Flight Crew Air Transport Pilot (ATP)
Situational Awareness; Confusion
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural MEL / CDL; Deviation / Discrepancy - Procedural Published Material / Policy
General Maintenance Action
Aircraft; Human Factors
After gate arrival; it was discovered that the No. 2 DC generator was indicating a load of approximately .85 with the No 2 engine shut down.  Maintenance could not resolve the problem and decided to MEL the Gen 2 load indicator in compliance with MEL 24-6-1.  No problem.  After discussing this with my First Officer; we decided that we could not operate the aircraft because we were unable to monitor the DC generator load to ensure we were in compliance with the DC generator load limits in the Limitations section of the AFM (.7 on the ground and 1.0 inflight).  Before contacting Maintenance Control; I contacted the Chief Pilot and discussed the situation. He was in agreement that we could not comply with the AFM limitations since there was no way to monitor it.  Maintenance Control was unaware of what the AFM load limitation was.  It turned out that the resolution to the problem was to inop the No. 2 DC Generator since there was no way to monitor the load.  The No. 2 DC generator was then MEL'd under 24-10-1.  All of us were in agreement that this was the best course of action.  And the No. 2 DC generator was inoped.  It wasn't until later that it was discovered that the 2 MEL's were non-compliant.  The weather was not a factor. I received a call after I arrived; my First Officer and I did some MEL research and found out how and where the error occurred. My opinion was that there were no provisions to operate the aircraft if one could not monitor a required generator limitation if the indicator was allowed to be MEL'd.  Additionally once the first MEL was issued; and then the second one issued; we did not look back at the MEL's because in their own right each was complied with in succession and not collectively. I think that MTC perhaps should know what limitations the pilots have to deal with; and why a MEL would be issued or allowed to be used if it usurps the AFM limitation.  To my knowledge there is no protection or other method for load limit protection except for the visual indication.
On the ground; the Captain called with a discrepancy saying that his No. 2 DC generator load meter was reading approximately .85 with his engines shut down. I issued MEL 24-6-1 after attempting to R and R the load meter; it was a no fix. We complied with MEL procedures and verified that the generator and all tru's did work normally. After his ground time; the Captain called back and said that his AFM says that he had to be able to read the loads to legally fly the plane. I then put the DC generator on MEL 24-10-1; again verifying the Maintenance procedure was complied with. DC generator turned off; both ac gens operate normally and both tru's ops normal. He then flew the plane for two legs. The next Captain said that we had incompatible MEL's. The 24-6-1 says that DC generators have to operate normally; which we verified when issuing the MEL. After discussion with the flight ops; we verified that the first Captain was incorrect about his AFM; it is complied with during normal operations; not when an MEL has been issued; so the DC generator MEL was unnecessary; and we again verified the operation of the DC generator and cleared MEL 24-10-1.The event occurred because of the Captain misunderstanding his AFM; and me not going back and rechecking the original MEL that I had given (24-6-1); in hindsight; I should have change the 24-6-1 to a 24-6-2; which is an MEL for a loadmeter that doesn't operate normally because of a DC generator being inoperative (which it wasn't; as verified numerous times during this procedure) once the problem was identified; I had Maintenance go to the aircraft; and yet again; verify that the DC generator operated normally; and cleared MEL 24-10-1 (DC gen) making the loadmeter MEL again legal.
DHC-8 flight crew discovers the load meter for the number two DC generator to be in operative and Maintenance attempts to MEL the load meter; but the crew will not accept it due to a FOM requirement to monitor load limits. The generator is then MELed; but the two MEL's are not compatible. Switching to MEL 24-6-2 from MEL 24-6-1 satisfied all requirements.