A B767-300 returned to the departure airport for a cargo smoke detector fan replacement because afte...

Narrative:

Aircraft arrived with deferral for #1 forward cargo compartment smoke detector fan inop. The deferral stated that the flight crew was to check that the remaining smoke detector fan in associated compartment must operate normally. I did not know how we were to accomplish that check; so I called maintenance. He stated that maintenance had determined the other fan worked when it was deferred and that if the second fan failed we would get an EICAS message. A short time later maintenance sent an ACARS message that said; 'do not taxi awaiting maintenance.' I called him again; and he said he wanted local maintenance to verify the operation of the remaining fan. The local maintenance and maintenance control then determined that the status message cargo det air had been deferred properly and that an EICAS message of fwd cargo det or fwd cargo fan would be our indication that the second fan failed. Therefore we had a good maintenance release. We departed and at level off we discussed the deferral; as it was odd to have us verify the operation of a cargo smoke detector fan with no guidance as to how we would do that verification. The first officer then consulted the flight manual and found in the system chapter for the cargo fire system that no status nor EICAS message was caused by a single fan failure; but that a status message cargo det air was the indication that both fans had failed. I called dispatch and maintenance control and decided to return for maintenance at our departure station versus going into ETOPS airspace. A fan was installed and it was determined that the other fan was still inoperative. We then departed with a single fan inoperative deferral. The MEL is not well written and caused confusion for maintenance to tell the flight crew how they would comply with the checking of the other fan; and the fact that this particular status message can indicate a significant system failure versus an EICAS message. We elected to do an overweight landing as we had maintenance capability and did not have any dumpable fuel .

Original NASA ASRS Text

Title: A B767-300 returned to the departure airport for a Cargo Smoke Detector Fan replacement because after departure it became unclear if the MEL had been complied with.

Narrative: Aircraft arrived with deferral for #1 forward cargo compartment smoke detector fan inop. The deferral stated that the flight crew was to check that the remaining smoke detector fan in associated compartment must operate normally. I did not know how we were to accomplish that check; so I called Maintenance. He stated that Maintenance had determined the other fan worked when it was deferred and that if the second fan failed we would get an EICAS message. A short time later Maintenance sent an ACARS message that said; 'Do not taxi awaiting maintenance.' I called him again; and he said he wanted local Maintenance to verify the operation of the remaining fan. The local Maintenance and Maintenance Control then determined that the status message Cargo Det Air had been deferred properly and that an EICAS message of Fwd Cargo Det or Fwd Cargo Fan would be our indication that the second fan failed. Therefore we had a good maintenance release. We departed and at level off we discussed the deferral; as it was odd to have us verify the operation of a cargo smoke detector fan with no guidance as to how we would do that verification. The First Officer then consulted the flight manual and found in the system chapter for the Cargo Fire System that no status nor EICAS message was caused by a single fan failure; but that a status message Cargo Det Air was the indication that both fans had failed. I called Dispatch and Maintenance Control and decided to return for maintenance at our departure station versus going into ETOPS airspace. A fan was installed and it was determined that the other fan was still inoperative. we then departed with a single fan inoperative deferral. The MEL is not well written and caused confusion for maintenance to tell the flight crew how they would comply with the checking of the other fan; and the fact that this particular status message can indicate a significant system failure versus an EICAS message. We elected to do an overweight landing as we had maintenance capability and did not have any dumpable fuel .

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.

Attributes
ACN	851222
Time
Date	200909
Local Time Of Day	1801-2400
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	B767-300 and 300 ER
Operating Under FAR Part	Part 121
Flight Phase	Climb
Flight Plan	IFR
Component
Aircraft Component	Cargo Compartment Fire/Overheat Warning
Person 1
Function	Captain Pilot Flying
Experience	Flight Crew Last 90 Days 240 Flight Crew Total 18500 Flight Crew Type 6593
Person 2
Function	Pilot Not Flying First Officer
Experience	Flight Crew Last 90 Days 180 Flight Crew Total 3800 Flight Crew Type 2200
Events
Anomaly	Aircraft Equipment Problem Critical Deviation - Procedural MEL

A B767-300 returned to the departure airport for a cargo smoke detector fan replacement because after departure it became unclear if the MEL had been complied with.