<< >> NASA ASRS Report 640821, December 2004

A B737-700 with history of #1 bleed overheat trips had the pressure regulator shutoff valve deferred as inoperative per the MEL. Dispatched with the wrong valve locked out.

Attributes
ACN	640821
Time
Date	200412
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	B737-700
Operating Under FAR Part	Part 121
Flight Phase	ground : maintenance
Person 1
Affiliation	company : air carrier
Function	maintenance : lead technician
Qualification	technician : airframe technician : powerplant
ASRS Report	640821
Person 2
Affiliation	company : air carrier
Function	maintenance : technician
Events
Anomaly	aircraft equipment problem : less severe maintenance problem : non compliance with mel non adherence : far non adherence : published procedure
Independent Detector	aircraft equipment other aircraft equipment : left duct press. ind. other other : 969
Consequence	other other
Factors
Maintenance	contributing factor : schedule pressure performance deficiency : logbook entry performance deficiency : fault isolation performance deficiency : non compliance with legal requirements
Supplementary
Problem Areas	Aircraft Maintenance Human Performance
Primary Problem	Maintenance Human Performance
Situations
Publication	MINIMUM EQUIP. LIST

Narrative:

Were advised early that aircraft was arriving with dual bleed trip and that aircraft would be late. #1 engine had history of bleed trips and were advised that we would not work the item. So aircraft proceeded to lock out the bleed valve (prsov). Instead we locked out the high stage valve. We ran the engines to make sure no other bleed trips appeared. At the time #1 engine bleed valve was off. No problems were noted and the plane was moved to another line and a different gate. The contributing factors were bad WX and a shift change going on, so trying to be expedient, we made the mistake of locking out the wrong valve. Also, our fail safe engine run should have caught the mistake and we missed that as well.

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Original NASA ASRS Text

Title: A B737-700 WITH HISTORY OF #1 BLEED OVERHEAT TRIPS HAD THE PRESSURE REGULATOR SHUTOFF VALVE DEFERRED AS INOP PER THE MEL. DISPATCHED WITH THE WRONG VALVE LOCKED OUT.

Narrative: WERE ADVISED EARLY THAT ACFT WAS ARRIVING WITH DUAL BLEED TRIP AND THAT ACFT WOULD BE LATE. #1 ENG HAD HISTORY OF BLEED TRIPS AND WERE ADVISED THAT WE WOULD NOT WORK THE ITEM. SO ACFT PROCEEDED TO LOCK OUT THE BLEED VALVE (PRSOV). INSTEAD WE LOCKED OUT THE HIGH STAGE VALVE. WE RAN THE ENGS TO MAKE SURE NO OTHER BLEED TRIPS APPEARED. AT THE TIME #1 ENG BLEED VALVE WAS OFF. NO PROBS WERE NOTED AND THE PLANE WAS MOVED TO ANOTHER LINE AND A DIFFERENT GATE. THE CONTRIBUTING FACTORS WERE BAD WX AND A SHIFT CHANGE GOING ON, SO TRYING TO BE EXPEDIENT, WE MADE THE MISTAKE OF LOCKING OUT THE WRONG VALVE. ALSO, OUR FAIL SAFE ENG RUN SHOULD HAVE CAUGHT THE MISTAKE AND WE MISSED THAT AS WELL.

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.