Failure Analysis, Cadmium Brush Plate Qualification and Salt Fog Testing of the AH-64 Shock Strut Mount, P/N 7-311113409

摘要

A failure analysis was performed on a shock strut mount from an AH-64 Apache attack helicopter. It was concluded that the failure was attributed to stress corrosion cracking and/or corrosion fatigue and had initiated at a region where the protective cadmium plating was worn away in service. Based upon this conclusion, it was necessary to qualify two facilities (Hunter Army Air Field, Savannah, GA and Ft. Lewis, Dupont, WA) for the cadmium brush plating rework of these components found to have worn coatings during routine inspections. The U. S. Army Research Laboratory was involved in the qualification process for both facilities, and the results of each quality audit are included. Finally, the results of salt fog testing of cadmium brush plated specimens, plated at the respective facilities, are also included, as well as a comparison of the grain size of the material in the failed component vs. the material from the struts plated at each facility.