Date: 201209
Local time of day: 1201-1800
Location: ZZZ.ARTCC, US
Flight conditions: VMC
Light: Daylight
Aircraft: EMB ERJ 145 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: Hydraulic System Pump
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Anomaly: Aircraft Equipment Problem Less Severe
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 Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: This was the first flight of the day for us. We took the aircraft from a crew and as usual I looked through the logbook for past entries; and noticed Hydraulic System 2 had been serviced earlier that morning. Checking the aircraft systems I had noticed the Hydraulic System 2 quantity at about 50%; but as this is within limits I did not feel it warranted calling Maintenance. We departed normally; and at top of climb I again checked the systems and noticed the Hydraulic System 2 quantity was much lower than before; yet still in the green range. I kept the Hydraulic System Page up on my MFD to monitor it. After just a few minutes the indicator slowly moves to the left (towards empty) and into the amber range; and we see a HYD 2 LO QTY on the EICAS. The QRH directs us to monitor the quantity and not use the speed brakes. We (First Officer and I) discuss the situation and go over the QRH for the Hydraulic System 2 failure; in the event that becomes necessary. I send a text message to Dispatch; and get no reply; and send another. We discover that ACARS can receive messages; but not send them; I later learned this was part of a widespread outage. I handed over control of the aircraft and communications with ATC to the First Officer; and proceed to contact Dispatch via radio. We discuss the issue; and also speak to Maintenance Control. We all agree diversion is the best course of action; that there is likely a leak in the hydraulic system somewhere. I elect to divert to a nearby airport since it is only approximately 120 miles away; and has excellent facilities; emergency equipment; and passenger handling ability. I brief the Flight Attendant that we are about 25 minutes from landing. I also make a PA to the passengers advising them of our diversion. Since the hydraulic quantity 2 indicator is now at the bottom of the indication range; we now expect to lose that hydraulic system at some point and again brief the QRH; noting that the QRH directs us to keep the airspeed under 250 KIAS. In coordination with ATC we keep the airspeed under 250 KIAS during the descent into our divert airport; again anticipating losing Hydraulic System 2. We contact Operations and arrange for a gate on arrival. Descent and approach are uneventful and normal. We request an approach to the longest runway at the airport. Our calculations per the QRH indicate we would only need about 4;000 FT anyway; but we choose the longest runway to maximize safety. At this point we still see only HYD 2 LO QTY; and both systems are still operating. We did not declare an emergency. Landing was normal; however we did see a HYD 2 SYS FAIL upon touchdown; which cleared several seconds later. We taxi to the gate; and park normally. Landing was well under Maximum Gross Landing Weight (MGLW). We perform some troubleshooting steps with the Contract Mechanic; who first refills the system with hydraulic fluid; then has us turn on the electric hydraulic pump and finally the engine; to test the system. He indicates the engine driven hydraulic pump is leaking badly. I visually saw hydraulic fluid dripping from the engine nacelle and pooling on the ground after the troubleshooting. I felt we identified and dealt with the threats very well. In retrospect declaring an emergency may have been a good idea.




Synopsis: EMB145 Captain notes Hydraulic System 2 at 50% during preflight; which is acceptable; and departs. Upon reaching cruise altitude the quantity is noted to be significantly lower; followed shortly by a HYD 2 LO QTY on the EICAS. The crew elects to divert to a suitable airport and is able to land before the system fails. Maintenance finds a significant leak at the engine driven hydraulic pump.