Narrative:

At cruise FL370 experienced loss of 'rt hydraulic system' quantity (fluid). Accomplished QRH procedures; declared emergency; returned to departure airport. Overweight landing (199;200 pounds). Airport rescue and fire fighting responded and followed to gate. Aircraft has history of 'rt hydraulic system' quantity depletion. Uneventful approach and landing.

Google
 

Original NASA ASRS Text

Title: B757 Captain experiences RT HYD SYS failure at FL370 due to fluid loss. Crew declared an emergency and returned to their departure airport for an overweight landing.

Narrative: At cruise FL370 experienced loss of 'RT HYD SYS' quantity (fluid). Accomplished QRH procedures; declared emergency; returned to departure airport. Overweight landing (199;200 LBS). Airport rescue and fire fighting responded and followed to gate. Aircraft has history of 'RT HYD SYS' quantity depletion. Uneventful approach and landing.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.