AN LJ35 ENCOUNTERED ICING CONDITIONS SHORTLY AFTER TKOF AT BJC; RESULTING IN CTL DIFFICULTIES. THEY DIVERTED TO COS AND LANDED SAFELY.

Narrative

DEPARTING ZZZ; THE R-HAND GEAR UNSAFE LIGHT REMAINED ILLUMINATED AFTER GEAR RETRACTION; ACCOMPANIED BY A LOUD RUMBLING NOISE. LEVELING AT OUR INITIAL ALT OF 8000 FT IN THE R-HAND TURN TO HDG 150 DEGS; THE ACFT BEGAN PITCHING AND STALL WARNINGS ACTIVATED. I INTENDED TO TURN ON NACELLE AND WING HEAT ONCE AIRBORNE BUT WAS DISTR BY THE GEAR AND ACFT CTL PROBS. I WAS REMINDED TO ACTIVATE ANTI-ICE SYS BY THE APPEARANCE OF ICE ON THE WINDSHIELD ABOUT 2 MINS INTO THE FLT. I INCREASED PWR AND REQUESTED HIGHER ALT TO GET ON TOP OF THE OVCST. SUBSEQUENT MANEUVERING RESULTED IN APCHS TO STALLS. APCH; CENTER; AND ZZZ1 TWR ASSISTED US BY PROVIDING VECTORS AND ALTS TO KEEP US CLR OF TERRAIN; TFC; AND FURTHER ICING CONDITIONS. AFTER EXPERIMENTING WITH DIFFERENT AIRSPDS AND FLAP SETTINGS WE SUCCEEDED IN GETTING THE ACFT SAFELY BACK ON THE GND AT ZZZ1. A POSTFLT INSPECTION BY THE FLT CREW AND A REPRESENTATIVE OF ZZZ1 ARPT OPS REVEALED A LARGE AMOUNT OF ICE BUILD-UP ON THE R-HAND GEAR DOOR AND TIP-TANK TIPS. PRIMARY AND SECONDARY FLT CTLS WERE ICE FREE.