SCC of 300M Steel Jackscrew Drive Pins
The jackscrew drive pins on a landing-gear bogie failed when the other bogie on the same side of the airplane was kneeled for tire change. The pins, made of 300M steel, were shot peened and chromium plated on the outside surface and were cadmium plated and painted with polyurethane on the inside surface. The top of the jackscrew was 6150 steel. Both ends of the pins were revealed to be dented where the jackscrew had pressed into them and were observed to have been resulted due to overdriving the jackscrew at the end of an unkneeling cycle. These dented...