What was found
HYDRAULIC SYSTEM 2 QUANTITY DROPPED TO 0 DURING FLIGHT. ALTERNATE GEAR EXTENSION HAD TO BE USED TO BRING GEAR DOWN (FLIGHT 6185) REF AML 1955743, REF AML 1955766, REF AML 1955767. UPON ARRIVAL INSPECTED HYD SYS NR 2 & FOUND HYD TUBING ASSY RETURN LINE, T/E, RT SLEEVE CRACKED. R & R HYD SYS NR 2 TUBING ASSY RETURN LINE IAW AMM 29-10-10. NO LEAKS NOTED. ACFT RTS.