A B737-300 had open deferred item #1 engine hydraulic depressurization system was inoperative. MEL r...

Attributes
ACN	656023
Time
Date	200505
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	agl single value : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Flight Phase	ground : parked ground : pushback
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Experience	flight time last 90 days : 230 flight time total : 18000 flight time type : 8000
ASRS Report	656023
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	aircraft equipment problem : critical maintenance problem : non compliance with mel non adherence : far non adherence : published procedure
Independent Detector	aircraft equipment other aircraft equipment : #1 hyd system press indicator other flight crewa other flight crewb
Resolutory Action	none taken : unable
Consequence	other other
Factors
Maintenance	contributing factor : schedule pressure performance deficiency : non compliance with legal requirements
Supplementary
Problem Areas	Maintenance Human Performance Environmental Factor Aircraft Chart Or Publication
Primary Problem	Maintenance Human Performance

Narrative:

As we met the inbound crew; we saw that our aircraft had an MEL 29-10 for a '#1 engine system 'a' depressurization function inoperative.' we were briefed by the inbound crew that they pushed back first -- had the tow bar released; and then started both engines. As I checked the MEL; I saw an additional requirement for the nosewheel steering override pin to be installed prior to push and the #1 engine to be started after tow bar release. I called ZZZ1 maintenance out to ask them to show me (and the ground pushback person) how to install the override pin. The maintenance person showed us where the override was located; but informed us that maintenance no longer used that pin and that they didn't even have any of them there. I then called maintenance in ZZZ2 and talked to maintenance control. I explained to him that the MEL required the override pin to be installed prior to push. He said that it was not required to pin the override as long as we waited to start the #1 engine until after tow bar release; and that it was not company procedure to use the pin. The actual write-up for the system 'a' hydraulic depressurization stated that 'the system did depressurize after a few mins.' in fact; the 'a' system was depressurized when I first entered the cockpit. Based on the facts that: 1) the 'a' system actually was depressurized for push; 2) ZZZ maintenance said that they did not even have a pin; and 3) ZZZ2 maintenance control stated that it was not company procedure to install the pin -- I pushed back and started both engines only after confirming that the tow bar was disconnected. I did this for 2 legs. Recommendation: if; in fact; it is not a requirement to pin the nose gear override prior to push as long as the #1 is stated after tow bar release; then the MEL requirement for override pin insertion prior to push should be removed from the MEL.

Original NASA ASRS Text

Title: A B737-300 HAD OPEN DEFERRED ITEM #1 ENG HYD DEPRESSURIZATION SYS WAS INOP. MEL REQUIRED DEPRESSURIZATION OVERRIDE PIN REQUIRED FOR PUSHBACK. PIN NOT USED!

Narrative: AS WE MET THE INBOUND CREW; WE SAW THAT OUR ACFT HAD AN MEL 29-10 FOR A '#1 ENG SYS 'A' DEPRESSURIZATION FUNCTION INOP.' WE WERE BRIEFED BY THE INBOUND CREW THAT THEY PUSHED BACK FIRST -- HAD THE TOW BAR RELEASED; AND THEN STARTED BOTH ENGS. AS I CHKED THE MEL; I SAW AN ADDITIONAL REQUIREMENT FOR THE NOSEWHEEL STEERING OVERRIDE PIN TO BE INSTALLED PRIOR TO PUSH AND THE #1 ENG TO BE STARTED AFTER TOW BAR RELEASE. I CALLED ZZZ1 MAINT OUT TO ASK THEM TO SHOW ME (AND THE GND PUSHBACK PERSON) HOW TO INSTALL THE OVERRIDE PIN. THE MAINT PERSON SHOWED US WHERE THE OVERRIDE WAS LOCATED; BUT INFORMED US THAT MAINT NO LONGER USED THAT PIN AND THAT THEY DIDN'T EVEN HAVE ANY OF THEM THERE. I THEN CALLED MAINT IN ZZZ2 AND TALKED TO MAINT CTL. I EXPLAINED TO HIM THAT THE MEL REQUIRED THE OVERRIDE PIN TO BE INSTALLED PRIOR TO PUSH. HE SAID THAT IT WAS NOT REQUIRED TO PIN THE OVERRIDE AS LONG AS WE WAITED TO START THE #1 ENG UNTIL AFTER TOW BAR RELEASE; AND THAT IT WAS NOT COMPANY PROC TO USE THE PIN. THE ACTUAL WRITE-UP FOR THE SYS 'A' HYD DEPRESSURIZATION STATED THAT 'THE SYS DID DEPRESSURIZE AFTER A FEW MINS.' IN FACT; THE 'A' SYS WAS DEPRESSURIZED WHEN I FIRST ENTERED THE COCKPIT. BASED ON THE FACTS THAT: 1) THE 'A' SYS ACTUALLY WAS DEPRESSURIZED FOR PUSH; 2) ZZZ MAINT SAID THAT THEY DID NOT EVEN HAVE A PIN; AND 3) ZZZ2 MAINT CTL STATED THAT IT WAS NOT COMPANY PROC TO INSTALL THE PIN -- I PUSHED BACK AND STARTED BOTH ENGS ONLY AFTER CONFIRMING THAT THE TOW BAR WAS DISCONNECTED. I DID THIS FOR 2 LEGS. RECOMMENDATION: IF; IN FACT; IT IS NOT A REQUIREMENT TO PIN THE NOSE GEAR OVERRIDE PRIOR TO PUSH AS LONG AS THE #1 IS STATED AFTER TOW BAR RELEASE; THEN THE MEL REQUIREMENT FOR OVERRIDE PIN INSERTION PRIOR TO PUSH SHOULD BE REMOVED FROM THE MEL.

Data retrieved from NASA's ASRS site as of January 2009 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.

A B737-300 had open deferred item #1 engine hydraulic depressurization system was inoperative. MEL required depressurization override pin required for pushback. Pin not used!