What was found
ON TAKEOFF AT GEAR RETRACTION, A POP WAS HEARD FOLLOWED BY (L) HYD, LOW CAS( L), HYD PUMP FAIL, PTU FAIL, AND RT HYD OVERTEMP. CHECKLIST FOLLOWED. GEAR BLOWN DOWN AND LANDED UNEVENTFULLY. ALL CAS OCCURED WITHIN 3 MINS. FOUND NOSE RETRACT LINE RUPTURED. REPLACED BOTH PRESSURE LINES BOTH ENGINE DRIVEN HYD PUMPS, PTU, SYS A & B PRESSURE & RETURN FILTERS. SYSTEMS FLUSHED. LEAK & OPS CHKS OK. IAW MM 29-10-00, 29-10-08, 29-20-04, 29-10-02, 32-30-00, & 32-00-01.