BFO95IA023

The failure of the right main landing gear's shock strut piston lug due to stress corrosion.

During takeoff roll, the airplane's right main landing gear failed. Post incident examination of the gear revealed that its shock strut piston lug had failed due to stress corrosion.

On December 25, 1994, at 0200 eastern standard time, a DC-8-54F, N427FB, had its right main landing gear shock strut fail during the takeoff roll on runway 31L at the John F. Kennedy International Airport, New York City, New York. The three crew members and two passengers were not injured. Visual meteorological conditions prevailed. The scheduled cargo flight was conducted under 14 CFR Part 121. According to the Captain, during the takeoff roll he noticed the airplane shaking. He stated he aborted the takeoff and turned the airplane onto taxiway KK and stopped it at the hold-short line. He stated he tried to taxi the airplane from the hold-short line but it would not move. On scene examination of the airplane's right main landing gear revealed the gear had separated near its torque links. The two outboard tires were deflated and the two inboard tires remained inflated. The failed landing gear was returned to the airplane manufacturer for examination. The examination revealed that the airplane's piston lug on the shock strut had failed. The manufacturer's Examination Report stated, "The failure of subject piston was attributed to stress corrosion cracking. The primary origin area occurred along the inner radius of the forward torque link attach lug. The slow growth crack propagation exhibited a predominant inter-granular (I.G.) mode of rupture with associated corrosion attack of the I.G. facets decreasing with increasing crack depth. At the crack depth of 0.06 inch the crack transitions into a dimple mode of rupture indicative of overload. The overload portion joined with two additional fractures resulting in complete separation of the part." -