A B737-500 hgs system was continued deferred on MEL and dispatched with only (2) of (4) bolts securi...

Attributes
ACN	730801
Time
Date	200703
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	agl single value : 0
Aircraft 1
Make Model Name	B737-500
Flight Phase	ground : maintenance ground : maintenance
Person 1
Function	oversight : supervisor
ASRS Report	730801
Events
Anomaly	aircraft equipment problem : less severe maintenance problem : improper maintenance maintenance problem : non compliance with mel
Independent Detector	other other : 1
Consequence	other
Factors
Maintenance	contributing factor : non availability of parts performance deficiency : non compliance with legal requirements performance deficiency : installation
Supplementary
Problem Areas	Chart Or Publication Maintenance Human Performance
Primary Problem	Maintenance Human Performance

Narrative:

Aircraft arrived in ZZZ with the hgs system on MEL for the combiner being 'loose.' after inspection of the combiner mounting bracket; it was discovered that 2 of 4 mounting bolts were missing. Tried several options to try and locate the correct part numbers for the bolts but all were unsuccessful. No part information was found in the flight dynamics manual; boeing ipc; hgs installation aco 6549-34. Decided to leave the item on MEL and ask for engineering assistance in locating the current parts. Called (engineering) and he was able to locate part numbers in a rockwell collins service bulletin (sb-south-0220-34 rev B). Aircraft already departed ZZZ. It was determined that the aircraft would be stopped in ZZZX (first flight) and parts/mechanics would be sent from ZZZ to correct discrepancy. We had no access/awareness that this service bulletin existed. Did not want to damage mounts by installing incorrect hardware. Hgs system was deactivated by pulling and collaring the circuit breakers before the aircraft departed ZZZ. Hgs combiner.

Original NASA ASRS Text

Title: A B737-500 HGS SYSTEM WAS CONTINUED DEFERRED ON MEL AND DISPATCHED WITH ONLY (2) OF (4) BOLTS SECURING HGS COMBINER UNIT.

Narrative: ACFT ARRIVED IN ZZZ WITH THE HGS SYS ON MEL FOR THE COMBINER BEING 'LOOSE.' AFTER INSPECTION OF THE COMBINER MOUNTING BRACKET; IT WAS DISCOVERED THAT 2 OF 4 MOUNTING BOLTS WERE MISSING. TRIED SEVERAL OPTIONS TO TRY AND LOCATE THE CORRECT PART NUMBERS FOR THE BOLTS BUT ALL WERE UNSUCCESSFUL. NO PART INFO WAS FOUND IN THE FLT DYNAMICS MANUAL; BOEING IPC; HGS INSTALLATION ACO 6549-34. DECIDED TO LEAVE THE ITEM ON MEL AND ASK FOR ENGINEERING ASSISTANCE IN LOCATING THE CURRENT PARTS. CALLED (ENGINEERING) AND HE WAS ABLE TO LOCATE PART NUMBERS IN A ROCKWELL COLLINS SVC BULLETIN (SB-S-0220-34 REV B). ACFT ALREADY DEPARTED ZZZ. IT WAS DETERMINED THAT THE ACFT WOULD BE STOPPED IN ZZZX (FIRST FLT) AND PARTS/MECHS WOULD BE SENT FROM ZZZ TO CORRECT DISCREPANCY. WE HAD NO ACCESS/AWARENESS THAT THIS SVC BULLETIN EXISTED. DID NOT WANT TO DAMAGE MOUNTS BY INSTALLING INCORRECT HARDWARE. HGS SYS WAS DEACTIVATED BY PULLING AND COLLARING THE CIRCUIT BREAKERS BEFORE THE ACFT DEPARTED ZZZ. HGS COMBINER.

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 B737-500 hgs system was continued deferred on MEL and dispatched with only (2) of (4) bolts securing hgs combiner unit.