PLT OF A CPR PIPER PA34; SENECA; WAS GIVEN ACFT CTL BY THE ASSIGNED PLT AND CLBED 400 FT WHILE ADJUSTING THE PWR AFTER LEVELOFF.

Narrative

AFTER LEVELING OFF AT 8000 FT; THE CAPT ASKED IF I WOULD LIKE TO SET THE PWR AND LEAN THE MIXTURES; IN ORDER TO GAIN FAMILIARITY WITH THE AIRPLANE. I BEGAN WORKING WITH THE PWR AND MIXTURE CTLS; AND WHEN I GLANCED AT THE FLT INSTS; WE HAD CLBED TO 8400 FT. I IMMEDIATELY LOWERED THE NOSE OF THE AIRPLANE AND RETURNED TO 8000 FT. DURING THE DSCNT TO 8000 FT; ATC REMARKED THAT OUR MODE C INDICATED 8400 FT. UPON REFLECTION; I THINK THAT WE SHOULD HAVE MAINTAINED CREW COORD; WITH 1 PLT MAINTAINING AN INST SCAN AND POSITIVE CTL OF THE AIRPLANE; AND THE OTHER PLT CONCENTRATING ON ADJUSTING THE PWR. ALTERNATIVELY; WE COULD HAVE SET THE AUTOPLT TO MAINTAIN HEADING AND ALT; AND THEN DISCUSSED THE PROC FOR SETTING CRUISE PWR. FINALLY; CONSIDERING THE EXISTING AND FORECAST VMC; WE COULD HAVE CARRIED OUT OUR TRAINING UNDER VFR. CONTRIBUTING FACTORS WOULD INCLUDE THE LATE HR; THE FACT THAT I HAD WORKED ALL DAY AT ANOTHER (NON FLYING) JOB AND WAS TIRED; AND MY LACK OF FAMILIARITY WITH THE AIRPLANE. ALSO; THE CAPT TYPICALLY FLIES SINGLE-PLT; AND IS NOT ACCUSTOMED TO CREW COORD; AND DOES NOT HAVE ANY COMPANY PROCS FOR DIVIDING DUTIES BTWN THE FLYING AND NON-FLYING CREW MEMBERS. I WAS SITTING IN THE R SEAT; AND SINCE THERE WERE NO COPLT INSTS; I WAS IN A MORE DIFFICULT POS TO KEEP THE FLT INSTS IN VIEW WHILE ADJUSTING PWR.