History of Flight
On September 13, 2017, at approximately 0723 eastern daylight time, a Cessna 402B (registration N836GW) was substantially damaged during a rejected takeoff at Nantucket Memorial Airport (ACK), Nantucket, Massachusetts. The commercial pilot and airplane owner sustained minor injuries. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a personal flight, with no flight plan filed. Visual meteorological conditions prevailed at the time. The intended destination was Barnstable Municipal Airport-Boardman/Polando Field Airport, Hyannis, Massachusetts.
According to the pilot, he completed his routine "takeoff flow" as confirmed by the before-takeoff checklist and was cleared for takeoff from runway 24. The airplane accelerated to between 90 and 95 knots, at which point he began rotation. After achieving a positive rate of climb, he retracted the landing gear. However, once airborne, he reported "fighting the controls to keep the aircraft from a nose down configuration." He used manual trim and verified the autopilot was not engaged, but the nose-down tendency persisted, making control increasingly difficult while maintaining altitude. He subsequently rejected the takeoff and executed an emergency landing on the remaining portion of the runway.
Aircraft Information
The seven-place, low-wing airplane was manufactured in 1977 and powered by two 300-horsepower Continental TSIO-520-E engines with constant-speed, manual feathering three-blade McCauley propellers. The elevator trim control system consisted of a control wheel on the left side of the pedestal, connected via a sprocket, chain, and cables to a trim tab actuator in the tailcone. A push rod connected the actuator to the elevator trim tab, mounted on the right elevator. The published maximum elevator trim tab trailing edge up deflection with the elevator neutral was 5° +1°, -0°.
Maintenance History
Airworthiness Directive (AD) 2016-07-24, effective April 26, 2016, required replacement of attaching hardware for the elevator trim pushrod at the actuator and trim tab ends within 90 days. A review of maintenance records revealed no compliance entry between March 3, 2016, and February 6, 2017. The pilot reported being unaware of the AD but believed the maintenance facility would comply during the annual inspection.
On August 31, 2016, the airplane was flown to a repair station in New Bedford, Massachusetts, for an annual inspection. During the incoming process, the chief inspector performed an AD search using Avantext and identified AD 2016-07-24 as recurring but did not include it in handwritten notes. Subsequently, AD 2016-17-08, effective September 12, 2016, replaced AD 2016-07-24 and required hardware replacement but revised inspection intervals and allowed a longer bolt. These ADs were issued to prevent jamming of the elevator trim tab outside normal travel limits due to loss of attachment hardware, which could result in loss of control.
During the annual inspection, the airplane was stripped and painted. Due to a cracked right elevator control tube assembly end fitting, an employee removed the right elevator, requiring separation of the elevator trim push rod from the trim tab end only. Repair station personnel reported that the push rod remained connected at the actuator and was safety wired to prevent actuator movement. However, photographs taken by the airplane owner in December 2016 showed the right elevator removed and the push rod disconnected from the actuator. The repair station owner stated he installed the right elevator after painting, with the push rod assembly already attached at the actuator and securing hardware in place, but he did not replace the hardware at the actuator and trim tab ends as specified by AD 2016-17-08, interpreting it as only requiring inspection.
The airplane was flown on January 28, 2017, and approved for return to service on February 6, 2017. The pilot reported no work, repairs, or adjustments to the elevator primary or secondary flight control system between the annual sign-off and the accident date. The airplane had accrued 58 hours since the inspection.
Wreckage and Impact Information
Examination of the accident site by an FAA inspector revealed the airplane impacted the runway approximately 36 feet left of the centerline and 1,773 feet from the departure end. The airplane came to rest upright about 1,400 feet from the initial impact point. Both main landing gear upper trunnion assemblies were fractured, separating the wheel assemblies and exposing barrel assemblies. The nose landing gear wheel was deformed, and the fork and tube assembly fractured, separating the nose wheel assembly on impact.
Further examination revealed that with the elevator in a neutral position, the elevator trim tab was extended approximately 24° tab trailing edge up (airplane nose-down), and the cockpit trim indicator was at the nose-up stop. The elevator trim push rod assembly was separated from the actuator but remained connected at the trim tab. The end of the push rod that had separated from the actuator was wedged against the forward spar of the elevator. A drilled bolt was recovered from inside the right elevator, but the associated washer, castellated nut, and cotter pin were not located. The bolt, push rod, and actuator were retained for laboratory examination.
The NTSB Materials Laboratory reported deformation of the bolt hole on one clevis yoke half, including rounding and a raised burr, along with an impression from rubbing between the clevis yoke and actuator end bearing. The cross-drilled bolt had remnants of paint on the head and did not appear to be a replacement; its threads had a flattened and polished appearance, and debris was found inside the cross-drilled hole.
Similar Accident Investigations
The NTSB has investigated several similar accidents involving Cessna models with the same elevator trim design, where separation of the push rod from the trim tab actuator led to extreme nose-down trim and loss of control. These include accidents in West Columbia, South Carolina (1988); Wenatchee, Washington (1995); Del Rio, Texas (2001); Winston Salem, North Carolina (2001); and Wichita, Kansas (2015). In each case, post-accident examination revealed the push rod detached from the actuator and wedged behind the elevator spar, resulting in trim tab deflections far beyond the normal limits.
Tests and Research
Postaccident review of the AD list printout provided by the airplane owner indicated that corrective action for AD 2016-17-08 dated February 6, 2017, stated the hardware was replaced. However, a copy provided to the FAA during a January 19, 2018 visit to the repair station stated "Inspected hardware per AD instructions." Documents provided by the repair station showed no documentation of replacement hardware at the elevator trim tab actuator or trim tab ends.