2025-09 · NASA ASRS report 2285804
Air carrier flight crew reported experiencing a master caution for the #2 hydraulic system pump resulting in the flight diverting to an alternate airport where they landed safely.
This flight was the first serious flight issue I have encountered in my career. We were flying when we got a master caution and had a #2 engine hydraulic pump low pressure light. I handed the aircraft and radios to the PF (pilot flying) and started to run the QRH procedure. We checked the systems page and saw that #2 Hyd was showing low pressure and 106 on quantity. We turned off the #2 pump per the procedure and started talking about diversion airports should the need arise. The weather was coming into our first alternate and we were picking up turbulence and icing; all while relaying info to ATC so we were a bit task saturated. The Electric pump seemed to be handling the job no problem. A few moments later; the electric pump showed low pressure; we again looked at the systems page and noticed the quantity was now at 0. We decided to request priority handling and proceed to an alternate that we agreed would be best with Dispatch concurrence. On the way to the diversion airport; I started running the Loss of system B QRH procedure. I went back to check my initial work and noticed I had missed a step. In scrolling through my iPad I accidently scrolled to the System A checklist. While running it I accidently turned off the wrong system flight control switch; we quickly caught the error and returned the flight control switch; that is when I realized I scrolled too far and was on the wrong checklist. I proceeded the correct checklist and turned off system B and we continued the flight with no issues. Cause: I would say; slow down; take a deep breath and remember training. Make sure we are both on the same page with each other; as I said we did get a little task saturated. I think that it would have been better to keep flying the aircraft and hold off on ATC until we both could go through the checklist more thorough.
We were getting vectors around ZZZ airspace due to a thunderstorm putting ZZZ into a ground stop. While getting vectored and looking at divert fields; we got a master caution with the #2 engine driven hydraulic pump low light. I took the radios and the aircraft while the Captain ran the QRH. The systems page showed that the quantity was at 106 and pressure was holding steady at 2950-3000 psi. After the completion of the checklist; we decided on ZZZ1 as an alternate in case we would need it and got dispatch concurrence. Shortly after; the #2 electric driven hydraulic pump low light illuminated. On the systems page we now had a quantity of 0 and a pressure rapidly falling to 0. We requested priority handling and diverted to ZZZ1. I ran the radios and flew the airplane while Captain ran the QRH. Shortly after this the Autopilot clicked off in the turn. After a Quick Look over; the Captain realized that he had shut off the wrong system flight control switch. He turned it back on and turned off the correct one. After analyzing; he said he scrolled too far forward to the incorrect checklist step; and after turning the flight control switch back on; and turning off the correct one per the correct checklist; the flight ended with no further issues.Cause: We were navigating through a quickly passing thunderstorm with icing and running a checklist we don't often see while also diverting. There were several things going on at once and we were quickly arriving to our new destination airfield. We felt like we didn't have time since that thunderstorm was moving quickly to our alternate but in reality we had more time than we thought. I would suggest next time that we slow down; even read the checklist entirely first before running any steps and before each step make sure it made sense. I have been on other aircraft and have seen other pilots run the incorrect checklist before and about halfway through someone says hey that doesn't really make sense. So just slow down and realize you have more time than you think you do in most scenarios.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.
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