Hello Sometimes there is just no quick fix, such as trouble shooting parts time a/c down time and so on, In the M.E.L book each item depending on importance is issued a time limit or category i.e. cat A which is 24 hours items such as flight data recorders and so on and cat C items such as APUs , Gives you a few days too work on the problem after the time limit is up you can apply for an extension from the FAA if you proved them the effort you put into it or the plane is grounded until its fixed. Thanks Michael Bolden MSP