What was found
FDR WAS REMOVED FROM THE ACFT TO INVESTIGATE AN UNCOMMANDED TORQUE INCREASE, AND AT THAT TIME IT WAS DETERMINED THAT THE FDR HAD BEEN UNSERVICEABLE FOR 111 HRS WITHOUT TURNING ON THE FDR FAIL LIGHT. LIGHT WAS DETERMINED TO BE SEVICEABLE. THE MOST RECENT DATA FOUND ON THE RECORDER WAS FROM ACFT 303 JAN 25, 2010. THE FDR WAS ON ACFT 855 FROM MAY 11 TO MAY 29 APPARENTLY UNSERVICEABLE THE ENTIRE TIME WITHOUT TURNING ON THE FDR FAIL CAUTION LIGHT.