What was found
HYD 1 LOW QUANTITY IN FLIGHT, QTY REMAINED STABLE BUT LOW FOR 45 MINUTES. ENGINE 1 HYD PUMP FAIL IN FLIGHT ASSOCIATED WITH LOUD SQUEAL NOISE REPORTED BY F/A IN REAR CABIN. CREW DECLARED EMERGENCY AIRCRAFT LANDED SAFELY. RAI EMERGENCY/PARKING BRAKE THERMAL RELIEF VALVE, OPS CHECK GOOD IAW EMB145 AMM 32-44-06, RETURNED AIRCRAFT TO SERVICE. (M)