ACFT EQUIP PROB. ENG OVERSPD OVER-TORQUE.

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ACFT IS A D328-110; EQUIPPED WITH PW-119B TURBO-SHAFT ENGS. ON DEP CLB; SHORTLY AFTER FLAPS UP; I NOTICED BOTH ENGS WERE 5-8 PERCENT BELOW THEIR TORQUE 'BUG' VALUES. AS I ADJUSTED THE PWR LEVERS UPWARD TOGETHER; THE R ENG WENT TO THE PROPER VALUE AND THE L ENG SURGED RIGHT OFF THE SCALE. WE CONTACTED OUR MAINT CTL VIA RADIO AND WERE ADVISED TO RETURN TO THE FIELD. WHEN WE CHKED THE EXCEEDANCE RECORD; IT SHOWED A TORQUE SPIKE TO 126 PERCENT ON THE L ENG. ITT; NH; AND NL SUPPORT THIS AS BEING ACCURATE; AND NOT AN INDICATION ERROR. IT HAS COME TO MY ATTN THAT MY COMPANY HAS REPLACED A NUMBER OF HYDRO-MECHANICAL UNITS (HMU'S) ON OUR ACFT AFTER OVER- TORQUES. MY UNDERSTANDING IS THAT SECTIONS OF SEVERAL DIFFERENT ENGS WERE COBBLED TOGETHER TO MAKE THIS UNIT; IE; EMB120 GEAR BOX; ATR COMPRESSOR; ATP HOT SECTION. I HAVE TO WONDER IF ALL THE SUB-ASSEMBLIES ARE REALLY COMPATIBLE IN LINE SVC CONDITIONS; AND WHAT OTHER EXCITING MODES OF OP WILL POP UP AS THESE UNITS AGE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR IS CONCERNED THAT WITH SUCH A NEW ACFT; THEY SEEM TO BE HAVING AN UNUSUAL AMOUNT OF ENG PROBS. AND; IF PROBS ARE ALREADY MANIFESTING THEMSELVES; WHAT WILL THE FUTURE HOLD? SINCE SUBMITTING THE RPT; HE HAS SPOKEN WITH A MAINT TROUBLESHOOTER WHO BELIEVES THEY HAVE DISCOVERED THE PRIMARY PROB CAUSING THE SPURIOUS ENG OVERSPDS AND HYDRO-MECHANICAL UNIT REPLACEMENTS; THE CANNON PLUG PINS ARE SLIGHTLY UNDERSIZED. CONSEQUENTLY; THEY BECOME MORE LIKELY TO CORRODE OR GET DIRT IN THE CONNECTOR AS WELL AS MOVE. THAT CAUSES ERRONEOUS AND SPURIOUS SIGNALS RESULTING IN OVERSPDS; ETC. THE COMPANY CAME UP WITH A TEMPORARY FIX BY CLEANING THE CANNON PLUGS AND BENT THE PINS SLIGHTLY TO MAKE A TIGHT FIT. THERE IS ALSO A NEW HARNESS ASSEMBLY BEING TESTED BY PRATT WHICH SHOULD ALSO CORRECT THE PROBS. IN ONE OF THE OVERSPD INCIDENTS AFTER LNDG; THE RPTR SAYS; HAD THE RWY BEEN WET OR CLUTTERED; THEY WOULD NOT HAVE BEEN ABLE TO MAINTAIN DIRECTIONAL CTL.