C172 STUDENT AND INSTRUCTOR ENCOUNTER TURB AND WINDSHEAR IN LNDG PATTERN. SUCCESSFUL LNDG ACCOMPLISHED AFTER 3 GAR'S.

Narrative

FLT MISSION WAS A PVT PLT STUDENT TRAINING FLT. THIS FLT WAS TO INCLUDE VOR AND NDB INTERCEPT AND TRACKING; SIMULATED INST; AND LNDG PRACTICE. I OBTAINED A DUAT WX BRIEF ABOUT 1 HR BEFORE THE FLT. VFR CONDITIONS WITH OCCASIONAL SNOW SHOWERS. THERE WAS AN AIRMET FOR MODERATE TURB OVER MOST OF THE MIDWEST. WINDS AT TKOF WERE FROM 180 DEGS AT 14 KTS; HOWEVER; OTHER NEARBY ARPTS WERE RPTING GUSTS IN THE LOW 20'S. SPENT ABOUT 1 1/2 HRS IN THE PRACTICE AREA WHERE WE EXPERIENCED LIGHT TURB. AS WE APCHED THE ARPT; ATIS RPTED THE WINDS FROM 180 DEGS AT 20 KTS GUSTING TO 27 KTS. BASED ON THE CONDITIONS; I DECIDED TO FORGO LNDG PRACTICE AND COMPLETE A FULL STOP LNDG. ARRIVING IN THE TFC PATTERN; I BRIEFED MY STUDENT (WHO WAS THE PF) ABOUT THE CONDITIONS; IE; MINIMUM FLAP SETTINGS; XWIND TECHNIQUE; AND WINDSHEAR AWARENESS. ARRIVING ON FINAL APCH TO RWY 14; WE EXPERIENCED MODERATE TO SEVERE TURB AND WINDSHEAR. UNABLE TO LAND; MY STUDENT ELECTED TO GO AROUND. WE INFORMED THE TWR WE WERE GOING AROUND AFTER WHICH THE CTLR OFFERED US A L DOWNWIND ENTRY TO RWY 23. WE ACCEPTED AND I; AS INSTRUCTOR; TOOK OVER CTL OF THE AIRPLANE. AGAIN; WE ENCOUNTERED TURB AND WINDSHEAR. I WAS ABLE TO MAINTAIN CTL OF THE AIRPLANE (WITH GREAT EFFORT) UP UNTIL ABOUT 50 FT ABOVE THE RWY WHEN TURB AND SHEAR FORCED A GAR IN ORDER TO MAINTAIN CTL OF THE ACFT. WE ADVISED THE TWR AND WERE INSTRUCTED TO ENTER A R PATTERN FOR A SECOND ATTEMPT OF RWY 23. WE WERE CLRED TO LAND BEHIND A FALCON JET. THE JET LANDED WITHOUT RPTING ANY SHEAR; SO WE ATTEMPTED ANOTHER APCH. ON SHORT FINAL WE AGAIN EXPERIENCED TURB AND SHEAR. AT THIS POINT; I ADVISED THE TWR WE WOULD LIKE TO CHANGE BACK TO RWY 14. WE WERE CLRED TO GO AROUND AND ENTER A L DOWNWIND TO RWY 14. AGAIN WE EXPERIENCED TURB AND SHEAR. I KEPT OUR APCH SPD HIGH AND WAS ABOUT 20 KTS FAST OVER THE THRESHOLD. I WAS ABLE TO LAND THE AIRPLANE; AND TAXI BACK TO PARKING. AFTER DEBRIEFING MY STUDENT; HE ADVISED ME WE HAD A 20 KT INSTANTANEOUS DROP IN AIRSPD JUST BEFORE TOUCHDOWN.