Tucson, AZ, USA
N9017H
Cessna 172M
The nose wheel broke during a hard landing substantially damaging the airplane's firewall. The accident occurred during the student pilot's first supervised solo flight. The student's certified flight instructor reported that the airplane porpoised two times during the landing rollout. The 30-year-old airplane's total time was over 9,500 hours. An examination of the nose wheel assembly revealed 1/2 of the wheel had broken due to excessive side load pressure. The pressure allowed the assembly's snap ring to release wheel components thereby impeding the nose wheel's rotation.
HISTORY OF FLIGHT On May 18, 2005, about 0840 mountain standard time, a Cessna 172M, N9017H, porpoised during landing rollout, and the firewall was bent. The accident occurred on runway 11R at the Tucson International Airport, Tucson, Arizona. The student pilot was not injured, and the airplane was substantially damaged. New Mexico Flying Eagle, Inc., Tucson, operated the airplane under the provisions of 14 CFR Part 91. Visual meteorological conditions prevailed. The local area solo instructional flight originated from the airport about 0750. According to the certified flight instructor (CFI), who was supervising and observing the flight, the accident occurred while his student was conducting her first supervised solo flight. Following two solo touch-and-go landings on runway 11R, the CFI instructed the student pilot to make a full stop landing. The CFI stated that the final approach was normal, and the airplane touched down on its main landing gear. He said that when the nose wheel touched down, the main landing gear came off the ground. The airplane porpoised twice as the main landing gear recontacted the runway. The airplane came to a stop on the centerline of the runway. The student pilot reported that "everything looked good" on her approach to runway 11R. She said "the speed was exactly 65 kts and altitude looked correct." The main landing gear contacted the runway surface, and then she lowered the nose wheel. When the nose wheel contacted the runway surface, "it felt like it was locked in the wrong position" and the airplane veered to the right side of the runway and "pitched forward." At this point, she thought the airplane was going to nose over. She pulled back on the yoke and used the rudder pedals to bring the airplane back to the center of the runway, whereupon it came to a stop. PERSONNEL INFORMATION The student pilot held a combined student pilot and aviation medical certificate. The original date of issuance was January 21, 2005. The student pilot reported that she had a total flight time of 13.1 hours. Her total flight experience had been in the Cessna 172. AIRCRAFT INFORMATION The Cessna 172M, serial number 17265901, was manufactured in 1975. It was maintained by the operator. At the last annual inspection, which was dated May 6, 2005, the airplane had a total airframe time of 9,520.6 hours. At the time of the inspection, the tachometer read 2,493.4 hours. At the time of the accident, the tachometer read 2,514.7 hours. The operator reported that the airplane had been operated about 21.3 hours since the inspection, which involved about 18 flights. WRECKAGE AND IMPACT INFORMATION AND EXAMINATION The registered owner of the airplane and his mechanic arrived on scene about 0900. The owner reported to the Tucson Airport Police that a snap ring holding the front wheel bearings in place failed and allowed the wheel bearings to work loose. A search for the retaining snap ring was conducted along the runway, but none was found. On January 19, 2006, the registered owner verbally reported to the National Transportation Safety Board investigator that he was the mechanic who had performed the last annual inspection on the airplane. His post accident examination of the airplane revealed that the snap ring was missing. Also, the wheel casting around the axle was cracked in the area where the snap ring was normally seated. The mechanic opined that, since the last maintenance was performed, a hard landing could have occurred, whereupon the casting cracked thus releasing the snap ring. A Federal Aviation Administration aviation safety inspector (airworthiness) examined the airplane. The inspector reported that the nose wheel inner bearing boss had separated from the inside of one wheel half assembly, which broke "due to excessive pressure" (side load)." Specifically, the McCauley nose wheel, part number C163005-201, "failed at the retaining ring flange on the left hand side of the wheel assembly. The failure of this flange allowed the retaining ring [part number A1636-23] to release" adjacent components, thus impeding rotation of the nose wheel.
The student pilot's improper flare that induced a porpoise, which resulted in the overload failure of the nose wheel assembly.
Source: NTSB Aviation Accident Database
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