During an MEL cross check review; a maintenance controller noted a maintenance discrepancy and troub...

Attributes
ACN	840852
Time
Date	200906
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Light	Daylight
Aircraft 1
Make Model Name	B737-400
Operating Under FAR Part	Part 121
Flight Phase	Parked
Component
Aircraft Component	Air Conditioning Distribution System
Person 1
Function	Technician
Qualification	Maintenance Powerplant Maintenance Airframe
Person 2
Function	Other / Unknown
Events
Anomaly	Aircraft Equipment Problem Critical Deviation - Procedural FAR Deviation - Procedural Published Material / Policy Deviation - Procedural MEL

Narrative:

I was sent out to a B737-400; for pilot write-up 'no exhaust from equipment cooling fans in normal position'. Verified equipment cooling fan operation; no warning lights in cockpit; for supply or exhaust issue. Confusion existed between next generation aircraft configuration and the B737-400 system. Next generation aircraft use the same (exhaust) outlet for equipment cooling and forward outflow; the B737-400 uses a separate outlet. I came to the first MEL that I believed to be the correct applicable MEL. I placed forward exhaust valve inop; in closed position; MEL 21-22a. This should have been MEL 21-40b; equipment cooling valve inop in closed position. I have since reviewed both type amm and MEL authorizations for this discrepancy to insure proper compliance.

Original NASA ASRS Text

Title: During an MEL cross check review; a Maintenance Controller noted a maintenance discrepancy and trouble shooting didn't appear to agree with the Logbook MEL 21-22A entry for the forward outflow valve outlet versus the equipment cooling exhaust outlet port.

Narrative: I was sent out to a B737-400; for pilot write-up 'no exhaust from Equipment Cooling fans in normal position'. Verified equipment cooling fan operation; no warning lights in cockpit; for supply or exhaust issue. Confusion existed between next generation aircraft configuration and the B737-400 system. Next generation aircraft use the same (exhaust) outlet for equipment cooling and forward outflow; the B737-400 uses a separate outlet. I came to the first MEL that I believed to be the correct applicable MEL. I placed forward exhaust valve inop; in closed position; MEL 21-22a. This should have been MEL 21-40b; equipment cooling valve inop in closed position. I have since reviewed both type AMM and MEL authorizations for this discrepancy to insure proper compliance.

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.

During an MEL cross check review; a maintenance controller noted a maintenance discrepancy and trouble shooting didn't appear to agree with the logbook MEL 21-22A entry for the forward outflow valve outlet versus the equipment cooling exhaust outlet port.