Narrative:

We arrived at the aircraft for the flight. On the release MEL 21-24-6 was listed. When the boarding door was closed an ovbd cool caution was displayed as well as an inbd cool fail status message. Going into the non-normal for ovbd cool it states; on the ground; do not take off. It says that if the overboard exhaust is failed open the aircraft will not pressurize properly. I then looked at the fault reset procedure and found that the circuit breaker for the reset was collared as part of the deferral procedure. Also reading into the deferral it had the overboard exhaust sov deactivated closed. I then looked at the status message for the inbd cool fail next. The fault reset procedure also directed me to reset a circuit breaker that was collared as a result of the deferral. Since I could not reset collared circuit breaker I determined that it was safe to depart despite the caution and status messages that were not listed in the deferral. During the flight I looked at the maintenance procedure for the 21-24-6 deferral. It has them deactivate the ovbd exhaust sov closed and also deactivate the inbd exhaust sov open. I then looked in the MEL and found a deferral for the inbd ex sov; 21-24-5. I wondered why this item was deactivated but not deferred. I queried dispatch about this and all I got from my dispatcher was that he couldn't even find the original deferral in the MEL. Getting no help from them I talked to the chief pilot about the situation. He stated that he had already talked to several captains about it since it had been deferred a few days earlier. According to the chief pilot; bombardier states that the inbd ex sov doesn't need to be deferred because it is just deactivated; not broken. I explained to him that other items; when deactivated need to be listed as deferrals and he said that the fleet manager was working on an MEL rewrite and that this was a badly written deferral. I told the chief pilot that I was not that comfortable taking off in an aircraft with caution messages that I didn't know were supposed to be there. On one hand we are told to follow the checklists as directed. I this instance however I had to disregard a non-normal checklist and use my systems knowledge to decide that the caution and status messages were part of the deferral process. I believe that the MEL is very poorly written and needs to be changed. There is no consistency in the MEL. On some items when you deactivate an item; it also needs to be deferred. With other items deactivation does not need to be listed as a deferral. There are also times when the MEL lists messages that will be displayed as a result of the deferral; and other times when you just have to use your system knowledge. It needs to be consistent across the board and right now it is badly lacking. If you have caution and status messages that will result from a deferral; they need to be listed on the deferral that they will be displayed.

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Original NASA ASRS Text

Title: A CRJ200 Captain found a contradition in MEL procedures requiring that a non malfunctioning item associated with an MEL'ed item not be MEL'ed even though the non malfunctioning item is disabled in order to comply with an MEL.

Narrative: We arrived at the aircraft for the flight. On the release MEL 21-24-6 was listed. When the boarding door was closed an OVBD COOL caution was displayed as well as an INBD COOL FAIL status message. Going into the non-normal for OVBD cool it states; on the ground; DO NOT TAKE OFF. It says that if the Overboard exhaust is failed open the aircraft will not pressurize properly. I then looked at the fault reset procedure and found that the CB for the reset was collared as part of the deferral procedure. Also reading into the deferral it had the Overboard Exhaust SOV deactivated closed. I then looked at the status message for the INBD COOL FAIL next. The fault reset procedure also directed me to reset a CB that was collared as a result of the deferral. Since I could not reset collared CB I determined that it was safe to depart despite the caution and status messages that were not listed in the deferral. During the flight I looked at the maintenance procedure for the 21-24-6 deferral. It has them deactivate the OVBD EXHAUST SOV closed and also deactivate the INBD EXHAUST SOV open. I then looked in the MEL and found a deferral for the INBD EX SOV; 21-24-5. I wondered why this item was deactivated but not deferred. I queried Dispatch about this and all I got from my Dispatcher was that he couldn't even find the original deferral in the MEL. Getting no help from them I talked to the Chief Pilot about the situation. He stated that he had already talked to several Captains about it since it had been deferred a few days earlier. According to the Chief Pilot; Bombardier states that the INBD EX SOV doesn't need to be deferred because it is just deactivated; not broken. I explained to him that other items; when deactivated need to be listed as deferrals and he said that the Fleet Manager was working on an MEL rewrite and that this was a badly written deferral. I told the Chief Pilot that I was not that comfortable taking off in an aircraft with caution messages that I didn't know were supposed to be there. On one hand we are told to follow the checklists as directed. I this instance however I had to disregard a non-normal checklist and use my systems knowledge to decide that the caution and status messages were part of the deferral process. I believe that the MEL is very poorly written and needs to be changed. There is no consistency in the MEL. On some items when you deactivate an item; it also needs to be deferred. With other items deactivation does not need to be listed as a deferral. There are also times when the MEL lists messages that will be displayed as a result of the deferral; and other times when you just have to use your system knowledge. It needs to be consistent across the board and right now it is badly lacking. If you have caution and status messages that will result from a deferral; they need to be listed on the deferral that they will be displayed.

Data retrieved from NASA's ASRS site as of April 2012 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.