A CANADAIR CL-65 ON DSCNT AT FL250;290 KNOTS HAD LEFT FLT SPOILER DEPLOY CAUSING QUICK L WING DIP. THEN SUDDEN SHARP R ROLL.

Narrative

DURING DSCNT I HAD THE ACFT ON AUTOPLT. AROUND FL250 AND 290 KTS THE ACFT'S LEFT WING DIPPED QUICKLY. THE ACFT THEN SHARPLY ROLLED RIGHT. I GRASPED THE YOKE FIRMLY SIMULTANEOUSLY DISCONNECTED AUTOPLT. I CORRECTED BY THE TIME WE REACHED 30 DEG ROLL. WHEN I ROLLED LEVEL; I SAW WE HAD A L FLT SPOILER CAUTION. NO OTHER PROBLEMS THE REST OF THE FLT. CAUTION REMAINED ON. ON GND; (IN ZZZ) ZZZ1 MAINT (ON PHONE) ASKED US TO PULL CIRCUIT BREAKERS. WE RESET THEM AND DISCREPANCY CLRED. ZZZ1 MX DID NOT THINK IT WAS NECESSARY TO SEND A MECH. IN FLT; I THINK THE LEFT SPOILER CAME UP CAUSING THE LEFT WING TO DROP. THEN THE AUTOPLT TRIED TO FIGHT IT BY ROLLING RIGHT. ANOTHER CREW WOULD FLY THE ACFT THE NEXT DAY WHERE MAINT WOULD CHECK IT AT THE NEXT STATION. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE ACFT WAS A CANADAIR CL-65 AND THE CAUSE OF THE LEFT SPOILER DEPLOYMENT WAS A FLT SPOILER POWER CTL UNIT. THE RPTR SAID THE SHARP RIGHT ROLL WAS THE AUTOPLT CORRECTION FOR THE LEFT WING DIPPING. THE RPTR STATED THE AUTOPLT WAS DISCONNECTED AND THE AIRPLANE WAS FLOWN MANUALLY WITH NO PROBS. THE RPTR SAID THE L FLT SPOILER WARNING LIGHT WAS ON CONTINUOUSLY UNTIL ON THE GND WITH MAINT CTL APPROVAL THE CB WAS RESET AND CANCELLED THE LIGHT.