DHC8 crew flew the aircraft with incompatible MEL items.

Attributes
ACN	544331
Time
Date	200204
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	agl single value : 0
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Dash 8 Series Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	ground : maintenance ground : parked
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 270 flight time total : 7000 flight time type : 3500
ASRS Report	544331
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	aircraft equipment problem : less severe maintenance problem : improper documentation maintenance problem : non compliance with mel non adherence : company policies non adherence : far non adherence : published procedure other anomaly other
Independent Detector	other flight crewa other flight crewb
Resolutory Action	none taken : detected after the fact
Consequence	other
Supplementary
Problem Areas	Company Maintenance Human Performance
Primary Problem	Company

Narrative:

Aircraft was flown with incompatible MEL's. 1 MEL was inoperative autoplt and the other was inoperative altitude selector. The 2 MEL's are not usually thought of as being interconnected (although they apparently are). The aircraft had been signed off and released by maintenance with numbers assigned to each MEL (which should not have happened). And the aircraft was flown by several other crews before the problem was found out. The breakdown started with maintenance and continued with the flight crew's. The flight crew's were slow to pick up on it due to the fact that the MEL's had been approved and the MEL's are relatively minor and not readily seen as being connected with each other. When looking at the maintenance log I was checking to see that the write-ups themselves were done correctly (which they were) and to see if the inoperative stickers were in the right place and that there were no associated performance penalties. I also checked the supplement chart which shows which MEL's are compatible with different aircraft operations (ie, MEL for anti-skid brakes invalidates the supplement that allows operation in tailwinds 10-20 KTS). We don't have an MEL chart which I think would have helped a great deal in avoiding this incident and keep it from happening again.

Original NASA ASRS Text

Title: DHC8 CREW FLEW THE ACFT WITH INCOMPATIBLE MEL ITEMS.

Narrative: ACFT WAS FLOWN WITH INCOMPATIBLE MEL'S. 1 MEL WAS INOP AUTOPLT AND THE OTHER WAS INOP ALT SELECTOR. THE 2 MEL'S ARE NOT USUALLY THOUGHT OF AS BEING INTERCONNECTED (ALTHOUGH THEY APPARENTLY ARE). THE ACFT HAD BEEN SIGNED OFF AND RELEASED BY MAINT WITH NUMBERS ASSIGNED TO EACH MEL (WHICH SHOULD NOT HAVE HAPPENED). AND THE ACFT WAS FLOWN BY SEVERAL OTHER CREWS BEFORE THE PROB WAS FOUND OUT. THE BREAKDOWN STARTED WITH MAINT AND CONTINUED WITH THE FLC'S. THE FLC'S WERE SLOW TO PICK UP ON IT DUE TO THE FACT THAT THE MEL'S HAD BEEN APPROVED AND THE MEL'S ARE RELATIVELY MINOR AND NOT READILY SEEN AS BEING CONNECTED WITH EACH OTHER. WHEN LOOKING AT THE MAINT LOG I WAS CHKING TO SEE THAT THE WRITE-UPS THEMSELVES WERE DONE CORRECTLY (WHICH THEY WERE) AND TO SEE IF THE INOP STICKERS WERE IN THE RIGHT PLACE AND THAT THERE WERE NO ASSOCIATED PERFORMANCE PENALTIES. I ALSO CHKED THE SUPPLEMENT CHART WHICH SHOWS WHICH MEL'S ARE COMPATIBLE WITH DIFFERENT ACFT OPS (IE, MEL FOR ANTI-SKID BRAKES INVALIDATES THE SUPPLEMENT THAT ALLOWS OP IN TAILWINDS 10-20 KTS). WE DON'T HAVE AN MEL CHART WHICH I THINK WOULD HAVE HELPED A GREAT DEAL IN AVOIDING THIS INCIDENT AND KEEP IT FROM HAPPENING AGAIN.

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.