History of Flight
On August 17, 2023, about 12:02 eastern daylight time, a Piper PA28-161 airplane, N9855S, was destroyed when it was involved in an accident near Fort Pierce, Florida. The airplane was operated by Aviator College under 14 CFR Part 91 as an instructional flight. One flight instructor was fatally injured and the other flight instructor sustained serious injuries.
According to the left-seat flight instructor, the purpose of the flight was to conduct a Part 141 proficiency check for the right-seat flight instructor. After departing Treasure Coast International Airport (FPR), the pilots proceeded about 10 miles southwest to perform training maneuvers. The right-seat instructor demonstrated chandelles, lazy eights, and slow flight. Subsequently, the right-seat instructor asked, “Can you show me something new?” The left-seat instructor responded, “I can show you an EASA maneuver,” which he described as a power-off aerodynamic stall and recovery without engine power.
The left-seat instructor took control, pitched the airplane up, and entered a full aerodynamic stall with engine power at idle. After the stall, he pitched to “Vg” (73 knots) to recover. During recovery, with power at idle, “the right wing came off” and the airplane experienced an “abrupt banking tendency” to the right. He retracted the flaps and applied rudder and aileron but noticed blurry vision, loss of altitude, and wind entering the cockpit. His next memory was waking in the hospital.
Multiple witnesses heard booms or bangs with variable engine noises. They observed the airplane descending in a near-vertical spinning descent with both wings separated and debris falling. A mobile phone video showed one wing falling to the ground.
Personnel Information
The left-seat flight instructor, administering the proficiency check, survived with serious injuries and was employed by Aviator College. The right-seat flight instructor, undergoing the check, was fatally injured. His official start date with the operator as a flight instructor was August 8, 2023, nine days before the accident.
Aircraft Information
The airplane was a Piper PA28-161, serial number 2842151, manufactured in 2002, and certificated in the normal and utility category. The Pilot’s Operating Handbook prohibited acrobatic maneuvers, including spins, in the normal category. Turns exceeding 60° were prohibited in the normal category. Flight load factor limits were 3.8 g normal and 4.4 g utility. The airplane was found to be within weight and balance limits at the time of the accident.
The wing spars were subject to FAA Airworthiness Directive 2020-26-16, requiring eddy current inspection of bolt holes. The most recent 100-hour inspection was completed on June 29, 2023, and the annual inspection on September 16, 2022. The AD inspection on March 22, 2021, found no defects.
Meteorological Information
Review of archived weather radar found no evidence of precipitation or convective weather along the route of flight.
Wreckage and Impact Information
The wreckage impacted a small aluminum-frame building housing an RV. The engine remained attached to the fuselage. Both wings and horizontal stabilator were located about 600 to 700 ft east of the fuselage. The left and right wings separated at the wing attachment area. The main spar center section box remained installed and was cut from the fuselage for examination. The carry-through spar showed deformation consistent with positive loading, bent upward about 5 inches on each side.
The NTSB Materials Laboratory examined the main spar center box structure. The right main spar lower cap fractured at the outboard attachment holes; fractures were consistent with ductile overstress. No preexisting cracks or defects were found. The left wing lower cap fractured outboard of attachment holes, with ductile overstress features and a smear pattern. Fatigue cracks were observed in both lower caps in areas of fretting damage, but they were not large enough to affect strength under accident loading.
Additional Information
The NTSB performance study used ADS-B data. It found four steep turns in the final minutes. At 12:01:30, the airplane entered a climbing left turn while slowing below 50 knots calibrated airspeed. It descended 800 ft while accelerating to over 120 knots in a 180° left turn. The airplane then flew level for about 30 seconds before another climbing left turn, reaching a minimum airspeed of 47 knots at 12:02:36. It began descending at 12:02:39, accelerating to 90 knots by 12:02:41, corrected altitude 4,820 ft. Just after 12:02:41, the descent rate increased to over 10,000 ft/min, and the track turned right, likely due to in-flight breakup.
The final two 180° turns had small radii: the turn at 12:01:45 had an estimated radius of 280 ft with a bank angle of at least 70° left. The final turn started with a 200 ft radius; at 99 knots true airspeed, the bank angle would be at least 75° left. The pilot reported the right wing departing first, which would cause a right rolling moment.
The operator’s Flight Operations Manual addressed steep turns with bank angles between 45 and 60°. The “EASA” maneuver demonstrated was not part of the formal training program.
The operator did not have a Safety Management System or Flight Data Monitoring program, but had an Aviation Safety Action Program (ASAP). Three ASAP reports involving the accident airplane or crew were related to ATC compliance.
The FAA Airplane Flying Handbook notes that steep turns at 75° of bank exceed the standard category load factor limit of 3.8 g.