SEA07LA062

After taking off and hearing a loud bang, followed by an unsafe landing gear indication and the inability to extend the right main landing gear, the pilot initiated an emergency landing. After touching down with the right main landing gear partially extended, the airplane veered to the right before coming to rest on the runway. An examination of the landing gear extension system revealed that the actuator body was cracked and separated at the forward bolt hole, preventing the main landing gear actuator piston from properly meshing with the Sector Gear, which precluded the landing gear from extending. An examination of the fracture surface was consistent with overload.

On February 8, 2007, approximately 1700 eastern standard time, a Cessna 172RG, N9395B, sustained substantial damage following the collapse of the right main landing gear during touchdown at the Daytona Beach International Airport (DAB), Daytona Beach, Florida. The instructor pilot and his student were not injured. Visual meteorological conditions prevailed at the time and no flight plan was filed for the 14 CFR Part 91 instructional flight. The flight departed DAB approximately 1630.

According to the Pilot/Operator Aircraft Accident/Incident Report (NTSB Form 6120.1), the flight instructor (pilot-in-command), who was seated in the left seat, reported that the landing gear retraction on the first takeoff produced a loud "bang," followed by a yellow UP light, which indicated an unsafe landing gear condition existed. The flight instructor stated that extending the landing gear did not result in a green DOWN light. The flight instructor further stated that the [gear] warning horn sounded with the power reduction and with flap extension; the student, who was seated in the right seat, observed no wheel on her side. The flight instructor reported trouble-shooting the situation by flying by the airport control tower for a visual observation, radio discussions with maintenance personnel, pitch ups, attempting to pump the landing gear down, all of which proved unsuccessful in getting the right main landing gear to extend fully to the down and locked position. The instructor stated that he decided to land on Runway 34, and approached the runway in a very flat and slow configuration, landing on a diagonal path across the runway to the left. The instructor further stated that after touching down the aircraft veered right, coming to a stop prior to departing the runway. The instructor also revealed that after landing the right main landing gear collapsed, which resulted in minor damage to the right wing tip and substantial damage to the airplane's right elevator and right horizontal stabilizer.

At the direction of the NTSB investigator-in-charge (IIC), a Federal Aviation Administration (FAA) certificated airframe and powerplant mechanic examined the landing gear extension system. The mechanic reported that the housing of the right main landing gear actuator body, part number 1281101-3, serial number 8178, was cracked and separated at the forward bolt hole, and that the rear bolt hole was cracked but not separated. The mechanic further reported that the separated part of the housing precluded the main gear actuator piston, part number 9882004-1, from properly meshing with the Sector Gear, part number 9882002-2.

The right main landing gear actuator body assembly, part number 1281101-3, serial number 8178, was sent to the National Transportation Safety Board's Materials Laboratory for examination. The examination of the fracture faces revealed features consistent with an overload.

FAA Airworthiness Directive (AD) 2001-06-06, with an effective date of May 14, 2001, required that the main landing gear pivot assemblies be checked for cracks. According to maintenance records, the AD was complied with on June 9, 2006, with total time on the actuator of 3,879.8 hours, and a total time since its last inspection of 385.6 hours.