An airbus A300-600 was dispatched in non compliance with both 'a' and 'B' sensor loops on the pneumatic leak detection system inoperative. #2 bleed system was deferred since one loop can be inoperative, but not both loops.

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Attributes
ACN	619722
Time
Date	200406
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	agl single value : 0
Environment
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	A300
Operating Under FAR Part	Part 121
Flight Phase	ground : maintenance
Person 1
Affiliation	company : air carrier
Function	maintenance : technician
Qualification	technician : airframe technician : powerplant
ASRS Report	619722
Person 2
Affiliation	company : air carrier
Function	other personnel other
Events
Anomaly	aircraft equipment problem : critical maintenance problem : improper maintenance maintenance problem : improper documentation maintenance problem : non compliance with mel non adherence : published procedure non adherence : far
Independent Detector	aircraft equipment other aircraft equipment : duct overheat test other other : person 1
Resolutory Action	none taken : detected after the fact
Consequence	other
Factors
Maintenance	contributing factor : schedule pressure contributing factor : manuals performance deficiency : repair performance deficiency : logbook entry performance deficiency : fault isolation performance deficiency : non compliance with legal requirements
Supplementary
Problem Areas	Flight Crew Human Performance Chart Or Publication Aircraft Maintenance Human Performance
Primary Problem	Maintenance Human Performance
Situations
Publication	Minimum Equipment List

Narrative:

Aircraft X has had a history of a false #2 bleed leak while on the ramp (never written up as an in-flight problem). Aircraft experienced a repeat of the #2 bleed leak while on ramp loading for flight. Crew wrote it up. I tried to clear the fault without success. Maintenance controller decided that MEL 36-11-01-a (bleed system inoperative) would be ok to defer it under. I felt it was a failure of the leak detection system. Both a&B loops were faulting. Selecting a or B alone would not turn off the 'leak' light. The MEL for a or B loops (MEL 36-22-03) says either -- may be inoperative, not both. The MEL does not say: 'if both are inoperative, it's ok to operate with the bleed system inoperative.' I feel that the aircraft was dispatched under the wrong MEL and should not have been dispatched.

Original NASA ASRS Text

Title: AN AIRBUS A300-600 WAS DISPATCHED IN NON COMPLIANCE WITH BOTH 'A' AND 'B' SENSOR LOOPS ON THE PNEUMATIC LEAK DETECTION SYS INOP. #2 BLEED SYS WAS DEFERRED SINCE ONE LOOP CAN BE INOP, BUT NOT BOTH LOOPS.

Narrative: ACFT X HAS HAD A HISTORY OF A FALSE #2 BLEED LEAK WHILE ON THE RAMP (NEVER WRITTEN UP AS AN INFLT PROB). ACFT EXPERIENCED A REPEAT OF THE #2 BLEED LEAK WHILE ON RAMP LOADING FOR FLT. CREW WROTE IT UP. I TRIED TO CLR THE FAULT WITHOUT SUCCESS. MAINT CTLR DECIDED THAT MEL 36-11-01-A (BLEED SYS INOP) WOULD BE OK TO DEFER IT UNDER. I FELT IT WAS A FAILURE OF THE LEAK DETECTION SYS. BOTH A&B LOOPS WERE FAULTING. SELECTING A OR B ALONE WOULD NOT TURN OFF THE 'LEAK' LIGHT. THE MEL FOR A OR B LOOPS (MEL 36-22-03) SAYS EITHER -- MAY BE INOP, NOT BOTH. THE MEL DOES NOT SAY: 'IF BOTH ARE INOP, IT'S OK TO OPERATE WITH THE BLEED SYS INOP.' I FEEL THAT THE ACFT WAS DISPATCHED UNDER THE WRONG MEL AND SHOULD NOT HAVE BEEN DISPATCHED.

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.