What was found
NLG FAILED TO EXTEND DURING NORMAL OPERATIONS DURING TRAINING FLIGHT. FLIGHT CREW PERFORMED EMERGENCY LANDING GEAR EXTENSION PROCEDURES; NOSE GEAR EXTENDED AND LOCKED. FLIGHT CREW PERFORMED NORMAL LANDING WITH NO FURTHER DIFFICULTY. MX PERSONNEL INSPECTED ACFT AND FUNCTIONALLY CHECKED LANDING GEAR RETRACTION/EXTENSION SYS. MX FOUND CRACKED HINGE ON 1 NOSE GEAR DOOR WHICH CAUSED THE DOORS TO JAM IN THE CLOSED POSITION.