Also the limitations that I find with the MEL is that sometimes although allowable in the book it doesn't take into account other failures or ADD's on the aircraft. I had an aircraft the other day where the APU was u/s and in line with the MEL was allowed to fly, on looking through the tech log though it became apparent that the generator on number one engine was not reliable, several reports of it dropping offline although the mighty engineers had checked it to be satisfactory on the ground. No matter how much the engineer thinks that I should accept an aircraft which could leave me with only one reliable generator doesn't mean that I will. When an engine fails and then the unreliable gen goes offline aswell he won't be the one sitting in the dark wishing that I had the APU as a backup.