NTSB Factual Report

On June 25, 2008, at 1346 eastern daylight time, a Cessna 172M, N13105, was substantially damaged during takeoff from Robert J. Miller Airpark (MJX), Toms River, New Jersey. The certificated flight instructor (CFI) and student pilot received minor injuries. Visual meteorological conditions prevailed, and no flight plan was filed for the instructional flight destined for Lakehurst Naval Air Station/Maxwell Field (NEL), Lakehurst, New Jersey, and conducted under Title 14 Code of Federal Regulations Part 91.

The airplane was operated by a Flying Club for the purpose of flight training.

According to the CFI, the student pilot was at the controls during the takeoff, as he was demonstrating a soft-field takeoff. As the airplane's nose lifted off the runway, the CFI's seat rolled backward, and he instinctively reached for the control yoke. The airplane then yawed to the left, and the left wing struck the ground. Upon impact, the airplane spun around, the nose wheel impacted a rut in the grass, and the airplane flipped over.

The CFI stated he "distinctly remembered adjusting the seat forward," prior to taxiing the airplane to the runway, "as it had been moved backwards to exit the airplane [after landing]." The CFI reported "shaking the seat" to assure it was in the locked position.

The student pilot stated he observed the CFI "rocking his seat to ensure it was secure" during the preflight. During the takeoff, the student pilot heard a noise which he thought was the tail of the airplane scraping the runway, followed by the CFI stating that his "seat was rolling back."

After the airplane came to rest inverted, the student pilot remained strapped into his seat by the seatbelt and shoulder harness; however, his seat was separated from the floor of the airplane during the accident sequence. The student pilot noted that the CFI was secured in his seat by his seatbelt and shoulder harness, and that the CFI's seat remained attached to the floor of the airplane. The student pilot removed his seat from the airplane during the egress.

Examination of the airplane by a Federal Aviation Administration (FAA) inspector and a representative of Cessna Aircraft revealed that the forward portion of the seat tracks for seat No. 1 (student pilot's seat) were cracked and slightly deformed upwards at the fifth adjustment hole. The aft portion of both tracks for seat No. 1 displayed impact damage consistent with the shape of the aft roller housings. The cap on the outboard track had wear grooves. The guide holes for the adjustment pin displayed oblong wear, and the bottom of the track holes exhibited wear spots, where the adjustment pins made contact. The adjustment pins were not bent, the roll pins were installed, and the spring was intact.

The forward portion of the seat tracks for seat No. 2 (CFI's seat) were also cracked and slightly deformed upwards at the fifth adjustment hole. All four roller housing tangs (feet) were spread and bent. The front feet were off the track, while the two rear feet remained partially attached to the track. The tracks were gouged where they were in contact with the rear seat legs. The guide holes for the adjustment pins displayed oblong wear, and the bottom of the track holes had wear spots, where the adjustment pins made contact. The adjustment pins were not bent, the spring was intact and the tension was strong.

Examination of the seat tracks for both seats revealed several seat pin adjustment holes exceeded the dimensions for acceptable wear as described in the Cessna Service Manual, and "excessive wear" was noted to the seat track cap widths and the roller housing tangs.

The airplane sustained substantial damage to the vertical stabilizer, rudder, and left wing.

Examination of the airplane's maintenance records revealed the airplane had accumulated 8,631 hours of total time. The seat tracks were replaced on July 23, 1993 at 6,019 hours total time.

The Seat Track Inspection Airworthiness Directive (AD) 87-20-03R2 was complied with during the most recent annual inspection on June 16, 2007 at 8,541 hours total flight time. The AD required the inspection of the seat tracks; specifically the holes in each track for excessive wear, dirt or debris, and limited vertical play. The AD did not require inspection for excessive wear to the seat track cap widths and the tangs of the seat housings. Inspection time and date criteria outlined in the AD required that aircraft operated under Part 91 regulations (not for hire) only required the inspection after accumulation of 1,000 hours, at the next annual inspection, and each subsequent annual inspection.

The CFI held a commercial pilot certificate with ratings for single-engine and multiengine land and instrument airplane. He also held a flight instructor certificate with a rating for airplane single-engine land. The CFI reported approximately 6,153 hours of total flight experience, 1,018 of which were in the Cessna 172. The CFI's most recent second-class medical certificate was issued on June 29, 2007. At that time, he reported a weight of 235 pounds.

The student pilot reported 92 hours of total flight experience, 91 of which were in the Cessna 172. His most recent third-class medical certificate was issued on July 15, 2006. At that time, he reported a weight of 250 pounds.

The winds reported at the airport at 1335, were from 280 degrees at 9 knots, gusting to 14 knots.

NTSB Probable Cause

The failure of the pilot's seat to engage or remain engaged due to the improper inspection of the worn seat tracks.