A CFII IN AN SMA WAS PRACTICING ENG OUT EMERS WITH A STUDENT WHEN HE HIT THE TOP OF A TREE. THERE WERE WIND GUSTS AND WINDSHEAR IN THE AREA. THERE WERE NO INJURIES; BUT THE ACFT WAS DAMAGED.

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CFII SIMULATED ENG FAILURE AT 3000 FT. STUDENT PICKED AIRSTRIP DIRECTLY BELOW US AS HIS EMER LNDG FIELD; THEN DID HIS EMER PROCS. SPIRALED DOWN AT BEST GLIDESPD. ENTERED DOWNWIND AT 1000 FT; TURNED BASE AT 700 FT AND FINAL AT 500 FT. WAS ON THE GLIDEPATH; AT GLIDESPD WITH PWR AT IDLE SUDDEN ALT DROP. CFII APPLIED FULL PWR. ENG PICKED UP NORMAL BUT AIRPLANE KEPT LOSING ALT. HIT TREE TOP WITH THE LEADING EDGE OF OUR R WING ABOUT MIDWING FOLLOWED BY A GAR. DIDN'T LAND AT OUR EMER FIELD. HAD ENOUGH AIRSPD TO GAR CLBED UP TO 1500 FT; THERE WE CHKED OUT THE PLANE AND OBSERVED THAT THE FLT CHARACTERISTICS WERE NOT ADVERSELY AFFECTED. WE RETURNED TO OCALA ARPT AND MADE A NORMAL UNEVENTFUL LNDG. POST-FLT INSPECTION REVEALED THAT THE DENT IN THE LEADING EDGE OF THE R WING WAS PLUS OR MINUS 2 FT IN LENGTH AND PLUS OR MINUS 3 INCHES AT THE CTR. CONTRIBUTING FACTORS: RPTED WINDS AT OCF NEAREST ARPT WITH AWOS WINDS 240/10 GUSTING UP TO 17 KTS. HOW IT WAS DISCOVERED: SUDDEN ALT DROP. CORRECTIVE ACTIONS: APPLIED FULL PWR AND TRY TO MAINTAIN ALT SINCE WE STILL HAD OUR AIRSPD. AIRPLANE WAS NEVER STALLED. JUDGEMENT-DECISIONS: EVERYTHING SEEMED NORMAL TO ME. WE WERE ON OUR GLIDE ANGLE WITH BEST GLIDESPD. THERE WAS NOTHING I COULD DO TO PREVENT THE ALT LOSS FROM HAPPENING. I APPLIED FULL PWR AND LEVELED OFF TO PREVENT TO A FURTHER DSCNT. WHAT REALLY CAUSED THE PROBLEM: SUSPECTED WINDSHEAR. WHAT CAN BE DONE TO PREVENT RECURRENCE: NO SIMULATED EMERS WHEN WINDSHEAR CONDITIONS EXIST.