A PA28 INSTRUCTOR NEW TO THE ACFT TYPE; USED CARB HEAT INCORRECTLY IN SNOW AND COLD NEARLY CAUSING THE ENG TO QUIT DURING A GAR.

Narrative

MY STUDENTS AND I WERE ON OUR FINAL LEG OF OUR LONG IFR XCOUNTRY. WE LEFT FOR ZZZ1 VIA ZZZ FOR THE GPS RWY APCH INTO ZZZ. PLANNED ON THE MISSED AND ON HOME TO ZZZ1. WX FORECAST FOR SNOW TO START IN THIS AREA AND ZZZ1 AROUND XC00. WE ENCOUNTERED SNOW ABOUT XA30 ABOUT 1/2 WAY TO ZZZ. WE WERE CTLED BY APCH CTLR. THE CLOSER TO ZZZ THE HEAVIER THE SNOW. I TURNED ON PITOT HEAT. WE STARTED OUR FIRST VECTORS ONTO THE APCH AND I PULLED THE PITOT HEAT TO SEE IF ANYTHING WAS BUILDING UP -- NO SIGNS OF ICE ETC. I HAVE NEVER USED PITOT HEAT ON THE CHEROKEE LIKE I DO IN A CESSNA. WE SHOT THE APCH DOWN TO THE MDA AND NEVER SAW ANY SIGNS OF THE GND. WE EXECUTED THE MISSED/CLBOUT INSTRUCTIONS GIVEN BY APCH CTLR. SOON THEREAFTER IN THE CLB WE WERE LOSING PWR. I IMMEDIATELY CHKED THAT THE FUEL PRIMER WAS IN; FUEL PUMP WAS ALREADY ON; AND FLOWED TO THE CARB HEAT LEVER. WHEN PULLED; THE ENG ALMOST DIED. WITH MY ALT AS IT WAS; I DECIDED TO TURN OFF THE CARB HEAT AND KEEP WHAT MOTOR I HAD LEFT -- BETTER GLIDE RATIO WERE MY THOUGHTS AT THE TIME. I CONTACTED APCH AND TOLD THEM I HAD A MOTOR PROB. I CAN'T REMEMBER THE EXACT DIALOGUE; BUT TOLD THEM I NEEDED VECTORS TO A CLR AREA OR THE ARPT. THEY OFFERED ME THE ILS BUT TOLD THEM I COULD NOT SUSTAIN ALT AND THEY GAVE ME TURNS BACK TO THE ARPT. I ZOOMED IN THE GARMIN 430 AND HAD ENOUGH ALT TO GET BACK TO ZZZ WITH AN UNEVENTFUL LNDG. ALTHOUGH THE MOTOR WAS ALMOST READY TO DIE I WAS ABLE TO TAXI BACK TO THE RAMP AND DROVE HOME TO ZZZ1. WAS NEVER ABLE TO RUN THE MOTOR UP TO TRY AND CLEAN UP WITH CARB HEAT AS THE PAVEMENT WAS ICY AT ZZZ AND COULD NOT STAY IN ONE SPOT. I TOLD THE MECHS ABOUT IT AT ZZZ1 AND FOR SURE IT WAS CARB ICING -- THEIR OPINIONS. I HAVE GIVEN A STATEMENT TO THE LCL FSDO WITH THIS INFO LAST WK. THOUGHT I WAS OK; BUT EVERYBODY TOLD ME TO SEND IN A NASA RPT SO HERE IT IS. HOPE THIS HELPS. I HAVE SINCE TALKED TO A LOT OF DIFFERENT PEOPLE AND ALL OF US SEEM TO BE ON THE SAME PAGE AS HOW WE HAVE USED CARB HEAT ON A CHEROKEE -- OBVIOUSLY WE AREN'T DOING THE RIGHT THING. MY PROCS HAVE CHANGED AFTER THIS EXPERIENCE!