An HS125 nose landing gear froze in the uplock during a flight which originated in wet rainy weather and terminated in very cold weather. The gear was ultimately released by high G force maneuvers.

Narrative

After the Captain called for 'gear down' on the ILS approach to Runway 23; I selected the landing gear down. I knew right away by the sound that the nose gear did not deploy. I verified with the primary and secondary indicating systems that the nose gear in fact did not come down. I advised the Captain and we executed a missed approach and declared an emergency. We diverted to a much larger nearby airport and ran the checklist procedure. On the way (33 NM away) we attempted to use 'G force' to lower the nose gear with no avail. The nose gear still did not come down. We cycled the landing gear approximately 15 times on the way. After coordination with maintenance the Captain opted to do a 'touch and go' to see if that would 'knock the gear down.' This procedure did not work. After the go around we obtained a block altitude from 3;000 to 6;000 FT. The Captain once again attempted to use 'G force' to lower the nose gear. He used an approximate 3-4 G pull up and the nose gear finally came down. Due to weather and maintenance considerations we returned to our original destination and had no further complications. Factors to this nose gear issue include the wet and icy conditions encountered in previous legs that day. The prior leg in Florida included flying through some light rain showers. Due to the temperature and lack of precipitation at the airfield we did not cycle the gear on departure. This may or may not have prevented this from occurring. The almost two hours at altitude gave sufficient time for freezing to happen. Icing conditions also existed at the landing field. In conclusion; professionalism; flight deck discipline and outstanding air traffic control prevented this from being a gear up landing.