On November 5, AAL121, a Boeing 757 enroute to JFK, encountered a hydraulic problem that forced the flight to declare an emergency. The flight landed at JFK without incident. The attached audio picks up at a point where the flight has checked in on ZBW 126.22 at FL380. It appears that this problem occurred while on this frequency although that portion of the recording was not captured (feed radio was probably on another frequency at the time).
http://flightaware.com/live/flight/AAL121/history/20151105/1135Z/LFPG/KJFK
