Date: 201212
Location: ZZZ.Airport, US
Flight conditions: VMC
Aircraft: EMB ERJ 170/175 ER/LR
Operator: Air Carrier
Operating under: Part 121
Mission: Passenger
Flight phase: Cruise
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Aircraft component: Hydraulic Main System
Component problem: Failed
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Second reporter function: First Officer; Pilot Not Flying
Anomaly: Aircraft Equipment Problem Critical
Detector: Automation Aircraft Other Automation; Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Flight Crew Diverted; Flight Crew Landed As Precaution; General Declared Emergency
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: During Cruise at FL370 we got the cyan 'Hyd 2 Qty low' massage. I pulled up the Hydraulic page on the MFD and we were showing 0 quantity and 2;600 PSI. All other indications were normal at that time. I monitored it for a few minutes and saw that the pressure in system 2 was dropping a few hundred PSI then stabilizing and then dropping some more. I handed the aircraft over to my First Officer and started looking at the Hydraulic Low Press 1 (2) QRH in anticipation of the pressure fully dropping off. While doing that we got the EDP 2 Fail and Hydraulic 2 low press amber massages almost simultaneously. The EDP 2 Fail was transient. I ran the Hydraulic 2 Low press QRH which called for turning on the Electric Hydraulic 2 pump. Once it was on the Low Press message extinguished and we were showing 16-1800 PSI on the system. With the light out the checklist was complete. With 0 qty and only about 50 percent of normal pressure in the system I assumed it was not going to hold and started preparing to run the Loss of Hydraulic 2 QRH. I contacted Dispatch and Maintenance Control and Maintenance had me push the EDP 2 shut off valve I assume just in case the leak was in the pump some fluid would be saved. But at 3;000 PSI I would say the fluid was long gone. We looked at PIT and CMH for a diversion and settled on CMH. We declared an emergency and had Dispatch notify CMH that we would need to be towed to the gate. At that point I contacted the flight attendants on the interphone and notified them of the situation and that I was going to have them brief the passengers and that I would first speak with passengers about the situation. I had them brief the passengers and later notified the flight attendants that I was not going to have them brace; knowing since they were briefed I could always command a brace on the PA if there was a need later. I took the aircraft back on the decent around 3;000 feet and performed the landing. The landing was uneventful. The ARFF guys inspected the brakes and we shut down on the runway and were escorted in by airport ops under tow.


Second narrative: We were cruising at FL370 when we got the Cyan 'HYD 2 Qty low.' The Captain was PF and I was PM at the time of the message. He pulled up the Hydraulics page and we watched the last of the quantity go to 0 in about 2 seconds with about 2;450 PSI; and then an amber x cover the EDP 2. He gave me control of the aircraft and he grabbed the QRH in anticipation of the failure messages. We then got an EDP 2 Fail and HYD 2 Press low messages now at 1600-1800 PSI. He ran the QRH and started communication with Dispatch and Maintenance via ACARS and radio. I continued on course until we decided on ZZZ as the best point of diversion for us as our destination was not a suitable airport for us to land. He continued to communicate with Maintenance and Dispatch and I let ATC know we needed to divert to ZZZ and we got turned around and started down. We were pretty high so I expedited the descent. We decided to declare an emergency on the descent. The Captain briefed the flight attendants and the passengers. The flight attendants briefed the passengers as well; prepared the cabin; and did a great job controlling the cabin for the situation. He briefed the approach and at about 3;000 feet the Captain took the controls and I ran the Loss HYD 2 checklists. We landed safely without issue stopped on the runway as we had no nose wheel steering. CFR checked out the aircraft all looked clear. We shut down and were towed to the gate via airport escort. Where another plane was waiting for our immediate reload of passengers and departure. Even though all worked out and it turned out uneventful; I have to say this was an unreasonable expectation of the company after working through this emergency procedure.


Synopsis: EMB175 flight crew experienced a Hydraulic 2 low quantity at FL370. After complying with QRH procedures the crew diverted to a suitable airport for an uneventful landing and tow to the gate.