A B737 PILOT TAXIES AN ACFT FOR A HIGH POWER RUN FOLLOWING A PACK VALVE CHANGE BUT IS NOT TOLD THAT THE THIS IS A MAINTENANCE ACTION NOT FOR PLTS.

Narrative

OUR INBOUND ACFT ARRIVED WITH A PACK-TRIP WRITE-UP AND MAINT CTL DIRECTED THE CONTRACT MAINT IN ZZZ TO REPLACE A PACK VALVE. AFTER THE VALVE WAS INSTALLED AND TESTED USING THE APU AND ENG MOTORING; I WAS ADVISED BY THE CONTRACT MAINT PERSONNEL THAT MAINT CTL REQUIRED THAT THE ENG BE RUN AT A HIGH PWR SETTING (80% N1) FOR 5 MINS PER A BOEING MAINT PROC TO ENSURE THAT THE PACK WOULD NOT TRIP OFF; AND THAT I WAS TO CONTACT MAINT CTL. I WASN'T COMFORTABLE WITH THE THOUGHT THAT I AND MY CREW WOULD HAVE TO DO THIS TEST AND I ASKED THE CONTRACT MECHS IF THEY WERE QUALIFIED ON B737-300/400 MODELS AND THEY SAID JUST CHK WITH OUR MAINT CTL TO MAKE SURE IT WAS OK FOR THEM TO TAXI OUR ACFT. I THEN CONTACTED MAINT CTL AND I RELAYED MY CONCERN FOR DOING THIS TEST AND ASKED IF THE ZZZ CONTRACT MECHS COULD DO IT. THE REPLY WAS 'ABSOLUTELY NOT!;' AND MAINT CTL IMPLIED THAT I HAD TO DO THE ENG RUN. THEY SAID THEY WERE FAXING ALL OF THE PROCS TO THE CONTRACT MAINT PEOPLE IN ZZZ. AFTER I HUNG UP THE PHONE; I STILL HAD MISGIVINGS ABOUT DOING THIS; AND I CALLED MAINT CTL BACK AND ASKED THEM WHO WAS AUTHORIZED TO BE ON THE ACFT FOR THIS ENG RUN AND; WERE THE FLT ATTENDANTS ALLOWED TO BE ON THE AIRPLANE? AND THEY SAID YES; THE FLT ATTENDANTS COULD REMAIN ON BOARD AND FOR THEM JUST TO ARM THE DOORS IN THE NORMAL MANNER FOR TAXI. I DIDN'T LIKE THE SOUND OF THIS WHOLE THING; BUT I HAVE NEVER BEEN PLACED IN THE SITUATION BEFORE AND I ASSUMED THAT MAINT CTL HAS BEEN DOING THIS FOR A LONG TIME AND IF THEY WERE TELLING ME THAT I HAD TO PERFORM THIS ENG RUN; THEN I HAD TO PERFORM THE ENG RUN AND THEY WOULD PROVIDE ME WITH ALL THE NECESSARY PROCS. NOW I FIND OUT AFTER THE FACT THAT WE AS PLTS ARE NOT TRAINED TO DO THESE RUNS AND THAT THERE ARE ALL KINDS OF SAFETY PROCS IN PLACE REGARDING SAFETY ZONES; CHOCKING OF WHEELS; CTR OF GRAVITY REQUIREMENTS; ETC. I WAS NOT INFORMED OF ANY OF THESE REQUIREMENTS BY MAINT CTL; NOT TO MENTION THE RISKS OF TAXIING THE AIRPLANE CLEAR ACROSS ONE OF THE BUSIEST ARPTS IN THE UNITED STATES XING 3 ACTIVE RWYS -- ONCE TO GET OUT TO THE ENG RUN LOCATION AND THEN AGAIN TO RETURN TO THE GATE. IN HINDSIGHT; I SHOULD NEVER HAVE DONE THIS TEST; AND I FEEL THAT I SHOULD NEVER HAVE BEEN PRESSURED INTO DOING IT BY MAINT CTL. I THINK THAT A STATEMENT NEEDS TO BE ADDED TO THE SECTION IN THE FOM REGARDING ENG RUNS AT IDLE; THAT STATES: 'FLT CREWS WILL NOT PERFORM ANY OTHER TYPES OF ENG RUNS.' I CHKED THIS PORTION OF THE FOM PRIOR TO DOING THIS ENG RUN AND IT REALLY ONLY SAID THAT ENG RUNS AT THE GATE WILL BE AT IDLE; IT SAID NOTHING THAT WOULD PROHIBIT ENG RUNS ABOVE IDLE AWAY FROM THE GATE. DIRECTED BY MAINT CTL TO PERFORM A HIGH-PWR ENG RUN; AND LED TO BELIEVE THAT THIS WAS REQUIRED AND THAT I AND MY FO WERE QUALIFIED TO PERFORM THE ENG RUN; AND NOT GIVEN ANY INFO AS TO THE RISKS; SAFETY PRECAUTIONS; AND PROCS FOR SAID ENG RUN.