Narrative:

Maintenance dropped the airplane on the gate 30 mins before scheduled departure; informing us that the left engine generator would not come on line until 55% N2. After some discussion they placarded the left channel and released the airplane; but due to ZZZ ramp engine-run restrs asked us to perform the CSD disconnect procedure during taxi; which we did without event. However; the recent revision to this MEL relief has muddied the waters. The MEL lists the actions to be taken to defer the generator as M or O permitting either pilots or maintenance to complete them. What follows is 7 pages of detailed; highly redundant text; most of which appears to be troubleshooting details for the flight crew; not MEL procedures. As the keeper of the MEL; I find capts frequently rely on my interpretation of the text in the outcome. Tonight as I write this I'm still not sure we did the right thing by performing the disconnect procedure ourselves at maintenance instruction. We made what seemed to be a reasonable decision based on the permissive wording of the text; the M or O header; and the detailed disconnect procedures that were provided to flight crews. However; we did not technically do the placarding of the item ourselves; which made it a sort of half pilot; half maintenance deferral. I've been involved in generator-out dispatch before; including CSD disconnect; and the MEL text used to be quite clear and straightforward. It isn't now. In addition to providing crews with troubleshooting information; which is not appropriate for an MEL; the new text appears to be catering to 2 different sets of APU altitude limits as well. At the end of the day; and in the interest of safety and clarity; I suggest the following: eliminate the troubleshooting details. Those belong in the QRH if they are included at all. Publish one set of relief instructions; and include a simple reminder note regarding the FL350 altitude limit of the older APU. Publish both operations and maintenance procedures; including CSD disconnect; so that all parties are aware of what is being done; regardless of who does the placarding. There are other minor details in the wording that I also find confusing; example -- one condition is that the AC x-tie be operative. Does this require it to be checked? The text does not say. Was this an omission? I sincerely hope that we did not contravene the intent or the letter of the MEL text in the way we handled this flight; but it is confusing to say the least.

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Original NASA ASRS Text

Title: AN MD80 PILOT QUESTIONS THE MEL PROCEDURE FOR A GND CSD DISCONNECT THAT MAY REQUIRE BOTH FLT CREW AND MAINTENANCE ACTIONS FOR PROPER COMPLETION.

Narrative: MAINT DROPPED THE AIRPLANE ON THE GATE 30 MINS BEFORE SCHEDULED DEP; INFORMING US THAT THE L ENG GENERATOR WOULD NOT COME ON LINE UNTIL 55% N2. AFTER SOME DISCUSSION THEY PLACARDED THE L CHANNEL AND RELEASED THE AIRPLANE; BUT DUE TO ZZZ RAMP ENG-RUN RESTRS ASKED US TO PERFORM THE CSD DISCONNECT PROC DURING TAXI; WHICH WE DID WITHOUT EVENT. HOWEVER; THE RECENT REVISION TO THIS MEL RELIEF HAS MUDDIED THE WATERS. THE MEL LISTS THE ACTIONS TO BE TAKEN TO DEFER THE GENERATOR AS M OR O PERMITTING EITHER PLTS OR MAINT TO COMPLETE THEM. WHAT FOLLOWS IS 7 PAGES OF DETAILED; HIGHLY REDUNDANT TEXT; MOST OF WHICH APPEARS TO BE TROUBLESHOOTING DETAILS FOR THE FLT CREW; NOT MEL PROCS. AS THE KEEPER OF THE MEL; I FIND CAPTS FREQUENTLY RELY ON MY INTERP OF THE TEXT IN THE OUTCOME. TONIGHT AS I WRITE THIS I'M STILL NOT SURE WE DID THE RIGHT THING BY PERFORMING THE DISCONNECT PROC OURSELVES AT MAINT INSTRUCTION. WE MADE WHAT SEEMED TO BE A REASONABLE DECISION BASED ON THE PERMISSIVE WORDING OF THE TEXT; THE M OR O HEADER; AND THE DETAILED DISCONNECT PROCS THAT WERE PROVIDED TO FLT CREWS. HOWEVER; WE DID NOT TECHNICALLY DO THE PLACARDING OF THE ITEM OURSELVES; WHICH MADE IT A SORT OF HALF PLT; HALF MAINT DEFERRAL. I'VE BEEN INVOLVED IN GENERATOR-OUT DISPATCH BEFORE; INCLUDING CSD DISCONNECT; AND THE MEL TEXT USED TO BE QUITE CLR AND STRAIGHTFORWARD. IT ISN'T NOW. IN ADDITION TO PROVIDING CREWS WITH TROUBLESHOOTING INFO; WHICH IS NOT APPROPRIATE FOR AN MEL; THE NEW TEXT APPEARS TO BE CATERING TO 2 DIFFERENT SETS OF APU ALT LIMITS AS WELL. AT THE END OF THE DAY; AND IN THE INTEREST OF SAFETY AND CLARITY; I SUGGEST THE FOLLOWING: ELIMINATE THE TROUBLESHOOTING DETAILS. THOSE BELONG IN THE QRH IF THEY ARE INCLUDED AT ALL. PUBLISH ONE SET OF RELIEF INSTRUCTIONS; AND INCLUDE A SIMPLE REMINDER NOTE REGARDING THE FL350 ALT LIMIT OF THE OLDER APU. PUBLISH BOTH OPS AND MAINT PROCS; INCLUDING CSD DISCONNECT; SO THAT ALL PARTIES ARE AWARE OF WHAT IS BEING DONE; REGARDLESS OF WHO DOES THE PLACARDING. THERE ARE OTHER MINOR DETAILS IN THE WORDING THAT I ALSO FIND CONFUSING; EXAMPLE -- ONE CONDITION IS THAT THE AC X-TIE BE OPERATIVE. DOES THIS REQUIRE IT TO BE CHKED? THE TEXT DOES NOT SAY. WAS THIS AN OMISSION? I SINCERELY HOPE THAT WE DID NOT CONTRAVENE THE INTENT OR THE LETTER OF THE MEL TEXT IN THE WAY WE HANDLED THIS FLT; BUT IT IS CONFUSING TO SAY THE LEAST.

Data retrieved from NASA's ASRS site as of January 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.