Date: 201207
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Light: Daylight
Aircraft: Regional Jet 200 ER/LR (CRJ200)
Operator: Air Carrier
Operating under: Part 121
Mission: Passenger
Flight phase: Parked
Aircraft component: Minimum Equipment List (MEL)
Reporter organization: Air Carrier
Reporter function: Other / Unknown
Reporter qualification: Maintenance Airframe; Maintenance Powerplant
Human factors: Communication Breakdown; Confusion; Situational Awareness
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural MEL / CDL; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: Pre-flight
Result: General Maintenance Action
Contributing factors: MEL; Manuals; Aircraft; Human Factors
Primary problem: MEL

Narrative: Deferred [# 2 Engine] IDG-2 per MEL 24-11-1b.  Followed the MEL instructions to defer IDG-2.  In the next station; the new Flight Crew was reviewing their MEL's.  The 3A Hydraulic Pump was previously deferred.  In MEL 29-12-1 for the 3A Hydraulic Pump; states that both IDG-1 and IDG-2 have to be operative. The MEL instructions for the IDG does not state that the 3A pump has to be operative. [Recommend] revision to the CL6002-B19 (CRJ-200) Aircraft MEL 24-11-1a and 24-11-1b for the IDG deferral that states that 3A Hydraulic Pump must operate normally to defer a Left or Right IDG.

Callback: Reporter stated the conflict between the two MEL deferrals was noticed by a downline Flight crew during their preflight Logbook MEL review. At the time; when he had deferred the # 2 Engine IDG; he only looked at MEL 24-11-1b; which did not have a proviso requiring the Electric Hydraulic Pump 3A to be operational. His Air Carrier at that time; had not set-up their Maintenance Computer System to reject an MEL IDG deferral request that would be in conflict with another section of their MEL Manual.Reporter stated he contacted the aircraft Manufacturer; requesting they revise their Master MEL language in the section for deferring an IDG; to include a 'Note' that Electric Hydraulic Pump 3A must be operational. The response from the Manufacturer indicated they were not going to change or revise the Master MEL and that the Operator was responsible for their own MEL. As a Maintenance Controller he realizes the Master MEL affects all Operators of the CRJ-200 aircraft. Just making revisions to their company MEL Manual does not address the lack of information that should be made available to other Maintenance Controllers; Mechanics and Flight Crews. That same information could prevent another unnecessary improper deferral and unsafe flight condition. His Air Carrier has made changes to their MEL Computer program to block issuing deferrals that would be in conflict with other sections of their MEL. They have also added a 'Note' item in the MEL section for the IDG deferral that the 3A-Hydraulic Pump must be operational.



Synopsis: A Maintenance Controller reports that MEL 24-11-1a and 24-11-1b instructions for an IDG deferral on a CRJ-200 aircraft does not state Electric Hydraulic Pump-3A must be operational. He also describes his efforts to have the aircraft Manufacturer revise the Master MEL (MMEL) to help prevent other CRJ Operators from making the same improper deferral.