When neither the dispatcher nor the captain noted the meled idg; combined with a previously noted AP...

Narrative:

Maintenance deferred the idg [integrated drive generator] on the aircraft. There was a previous MEL that stated operations could not be dependant on the APU. Looking over the MEL's at the time of deferral I discussed it with the PIC and we did not realize both MEL's would render the plane unairworthy. We amended the release with the idg deferral and the flight departed. Maintenance did not call to advise us of the deferral of the idg or discuss the issues having both MEL's on the aircraft at the same time. Looking over the previous MEL it was not clear to me that the APU could not be depended on for operations. The captain also did not realize that plane should not depart with the deferrals.we need better communication between maintenance and dispatch regarding airworthiness. I need to understand clearly what the MEL's are indicating and the performance issues that will arise when more than one deferral is on the aircraft. The MEL should be clearer with possible notes indicating that the idg's must be operative.

Original NASA ASRS Text

Title: When neither the Dispatcher nor the Captain noted the MELed IDG; combined with a previously noted APU MEL declaring it unable to provide electrical system redundancy; the flight was released with only a single source of electrical AC power.

Narrative: Maintenance deferred the IDG [Integrated Drive Generator] on the aircraft. There was a previous MEL that stated operations could not be dependant on the APU. Looking over the MEL's at the time of deferral I discussed it with the PIC and we did not realize both MEL's would render the plane unairworthy. We amended the release with the IDG deferral and the flight departed. Maintenance did not call to advise us of the deferral of the IDG or discuss the issues having both MEL's on the aircraft at the same time. Looking over the previous MEL it was not clear to me that the APU could not be depended on for operations. The Captain also did not realize that plane should not depart with the deferrals.We need better communication between Maintenance and Dispatch regarding airworthiness. I need to understand clearly what the MEL's are indicating and the performance issues that will arise when more than one deferral is on the aircraft. The MEL should be clearer with possible notes indicating that the IDG's must be operative.

Data retrieved from NASA's ASRS site as of July 2013 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.

Attributes
ACN	1097488
Time
Date	201306
Local Time Of Day	1201-1800
Place
Locale Reference	SEA.Airport
State Reference	WA
Environment
Flight Conditions	VMC
Aircraft 1
Make Model Name	Regional Jet 700 ER/LR (CRJ700)
Operating Under FAR Part	Part 121
Flight Plan	IFR
Component
Aircraft Component	APU
Person 1
Function	Dispatcher
Qualification	Dispatch Dispatcher
Events
Anomaly	Aircraft Equipment Problem Critical Deviation - Procedural FAR Deviation - Procedural MEL

When neither the dispatcher nor the captain noted the meled idg; combined with a previously noted APU MEL declaring it unable to provide electrical system redundancy; the flight was released with only a single source of electrical AC power.