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A B737-800 had a failed digit on the standby side of the 'navigation' control panel. Maintenance deferred the first officer's ILS system to continue in service.
| Attributes | |
| ACN | 639300 |
| Time | |
| Date | 200411 |
| Day | Tue |
| Local Time Of Day | 0001 To 0600 |
| Place | |
| Locale Reference | airport : zzz.airport |
| State Reference | US |
| Altitude | agl single value : 0 |
| Environment | |
| Light | Night |
| Aircraft 1 | |
| Operator | common carrier : air carrier |
| Make Model Name | B737-800 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | ground : parked |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| ASRS Report | 639300 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Events | |
| Anomaly | aircraft equipment problem : critical maintenance problem : improper maintenance maintenance problem : non compliance with mel non adherence : far non adherence : published procedure |
| Independent Detector | aircraft equipment other aircraft equipment : fo ils system other flight crewa other flight crewb |
| Resolutory Action | none taken : detected after the fact |
| Consequence | other other |
| Factors | |
| Maintenance | contributing factor : schedule pressure performance deficiency : non compliance with legal requirements performance deficiency : logbook entry |
| Supplementary | |
| Problem Areas | Flight Crew Human Performance Maintenance Human Performance Chart Or Publication Aircraft |
| Primary Problem | Maintenance Human Performance |
| Situations | |
| Publication | Minimum Equip List |
Narrative:
Aircraft arrived at ZZZ from ZZZ1 with an MEL deferral of item 78 in the aircraft log which had been written up at ZZZ1 prior to departure on flight abc to ZZZ. The problem was with in inoperative digit on the standby side of the 'navigation' control panel on the first officer's side. The item was deferred by using an MEL item that stated that the first officer's ILS was inoperative. The code that was used to write up this problem was for the 'ILS control panel or display.' there is no ILS control panel in the B737. There is also a code for the 'VOR control panel or display.' there is no VOR control panel in the B737. There is a 'navigation' control panel with an 'active' and a 'standby' display. The 'navigation' control panel controls the frequency selection for either/both the ILS and the VOR. The problem was with the display on the standby side of the first officer's navigation control panel. The ILS, the VOR, and the HUD all were operating perfectly. But the signoff was to defer the ILS as inoperative and also downgrade the HUD to CAT I only, in spite of the fact that with the ILS inoperative, the aircraft cold not be dispatched to an airport where the ILS was required. En route, I examined the MEL and the logbook at length and decided all was not well. In spite of the fact that the ILS and the VOR were in fact operating perfectly, the 'navigation' control panel was not. But there is no valid MEL provision for operating the aircraft with a malfunctioning navigation control panel. It was signed off using an inoperative ILS MEL provision, apparently, in order to move the airplane in spite of the fact that there was a navigation control panel in stock in ZZZ1. When we arrived at ZZZ1, I wrote up the problem again. The navigation control panel was replaced, and we were on our way to ZZZ2 after taking a maintenance delay of approximately 20 mins. But the aircraft had operated 'illegally' for 2 flts because an inappropriate MEL provision had been used to defer maintenance on an item not covered by the MEL.
Original NASA ASRS Text
Title: A B737-800 HAD A FAILED DIGIT ON THE STANDBY SIDE OF THE 'NAV' CTL PANEL. MAINT DEFERRED THE FO'S ILS SYS TO CONTINUE IN SVC.
Narrative: ACFT ARRIVED AT ZZZ FROM ZZZ1 WITH AN MEL DEFERRAL OF ITEM 78 IN THE ACFT LOG WHICH HAD BEEN WRITTEN UP AT ZZZ1 PRIOR TO DEP ON FLT ABC TO ZZZ. THE PROB WAS WITH IN INOP DIGIT ON THE STANDBY SIDE OF THE 'NAV' CTL PANEL ON THE FO'S SIDE. THE ITEM WAS DEFERRED BY USING AN MEL ITEM THAT STATED THAT THE FO'S ILS WAS INOP. THE CODE THAT WAS USED TO WRITE UP THIS PROB WAS FOR THE 'ILS CTL PANEL OR DISPLAY.' THERE IS NO ILS CTL PANEL IN THE B737. THERE IS ALSO A CODE FOR THE 'VOR CTL PANEL OR DISPLAY.' THERE IS NO VOR CTL PANEL IN THE B737. THERE IS A 'NAV' CTL PANEL WITH AN 'ACTIVE' AND A 'STANDBY' DISPLAY. THE 'NAV' CTL PANEL CTLS THE FREQ SELECTION FOR EITHER/BOTH THE ILS AND THE VOR. THE PROB WAS WITH THE DISPLAY ON THE STANDBY SIDE OF THE FO'S NAV CTL PANEL. THE ILS, THE VOR, AND THE HUD ALL WERE OPERATING PERFECTLY. BUT THE SIGNOFF WAS TO DEFER THE ILS AS INOP AND ALSO DOWNGRADE THE HUD TO CAT I ONLY, IN SPITE OF THE FACT THAT WITH THE ILS INOP, THE ACFT COLD NOT BE DISPATCHED TO AN ARPT WHERE THE ILS WAS REQUIRED. ENRTE, I EXAMINED THE MEL AND THE LOGBOOK AT LENGTH AND DECIDED ALL WAS NOT WELL. IN SPITE OF THE FACT THAT THE ILS AND THE VOR WERE IN FACT OPERATING PERFECTLY, THE 'NAV' CTL PANEL WAS NOT. BUT THERE IS NO VALID MEL PROVISION FOR OPERATING THE ACFT WITH A MALFUNCTIONING NAV CTL PANEL. IT WAS SIGNED OFF USING AN INOP ILS MEL PROVISION, APPARENTLY, IN ORDER TO MOVE THE AIRPLANE IN SPITE OF THE FACT THAT THERE WAS A NAV CTL PANEL IN STOCK IN ZZZ1. WHEN WE ARRIVED AT ZZZ1, I WROTE UP THE PROB AGAIN. THE NAV CTL PANEL WAS REPLACED, AND WE WERE ON OUR WAY TO ZZZ2 AFTER TAKING A MAINT DELAY OF APPROX 20 MINS. BUT THE ACFT HAD OPERATED 'ILLEGALLY' FOR 2 FLTS BECAUSE AN INAPPROPRIATE MEL PROVISION HAD BEEN USED TO DEFER MAINT ON AN ITEM NOT COVERED BY THE MEL.
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.