ARDMORE, OK, USA
N100EJ
North American NA-265-80
Prior to the accident flight, the airplane was completely stripped and repainted by a maintenance facility at the departure airport. When the gear was retracted after takeoff, the pilot noticed that the landing gear warning light was illuminated. He lowered the landing gear, and the down and locked indicator light for the right main gear did not illuminate. Emergency gear extension procedures did not correct the discrepancy. The pilot elected to return to the airport and decided not to use thrust reversers during the landing roll to minimize yaw. There was 'no significant pedal pressure' when he applied brakes following touchdown, and the airplane overran the runway. The right main landing gear collapsed, and the right wing contacted the ground. Examination revealed that the main gear downlock pins had been painted which resulted in the right pin sticking in the retracted (unlocked) position when the gear was raised after takeoff. Additionally, the power brake valve pistons had been painted which resulted in the left piston sticking in the emergency (power off) position when the pilot tested the emergency brakes before takeoff.
On July 5, 1997, at 1700 central daylight time, a North American NA-265-80 airplane, N100EJ, was substantially damaged when the right main landing gear collapsed during the landing roll on runway 13 at the Ardmore Municipal Airport, in Ardmore, Oklahoma. The airline transport rated pilot in command (PIC) and copilot were not injured. The airplane was registered to and operated by Silver Lining Aviation LLC of Westlake, Ohio. Visual meteorological conditions prevailed and an IFR flight plan was filed for the cross country positioning flight which departed Ardmore approximately 1645 with an intended destination of Cleveland, Ohio. During a telephone interview conducted by the NTSB investigator-in-charge, and in a written statement, the PIC reported that he tested the operation of the emergency brake system by pulling the cockpit handle, pumping the brake pedals, and applying the brakes to bring the airplane to a stop as he taxied into takeoff position on the runway. He then returned the handle to the normal (non-emergency) position and did not recheck the brakes prior to takeoff. According to the PIC, upon gear retraction after takeoff, he noticed that the warning light in the landing gear handle was illuminated. He elected to recycle the landing gear and when the gear was lowered, the down and locked indicator light for the right main gear did not illuminate. He returned to the airport, performed a flyby of the control tower, and was advised by the tower controller that the landing gear appeared to be extended. After discussing the situation with the copilot, the PIC decided not to use the thrust reversers during the landing roll due to a concern that they might not deploy evenly which could result in the airplane yawing and the unsafe gear collapsing. After completing the landing checklist and the emergency gear extension checklist, a landing was made on runway 13. The PIC reported that the "touchdown was normal and the aircraft tracked along the centerline." However, when he applied brakes, "there was no significant pedal pressure." After asking the copilot to apply his brakes with the same lack of results, the PIC requested emergency brake system selection. He stated that "the required pumping action produced no noticeable pedal pressure on either pilot or copilot brakes." As the airplane approached the end of the runway at "an estimated 15 - 20 mph," the PIC shut down the engines. The airplane departed the runway onto the grass overrun and traveled "approximately 20 yards" before the right main landing gear collapsed. The right wing contacted the ground, and the airplane came to a stop. An A&P mechanic, who was present when the airplane was lifted with a crane on July 7, 1997, reported that the right main gear downlock pin was found "stuck in the "UP" position." After manually pulling the pin to the down position using pliers and lubricating oil, the mechanic "could see that it was covered with paint." He removed the paint from the pin and operation of the downlock was then "normal." The mechanic further reported that the left main gear downlock pin, although found in the down position, was also covered with paint. On scene investigation by a FAA inspector revealed that immediately prior to the accident flight, the airplane had been completely stripped and repainted by a maintenance facility at the Ardmore airport. Examination of the airplane by the inspector revealed that the outboard 6 to 7 feet of the right wing sustained structural damage requiring a major repair. Additionally, the inspector found that the piston on the left power brake valve was stuck in the power off (emergency) position. The piston on the right power brake valve was found in the power on (normal) position. Both power brake valves, which mount in the nose gear well, were coated with paint over spray. The emergency brake levers, which push the pistons to the power off position when the emergency brake handle in the cockpit is pulled, were both found in the power on position. Both the left and right power brake valves, P/N 516165-1, S/N 1201G and 1299G respectively, were removed from the airplane and forwarded to the manufacturer, Crane Hydro-Aire, Inc., in Burbank, California. On August 7, 1997, the valves were examined and tested under the supervision of a FAA inspector. A functional test of the left valve (S/N 1201G) in the as received condition (piston stuck in the power off position) showed that emergency brake pressure was available. After the piston was dislodged, the valve was found to be capable of supplying brake pressure in the normal position. Following the functional test, the piston was removed from its sleeve, and numerous white paint chips were found adhering to the piston and the o-rings. The right valve (S/N 1299G) passed the functional test except for an audible noise and chatter, which did not prevent brake pressure from being applied in either the normal or emergency position. It was noted that the piston had paint over spray adhering to it and that some of the paint appeared to have been scraped off by movement of the piston in the sleeve.
The failure of maintenance personnel to mask the gear locking pins prior to painting the airplane which resulted in the right main gear locking pin jamming in the unlocked position due to contamination with paint. A factor was the failure of maintenance personnel to mask the power brake valve pistons prior to painting which resulted in the left power brake valve jamming in the emergency (power off) position due to contamination with paint.
Source: NTSB Aviation Accident Database
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