CPR LTT ALT DEVIATION OVERSHOT DURING CLIMB.

Narrative

AFTER DEPARTING LUNKEN FIELD WE SWITCHED TO DEP AND WERE GIVEN HDG VECTORS; A 250 KT SPD RESTRICTION AND A CLB TO 12000'. THE AUTOPLT WAS COUPLED; AND THE MODE CONTROL PANEL WAS PROGRAMMED FOR ALT CAPTURE AND HDG TRACK. WE ENCOUNTERED MODERATE RAIN FREEZING AND TEMPS; SO ANTI-ICE WAS SELECTED. MAINTAINING 250 KTS RESULTED IN APPROX 4000' PER MIN RATE OF CLB. WE WERE GIVEN A CHANCE TO CTR FREQ. AT THAT MOMENT THE F/0 CALLED '12000' AND I SAW THAT THE ACFT WAS PASSING 12500 AND CLBING. THE ALT SELECT HAD NOT CAPTURED. I IMMEDIATELY DISCONNECTED THE AUTOPLT AND PUSHED OVER TO DESCENDED TO 12000' MSL. I ALSO INSTRUCTED THE F/O TO RPT 'DESCENDING TO 12000' TO THE DEP CTLR. HE DID SO. WE LEVELED AT THE ASSIGNED ALT AND WERE AGAIN INSTRUCTED TO CONTACT CTR. CTR GAVE US ANOTHER ALT AND WE PROCEEDED ENROUTE. ON THE PREVIOUS LEG AS WELL AS THE LEG TO FOLLOW; THE ALT SELECT CAPTURED AND THEN DISCONNECTED ON 2 LEVEL-OFFS INVOLVING DSCNT. NEITHER INVOLVED DEVIATION FROM ASSIGNED ALT. BOTH REQUIRED MANUAL LEVEL OFF. DISCUSSION WITH THIS F/O INDICATED 2 OTHER OCCASIONS ON WHICH HE HAD SIMILAR EXPERIENCES WITH THIS PARTICULAR AIRPLANE. I PERSONALLY RECALL ANOTHER INSTANCE WITH THIS SYS NEAR ORL FL; IN JANUARY; WHICH COULD HAVE BEEN ANOTHER FAILURE OF THE SAME TYPE. ACFT COMPANY ISSUED A SVC LETTER FOR 4 SPECIFIC ACFT; WHICH WHEN COMPLIED WITH; RESULTED IN WIRING SOME FMS MODES INCORRECTLY TO THE AUTOFLT SYS. THIS LTT ACFT IS SCHEDULED FOR REWIRING ON 3/TH/88 AT THE FACTORY SVC CENTER. A TEST FLT WILL FOLLOW INVOLVING AUTOMATIC LEVEL-OFFS FROM HIGH AND LOW RATES OF CLB AND DSCNT. I BELIEVE THE AUTOMATION OF SOME OF THE ELEMENTS OF FLYING HAS TAKEN THE PLT OUT OF THE 'BASIC LOOP;' AND THE HUMAN CHALLENGE IS TO NOW MANAGE THE 'ELECTRONIC ASSISTANTS' EFFICIENTLY AND SAFELY. ONE SHOULD ALWAYS QUESTION THE RELIABILITY OF THIS EQUIP; EVEN IF YOU HAVE NO REASON TO SUSPECT FAILURE. CALLBACK CONVERSATION REVEALED THE FOLLOWING. THE MAIN REASON THIS RPT WAS SENT WAS THE RPTR'S CONCERN ABOUT THE MANUFACTURER'S SERVICE LETTER THAT SET UP THE PROBLEM. THIS CORP OWNS THREE OF THE FOUR ACFT THAT RECEIVED THE SERVICE LETTER AND ALL HAVE BEEN MODIFIED AND THE PROBLEM APPARENTLY CORRECTED. RPTR SAID HE WAS CONCERNED ABOUT THIS ACFT MANUFACTURER'S RESPONSE TO CUSTOMER PROBLEMS AND THINKS THEY SEEM MORE ATTUNE TO SMALL ACFT OWNER PROBLEMS AND TEND TO IGNORE THE CORPORATE SECTOR.