CHI95FA191

The private pilot-owner was giving aerobatic instruction to another private pilot. The pilot had the second pilot place the airplane into inverted flight so he could see where the nose of the airplane should be during an aileron roll. The second pilot was flying the airplane in an inverted attitude with full power and high RPM. He told the second pilot to roll out of the inverted flight. The second pilot pulled aft on the control stick and did a split-s maneuver. The airspeed was above the never exceed speed during its descent. He knew this because he had flown above that speed before so that he could know what it sounded like. As he began to start recovery the right wing separated, and was the first airframe component along the wreckage trail. The left wing was the second item along the wreckage trail, and was mangled and twisted. The left wing's main wing strut attach fitting had a fatigue striation pattern through about 90% of its aft leg. Fatigue cracking went through about 25 percent of the fitting's forward leg.

History of flight

On June 20, 1995, at 1927 central daylight time (cdt), an American Champion 8KCAB, N109AC, registered to the Alpha Charley Flying Club, Incorporated, of Olympia Fields, Illinois, and piloted by a private pilot, was destroyed during a collision with the ground following an in-flight structural failure. Visual meteorological conditions prevailed at the time of the accident. The aerobatic 14 CFR Part 91 training flight was not operating on a flight plan. The pilot/part owner of the airplane received serious injuries. The second occupant, also a private pilot, was fatally injured. The flight departed New Lenox, Illinois, at 1912 cdt.

The pilot/owner (pilot) of the airplane said he was teaching the second pilot how to do aileron rolls. According to the pilot the second pilot had allowed the airplane to pitch down during the inverted position of the roll maneuver. The pilot said he had the second pilot place the airplane into an inverted flight attitude. He said he did this so the second pilot could "...feel how much forward pressure [is required] to keep the plane level in inverted flight... ." The pilot said the airplane's speed at this time was about 140 miles per hour (MPH) and it was about 2,900 feet above the ground.

After a short time of inverted flight the pilot told the second pilot to roll the airplane into an upright position. The pilot said the second pilot "...pulled back on [the] stick." The pilot said he "...chopped [the] power..." after the airplane was descending vertically toward the ground. At this point in the flight the pilot said he placed his hands on the control stick to begin recovery. He said the airspeed sounded "...very fast..." as the airplane descended. Shortly after taking control of the airplane the pilot said he heard a "...loud noise (boom) then [an] air noise. I watched the right wing depart [the] aircraft, also watched [the] door depart at same time."

During an interview the pilot said that the second pilot had pulled the stick back hard and caused what he felt was a grey-out condition for him. He said he had the second pilot flying inverted with full power and a high RPM propeller setting. The pilot said the airspeed indicator needle was pointing at the junction of the yellow and green arc when he told the second pilot to roll out of inverted flight. He said the airplane was too fast when the split-S maneuver was entered by the second pilot. The pilot estimated the entry G-load to be 5 or 6 G's. He said the fuselage's right front corner broke away at the door's corner post.

The pilot said he knew N109AC was close to, or beyond the airplane's never exceed speed as the airplane started its descent. The IIC asked the pilot how he knew this. He said he had flown the airplane at speeds above the never exceed speed several times in the past. When asked why he replied that he wanted to hear what it was like. Witness statements were taken by the Will County Illinois, Sheriff's Department. All four witnesses stated they heard N109AC's engine accelerate and looked up to see the airplane breaking apart. According to the Sheriff's Department report, the pilot said he only knew the second pilot by his first name. He said that they were both flying the airplane during the accident flight.

Personnel information

According to the pilot's logbook he had not flown N109AC, or any other American Champion 8KCAB, since January 4, 1995. His logbook showed 14.5 hours of flight time in N109AC between January 2 and 4, 1995. April and May 1995, entries showed 20.4 hours of flight time in a Pitts S2B. His logbook showed he had flown a Pitts S2B during June 1995, for 20.4 hours. The monthly entry stated: "Advance sequence (fair)." The accident date flight of .5 hour was in his logbook.

The pilot's logbook showed he obtained his private pilot certificate on March 31, 1988, after flying 70.7 hours. According to his logbook, the pilot began aerobatic flying on June 30, 1988. His logbook showed a total aerobatic dual instruction of 25.5 hours. His logbook showed a total time in the American Champion 8KCAB was 257.8 hours on the accident date.

The second pilot on N109AC received his private pilot certificate on May 21, 1991, after accumulating 54.9 hours of flight time. The pilot's 14 CFR Part 61.56 biennial flight review had been completed on February 18, 1994. His logbook showed 26.6 hours of single-engine tailwheel airplane experience. None of the pilot's experience had been in the American Champion 8KCAB. He had received 3.1 hours' dual instruction in a Champion 7KCAB about eight months before the accident. No instructional aerobatic flights were found in his logbook.

Aircraft information

N109AC's total airframe time, as of May 12, 1995, was 899.5 hours according to its airframe logbook. The airplane's airframe logbook showed its last annual inspection was on April 1, 1995. At that time, N109AC had 872.6 hours.

Wreckage and impact information

The wreckage was located in Sections 13W-30S and 14W-31S of Green Garden Township of Will County, Illinois. The general wreckage trail was oriented on an East-West line about 1/4 mile east of Center Road and 3/4 mile north of Manhattan-Monee Road. A diagram appended to this report illustrates the location of N109AC's wreckage.

Elevator and rudder flight control continuity was established. The empennage's flying wires were intact but tension could not be checked due to crash and fire damage. The trim tab control handle, bellcrank and cables were attached to the elevator trim tab control horns. Examination of the separated aileron control cables revealed broomed ends that were necked.

The engine's right side and nose were buried in the ground. It was attached to the airframe and had sustained fire damage. Mechanical continuity within the engine was established. Ground collision damage prevented the engine's crankshaft from being rotated beyond a 20 degree arc.

The propeller had separated from the engine and was buried in the ground directly in front of the engine. It had separated from the engine about 4 inches aft of the crankshaft flange. One blade of the propeller was torsionally twisted. The second blade was bent aft about 80 degrees at midspan. Both blades had chordwise scratching on the face and front surfaces.

The right wing had separated from N109AC's fuselage. It was the first item on the wreckage trail. The wing's front and rear strut assembly had separated at the jury strut junction. The wing strut was still attached to the wing from the jury strut outboard. The wing's top, inboard surface, had black skid marks on part of the white colored three star pattern. The right main landing gear tire had white colored scuff marks on its tread area.

The leading edge of the right wing's strut attach fitting was buckled outward between its spar attach point and the wing's tie down ring. The rear jury strut spar fitting had separated from the spar. Rivets holding that fitting to the spar were still in the spar assembly. The front wing strut's fuselage attach fitting had separated at the strut's fuselage end. The fitting end appeared necked with its separated end surface having a granular surface appearance.

The left wing's outboard half was observed rotated 90 degrees aft, leading edge up, to the inboard half. The junction between the outboard and inboard sections was mangled and twisted in many directions. The wing's inboard section, from the wing root outward to the midspan point was crushed aft and twisted in various directions.

The left wing strut assembly had separated from the wing and fuselage at all three attachment points. Sections of the strut's spar mounting fitting were attached to each strut assembly. The forward strut had an approximate 60 degree upward bend about 3 feet from the fuselage attachment end.