Gulfstream IV / G350 / G450
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Critical
Flight Crew Diverted; Flight Crew Landed in Emergency Condition; General Declared Emergency; General Maintenance Action
Aircraft
When the landing gear handle was lowered for landing; the landing gear didn't move and we got LH Hydraulic low quantity and fail amber CAS messages. We consulted the appropriate checklist and blew the gear down. The mains indicated down and locked but the nose gear did not. I called company and [we decided to] divert to ZZZ. We ran through checklists; consulted with ACP; Maintenance and the Manufacturer. We tried alternate procedures provided by the Manufacturer but the nose gear still indicated not down. We performed fly bys at both airports and gear appeared to be down but the taxi light on nose gear did not illuminate. When all options were exhausted we decided to land with the concurrence of all. FA had been kept in loop and he did a GREAT job with [passengers.] I went aft and briefed the passengers. We then landed without problem but since the nose gear wasn't [locked] down couldn't pin gear. Eventually; the over center strut was forced into position manually and the gear was pinned. We were then able to taxi to parking without assistance. The passengers deplaned normally.Past training was a big help but you are never totally ready for something like this. The First Officer did a great job in right seat.
A G-IV diverted to an airport with a longer runway when the nose gear failed to give a down and locked indication. They landed without incident at the diversion airport but found the overcenter strut had failed to correctly position itself. A pin was inserted after forcing it overcenter and the aircraft was taxied to parking.