HISTORY OF FLIGHTOn May 31, 2020, at 1546 central daylight time, a Piper PA-28-235 airplane, N8991W, was destroyed when it was involved in an accident near Carlinville, Illinois. The pilot and three passengers were fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.
According to automatic dependent surveillance – broadcast (ADS-B) and Appareo Stratus position data, the flight departed about 1518 and proceeded on a northeast course toward the intended destination, ultimately climbing to an approximate altitude of 5,500 ft mean sea level (msl). About 1543, the airplane entered a 15° banked left turn which continued until the airplane was on a southwest course. About 1545, the left turn steepened to about 50° and continued until the airplane returned to a northeast course. About 25 seconds later, the airplane rolled out of the left turn and immediately into a 60° banked right turn. The airplane reached an altitude of 5,685 ft and had slowed to about 85 kts during the right turn. The airplane then entered a descent, and the airspeed began to increase. At 1545:54, the right turn steepened to about 110° right bank.
By 1546:07, the airplane altitude decreased to 2,850 ft, the descent rate increased to over 18,700 ft/minute, and the airspeed increased to over 200 kts. During this timeframe, the pitch angle recorded by the Stratus unit decreased from +10° (up) to -52° (down) and decreased further to -63° (down) before the end of the data. The data ended about 1546:10. At that time, the airplane altitude was between 2,000 ft and 2,500 ft msl (1,400 ft and 1,900 ft above ground level). During the timeframe covered by the available data, the maximum computed load factor of 4.72 G occurred about 1546:06.
At the end of the data, the airplane was in a steep, spiral dive and about 35 kts above the never-exceed airspeed (VNE) of 171 kts. The airplane was established on a southwest course at that time and oriented away from the accident site located about 0.15 nm north-northeast from the final data point. The investigation did not have any data from which to determine the flight path from the final data point to the accident site.
A witness reported observing the airplane “going up and down,” doing “dips in the air.” She noted five or six “dips” where the airplane would “come back up” each time. She subsequently observed the airplane enter a “nosedive” and begin “spiraling down.” The airplane was initially heading south when it entered the dive and appeared to be intact at that time. As it neared the ground, the airplane “burst into pieces in the air.” AIRCRAFT INFORMATIONA weight and balance calculation based on estimated occupant, baggage, and fuel loadings, suggested that the airplane was within the gross weight and center-of-gravity limitations specified by the airframe manufacturer.
The airplane was certificated as a normal category airplane. The applicable limit load factor was 3.8 G’s. The corresponding ultimate load factor was 5.7 G’s. AIRPORT INFORMATIONA weight and balance calculation based on estimated occupant, baggage, and fuel loadings, suggested that the airplane was within the gross weight and center-of-gravity limitations specified by the airframe manufacturer.
The airplane was certificated as a normal category airplane. The applicable limit load factor was 3.8 G’s. The corresponding ultimate load factor was 5.7 G’s. WRECKAGE AND IMPACT INFORMATIONThe airplane wreckage was located in an open field adjacent to a storage building and a pond. A portion of the left wing passed through the storage building roof and came to rest within the building. The debris path was about 400 feet long. The main wreckage consisted of the fuselage, engine, and propeller. The fuselage was fragmented, and the cabin was compromised. The engine was damaged consistent with impact forces and the engine mount was fragmented. The propeller remained attached to the engine. Both wings, the vertical stabilizer, and the stabilator had separated from the fuselage. All flight control surfaces were located within the debris field. The wreckage distribution appeared consistent with a low-level, in-flight break up.
A postaccident examination revealed that both wings had separated at the root. The wing spars exhibited upward bending adjacent to the fracture surfaces consistent with positive load factors (pitch up) at the time of the separation. The fracture surfaces exhibited a dull, grainy appearance consistent with overstress. The ailerons, including the counterweights, were separated from the wings and located within the debris path. Control cable and control rod separations were consistent with overstress. The stabilator was separated except for the center spar section which remained attached to the aft fuselage hinge points. The balance weight and mast remained attached to the center spar section, and the stabilator control cables remained attached to the mast attachment points. The cables were continuous to the cockpit area. The vertical stabilizer was separated with exception of the aft spar which remained attached to the fuselage. The rudder remained attached to the spar at each hinge point. The rudder control cables were attached to the control surface and were continuous to the cockpit area. No preimpact anomalies with respect to the flight control system were identified.