ERA16FA043

The pilot's failure to maintain adequate airspeed while turning to join the final approach leg of the airport traffic pattern with full airplane-nose-up trim, which resulted in the airplane exceeding its critical angle of attack and experiencing an aerodynamic stall. Contributing to the accident were the pilot's mis-use of the forward elevator flight control input with the autopilot engaged, which resulted in the full airplane-nose-up trim; his failure to recognize and correct the mis-trimmed airplane per the emergency procedures; and the excessive control forces required to maintain control of the airplane in the mis-trimmed condition, which resulted in pilot fatigue.

The private pilot was beginning a cross-country flight and was instructed by the ground controller to remain clear of Class B airspace. After an uneventful takeoff, while in Class B airspace, the pilot was instructed by the local controller to remain outside the Class B airspace, and the pilot advised the controller that the flight was descending. However, the airplane climbed briefly, followed by a series of descents and climbs with varying airspeeds that continued for about 5 minutes. The pilot informed the controller that he could not disengage the autopilot and requested radar vectors to return to the departure airport. While returning, the pilot informed the controller that it took full forward and back control pressure to descend and climb, respectively, and he solicited and received assistance from another pilot on how to turn off the autopilot. The advice included pulling the autopilot circuit breaker, which the pilot said he did. The pilot apparently did not consult the emergency procedures for an autopilot pitch trim malfunction, which included a step to manually retrim the airplane. The other pilot then suggested powering down the airplane, intending for the pilot to turn off the electrical power. However, the accident pilot reduced the airplane's power setting based on his misinterpretation of the advice from the other pilot. About 9 minutes after takeoff, the airplane slowed to within 12 knots of its stall speed and continued to slow. As the airplane turned to join the final approach leg of the airport traffic pattern, witnesses saw the airplane enter a vertical descent and impact a lake. Airplane performance studies showed that, during the turn, the airplane was just 2 knots above its stall speed. Based on the low airspeed and the witness observations, it is likely that the airplane's wing exceeded its critical angle of attack and experienced an aerodynamic stall. Postaccident examination of the airplane found the pitch trim in the full airplane-nose-up position. In the pilot's haste to mitigate an airspace violation while climbing with the autopilot engaged, he likely pushed and held the control yoke to arrest the climb. This action would have resulted in the autotrim running in the opposite (airplane-nose-up) direction to reduce the force on the pitch servo. Although the pilot's comment about pushing as hard as he could on the control yoke to descend was consistent with the full airplane-nose-up trim found during the investigation, his subsequent comment about using full force to climb was not consistent with the trim position. It could not be determined if the autotrim changed the trim position between the time the pilot first reported the autopilot issue and the time he reported that he had pulled the circuit breaker; however, it likely did not change after he reported pulling the circuit breaker. The electrical connection between the pitch servo and the airframe wiring harness was found not fully seated, but this likely occurred during recovery. Postaccident examination and testing of the autopilot system and components of the electric and manual trim systems revealed no evidence of preimpact failure or malfunction that would have caused an uncommanded full airplane-nose-up trim or would have prevented application of manual or electric trim to correct the mis-set trim condition. Although testing of the maximum torque of the trim servo could not be performed because the circuit was damaged during postaccident operational testing, the as-found position of the pitch trim in the full airplane-nose-up direction indicates that the trim servo motor had adequate torque to overcome the aerodynamic force of full trailing-edge-tab deflection and would have been capable of moving the trim tab toward a neutral position if this had been selected by the pilot. It is likely that the pilot could have corrected the full airplane-nose-up trim by applying either manual or electric trim. Although it could not be determined why the pilot in this accident did not promptly recognize and take corrective action regarding the mis-set trim, his lack of recognition was likely because he misinterpreted the cues as an autopilot failure. The excessive control forces required to maintain control and pilot muscle fatigue caused by prolonged operation of the airplane with mis-set pitch trim likely contributed to the pilot's failure to maintain control of the airplane.

The District Nine Medical Examiner's Office performed postmortem examinations of the pilot and passenger. The cause of death for both was blunt force trauma. Forensic toxicology of specimens of the pilot were performed by the FAA Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma, and Wuesthoff Reference Laboratory, Melbourne, Florida. Forensic toxicology of specimens of the passenger was performed by Wuesthoff and Orlando Health Clinical Laboratories. The pilot's FAA toxicology report indicated that the results were negative for carbon monoxide and volatiles. An unquantified amount of diphenhydramine, which is a sedating antihistamine available in a wide variety of over the counter products used to treat cold symptoms, allergic reactions, and as a sleep aid, was detected in urine but not detected in cavity blood. The pilot's Wuesthoff toxicology report indicated that the results were negative for volatiles, and the blood immunoassay screen detected 4.9% carboxyhemoglobin in the heart blood. The passenger's Wuesthoff toxicology report indicated that the results were negative for volatiles. The blood immunoassay screen was negative for all tested drugs except benzodiazepines; a note on the report suggested the need for further testing; and 5.3% carboxyhemoglobin was detected in the left chest blood. Unquantified amounts of caffeine, sertraline, trazodone, and trazodone metabolite were detected in the blood drug screen. Although specimens of the passenger were submitted to the FAA, testing was not performed. At 1153, a surface weather observation taken at ORL, which was located about 3.7 nautical miles east-northeast from the accident site, reported wind 020° at 8 knots, scattered clouds at 2,300 ft, temperature and dew point were 27°C and 21°C, respectively, and altimeter setting 30.04 inches of mercury. The pilot, age 61, held a private pilot certificate with ratings for airplane single-engine land, airplane multi-engine land, and instrument airplane. He held a third-class medical certificate, issued July 3, 2015, with a limitation to wear corrective lenses. A review of the pilot's second logbook, which contained entries dated between November 3, 1995, and October 30, 2015, revealed that he logged a total time of about 1,541 hours of which 1,374 hours were in single-engine airplanes. No logged flights were noted between July 16, 2006, and March 9, 2012. The pilot logged three flights in 2013; the last one was on November 17, 2013. The pilot's next logged flight was on July 16, 2015, which was a sign-off for a flight review in accordance with 14 CFR Part 61.56. Since purchasing the airplane on September 9, 2015, the pilot had logged about 37 hours in the airplane of which 12.5 hours were in the last 30 days. The remarks section of an entry in his pilot logbook for a flight 19 days after the airplane's purchase stated, "GPS + Autopilot Practice," and the logged duration was 4.2 hours. The accident site was located about 3.7 nautical miles west-southwest from the approach end of runway 7 at ORL. The wreckage was raised from the bottom of Clear Lake and towed to a nearby boat ramp, then lifted while being pulled onto land. To facilitate transportation, the fuselage was cut at fuselage station 147, located near the middle of the utility doors. Examination of the cockpit revealed that an aftermarket mount for a tablet computer was attached to the center portion of the pilot's control yoke. Neither grip of the pilot's control yoke was fractured, and the left grip of the co-pilot's control yoke was fractured. The interconnect aileron chain was around the sprockets of the pilot's control yoke, but the chain was separated. The top portion of the autopilot disconnect/trim interrupt switch located on the left grip of the pilot's yoke was missing and not recovered. The dual rocker switches of the autopilot trim switch assembly were not aligned; the left screw was broken; and the right screw was engaged and tight. The go-around switch, which is also located on the left grip of the pilot's yoke, was missing and not recovered. Normal operation of the CWS switch installed on the right grip of the pilot's yoke was noted when actuated by hand, and electrical continuity was noted from the switch to the appropriate pin of the autopilot computer and from the other wire to a ground terminal connection. Testing of the autopilot disconnect/trim interrupt switch revealed continuity between terminals 3 and 4, which is consistent with the switch being engaged to disconnect the autopilot; no continuity was noted between terminals 1 and 2 (normal relaxed state). Further examination of the cockpit revealed that the KC 290 mode controller was impact damaged. The flight level trim switch was in the up position, and the plastic on/off switch was deformed. The pre-impact switch positions of the mode controller could not be determined. The KA 285 mode annunciator was not crushed. The connector remained secured by the screws and was fully seated, but the backshell was cracked. Examination of the autopilot disconnect relay revealed no evidence of visible damage. Continuity was noted between pins 4 and 12 of the relay (normal) and from terminal 14 to a ring terminal connection with multiple wires; the ring terminal was impact separated from its airframe attach point. The mode controller, mode annunciator, and autopilot disconnect relay were retained for further examination. Examination of the wiring from the autopilot disconnect/trim interrupt switch to the autopilot disconnect and trim interrupt relay installed on the upper aft side of the firewall (identified as KPN 032-0029-01) revealed continuity from terminal 13 of the relay to terminal 4 of the autopilot disconnect/trim interrupt switch (normal). The wires at the pilot's control yoke were cut to facilitate removal of the autopilot disconnect/trim interrupt switch and the autopilot trim switch assembly, which were retained for further examination. Examination of the avionics bus bar revealed that the top portions of the autopilot and trim circuit breakers were damaged. Both circuit breakers were removed from the panel, and the housings of both were missing and not recovered. Both power side screws remained tightly secured to the bus bar. Examination of the left and right wings revealed that both remained attached by the forward and aft spars, and both exhibited impact damage. Both main landing gears were in the wheel wells, and both flap actuators were extended 2.0 inches, which equates to flaps retracted. The stall warning vane remained electrically connected but was separated from the wing. Examination of the empennage revealed that the left and right elevator trim tab actuators were symmetrically extended 1 7/8 inches, which equates to the full airplane nose-up stop. All structure and primary and secondary flight controls remained attached or were recovered with the exception of the outboard portion of the right elevator. Impact damage was noted to the inboard portion of the right elevator and horizontal stabilizer. Examination of the aileron servo revealed that the bridle cable remained secured to the balance cable, and the middle ball was in the slot of the capstan, which rotated freely. The connector was fully seated to the airframe harness, and each swaged ball was at the end of each clamp. Examination of the autopilot components, which were located in the aft fuselage, revealed that both electrical connections and the static line of the autopilot computer remained secured. The pitch servo and the airframe electrical connection were not fully mated. Further examination of the airframe wiring harness revealed that it was pulled free of the airframe security plastic clamp. One of the locks for the airframe side of the harness remained secured to the female side of the electrical connection, but the opposite side lock was separated. Further examination of the electri