The document provides step-by-step instructions for installing aircraft spark plugs. It begins by warning technicians to treat the propeller as if the ignition is on for safety. Next, it instructs choosing the proper spark plugs and tools. The steps then detail removing cowling, disconnecting leads, removing old plugs, inspecting and gapping new plugs, installing plugs and torquing to specifications, reattaching leads, reinstalling cowling, and making a logbook entry. Safety cautions are included throughout.