What was found
IN CRUISE AT FL 37,000 FT RECEIVED R HYD SYS PRESS AND R HYD SYS QTY MESSAGES. QUANTITY SHOWED ZERO IN RT SYSTEM. DECISION WAS MADE TO DIVERT TO DTW. LANDING UNEVENTFUL, MAINTENANCE FOUND THE RETURN LINE FROM THE RT (ALTERNATING CURRENT MOTOR PUMP (ACMP) CRACKED AT B-NUT. VERIFIED SYSTEM WAS EMPTY AND INSTALLED TEMPORARY FLEX LINE (P/N 00255030499). AFTER SERVICING SYSTEM FOUND RT ACMP WITH CAVITATIONS AT 1230 PSI. REMOVED AND REPLACED AC HYDRAULIC PUMP 55-2911-9-0013 S/N OFF 56289 AND ENGINE DRIVEN PUMP 55-2911-9-0016 S/N OFF 58288.