EMB ERJ 145 ER/LR
Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Confusion; Situational Awareness; Troubleshooting
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Landed in Emergency Condition; Flight Crew Overcame Equipment Problem; Flight Crew Requested ATC Assistance / Clarification
Aircraft
Earlier in the day I wrote up the airplane for a pack 2 overheat. We were flying an airplane with an MEL on pack 2. We were cruising at FL250 about 90 miles north of our destination when we got a red 'bleed 1 leak' warning message on EICAS. I notified ATC that I wanted an immediate descent to 10;000 ft. for a bleed leak. The FO (First Officer) handed me the QRH and we began the descent and notified the FA (Flight Attendant) to take her seat because hot air was going somewhere it shouldn't and that we would call her back. I began to run the QRH. ATC gave us FL200 as the initial descent. He asked if I was requesting priority handling; I said YES. He asked for clarification on what a bleed leak meant for us and gave us 10;000 ft. subsequently. Our initial descent rate was about ~3500 fpm; faster than normal; to get out of the icing conditions and closer to a safer pressure altitude. I ran the QRH as written until I reached END. Once I finished running the QRH and put it back in the storage cubby; we began to breathe a sigh of relief that things are probably going to be okay. I directed the FO to slow the descent rate to ~1000 fpm. We were at about 16;000 ft. by this point. The FO then pointed out to me that cabin pressure dropping as indicated by the amber boxed Cabin Alt reading on the EICAS. Cabin altitude was at roughly 9;800 ft. and climbing. We elected to keep pace down to 10;000 ft. in order to get in front of the reducing cabin pressurization. The checklist list was not written with a pack 2 MEL in mind. I began to realize the ramifications of what I had just done by turning off Bleed 1; Pack 1; and closing the cross-bleed switch.The priority handling request with ATC and the events we had just gone through had my mind racing from adrenaline. I decided that 'worrying' about the pressurization system wasn't necessary. We were at 12;000 ft. and descending and if I recall correctly cabin pressure differential was about 2.2 psid. I decided to press dump on the cabin pressurization controller after looking over at the FO and mentioning that pressing the dump button wouldn't harm anything and that we weren't in dangerous territory as far as what happens if I press it. We felt a minor pressurization change as the airplane equalized. In hindsight; this was entirely unnecessary. I should have simply let the airplane depressurize on its own.I then began to evaluate how much fuel our descent to 10;000 ft. would burn instead of being at FL250. It took a minute for the FMS to catch up to the descent we had done. The initial fuel numbers it gave us led me to believe we would be very close to divert. I gave it some time and the numbers got more accurate for fuel calculations. I determined we had no need to divert on account of fuel. I notified dispatch; ATC; and the FA that the urgency was over and we would continue to our destination.Next; the airplane began to get hot and stuffy. One consideration was diverting to the nearest airfield. I didn't want to have a heat casualty in the back. The other was to get air into pack 1 so that it was useful in cooling the cabin. I looked at the overhead panel and discussed with my FO the notion of starting the APU to feed pack 1. This was a risky decision because if the leak was closer to pack 1 then feeding APU bleed air into the system would induce basically the same situation. I figured that I could simply turn the APU back off if that turned out to be the case. I figured the air and pressure coming from the number 2 bleed was hotter and higher pressure than the APU. The checklist had given me the steps to solve the problem perfectly if only my number 2 pack weren't MEL'd. I had a short mental struggle with my decision to do something that contradicted what the checklist had just made me do a few minutes earlier and really felt strange using Captain's authority to bypass it. I pride myself on checklist discipline and following the books as best I possibly can. In hindsight; I think alittle thermal discomfort and more rigidity with regards to the checklist would have been wise.I selected auto on the cross-bleed switch and turned on the APU and fed the number 1 pack. The airplane cooled down inside. I spoke with the flight attendant once more to ask about the faces of the passengers and if anyone knew about what just happened. She said they didn't have any idea and that we would keep it that way. We shot an ILS approach and landed normally.This situation was a learning experience of the highest caliber for me. I have since re-learned how the cross-bleed switch logic works. I have studied the layout and function of the bleed and pneumatic systems and learned much more about airplane pressurization. Pressing dump was not the right decision and I wouldn't do it that way again. Selecting the recirc fan off to bring in fresher air would have been a better choice than turning on the APU.
EMB-XRJ Captain reported running QRH procedure of number 2 ACM failure.