THE RPTR'S AUTOPLT TRIMMED NOSE UP ON THE DSCNT SO THAT AFTER LEVELING AT THE ASSIGNED ALT THE ACFT POPPED BACK UP 1000 FT WHEN THE AUTOPLT WAS DISCONNECTED. ALTDEV ALT EXCURSION.

Narrative

SAME AUTOPLT THAT WAS WRITTEN UP ON AN ASRS FORM DATED FEB/XX/95. LEVELING OFF AT FL290 USING THE AUTOPLT PITCH CTL; THE PF TRIMMED NOSE UP. AFTER THE INPUT; HE AND I BOTH NOTICED THAT THE TRIM CLICKER WAS STILL AUTOPLT ACTIVATED. THE ACFT HAD BEEN TRIMMED TO AN ATTITUDE OF MORE THAN 5 DEGS NOSE UP. THE PF THEN TRIED TO TRIM NOSE DOWN IN AUTOPLT MODE WITH NO RESPONSE. HE THEN DISCONNECTED THE AUTOPLT AND TRIED TO TRIM NOSE DOWN AND AFTER A FEW SECONDS THAT ACFT RESPONDED. BY THIS TIME THE ACFT HAD CLBED TO 1000 FT ABOVE OUR ASSIGNED ALT. WE CORRECTED TO OUR ASSIGNED ALT AND HAND FLEW THE ACFT THE REMAINDER OF THE TRIP. ONCE ON THE GND; I WAS ABLE TO DUPLICATE THE MALFUNCTION. THE SWITCH USED FOR PITCH TRIM IN THE AUTOPLT WILL OCCASIONALLY JAM AND WILL NOT DISCONNECT EVEN WITH THE SWITCH IN THE NEUTRAL OR OPPOSITE POS. AGAIN; I BELIEVE THE AUTOPLT NEEDS TO BE REPAIRED OR REPLACED AND BARRING THAT; NEEDS TO BE CLOSELY MONITORED. THE ONLY OTHER OPTION IS NOT TO USE IT. I BELIEVE THE ALTDEV COULD HAVE BEEN LIMITED IF THE AUTOPLT HAD BEEN MORE CLOSELY MONITORED AND RESPONSE HAD BEEN FASTER ON THE CTLS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE FORM WAS INCOMPLETE. THE ACFT TYPE WAS A LEAR 25 THE RPTR SAID. HE COULD CAUSE THE STICKING PROB TO OCCUR ON THE GND BUT MAINT COULD NOT. FINALLY; AFTER A COUPLE OF MONTHS THE AUTOPLT PROB WAS ADDRESSED AND CORRECTED.