Date: 202109
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: EMB ERJ 170/175 ER/LR
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Aircraft component: Indicating and Warning - APU
Component problem: Failed
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Human factors: Communication Breakdown; Troubleshooting
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural MEL / CDL; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Automation Aircraft Other Automation; Person Flight Crew
When detected: In-flight
Result: Flight Crew Requested ATC Assistance / Clarification; General Maintenance Action
Contributing factors: Manuals; Aircraft; Chart Or Publication; Procedure
Primary problem: Procedure

Narrative: Prior to departure we briefed the multiple MEL/CDL (Configuration Deviation List)/NEFs (Non-Essential for Flight) on file for this aircraft including MEL XX-XX-XX AUXILIARY POWER UNIT. While the Form sticker said BLEED APU LEAK; the APU as a whole was deferred; so we briefed and followed the procedures for MEL XX-XX-XX as opposed to MEL YY-YY-YY (which was not listed). While in cruise at approximately XA50Z the EICAS displayed caution message BLEED APU LEAK while the APU was inoperative; off and the APU BLEED button was pushed OUT. MEL XX-XX-XX makes no mention of BLEED APU LEAK being an expected EICAS message but the QRH procedure did not make sense to me in this situation. My FO (First Officer) and I decided together it would be best to contact Maintenance for further insight; so I transferred the radios and flight controls to the FO and proceeded to contact dispatch via ARINC (Commercial Radio) at around XA53Z. After a normal exchange with ZZZ1 Radio and patching into our Dispatcher I requested to talk to Maintenance and the Dispatcher responded that 'Maintenance would not talk to me in flight and to follow the QRH' even after insisting several times. We proceeded to follow the remainder of the QRH and had to descend to FL300 and continue the flight with single bleed. Upon arrival into ZZZ2 I made the appropriate entry into the AML (Aircraft Maintenance Logbook) for a BLEED APU LEAK EICAS caution message. In my opinion this was a complete breakdown in CRM between the flight crew and Dispatch/Maintenance. I accept responsibility if this MEL was incorrect and should have been YY-YY-YY; but if that is the case; it has been incorrect for 10 days worth of flights. When I saw the APU deferred as a whole I considered that an acceptable solution to an APU Bleed leak; however there is no mention in XX-XX-XX of any special procedure for BLEED APU LEAK EICAS message. Furthermore; I do not have the full information in flight as to why the APU was deferred as opposed to the APU BLEED over a week prior to this event. I believe our decision to contact Maintenance for further guidance via ARINC was sound; and if they had simply answered our call for help we could have avoided descending to FL300 with a single bleed/PACK. There are numerous examples of NTSB accident reports where a safer outcome was achieved thanks to the pilots communicating with Maintenance while in flight; and throughout my training with Company I have always been trained to use all resources available. While I do not know whether Dispatch refused to talk to Maintenance or Maintenance refused to talk to me; I strongly recommend this practice of not allowing pilots to contact Maintenance during irregular situations in flight cease immediately.




Synopsis: EMB-175 Captain reported not finding a QRH procedure for an EICAS caution message and confusion over an associated MEL. The crew requested communicating with maintenance but was denied assistance while in flight.