i have scrolled thru the whole thread, and I can't see anyone asking - what is the release number/batch number for the cap? If it doesn't have one (ie - traceability), can the cap that the engineer finds in his pocket/toolbox/off his car be put onto an aircraft?
are you going to ground an airliner for want of a valve cap without a release note?
this question asked by someone who has a nice array of valve caps in his pocket/toolbox/car/bikes