NTSB Factual Report

History of Flight

On August 19, 1996, at 1300 central daylight time, a Bellanca 7GCAA (Citabria), N5026Q, was destroyed when it impacted the ground during an instructional flight. A witness observed the airplane in a left spiral at about 500 to 700 feet above ground level (AGL). The witness reported that the right wing separated from the airplane at about 150 feet AGL. The instructor pilot and student pilot received fatal injuries. The 14 CFR Part 91 flight had departed Hinckley Airport, Hinckley, Illinois, on a local flight. Visual meteorological conditions prevailed and no flight plan had been filed.

The aircraft was a two seat aircraft used for tailwheel and tow plane instruction. The logbook used by the operator to keep track of aircraft usage for billing purposes indicated that the aircraft had been used for two flights on the morning of August 19, 1996. The tach time at the end of the second flight was recorded as 5,101.35 total tach time. The tach time at the time of the accident read 5,101.435. That meant the accident aircraft had been operating for about .085 hour, or for about 5 minutes before the accident occurred.

There were no witnesses who saw the airplane takeoff or do any landings at the airstrip. The person who issued the aircraft to the instructor pilot and dual student reported he did not see the aircraft doing any touch and go landings at the airstrip.

A witness, who operated a sky diving business at the airport, reported that he was walking back from the aircraft used by sky divers and was facing to the south when he observed the accident aircraft. The reported that he did not see the aircraft enter the spiral, but he observed the airplane in a steep left spiral at about 500 to 700 feet AGL. The airplane was in about a 70 degrees nose down attitude. He reported that nothing was broken on the airplane, and that he clearly saw both wings with no damage on the airplane as it spiraled downward. He reported that the airplane was going at a high speed. He reported that the first spiral was fast, and that the second spiral was "really fast." He reported seeing the airplane do two spirals, and then the right wing separated from the aircraft. He described the wing separating straight back along the side of the aircraft without the wing going up or down. He reported that he thought the front edge of the wing tucked under the fuselage as it separated from the aircraft, but he reported he could not be 100 percent sure. He reported the wing came off at about 100 to 150 feet AGL, and the airplane did another 1/4 to 1/2 spiral before it impacted the ground. He reported that the event lasted about 4 seconds in duration. He reported the engine had sounded normal. He reported that the engine was not at full power, but more like it was at cruise power while it was in the spiral.

The airplane impacted the ground in a corn field about one half mile to the south, southwest of the airport.

Personnel Information

The instructor pilot was a 22 year old, male commercial pilot with instructor ratings in single engine land airplanes and gliders. He had 1,104 total flight hours which included 115 hours in gliders. He had a total of 217 hours of instructor experience which included 130 hours of instruction given in the Citabria. He had a first class medical certificate. Records indicated he weighed 199 pounds.

The student pilot was a 43 year old, male private pilot with a glider rating. He had been flying gliders for about three years, but the logbook which indicated his total hours of flight time in a glider was not obtained. He began his flight instruction in airplanes on June 2, 1996, and had a total of 39.6 flight hours as of August 19, 1996. He had soloed in the Citabria and had been endorsed on August 15, 1996, to conduct solo takeoff and landings at Aurora Airport, Aurora, Illinois. He had a third class medical certificate. Records indicated he weighed 220 pounds.

Aircraft Information

The airplane was a Bellanca 7GCAA with a Lycoming 150 horsepower engine. It was owned and operated by the Hinckley Soaring Club located at the Hinckley Airport, Hinckley, Illinois. The last annual inspection was performed on August 1, 1996. The total airframe hours were 5,101.43 tach hours. The aircraft operator had placed a placard on the instrument panel which prohibited aerobatic flight in the airplane.

The airplane held 36 gallons total fuel on board. The airplane had been topped off prior to the first flight of the day and had been flown twice before the accident occurred. The fuel at the time of takeoff was estimated at about 24 gallons, or 144 pounds of fuel.

The weight and balance figures that were provided in the Pilot's Operating Handbook located in the airplane was used to calculate weight and balance information. The maximum gross weight of the aircraft was 1,650 pounds. According to the weight and balance calculations, the aircraft weighed 1,744 pounds at takeoff which was over the maximum gross weight by 94 pounds. (See Weight and Balance Calculations)

The Pilot's Operating Handbook provided the following information concerning the maximum gross weight of the aircraft:

"The Citabria structure is designed to withstand a maximum load factor of +5 G's and -2 G's at a maximum of 1650 lbs.

WARNING

Do not exceed +5.0 G positive load factor or -2.0 G negative load factor; do not exceed 135 mph IAS during negative G condition Do not perform aerobatics in turbulent air.

A change in the gross weight also changes the effective load factor limit. To fly at reduced weight increases the safety factor and improves performance. To fly above 1650 lbs. is not only prohibited, but also greatly increases the chances of a serious overstress resulting in damage or possible structural failure."

Meteorological Information

The weather reported at Aurora Airport about eight miles from Hinckley Airport was:

Winds were from 130 degrees at 10 nautical miles per hour, Scattered clouds at 1,600 feet, Overcast at 10,000 feet, altimeter 30.14.

Wreckage and Impact Information

The airplane impacted the ground in about a 70 degree nose down attitude. The airplane landed on the right side of the engine cowling and what remained of the right wing. The heading of the aircraft at impact was about 120 degrees. The ground was soft as a result of recent rains and the aircraft remained in the same location as the initial impact. The engine and propeller were in about a two foot crater. The left wing had impact damage along the leading edge of the wing. The left wing aft spar had separated during impact. The outboard half of the wing had twisted forward, and the aft edge of the wing was pointing forward. The tail had buckled forward and to the right during impact. The left horizontal stabilizer separated and twisted forward during impact. The right horizontal stabilizer and rudder remained attached to the fuselage during the impact.

The right wing was found about 60 feet to the southeast of the airplane wreckage. The main spar had separated at one place along the spar. The rear spar had separated in two places along the spar. (See Forest Laboratory Report)

Both metal wing fuel tanks had ruptured. Fuel was found pooled in the crater made by the engine and propeller.

The flight controls were checked for continuity. The cables leading to the ailerons, rudder, elevator, and elevator trim were checked. All cables and controls exhibited continuity.

The engine was examined. The inspection revealed that the engine had continuity. All cylinders had compression and suction. The impulse coupling was clicking in the left magneto. The spark plugs exhibited normal coloring and wear. The engine tachometer read 1950 RPM's.

The right wing front strut attach fitting was sent the National Transportation Safety Board's (NTSB) Materials Laboratory for examination. The metallurgist inspected the strut fitting and reported the following findings:

"...visual magnified examination of the fractures found features typical of overstress separations on all of the breaks."

"Both channels and the cross plate exhibited significant deformation. The deformation patterns on all of the pieces was consistent with a combination of a downward deflection of the wing tip and a trailing edge up twisting of the outboard wing section." (See Metallurgist's Factual Report No. 96-149)

The right wing inboard lift strut assembly where the rear strut attaches to the clevis fitting was examined at an independent metallurgical laboratory, Engineering Systems, Inc. (ESI). The metallurgist reported that the fracture exhibited shear lips around most of the fracture perimeter with no evidence of fatigue. The overall fracture mode was reported as "tension overload." (See ESI Report dtd October 21, 1996)

The clevis fitting was checked for hardness. The test indicated that the clevis had the proper hardness. (See ESI Report dtd December 23, 1996)

The fore and aft wing spars on 7GCAA Citabria were manufactured using Sitka spruce. The wing spars were examined by the United States Department of Agriculture, Forest Products Laboratory. The wood specialist who examined the wooded spars reported that, "We have not found any reason to believe that failure of wood spars or any other structural part caused the airplane to go into an uncontrolled spin." (See Forest Products Laboratory Report)

Medical and Pathological Information

Autopsies were performed on the instructor pilot and student pilot at the DeKalb County Coroner's Office, Sycamore, Illinois. The body weights listed in the reports were estimated weights and not actual weights.

Forensic Toxicology Fatal Accident Reports were prepared by the Federal Aviation Administration's Civil Aeromedical Institute. The reports on both pilot's indicated negative results.

Additional Information

Parties to the investigation included Textron Lycoming, American Champion Aircraft, the USDA Forest Products Laboratory, and the Federal Aviation Administration.

The aircraft wreckage and logbooks were released to A. G. Plumley, Inc.

NTSB Probable Cause

the instructor pilot exceeded the design stress limits of the aircraft which resulted in the overload failure of the wing. A factor was that the weight and balance of the aircraft was exceeded by the instructor pilot.