B757-200 Captain is informed by Ramp personnel that cargo doors will not operate. Maintenance is called and utility busses are cycled to correct the problem. Reporter does not understand this fix and requests more documentation.

Narrative

Aircraft was parked at gate approximately 15 minutes before departure when Ramp personnel came to cockpit to inform me that he could not open or close cargo doors. Later I learned that cargo loading system and pit lights were also inoperative. Concerned for his safety; I told him to keep away from the inoperative doors until we had a Mechanic look at it; lest the doors start operating independently and injure someone. We called Maintenance. When the Mechanic arrived; he looked at the electrical panel; disconnected external power momentarily; then deduced (from the silence and dark) that we did not have APU on yet. Our procedures call for starting APU 10 minutes before departure. We then started APU per his request. I advised him that I had told Ramp to stay away from the cargo doors and that we would not touch anything until he informed us that his work was complete; in order to prevent harm to people outside the aircraft. He disappeared and we never saw him again. Shortly thereafter; a Service Representative came up and wanted to close the door. We advised we were working on a mechanical. She checked; came back and said Zone said we were good to go. About that time a Service Representative advisement came over the printer which said 'utility busses cycled; Operations Checks OK' in response to our write-up. Since the cargo doors; cargo lights; cargo loading system and fueling panel are on the ground handling bus; which can ONLY be powered by external power or APU; I failed to see a connection between cycling utility busses and our reported problem. We asked Maintenance to have the Mechanic come back to the airplane and explain what he did. I was also concerned: if ground handling bus was only accepting power from the APU; and not External; I was willing to accept the airplane; but wanted a Maintenance Release which accurately reflected that fact. I also wanted to know if there was a problem. If there were problems with APU accepting a load leaving a maintenance station with cargo doors which only accepted APU power might require some evaluation. Maintenance (over the radio) advised the mechanic had left due to shift change; but they would get a new mechanic. About this time; First Officer's radio altimeter also quit; leaving us with Autoland 2 and reducing us to Category II. We sent the code and called that in as well. Eventually a new Mechanic arrived. He cycled the CB for the RA and achieved no success. His attitude was that the cargo doors were now operating; and cycling the utility busses had done it. I advised that our manuals indicated there was no connection between the utility busses and the cargo doors; he insisted that the utility busses reset the cargo door controls. As nicely as possible; I attempted to defuse the situation by mentioning that often our manuals contradict each other; I know Maintenance has much more detail than we have; but I would like to have some Maintenance Release which actually reflected the status of the airplane. Again I mentioned I would be happy to take the aircraft to ZZZ1; which was VFR without an RA or Ground handling bus accepting external power; I just needed the Maintenance Release to reflect our status. The Mechanic appeared to take offense at this and insisted cargo doors were on the utility bus; and 'we sent you a good Maintenance Release.' I then explained that if he had a wiring diagram or something in his books which confirmed that; I would be happy to take it; however; based on our (limited) manuals; the Maintenance Release did not address the reported problem. He then twice informed me 'I don't know how long that will take' and disappeared for a long time. As far as I can tell; the Mechanic then decided to take as long as possible; since the delay code was on the pilot who wanted a wiring diagram she didn't need to have. We had a company Executive on board who made some phone calls to Maintenance Supervisors elsewhere. All of a sudden we started getting attention from the topdown. Maintenance Supervisors called on the jetway phone and showed up at the airplane. I again explained our willingness to take a deferral and get out of town; or have a link between utility busses and external power. After about 45 minutes; Maintenance Supervisors showed up with a wiring diagram and we reviewed it together. I was a bit concerned to learn that the Maintenance Supervisor could not read the wiring diagram. We traced the route together from cargo doors; showed external or APU power connectors; and also the lead-in lines to other items on the Ground handling bus. The Maintenance Supervisor then asked me if that confirmed whether the Maintenance Release showing utility busses was right; or whether I was right. I did my best to defuse the 'us versus them' mentality; but explained that the diagrams he had obtained confirmed our limited wiring diagram in our manual. He then became upset and took the diagram back and wouldn't let me have it. Eventually; a mechanic showed up who was instructed to fix the problem. He determined that Ground handling bus could be powered by external or APU power. When he reset the system by turning the APU off and the airplane external power off and then back on; the First Officer RA was also restored. We received a new Maintenance Release which said everything was working; but kept the utility bus cycling language. Everyone was delayed for over 1 hour. Most passengers were rebooked to another flight. However; many connections did not make it -- all because of this delay. If the mechanic who worked on the airplane had just taken the time to speak to us; or if anyone had been willing to speak to us rather than have a turf fight over 'I sent a good Maintenance Release if she doesn't like it; it's Flight Operations delay;' then we could have left 1 hour earlier. Note: On the next leg; we had another (apparent) electrical system error: the Trailing Edge Flaps Disagreement EICAS message illuminated and we had a Trailing Edge Flaps problem. This resolved itself through the irregular e-checklist; but we had to do a missed approach and irregular procedure. The problem seems to have been an electrical signal 'the Electrical Status' message and Electrical Flap Motor Status messages appeared at the time of the fault. The most disappointing part of this problem was that Maintenance people cold not understand that the Maintenance Release must reflect certain facts about the airplane; they honestly seemed to think that if they sent a Maintenance Release; any Maintenance Release; then it was the pilot's fault for not taking the aircraft. One mechanic was very nice; pointed out that they are trained on many airplanes; and that recycling utility busses; which brings back coffee and galleys; is the usual fix for other problems. I appreciate their manpower limitations and understand we are all fatigued; but turf wars and resentment only increase delays and seriously inconvenience our passengers. An accurate and complete flow of information regarding the Maintenance state of our airplanes is necessary for crews flying the airplanes and also mechanics who are assigned to fix them. The First Officer and Flight Attendants and Service Representative did an excellent job of keeping passengers informed and working to minimize their distress.