Charleston, WV, USA
N6238D
CESSNA 172N
The flight instructor, who was controlling the airplane, and the student pilot were conducting an instructional flight. During the takeoff the airplane lifted off about 1,000 ft down the runway, pitched nose up, and rolled left to an inverted attitude before it impacted terrain next to the runway in a nose-down attitude. The student pilot recalled that as the airplane rotated during the takeoff, he heard the flight instructor exclaim, but could not recall any subsequent events. Postaccident examination of the flight controls revealed no evidence of any preimpact mechanical malfunctions or failures that would have precluded normal operation. Examination of the wreckage revealed witness marks along the flight instructor's seat tracks that corresponded with the seat in the nearly full-aft position. Given the flight instructor's stature, it is unlikely that this position would allow her to fully actuate the flight controls, and it is therefore unlikely she purposefully initiated the takeoff with her seat in this position. While one of the two locking pins that would have secured the seat from sliding fore and aft was found fractured, it is likely that the jockeying of the seat during the victim extraction process resulted in the fracture of the locking pin, and left the witness marks observed on the seat track. Examination of the wreckage and maintenance documents also revealed that the airplane was not equipped with a manufacturer-recommended secondary seat stop mechanisms for either of the pilot seats. Review of operational and maintenance documents published by the airframe manufacturer showed the critical importance of ensuring that the pilot seats were secured prior to initiating a flight, and that accelerations such as those encountered during a takeoff could dislodge an unsecured seat. Had the flight instructor, who was performing the takeoff, not properly secured her seat prior to initiating the takeoff, it may have resulted in her seat sliding aft, and her inadvertent application of control inputs to the control yoke during the rotation and initial climb, consistent with steep climb, descent, and impact. The aft seat position could have also likely resulted in her inability to apply complete or sufficient control inputs to the rudder pedals, consistent with the left yaw/roll observed during the takeoff.
HISTORY OF FLIGHTOn March 26, 2016, about 1208 eastern daylight time, a Cessna 172N, N6238D, impacted terrain during an attempted takeoff at Yeager Airport (CRW), Charleston, West Virginia. The flight instructor was fatally injured, and the student pilot was seriously injured. The airplane was registered to Skylane Aviation LLC and the flight was being conducted as a 14 Code of Federal Regulations Part 91 instructional flight. Visual meteorological conditions existed at the airport about the time of the accident, and no flight plan had been filed for the local flight. The student pilot stated that the flight instructor let him taxi the airplane out from the fixed-base operator. The student was having difficulty with the brakes, so the instructor took over the controls and taxied the rest of the way to the runway and run-up area. The student pilot stated that he did not remember much after that. However, he did remember that air traffic control told them to expedite the takeoff because another aircraft was coming in for a landing and that the flight instructor then taxied out for takeoff. He recalled that as the airplane rotated during the takeoff, he heard the flight instructor exclaim, but could not recall any subsequent events. Review of airport security surveillance video revealed that the airplane lifted off about 1,000 ft down runway 5, pitched up, rolled left, and then became inverted before it impacted terrain next to the runway in a nose-down attitude. PERSONNEL INFORMATIONFlight Instructor According to Federal Aviation Administration (FAA) records, the flight instructor held a commercial pilot certificate with airplane single-engine land, airplane multiengine land, and instrument airplane ratings. She also held a flight instructor certificate with airplane single-engine and instrument airplane ratings. She was issued an FAA second-class medical certificate on June 11, 2015. At the time of the medical examination, the flight instructor reported 1,694 total hours of flight experience. The flight instructor's personal flight logs were not located. Student Pilot The student pilot held a student pilot/FAA third-class medical certificate, issued on March 9, 2016. The student's logbook had two entries indicating 3 total hours of flight experience. AIRCRAFT INFORMATIONThe four-seat, high-wing, tricycle landing gear-equipped airplane was manufactured in 1979. It was powered by a 160-horsepower Lycoming O-320-H2AD engine and was equipped with a two-bladed McCauley propeller. Review of maintenance records revealed that the airplane's most recent annual inspection was completed on October 20, 2015. At that time, the airframe had accumulated 10,995.9 total hours of operation, and the engine had accumulated 1540.4 hours since major overhaul. The airplane had been operated about 7 hours since the last annual inspection was completed. Examination of the airframe logbooks revealed that the seat tracks were replaced on February 12, 2015. Airworthiness Directive (AD) 2011-10-09 was accomplished about 8 months later during the most recent annual inspection. The AD required the inspection of the seat tracks, including but not limited to, the visual inspection of the holes in each track for excessive wear, the seat tracks for dirt or debris, and the seat locking pin for limited vertical play. The pilot and copilot seats were mounted onto a set of seat tracks, which allowed the seats to slide fore and aft. An adjustment bar was used to raise and lower two locking pins into one of twelve positions along each of the seat tracks, which would secure the seat to the desired position. The locking pins downward travel and positive locking action was aided via a spring mechanism that tensioned the adjustment bar (see figure 1). Figure 1. Illustrated Parts Catalog, Seat Diagram. AIRPORT INFORMATIONThe four-seat, high-wing, tricycle landing gear-equipped airplane was manufactured in 1979. It was powered by a 160-horsepower Lycoming O-320-H2AD engine and was equipped with a two-bladed McCauley propeller. Review of maintenance records revealed that the airplane's most recent annual inspection was completed on October 20, 2015. At that time, the airframe had accumulated 10,995.9 total hours of operation, and the engine had accumulated 1540.4 hours since major overhaul. The airplane had been operated about 7 hours since the last annual inspection was completed. Examination of the airframe logbooks revealed that the seat tracks were replaced on February 12, 2015. Airworthiness Directive (AD) 2011-10-09 was accomplished about 8 months later during the most recent annual inspection. The AD required the inspection of the seat tracks, including but not limited to, the visual inspection of the holes in each track for excessive wear, the seat tracks for dirt or debris, and the seat locking pin for limited vertical play. The pilot and copilot seats were mounted onto a set of seat tracks, which allowed the seats to slide fore and aft. An adjustment bar was used to raise and lower two locking pins into one of twelve positions along each of the seat tracks, which would secure the seat to the desired position. The locking pins downward travel and positive locking action was aided via a spring mechanism that tensioned the adjustment bar (see figure 1). Figure 1. Illustrated Parts Catalog, Seat Diagram. WRECKAGE AND IMPACT INFORMATIONThe wreckage was contained in a small area, and ground scars were consistent with the airplane impacting in a nose-low, right-wing-down attitude. The airplane impacted the ground about 20 yards left and midfield of runway 5 and came to rest inverted. The engine and propeller were forced up and into the instrument panel and cockpit area. The leading edges of both wings were crushed due to impact forces. The fuselage had one wrinkle in the skin behind the rear window. The rudder and elevator were intact and unremarkable. The flaps and aileron were intact and unremarkable. Control cable continuity was established to all flight controls. Measurement of the elevator trim jackscrew corresponded to an approximate neutral trim setting. When the engine crankshaft was rotated by hand, valve train continuity was established, and thumb compression was attained on all cylinders. The propeller exhibited rotational scoring, and one blade tip was missing. All four roller housing tangs (feet) on the flight instructor's seat were spread and bent. The seat tracks were gouged where they were in contact with the locking pins. One locking pin was fractured off at the roll pin. There were lockpin contact marks in the eleventh hole location from the front to back of the inboard seat rail, consistent with the seat being near the full-aft position at impact. The inboard seat-position locking pin and outboard seat-post from the flight instructor's seat were sent to the National Transportation Safety Board's Materials Laboratory for examination. The inboard seat position locking pin had fractured, and the overall deformation pattern adjacent to the fracture was consistent with bending deformation where the outboard side of the locking pin was in tension and the inboard side was in compression. The stop-pin hole below the fracture surface on the outboard side of the rod showed necking deformation, whereas the upper side of the hole remained close to its original diameter, consistent with the stop pin being in the upper side of the hole as the locking pin was bent. Contact marks were observed on the lower side of the stop-pin hole at the inboard end of the hole, consistent with contact along the roll pin split line on the compression side of the bending fracture. ADDITIONAL INFORMATIONThe airplane's Pilot's Information Manual, before starting engine checklist, advised pilots to verify the seats, seat belts and shoulder harnesses are adjusted and locked. The Cessna Pilot Safety and Warnings Supplements document warned that a pilot should perform a visual check to verify that their seat was securely on the seat tracks and assure that the seat was locked in position. Failure to ensure that the seat was locked in position could result in the seat sliding aft during a critical phase of flight, such as initial climb. The airframe manufacturer also issued a Service Bulletin (SEB07-R06 Revision 6, issued June 11, 2015), which required the installation of a secondary seat stop for the pilot seat, and recommended one for the co-pilot seat. A secondary seat stop was not installed on either of the accident airplane's front pilot seats. The supplement also warned that there had been previous reported events involving seats slipping rearward or forward during acceleration or deceleration related to discrepancies in the seat mechanisms. The investigations following these events revealed discrepancies such as gouged lockpin holes, bent lockpins, excessive clearance between seat rollers and tracks, and missing seat stops. Also, dust, dirt, and debris accumulations on the seat tracks and in the intermediate adjustment hoes have been found to contribute to the problem. MEDICAL AND PATHOLOGICAL INFORMATIONThe Office of the Chief Medical Examiner, Charleston, West Virginia, performed an autopsy on the flight instructor. The cause of death was reported to be "multiple injuries." The report also noted that the flight instructor's height was 69 inches. The FAA Bioaeronautical Sciences Research Laboratory, Oklahoma City, Oklahoma, conducted toxicology testing on specimens from the pilot. The results were negative for carbon monoxide and drugs.
The flight instructor's failure to ensure that her seat was properly secured before initiating the takeoff, which resulted in a subsequent loss of control. Contributing was the lack of an installed secondary seat stop.
Source: NTSB Aviation Accident Database
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