Narrative:

B-system hydraulic pump low pressure light inoperative -- deferred improperly using incorrect MEL. This item is not deferrable per current MEL procedures. Our MEL's cover both B737-291, B737-300 and B737-500 series aircraft. Many system are identical, but many are not. Although the MEL is correct, due to many MEL cards in this air traffic area chapter and unclr information along with a lack of experience in this system or in addressing this issue, I inadvertently applied the MEL. After dispatch, in-flight the crew communicated that the placard applied did not fit the condition. I reviewed the MEL and found no reference to the electric pump (B) low pressure light. The engine driven low pressure light, however is deferrable per the MEL. Aircraft was stopped at next station and item repaired before next flight.

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Original NASA ASRS Text

Title: A B737-500 WAS DISPATCHED IN NON COMPLIANCE WITH A 'B' SYS HYD LOW PRESSURE WARNING LIGHT DEFERRED AS INOP. MEL DOES NOT PERMIT THIS DEFERRAL.

Narrative: B-SYS HYD PUMP LOW PRESSURE LIGHT INOP -- DEFERRED IMPROPERLY USING INCORRECT MEL. THIS ITEM IS NOT DEFERRABLE PER CURRENT MEL PROCS. OUR MEL'S COVER BOTH B737-291, B737-300 AND B737-500 SERIES ACFT. MANY SYS ARE IDENTICAL, BUT MANY ARE NOT. ALTHOUGH THE MEL IS CORRECT, DUE TO MANY MEL CARDS IN THIS ATA CHAPTER AND UNCLR INFO ALONG WITH A LACK OF EXPERIENCE IN THIS SYS OR IN ADDRESSING THIS ISSUE, I INADVERTENTLY APPLIED THE MEL. AFTER DISPATCH, INFLT THE CREW COMMUNICATED THAT THE PLACARD APPLIED DID NOT FIT THE CONDITION. I REVIEWED THE MEL AND FOUND NO REF TO THE ELECTRIC PUMP (B) LOW PRESSURE LIGHT. THE ENG DRIVEN LOW PRESSURE LIGHT, HOWEVER IS DEFERRABLE PER THE MEL. ACFT WAS STOPPED AT NEXT STATION AND ITEM REPAIRED BEFORE NEXT FLT.

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.