Date: 201907
Local time of day: 1201-1800
Light: Daylight
Aircraft: EMB ERJ 170/175 ER/LR
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Climb
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Aircraft component: Pressurization System
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Human factors: Situational Awareness; Time Pressure; Troubleshooting; Workload
Anomaly: Aircraft Equipment Problem Critical
Detector: Automation Aircraft Other Automation; Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Air Traffic Control Provided Assistance; Flight Crew Landed in Emergency Condition; Flight Crew Returned To Departure Airport; General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: Leveled at FL320 during climb to cruising altitude of FL340 en route from ZZZ to ZZZ1. We received a CABIN ALT HI EICAS while climbing through FL330. After cancelling the MASTER WARNING the FO (First Officer) and I donned our oxygen masks and established communication. No abnormal sounds prior to alert. The FO called for the QRC and we initiated the emergency descent per the procedure. During the descent back through FL330 the cabin altitude was approximately 8;800 ft. I wanted to confirm it was descending; or at least under control; to confirm it was more than likely a leak and not an explosive decompression. Prior to EICAS message climb pressurization seemed normal; all indications in the green. CABIN ALT typically around 6;900 ft. in the low FL300s. I contacted Center and informed them we had a CABIN ALT HI alert; we needed an immediate descent to 10;000 ft.; we needed vectors back to ZZZ. We were given present heading and a descent to FL240. After finishing the QRC we moved to the QRH and began those procedures. The FO remained on the controls so that I could better manage the emergency procedures.About this time we received an EMERG call from the cabin. The FA (Flight Attendant) informed us that the masks had dropped and asked what to do. I said we had received a CABIN ALT HI and were descending now to thicker air. I said to tell the passengers to put the masks on and breathe normally. I looked up to confirm that the PRESSURIZATION and PASS OXY switches were both in AUTO and they were. We were given subsequent descents to FL180 and then 10;000 ft. with vectors for a turn back to ZZZ. During this time I made an initial PA informing the passengers to breathe oxygen from the masks; that we were returning to ZZZ and that the aircraft was under control. We also received a message from Dispatch asking about the situation. Dispatch then sent new performance numbers for the return flight and Amendment 1 to our release for return to ZZZ. They also asked if there were any injuries.At this point we had leveled at 10;000 ft. The Cabin Alt was reading 0. For ease of communication the FO and I removed our masks and stowed them. Due to the low Cabin Alt and our 40 min plus flight back I decided to not to press the DUMP button in order to keep the PACKs running and the CABIN ALT low. No structural damage was suspected. QRH actions were complete.I called FA back and asked about injuries; the general state of the passengers; asked about any noticeable structural issues and to confirm that the LAVs were clear per the QRH. The FA confirmed the LAVs were clear; no injuries and that the passengers were mostly doing pretty well; but that one woman seemed very excited and was concerned about seeing her children. He asked about whether the passengers should keep the masks on; as some of them seemed to be running out; and I said to keep them on for now; but that I would advise. I relayed the injury information to Dispatch and told them no emergency medical was required at the gate at this time. I made a 2nd PA to the passengers explaining that we believe we received the alert due to a faulty seal; told them again that the aircraft was under control; apologized for the excitement and said that we would be back at ZZZ in approx. 30 min. Third PA made telling passengers to remove masks as we were in thicker air and to prepare for a normal landing in approx. 20 min. Approach vectored us for the ILS XXL at ZZZ. We had previously relayed our FOB (Fuel on Board) and SOB (Souls on Board) to ATC. After running the numbers we confirmed that we would be below max landing weight and would not require an additional write up for that. We had 75 PAX (Passengers) and were above MLDW (Maximum Landing Weight) at takeoff. We informed ATC that we would not need to stop on the runway and should be able to land normally and taxi in under our own power. Previous ATC comms led us to believe they were coordinating for us to stop on the runway. I made another PA to the passengers telling them to expect a normal landing and to remain seated and buckled in after landing. I contacted the FAs and told them to expect the same and that no brace calls were needed. After we were on a long base to final I took controls in the left seat. Normal landing. CFR (Crash Fire Rescue) was standing by but not needed. Taxi and parking normal.Before speaking to Dispatch I left the flight deck and personally ensured all of the passengers were deplaned safely and properly and that no injuries had occurred that I was not tracking. All 75 walked off plane and seemed in remarkably good spirits overall. I spoke to dispatch and the pilot on duty to inform them of the situation.I wrote in the logbook CABIN ALT HI EICAS AT 330. ALL PAX MASKS DEPLOYED. NO AURAL INDICATION. CAB ALT APPROX 8;800 AT 320 IN DESCENT. MASKS DEPLOYED AUTO. The FO contacted [Maintenance Control] on the phone. I went down to the ramp to visually inspect the vent flap on the FWD E-BAY with a Mechanic. He mentioned it had a lot of play when were first spoke to them after landing. Vent flap had approximately 3/4 to 1 inch of play upward and the inside of the E-BAY was just barely visible. Other aircraft have maybe a 1/4 inch of play. Note on the aircraft: upon receiving the plane from the previous Captain he mentioned that it had a series of write-ups regarding the CABIN ALT climbing to 8;700 then back down to normal around FL220 accompanied by a thumping or hissing sound. Ref. the logbook on [dates] and prior. Troubleshooting had previously led to a realignment of the FWD E-BAY vent flap door; a replacement of FWD E-BAY seal and the manual SOV (Shut-Off Valve) for the LAV being adjusted. Aircraft had been released back to flight following episodes. The write-up out of ZZZ3; signed off on [date]; involves a similar incident to ours; but occurred at FL220. I believe the vent flap fluttering in the wind maybe the source of the noise and the leak. Prior to his initial preflight I asked the FO to pay special attention to the areas affected by the troubleshooting. He saw nothing obviously abnormal; but we also never manual check the play in that vent flap.Actions and CRM by FO and FAs were commendable. Very calm and professional reaction to abnormal situation.




Synopsis: ERJ-175 Captain reported a loss of cabin pressure during climb out; resulting in an emergency descent and a return to the departure airport.