PLT OF AN SMA TWIN ERRONEOUSLY ENTERED CLASS B AIRSPACE DURING AN ENCODING ALTIMETER XPONDER TEST FLT.

Narrative

THE FLT SCHOOL I WORK OUT OF JUST RECEIVED A SENECA II. I WAS SITTING IN THE ACFT FAMILIARIZING MYSELF WITH THE AVIONICS; WHEN THE OWNER WALKED UP AND SAID HE WAS GOING TO FLY THE AIRPLANE AND CHK THE XPONDER MODE 'C.' THAT SAME DAY THE XPONDER HAD BEEN CHKED FOR MODE 'C' AND WAS FOUND TO BE WORKING PROPERLY. I HAD NEVER FLOWN A SENECA II SO I THOUGHT THIS WOULD BE A GOOD OPPORTUNITY TO WATCH AND LEARN. WE PULLED THE AIRPLANE OUT; THE OWNER GOT SEATED INTO THE L SEAT; A BACK PAX JUMPED IN THE BACK; AND THEN I GOT SEATED IN THE R SEAT. WE THEN TAXIED TO RWY 13 AT ALLEGHENY COUNTY ARPT; AND THEN DID THE NORMAL RUNUP AND CHKS. HE CALLED TWR AND TOLD TWR WE WERE GOING TO DEPART TO THE SW WHICH IS THE NORMAL PRACTICE AREA. WE DEPARTED TO THE SW INITIALLY AND THEN HE CALLED TWR TO GET A MODE 'C' CHK. THE TWR SAID; 'SENECA ALT READS 2400 FT MSL.' THE OWNER WAS SATISFIED AND CONTINUED CLBING. AT 3500 FT MSL I ASKED WHAT ALT HE WAS CLBING TO; FOR THE CLASS 'B' FLOOR ABOVE ALLEGHENY COUNTY ARPT IS 4000 FT. HE THEN SAID HE WOULD LEVEL OFF AT THIS ALT. AT THIS TIME WE HAD TURNED TO A HDG DUE W AND GOING FOR THE HEART OF CLASS 'B' AIRSPACE. I THOUGHT MAYBE HE REALIZED THIS AND WAS GOING TO TALK TO PITTSBURGH DEP FOR ANOTHER MODE 'C' CHK; BUT HE DIDN'T. INSTEAD HE REACHED OVER AND STARTED TO SHOW ME HOW THE MOVING MAP WORKS. AT THIS TIME I REALIZED HE HAD NO IDEA OF HOW CLOSE WE WERE TO THE CLASS 'B.' SO I HINTED TO HIM ABOUT SOME DIFFERENT HDGS AND THEN I TOOK THE AIRPLANE AND BANKED TO THE L AND DSNDED RAPIDLY TO 2700 FT MSL. AT THIS TIME TWR CALLED AND SAID; 'SENECA I SUGGEST CONTACTING PIT DEP FOR FLT FOLLOWING.' AS I WAS BANKING THE AIRPLANE HE GOT THE MOVING MAP TO SHOW THAT WE WERE RIGHT ON THE BORDER OF THE CLASS 'B' AIRSPACE. THE OWNER THEN MENTIONED HOW CLOSE WE WERE AND HOW HE NEVER HAS TO WORRY ABOUT THIS WHEN HE FLIES THE HELIS. FROM THAT POINT HE LET ME FLY AROUND AND THEN BACK TO ALLEGHENY COUNTY ARPT FOR SOME LNDGS. THE PROB INITIALLY AROSE THINKING THAT THE OWNER HAS BOTH THE EXPERIENCE AND THE QUALIFICATIONS AND SHOULD KNOW THE BOUNDARIES OF THE CLASS 'B' AIRSPACE. THE OTHER THOUGHT WAS; I WAS THE FIRST PAX AND I CAN'T TAKE THIS AIRPLANE FROM HIM. TO FIX THIS PROB SO IT NEVER HAPPENS AGAIN IS TO CLARIFY THE EXACT DIRECTION AND ALT THAT WE WILL DEPART ON; SO IF THERE IS A DISAGREEMENT IT IS ON THE GND.