|37000 Feet||Browse and search NASA's
Aviation Safety Reporting System
|Local Time Of Day||0601 To 1200|
|Locale Reference||atc facility : zzz|
|Operator||common carrier : air carrier|
|Make Model Name||Medium Large Transport, Low Wing, 2 Turbojet Eng|
|Navigation In Use||Other|
|Flight Phase||cruise other|
descent : approach
|Affiliation||company : air carrier|
|Function||flight crew : first officer|
|Qualification||pilot : commercial|
pilot : atp
pilot : flight engineer
pilot : instrument
|Experience||flight time last 90 days : 210|
flight time total : 3400
flight time type : 1600
|Affiliation||company : air carrier|
|Function||flight crew : captain|
oversight : pic
|Qualification||pilot : atp|
|Anomaly||aircraft equipment problem : less severe|
other anomaly other
|Independent Detector||other other : unspecified cockpit|
|Resolutory Action||none taken : anomaly accepted|
|Primary Problem||Chart Or Publication|
|Air Traffic Incident||other|
This event involved an ambiguity in the company's MEL for the medium large transport aircraft. On this particular trip the aircraft had a previous write-up in the E6 log book which stated that the altitude hold caused an oscillation in the control column with either the #1 or #2 autoplt selected. Repair of this discrepancy was deferred and a placard was placed in the E6 log book stating 'altitude hold #1 and #2 inoperative as per MEL.' the altitude hold button on the autoplt control panel was also placarded as inoperative. The lmp status remained CAT III. The company MEL stated simply not to use the altitude hold mode in this situation. (No mention was made not to use the autoplt). A check of the MEL under the 'perf' section specifically stated that any part of the system not listed as inoperative may be used. The initial write-up, the sign-off and the MEL system description did not specifically prohibit using the autoplt. We therefore decided the use of the autoplt in the perf mode was acceptable and legal. An FAA maintenance inspector who was riding the jump seat later questioned the use of the autoplt in light of the discrepancy. If the FAA inspector is correct in this matter, then it seems that the company MEL should be rewritten to specifically prohibit the use of all autoplt modes in this situation. Additionally, if autoplt use in this situation is inappropriate, then the company MEL and maintenance manual should dictate that the lmp status of the aircraft be downgraded to category I only.
Original NASA ASRS Text
Title: FAA MAINTENANCE INSPECTOR WONDERED IF IT WAS OK TO USE AUTOPLT WITH THE ALT HOLD FEATURE PLACARDED INOPERATIVE.
Narrative: THIS EVENT INVOLVED AN AMBIGUITY IN THE COMPANY'S MEL FOR THE MLG ACFT. ON THIS PARTICULAR TRIP THE ACFT HAD A PREVIOUS WRITE-UP IN THE E6 LOG BOOK WHICH STATED THAT THE ALT HOLD CAUSED AN OSCILLATION IN THE CONTROL COLUMN WITH EITHER THE #1 OR #2 AUTOPLT SELECTED. REPAIR OF THIS DISCREPANCY WAS DEFERRED AND A PLACARD WAS PLACED IN THE E6 LOG BOOK STATING 'ALT HOLD #1 AND #2 INOP AS PER MEL.' THE ALT HOLD BUTTON ON THE AUTOPLT CONTROL PANEL WAS ALSO PLACARDED AS INOP. THE LMP STATUS REMAINED CAT III. THE COMPANY MEL STATED SIMPLY NOT TO USE THE ALT HOLD MODE IN THIS SITUATION. (NO MENTION WAS MADE NOT TO USE THE AUTOPLT). A CHK OF THE MEL UNDER THE 'PERF' SECTION SPECIFICALLY STATED THAT ANY PART OF THE SYS NOT LISTED AS INOP MAY BE USED. THE INITIAL WRITE-UP, THE SIGN-OFF AND THE MEL SYS DESCRIPTION DID NOT SPECIFICALLY PROHIBIT USING THE AUTOPLT. WE THEREFORE DECIDED THE USE OF THE AUTOPLT IN THE PERF MODE WAS ACCEPTABLE AND LEGAL. AN FAA MAINT INSPECTOR WHO WAS RIDING THE JUMP SEAT LATER QUESTIONED THE USE OF THE AUTOPLT IN LIGHT OF THE DISCREPANCY. IF THE FAA INSPECTOR IS CORRECT IN THIS MATTER, THEN IT SEEMS THAT THE COMPANY MEL SHOULD BE REWRITTEN TO SPECIFICALLY PROHIBIT THE USE OF ALL AUTOPLT MODES IN THIS SITUATION. ADDITIONALLY, IF AUTOPLT USE IN THIS SITUATION IS INAPPROPRIATE, THEN THE COMPANY MEL AND MAINT MANUAL SHOULD DICTATE THAT THE LMP STATUS OF THE ACFT BE DOWNGRADED TO CATEGORY I ONLY.
Data retrieved from NASA's ASRS site as of August 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.