Orlando, FL, USA
N7FG
BEECH A36TC
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.
HISTORY OF FLIGHTOn November 20, 2015, about 1127 eastern standard time, a Beech A36TC, N7FG, descended into Clear Lake, Orlando, Florida. The private pilot and the passenger were fatally injured, and the airplane was destroyed. The airplane was registered to Kavak Aviation, LLC, and was being operated by the pilot as a 14 Code of Federal Regulations (CFR) Part 91 personal flight. Visual meteorological conditions prevailed at the time, and a visual flight rules (VFR) flight plan was filed. The flight originated from Orlando Executive Airport (ORL), Orlando, Florida, about 1115, and was destined for Gainesville Municipal Airport (GLE), Gainesville, Texas. According to a chronological summary of flight communications, audio recordings, and transcriptions of communications, prepared by the Federal Aviation Administration (FAA), while in contact with ground control, the pilot was advised to remain outside of Class B airspace, provided departure instructions, and cleared to taxi to runway 7. The flight was then cleared for takeoff, and the pilot was instructed to turn left on course. Radar data indicated that, between 1116:39 and 1118:43, the airplane proceeded in an east-northeasterly direction, turned to a northwesterly direction, and climbed from 200 ft to 1,800 ft mean sea level (msl). About 1118:47, while the airplane was flying in a northwesterly direction about 1,900 ft msl, the local controller advised the pilot, "november seven foxtrot golf remain outside Bravo airspace at or below one thousand five hundred and contact Orlando departure one one niner point four," and the pilot immediately replied, "alright one one niner point four what was the altitude restriction." The controller replied, "at or below one thousand five hundred," and, at 1118:59, the pilot replied, "at or below one thousand five hundred I'm already at two thousand" followed by a pause and then, "I'm descending for seven foxtrot golf (unintelligible)." At 1119:09, when the airplane was about 2,100 ft msl, an Orlando Approach Control controller advised the local controller that the airplane needed to descend immediately, and the local controller replied, "yeah I'm starting him down." While the airplane was flying in a northwesterly direction at 1,900 ft msl, the pilot established contact with Orlando Approach Control, and, at 1119:54, he advised the controller, "…seven foxtrot golf with you at uh one thousand eight hundred descending." The controller instructed the pilot to "ident," provided the Orlando altimeter setting, and asked him his request. The pilot replied by correctly reading back the altimeter setting and advised that he was requesting flight following. The controller asked the pilot for his destination, and the pilot said that it was GLE and asked to start his climb as there was an opening in the clouds. Between 1120:05, and 1120:30, the airplane climbed from 1,700 to 2,200 ft msl. The controller asked several times about the pilot's destination, and, at 1120:37, when the airplane was about 2,200 ft msl, the controller advised the pilot, "seven foxtrot golf okay, you have not been given a clearance through the Bravo why are you climbing;" the pilot did not reply. The controller then instructed the pilot to turn left to a heading of 270°, and the pilot did not reply. At 1120:51, the controller advised the pilot, "seven foxtrot golf I need you to listen cause you're in my Bravo without a clearance turn left heading 270." Between 1120:40 and 1120:53, the airplane descended from 2,200 ft msl to 1,700 ft msl. At 1120:59, while the airplane was flying in a northwesterly direction at 1,700 ft msl, the pilot advised the controller that he was turning left to a heading of 270° and that "for some reason" he could not get the airplane's autopilot to disengage. The controller immediately replied, "thank you." The controller provided the pilot with a transponder code, which the pilot read back, and the pilot then said, "listen I think we need to put this thing on the ground I don't know what's going on." The controller asked if the pilot wanted to return to ORL, and the pilot replied, "affirmative can you help me get there." The controller instructed the pilot to maintain VFR at 1,600 ft msl, to fly a heading of 210°, and to expect vectors to runway 7. At 1121:53, when the airplane was about 1,800 ft msl, the pilot advised the controller, "ok listen um I have to use full force does anybody have any ideas what I can do to shut off this autopilot." The pilot then asked the controller for the assigned heading, which the controller provided, and, about 20 seconds after the pilot's request for assistance, the pilot of another airplane said, "pull your circuit breaker." At 1122:55, when the airplane was about 2,200 ft msl, the controller asked the pilot if he was able to descend, and the pilot replied, "…I'm trying I'm pushing as hard as I can on the yoke." The controller instructed the pilot to fly a heading of 180° when able, and the pilot replied, "descending to one eight I'm sorry going to one eight." At 1123:34, the pilot of the other airplane advised the controller to have the pilot pull the circuit breaker. The accident pilot said that, "uh we pulled the circuit breaker but it just keeps uh porpoising up and down and it's taking full forward to go down and full back to go up to com compensate." The pilot of the other airplane advised the pilot to "power off the airplane" for 30 seconds, and the controller instructed the pilot to make a right turn to stay away from airplanes departing from Orlando International Airport. At 1124:34, when the airplane was about 1,800 ft msl, the pilot stated, "we're powered way down." The pilot of the other airplane advised the pilot not to reduce engine power but to turn off the airplane's master switch, which would remove electrical power and disconnect the autopilot. The accident pilot asked the other pilot if he was referring to the key (ignition) switch, and the other pilot replied, "no don't turn the key to the off position just turn your master switch your electrical master switch off." The accident pilot asked if the other pilot was referring to the avionics master switch and said that he was "relatively new" to the airplane. The pilot of the other airplane clarified that the pilot was to turn off the battery and alternator switches. Between 1124:34 and 1126:15 (the time of the last secondary radar return), the airplane descended from 1,800 to 1,100 ft msl and leveled off momentarily every 100 ft between 1,500 and 1,100 ft msl. At 1126:18, the controller advised the pilot that he was cleared to land on runway 7 at ORL. Primary radar returns (with no altitude reported) continued in a south-southeasterly direction from the location where the secondary radar returns ended, and, at 1126:58, the pilot said, "Orlando I'm (unintelligible)." The last primary radar return at 1127:02 was located about 0.1 nautical mile and 319° from the accident site location. At 1127:11, the ORL local controller advised the approach controller, "ah he just rolled over straight down he's in the ground." Another air traffic controller said, "he rolled it over," and the local controller replied, "uh yeah it looked like he started a right turn to rejoin the final which turned into kind of a wing over uh it was nose down and uh he he went straight down and I lost sight of him…." Several witnesses noticed the airplane immediately before it impacted Clear Lake. The witnesses saw the airplane in a "hard" right bank, which was followed by the airplane entering a vertical descent and impacting the lake. The witnesses did not see smoke trailing behind the airplane or parts separating during the descent. Before first responders arrived, bystanders rushed to the area and recovered the occupants from the submerged wreckage. PERSONNEL INFORMATIONThe 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. AIRCRAFT INFORMATIONThe airplane was certificated in accordance with Civil Air Regulations 3 and was manufactured by Beech in 1981. It was powered by a 300-horsepower Continental TSIO-520-UB engine and equipped with a Hartzell PHC-C3YF-1RF constant speed propeller. A two-axis KFC 200 autopilot system was installed at manufacture in accordance with Supplemental Type Certificate SA1496CE. Components of the system consisted of a KA 285 mode annunciator, KI 256 flight command indicator, KC 290 mode controller, KC 295 flight computer, KS 270 pitch servo and mount, KS 272 trim servo and mount, and KS 271 roll servo and mount. The bridle cable of the KS 270 pitch servo attached to the primary elevator flight control cable by a clamp at each end of the bridle cable. A manual electric autopilot trim switch assembly installed on the pilot's left control yoke grip controlled the KS 272 trim servo, which was connected to the elevator trim actuator by a control cable. Actuation of trim using the switch required movement of both switch rockers in the same direction. An autopilot disconnect/trim interrupt switch was also installed on the pilot's left grip, and a control wheel steering (CWS) switch was installed on the pilot's right grip. Depressing the CWS switch with the autopilot engaged released the autopilot servos allowing manual manipulation of the flight controls without the need to disengage and re-engage the autopilot or reselect any modes of operation. When the pitch servo, which was mechanically connected to the elevator primary control cables, sensed control forces that continued for longer than 3 seconds with the autopilot engaged, the autopilot computer activated the trim servo to trim away the control force on the pitch servo. The autotrim was specified to go from stop to stop in 94 seconds, and the manual electric trim was specified to go from stop to stop in 42 seconds. There was no audible annunciation when the autotrim was in motion; however, autotrim in motion could be detected by observing movement of the manual elevator pitch trim wheel, which was located in the lower portion of the pilot's side instrument panel. The KA 285 mode annunciator had a "Trim Warning" light bulb that illuminated when an autotrim failure occurred or when the trim circuit breaker was pulled. The light was designed to flash at least 4 times when the test switch on the KC 290 mode controller was depressed. Review of the airplane's maintenance records revealed an entry dated May 15, 2003, that indicated a new autopilot trim switch assembly (part number 200-02276-0000) was installed and operationally checked satisfactory at an airplane total time of about 4,390 hours. There were no other entries in the maintenance records related to the autopilot trim switch assembly. The airplane's last annual inspection was signed off as being completed on June 1, 2015, at an airplane total time of about 5,240 hours. The previous owner of the airplane reported that, in over 4 years of owning the airplane and operating it for about 400 hours, he did not have any issues with the autopilot. The airplane total time when the pilot purchased it in September 2015 was about 5,268 hours, and, since that time, there was no documented repair performed to any component of the autopilot system or the pitch trim system. The airplane total time at the time of the accident was about 5,310 hours. According to a logbook entry dated November 13, 2015, two defective static wicks were replaced, loose headphone jacks at the pilot and co-pilot positions were tightened, and troubleshooting of the primary turbine inlet temperature gauge occurred. There was no other documented maintenance performed before the accident flight. According to the pilot who ferried the airplane to the pilot when the pilot purchased the airplane, during the course of several flights totaling between 6 and 7 hours, when using the electric pitch trim, he noticed a lag of about 2 seconds from activation until seeing the trim wheel move. Because of the lag time and his personal preference, the ferry pilot used the manual pitch trim wheel and did not use the electric pitch trim further. The ferry pilot also reported that, with respect to the autopilot, the only issue he noted was that, when he disconnected the autopilot, the airplane had a tendency to have some nose-down trim, which was easily corrected by about 1/2 turn of the manual pitch trim wheel in the airplane nose-up direction. The autopilot disconnect/trim interrupt switch on the left grip of the pilot's control yoke did disconnect the autopilot. The ferry pilot indicated there were no further issues with the airplane's pitch trim or autopilot. METEOROLOGICAL INFORMATIONAt 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. AIRPORT INFORMATIONThe airplane was certificated in accordance with Civil Air Regulations 3 and was manufactured by Beech in 1981. It was powered by a 300-horsepower Continental TSIO-520-UB engine and equipped with a Hartzell PHC-C3YF-1RF constant speed propeller. A two-axis KFC 200 autopilot system was installed at manufacture in accordance with Supplemental Type Certificate SA1496CE. Components of the system consisted of a KA 285 mode annunciator, KI 256 flight command indicator, KC 290 mode controller, KC 295 flight computer, KS 270 pitch servo and mount, KS 272 trim servo and mount, and KS 271 roll servo and mount. The bridle cable of the KS 270 pitch servo attached to the primary elevator flight control cable by a clamp at each end of the bridle cable. A manual electric autopilot trim switch assembly installed on the pilot's left control yoke grip controlled the KS 272 trim servo, which was connected to the elevator trim actuator by a control cable. Actuation of trim using the switch required movement of both switch rockers in the same direction. An autopilot disconnect/trim interrupt switch was also installed on the pilot's left grip, and a control wheel steering (CWS) switch was installed on the pilot's right grip. Depressing the CWS switch with the autopilot engaged released the autopilot servos allowing manual manipulation of the flight controls without the need to disengage and re-engage the autopilot or reselect any modes of operation. When the pitch servo, which was mechanically connected to the elevator primary control cables, sensed control forces that continued for longer than 3 seconds with the autopilot engaged, the autopilot computer activated the trim servo to trim away the control force on the pitch servo. The autotrim was specified to go from stop to stop in 94 seconds, and the manual electric trim was specified to go from stop to stop in 42 seconds. There was no audible annunciation when the autotrim was in motion; however, autotrim in motion could be detected by observing movement of the manual elevator pitch trim wheel, which was located in the lower portion of the pilot's side instrument panel. The KA 285 mode annunciator had a "Trim Warning" light bulb that illuminated when an autotrim failure occurred or when the trim circuit breaker was pull
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.
Source: NTSB Aviation Accident Database
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