Sometimes repairs go smoothly. But sometimes they don't. What can happen is the owner has a list. Replace parts A, B, C and D. So the mechanic orders the parts and starts putting them in. Replaces A and B. When he gets to C, hmm, wrong part. Now come the problems. There isn't any agreed procedure for changing the work order. Mechanic might call the plane owner, but it goes into the recording. Mechanic might call the parts supplier or the aircraft manufacturer to get the reason for the wrong part. But the mechanic might just decide to take the old part out, take it apart and put it back together and make do with it. Or maybe he goes ahead and puts the non-fitting part in, making it work as best he can. After he does this owner gets the message and calls the parts suppliers and finds the right part. But the mechanic has all that buttoned up and "done" now, so its going to have to be undone and redone or left substandard, and need to be fixed later on.
The point it, problems occur when somebody CHANGES the agreed upon and worked out procedures. Be very cautious about changing things without thinking it through and getting everyone onboard.
This is why, in large organizations that know what they are doing, there are agreed upon procedures for changing the work order. Certain people have to be contacted, the new work figured out, the problem part needs to be understood, and decisions need to be made and responsible people need to be contacted. And it has to be done in writing. All this costs time and money. And if its not done, it can cause more problems later on.
Things like this are WHY airplane owners want to be included in process. It makes the process better. The owner has a responsibility not to be disruptive. And no one wants to work on and airplane while the owner looks over his shoulder. Line of communication is essential. In some ways things were better when we wore pagers. People are missing some of their important phone calls.
