Narrative:

I took a turn over from the graveyard technicians that included troubleshooting a wing to body overheat condition. The graveyard technicians had indicated that they could duplicate the problem by running both packs for 15 minutes. The graveyard technicians subsequently narrowed the problem down to a bad M275 overheat loop. I removed and replaced the loop which subsequently fixed the discrepancy.upon review in our maintenance computer history; for air traffic area (air transport association) chapter 21-00 and 26-00; I found the MEL had been changed; which changed the ddp (dispatch deviation procedures) procedure. I confirmed that D488 [connector] was connected to the left pack flow control valve prior to functional checks of the left pack; which were good.1) I suggest removing the ddp procedure under MEL xx-00 that requires manually closing a valve whose primary purpose is to shut off air to a crew rest compartment in case of smoke; reference functional description in ipc (illustrated parts catalog). Furthermore; this valve had no provisions for wiring. The connector on the valve is capped. 2) simplify/clean-up MEL xx-00. It is four pages long to cover all of our effectivities; but the ddp procedures are scattered throughout the four pages.we currently have a ddp procedure that addresses a crew rest configuration that we don't fly. I spent nearly four hours in the compartment aft of the potable water tank. Access was through the removed outflow valve. The aircraft was located on the pad. I understood from the graveyard technicians that both packs were running during their troubleshooting; but I neglected to ask if they had undone the ddp [procedure]. Additionally; after having read the history in maintenance computer I was under the impression that a different ddp was in effect that didn't require checking the forward cargo heat outflow valve position.

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Original NASA ASRS Text

Title: A Mechanic reports his carrier currently has a Dispatch Deviation Procedure (DDP) that addresses a crew rest compartment configuration that they don't fly on their B737-900's. An MEL for a left pack deferral discrepancy has a dispatch procedure requiring the Forward Cargo Heat Duct Shutoff valve to be manually closed. Normal operation is for valve to be always 'Open'.

Narrative: I took a turn over from the graveyard technicians that included troubleshooting a wing to body overheat condition. The graveyard technicians had indicated that they could duplicate the problem by running both packs for 15 minutes. The graveyard technicians subsequently narrowed the problem down to a bad M275 overheat loop. I removed and replaced the loop which subsequently fixed the discrepancy.Upon review in our maintenance computer history; for ATA (Air Transport Association) Chapter 21-00 and 26-00; I found the MEL had been changed; which changed the DDP (Dispatch Deviation Procedures) procedure. I confirmed that D488 [Connector] was connected to the left Pack Flow Control valve prior to functional checks of the left pack; which were good.1) I suggest removing the DDP procedure under MEL XX-00 that requires manually closing a valve whose primary purpose is to shut off air to a Crew Rest compartment in case of smoke; reference functional description in IPC (Illustrated Parts Catalog). Furthermore; this valve had no provisions for wiring. The connector on the valve is capped. 2) Simplify/clean-up MEL XX-00. It is four pages long to cover all of our effectivities; but the DDP procedures are scattered throughout the four pages.We currently have a DDP procedure that addresses a crew rest configuration that we don't fly. I spent nearly four hours in the compartment aft of the potable water tank. Access was through the removed outflow valve. The aircraft was located on the pad. I understood from the graveyard technicians that both packs were running during their troubleshooting; but I neglected to ask if they had undone the DDP [procedure]. Additionally; after having read the history in maintenance computer I was under the impression that a different DDP was in effect that didn't require checking the forward Cargo Heat Outflow valve position.

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.