Narrative:

Ship X arrived ZZZ with an inbound PIREP 'door 1R (1L) interphone inoperative. Cannot chime captain.' the time restraint for the flight called for deferral. MEL 23-00-04A, flight deck to cabin, cabin to flight deck functions was used for deferral and the aircraft was eventually dispatched. After entering the log page I was contacted by ZZZ1 maintenance coordination and told that the chime system is not covered by this MEL and is not deferrable. The write-up was self explanatory and I decided to look the deferral up using the ship's mechanical dispatch manual. The MEL which seemed to cover this problem did not need dispatch approval. I made sure that the interphone functioned between the forward position and the cockpit and noted such in my signoff. I was later called out to the airplane for an external power problem. While working the problem I decided to check the cockpit call button one last time and it did, in fact, work normally. However, because the airplane was already on delay I decided to leave the deferred item as it was. The chime system that was faulted is a direct function of the interphone system, or so closely related that it is easily mistaken to be a function. (You use the chime to get the crew's attention, then you talk to them on the interphone.) the MEL I used does not mention the chime at all. Unless you had first hand experience in what I am going through, you would be hard pressed to make the distinction. The MEL should have a simple note stating that inoperative chimes are not covered by this MEL.

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Original NASA ASRS Text

Title: A B737-200 WAS DISPATCHED IN NON COMPLIANCE WITH THE CABIN TO COCKPIT CALL CHIME INOP AND DEFERRED IN CONFLICT WITH THE MEL.

Narrative: SHIP X ARRIVED ZZZ WITH AN INBOUND PIREP 'DOOR 1R (1L) INTERPHONE INOP. CANNOT CHIME CAPT.' THE TIME RESTRAINT FOR THE FLT CALLED FOR DEFERRAL. MEL 23-00-04A, FLT DECK TO CABIN, CABIN TO FLT DECK FUNCTIONS WAS USED FOR DEFERRAL AND THE ACFT WAS EVENTUALLY DISPATCHED. AFTER ENTERING THE LOG PAGE I WAS CONTACTED BY ZZZ1 MAINT COORD AND TOLD THAT THE CHIME SYS IS NOT COVERED BY THIS MEL AND IS NOT DEFERRABLE. THE WRITE-UP WAS SELF EXPLANATORY AND I DECIDED TO LOOK THE DEFERRAL UP USING THE SHIP'S MECHANICAL DISPATCH MANUAL. THE MEL WHICH SEEMED TO COVER THIS PROB DID NOT NEED DISPATCH APPROVAL. I MADE SURE THAT THE INTERPHONE FUNCTIONED BTWN THE FORWARD POS AND THE COCKPIT AND NOTED SUCH IN MY SIGNOFF. I WAS LATER CALLED OUT TO THE AIRPLANE FOR AN EXTERNAL PWR PROB. WHILE WORKING THE PROB I DECIDED TO CHK THE COCKPIT CALL BUTTON ONE LAST TIME AND IT DID, IN FACT, WORK NORMALLY. HOWEVER, BECAUSE THE AIRPLANE WAS ALREADY ON DELAY I DECIDED TO LEAVE THE DEFERRED ITEM AS IT WAS. THE CHIME SYS THAT WAS FAULTED IS A DIRECT FUNCTION OF THE INTERPHONE SYS, OR SO CLOSELY RELATED THAT IT IS EASILY MISTAKEN TO BE A FUNCTION. (YOU USE THE CHIME TO GET THE CREW'S ATTN, THEN YOU TALK TO THEM ON THE INTERPHONE.) THE MEL I USED DOES NOT MENTION THE CHIME AT ALL. UNLESS YOU HAD FIRST HAND EXPERIENCE IN WHAT I AM GOING THROUGH, YOU WOULD BE HARD PRESSED TO MAKE THE DISTINCTION. THE MEL SHOULD HAVE A SIMPLE NOTE STATING THAT INOP CHIMES ARE NOT COVERED BY THIS MEL.

Data retrieved from NASA's ASRS site as of July 2007 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.