Date: 201511
Local time of day: 0601-1200
Location: ZZZ.ARTCC, US
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: Pneumatic Valve/Bleed Valve
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness
Anomaly: Aircraft Equipment Problem Critical
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Flight Crew Diverted; Flight Crew Landed As Precaution; General Maintenance Action
Contributing factors: Aircraft; Procedure
Primary problem: Aircraft

Narrative: When I arrived at the aircraft; the local maintenance personnel were clearing a previous BLEED 1 MEL. I contacted dispatch and we were issued a new release with the updated MEL status - only the APU was deferred.  We departed with just the deferred APU without incident. Climbing through FL314; we got a BLEED 1 FAIL message. I requested a descent to FL310 from ATC; was issued the clearance; and we complied. Level at FL310; I gave the radios to the FO and proceeded with the QRH procedure. The procedure was successful in restoring the bleed; but having had this exact issue a few days ago; I monitored the ECS synoptic page and noticed that the Bleed 1 pressure was varying between about 10 and 50 psi. After a few moments; it failed again. I ran the QRH a second time and it was again successful; but within a few minutes Bleed 1 failed a second time. I tried the QRH procedure a third time and this time the procedure was again successful; but within maybe 30 seconds Bleed 1 failed again. I told the FO I considered it to be failed; and he concurred. Proceeding with the checklist; I was led to line 12; which asks; 'Are both bleeds affected?' At first; the answer was 'no' so we switched to the original flight plan (at FL310) to check fuel and notified dispatch via ACARS. Everything was fine; but then Bleed 2 started to fluctuate rapidly between 9 and 50 psi; just like Bleed 1 had done before it failed. I looked at the QRH procedure for 'both bleeds are affected' and it has you start the APU and descend to 15000 feet. We could not start the APU since it was deferred; so I called dispatch. I explained the situation and asked to speak with a maintenance controller to ascertain if the cycling pressure on Bleed 2 meant it was 'affected.' We agreed that it was. This led us out of the checklist; because there is no procedure for both bleeds affected AND no APU (at this point; I was formulating a plan in my head and I asked the FO to ask ATC for speed at our discretion. ATC issued the speed our discretion clearance and I asked the FO to slow down so we could 1- conserve fuel if need be and 2- not get further away from ZZZ) I told dispatch and maintenance that I suggested we divert to ZZZ. It was about 80 NM behind us and the grid MORAs from our present position to ZZZ were acceptable in the event of a depressurization. There was some discussion; a chief pilot was conferenced in (I can't remember who it was) and I briefed him on out situation. He agreed with my assessment that a diversion to ZZZ was the safest course of action. Dispatch concurred and sent us weather and NOTAMs to the flight deck printer and advised that a release amendment for ZZZ was on the way via ACARS. I briefed the FO and with both of us up to speed; I advised ATC of our situation and requested the diversion to ZZZ. From our present position near the ZZZZZ intersection we were cleared direct ZZZZZ1 and the ZZZZZ2 6 RNAV arrival; runway 8 transition. I again divided the duties; giving the FO the aircraft and the radios; and I briefed the FAs. I then briefed the passengers and completed the in range duties. Around this time the amendment came and I amended the release to show ZZZ as our destination. With all of this complete; I took back the radios; we briefed remainder of the arrival and the approach; and landed uneventfully in ZZZ. I then called maintenance; and they suggested I write up both bleeds separately; which I did; followed by deferring them each separately. With this complete; I asked Dispatch for an update and were told an aircraft was being re-positioned from ZZZ1 for us to continue. I also spoke with the duty manager who made it clear that everyone thought I made the right call and that he was glad everything was OK. Eventually the replacement aircraft arrived and we departed without further incident.




Synopsis: EMB175 Captain reported being dispatched with an inoperative APU after having a previous BLEED 1 MEL repaired prior to departure. While enroute BLEED 1 fails again and resets are only successful for short periods of time. The ECS synoptic is checked and BLEED 2 exhibits the same fluctuating pressure as BLEED 1 did before failure and; with no APU; the crew elects to divert to a suitable airport.