Narrative:

This situation involves the use of autoplt components placarded as inoperative but used due to an ambiguity as to its use in the MEL of the company. The aircraft is an medium large transport with EFIS display, autoplt and perf management system. In the aircraft log was a write up stating the altitude hold caused an oscillation in control column in both 1 and 2 autoplts. The sign off was deferred and stated, 'altitude hold 1 and 2 inoperative as per MEL #.' I then referred to the MEL which simply stated not to use the altitude hold. (No mention was made not to use the autoplt.) I next checked the MEL under the perf section and it stated that any part of the system not listed as inoperative may be used. Since the initial write up, sign off and MEL system description did not specify not using the autoplt, I decided the use of the autoplt and the perf mode only would be acceptable and legal. However, an FAA inspector riding the jump seat questioned the use of the autoplt with the given discrepancy. The flight was conducted from dfw to msy utilizing perf mode to level and maintain altitude with normal operation and no excursions from selected altitude. I submit to you that if my interpretation of the MEL is incorrect then there is a gross ambiguity in determining what components of the autoplt are usable and the company policy as it is described in the mle is in error with the FAA conclusion. Conclusion: if the FAA is correct that when the altitude hold function is inoperative then the autoplt cannot be used and the MEL should state just that secondly if the autoplt can't be used then the lmp status must also be changed to reflect that the aircraft is a category I only and cannot go to CAT ii or III minimums. (Nowhere does it say this, nor was the aircraft lmp status lowered.)

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Original NASA ASRS Text

Title: ACI QUESTIONS LEGALITY OF AUTOPLT USE WITH ONE COMPONENT PLACARDED INOPERATIVE.

Narrative: THIS SITUATION INVOLVES THE USE OF AUTOPLT COMPONENTS PLACARDED AS INOP BUT USED DUE TO AN AMBIGUITY AS TO ITS USE IN THE MEL OF THE COMPANY. THE ACFT IS AN MLG WITH EFIS DISPLAY, AUTOPLT AND PERF MGMNT SYS. IN THE ACFT LOG WAS A WRITE UP STATING THE ALT HOLD CAUSED AN OSCILLATION IN CONTROL COLUMN IN BOTH 1 AND 2 AUTOPLTS. THE SIGN OFF WAS DEFERRED AND STATED, 'ALT HOLD 1 AND 2 INOP AS PER MEL #.' I THEN REFERRED TO THE MEL WHICH SIMPLY STATED NOT TO USE THE ALT HOLD. (NO MENTION WAS MADE NOT TO USE THE AUTOPLT.) I NEXT CHKED THE MEL UNDER THE PERF SECTION AND IT STATED THAT ANY PART OF THE SYS NOT LISTED AS INOP MAY BE USED. SINCE THE INITIAL WRITE UP, SIGN OFF AND MEL SYS DESCRIPTION DID NOT SPECIFY NOT USING THE AUTOPLT, I DECIDED THE USE OF THE AUTOPLT AND THE PERF MODE ONLY WOULD BE ACCEPTABLE AND LEGAL. HOWEVER, AN FAA INSPECTOR RIDING THE JUMP SEAT QUESTIONED THE USE OF THE AUTOPLT WITH THE GIVEN DISCREPANCY. THE FLT WAS CONDUCTED FROM DFW TO MSY UTILIZING PERF MODE TO LEVEL AND MAINTAIN ALT WITH NORMAL OPERATION AND NO EXCURSIONS FROM SELECTED ALT. I SUBMIT TO YOU THAT IF MY INTERPRETATION OF THE MEL IS INCORRECT THEN THERE IS A GROSS AMBIGUITY IN DETERMINING WHAT COMPONENTS OF THE AUTOPLT ARE USABLE AND THE COMPANY POLICY AS IT IS DESCRIBED IN THE MLE IS IN ERROR WITH THE FAA CONCLUSION. CONCLUSION: IF THE FAA IS CORRECT THAT WHEN THE ALT HOLD FUNCTION IS INOP THEN THE AUTOPLT CANNOT BE USED AND THE MEL SHOULD STATE JUST THAT SECONDLY IF THE AUTOPLT CAN'T BE USED THEN THE LMP STATUS MUST ALSO BE CHANGED TO REFLECT THAT THE ACFT IS A CATEGORY I ONLY AND CANNOT GO TO CAT II OR III MINIMUMS. (NOWHERE DOES IT SAY THIS, NOR WAS THE ACFT LMP STATUS LOWERED.)

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.