NTSB Factual Report

HISTORY OF FLIGHT

On September 18, 2005, at 1135 central daylight time, a single-engine Akro Tech Aviation Incorporated Giles G-300 experimental airplane, N300NW, was destroyed after it collided with terrain near Yukon, Oklahoma. The commercial pilot, sole occupant of the airplane, was fatally injured. The airplane was registered to and operated by the pilot. No flight plan was filed for the flight that originated from the Clarence E. Page Airport (F29), near Oklahoma City, Oklahoma, about 1130. Visual meteorological conditions prevailed for the personal flight conducted under 14 Code of Federal Regulations Part 91.

According to several witnesses, the pilot had just started a practice session in preparation for an aerobatic competition that was scheduled the following week. She began the flight with a 3-5 minute warm-up, which included vertical lines, half roll-ups, and circles to determine wind drift. The pilot then turned to the north and initiated a 45 to 55-degree nose-up climb, at which time the witnesses observed the Plexiglas canopy separate in fragments from the airplane. The airplane continued to climb to an altitude of approximately 2,300 feet above ground level (agl), before it rolled to the right and entered an approximate 60-degree nose-down descent. The witnesses stated that the engine remained at full power during the descent and no flight control movements were observed after the canopy had separated.

The pilot's aerobatic coach reported that he was standing near the airport's main terminal building when he observed the pilot initiate a 45-degree nose-up climb near the approach end of Runway 17L. He was also communicating with the pilot via a handheld radio. The coach, who had worked with the pilot for the past 6 or 7 years and was familiar with the airplane, stated that as the pilot pulled the airplane into the vertical ascent, he saw what looked like an explosion. He then realized that the canopy had shattered and he observed the canopy depart on the left side of the airplane. The airplane continued to climb before it began a slow roll to the right and subsequently descend toward the ground. The coach made several attempts to contact the pilot, but there was no response.

PILOT INFORMATION

The pilot held a commercial pilot certificate for airplane single-engine, multi-engine land, and instrument airplane. She also held a certified flight instructor certificate for airplane single-engine land. In addition, the pilot was a certified airframe and power plant mechanic. Her last second-class FAA medical was issued on July 21, 2005. At that time she reported a total of approximately 6,700 flight hours. The pilot successfully completed a biannual flight review on August 20, 2005.

AIRCRAFT INFORMATION

The accident airplane was the first and only prototype Giles G-300 in operation, and was being considered as the "next generation aerobatic aircraft." The pilot and her husband had partnered with the kit manufacturer, and were involved in the design and flight test of the airplane. A review of maintenance logbooks revealed that the airplane was built in 1997 and had accrued a total of approximately 900 hours at the time of the accident.

METEOROLOGICAL INFORMATION

The witnesses reported the weather at the time of the accident was wind from the south-southwest about 18-25 knots, clear skies, and a temperature of 92 degrees Fahrenheit.

WRECKAGE INFORMATION

The airplane impacted terrain upright in a plowed field about a quarter mile northeast of the approach end of Runway 17L, on a magnetic heading of 030 degrees, at a field elevation of approximately 1,350 feet mean sea level (msl).

An on-scene examination of the main wreckage was conducted on September 19-20, 2005. All major components of the airplane were found at the site. A majority of the main wreckage, which included the tail section, cockpit area, engine, propeller assembly, and both wings, came to rest in and around an approximate 5-foot-wide by 6-foot-deep impact crater. Two horizontal impact marks similar in size/shape/length to the airplane's wings, extended to the left and right of the impact crater. Imbedded in each of these impact marks were portions of the left and right wings respectively.

Prior to the Safety Board's arrival to the accident site, a Federal Aviation Administration (FAA) aviation safety inspector, the pilot's aerobatic coach, and other witnesses found broken fragments of the canopy, including small and large pieces of acrylic, in the grassy and heavily wooded area that was situated between the approach end of Runway 17L and where the airplane came to rest. According to the coach, the largest section of the canopy, which included the entire locking mechanism, was found directly below where he saw the airplane begin its vertical ascent. In addition, he found the left side of the aft portion of canopy several hundred feet forward of the locking mechanism.

Materials Examination

There were two hinges that fastened the canopy to the fuselage. Only the rear canopy hinge was located at the accident site. This hinge along with the section of fuselage that it was attached to were sent to the Safety Board's Materials Laboratory, Washington DC, for examination. According to the Materials Laboratory Factual Report, both hinges were fastened directly to the fuselage with four flat-head bolts. There was no evidence of bonding material or adhesive in the area of the fuselage underneath the mounting plate of either hinge. A closer view of the location where the front canopy hinge was located indicated there were rub marks on the surface of the fuselage underneath the hinge pin lock wire, which was indicative to contact wear with the bent end of the hinge pin. The hinge pin lock wire was also worn and flattened in areas, which corresponded to contact wear with the bent end of the hinge pin.

The rear canopy hinge was fractured into two pieces through the mounting plate at the fuselage side of the hinge. Deformation was observed around the rivet holes where the hinge was attached to the fuselage, indicative of overstress. Bolt holes in the mounting plate at the canopy side of the hinge were deformed, and the edges of the holes were cracked or fractured, consistent with overstress. One of the four bolts remained in the mounting plate on the canopy side of the hinge. Rub marks similar to those found in the area of the front hinge pin lock wire were not present. In addition, there was no damage to the hinge pin lock wire.

MEDICAL AND PATHOLOGICAL INFORMATION

The Office of the Chief Medical Examiner, Oklahoma City, Oklahoma, conducted an autopsy on the pilot on September 19, 2005. The cause of death was determined as multiple injuries.

The FAA Toxicological Laboratory in Oklahoma City, Oklahoma, completed toxicological testing on the pilot. The tests were negative for all items tested.

ADDITIONAL INFORMATION

The airplane wreckage was released to a representative of the owner's insurance company on November 22, 2006.

NTSB Probable Cause

The catastrophic separation of the canopy as result of the failure of the forward canopy hinge while performing aerobatics and the subsequent incapacitation of the pilot.