to determine if there were any fault codes. The dates of all fault codes were prior to 2009 and none of the fault codes were related to servo issues or the autopilot. The static wicks on the ailerons, elevator, and rudder were tested using a MEG OHM tester. All static wicks were found to test between 6 to 15 MEG OHMS with 1,000 volts applied, which was within allowable limits. On January 31, 2013, the pitch servo, the pitch trim servo, and the roll servo were tested at another avionics facility, with FAA oversight, to measure breakaway torque. The inspection of the pitch servo was found to have a torque reading of 50 in/lb., which was +2 in/lb. above the 42+/-6 in/lb. specification. The pitch trim servo was tested and found to have a torque reading of 70 in/lb. The specification is 70+/-9 in/lb. The roll servo
An initial nose-pitch-up event and out-of-trim condition, the reason for which could not be determined because the examinations of the airplane did not reveal any anomalies that would have precluded normal operation. Contributing to the accident was the pilot’s failure to use the manual trim wheel to reset the pitch trim.
Source: NTSB Aviation Accident Database
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