PRACTICING LNDGS IN A TAILWHEEL ACFT WITH AN INSTRUCTOR ONBOARD ENDS WITH A RWY EXCURSION ATTRIBUTED TO XWIND.

Narrative

I WAS PRACTICING LNDGS IN A PA18-135; WITH AN INSTRUCTOR (WHO IS ALSO THE OWNER OF THE ACFT). WE WERE LNDG ON RWY 3; WITH A STRONG; ALMOST DIRECT; L XWIND. I HAD COMPLETED 3; 3-POINT LNDGS; ALL TOUCH AND GOES. THE 4TH WAS TO BE A STOP AND GO WHEEL LNDG. THE LNDG WAS ROUGH; BUT NOT TOO BAD. THE ACFT HAD SLOWED; AND THE TAIL HAD COME DOWN. AT THAT POINT; EITHER THERE WAS A GUST OF WIND; OR I FAILED TO ALLOW FOR THE DECREASED CTL EFFECTIVENESS (PROBABLY A LITTLE OF BOTH) AND THE TAIL WAS PUSHED TO THE R POINTING THE ACFT AT THE L SIDE OF THE RWY. MY INSTRUCTOR AND I BOTH WORKED TO GET THE ACFT LINED UP WITH THE RWY AGAIN. WE OVERCORRECTED; AND ENDED UP WITH THE TAIL POINTING INTO THE WIND. THE WIND GOT UNDER THE TAIL; AND PUSHED IT UP; FORCING THE NOSE DOWN TO THE RWY; WHERE THE PROP STRUCK. WE BOTH EXITED THE ACFT WITHOUT INJURY. IN MY OPINION; THE PRIMARY CAUSE OF THIS INCIDENT WAS MY FAILURE TO ALLOW FOR THE DECREASED CTL EFFECTIVENESS AS THE ACFT SLOWED DOWN. PART OF THE REASON FOR THAT IS THAT; UP TO THAT POINT; NONE OF THE LNDGS HAD BEEN STOP AND GOES; AND I HAD NOT EXPERIENCED THE DECREASING CTL EFFECTIVENESS. ALSO; I'M SURE MY LOW TIME IN THE TAILWHEEL ACFT PLAYED A PART. I HAD READ THAT; WITH TAILWHEEL ACFT; YOU NEED TO KEEP 'FLYING THE AIRPLANE' UNTIL IT COMES TO A COMPLETE STOP. WHILE I HAD READ THAT; AND THOUGHT I BELIEVED IT; THIS INCIDENT HAS DRIVEN THAT FACT HOME. IF I HAD NOT STARTED TO RELAX AS THE ACFT SLOWED DOWN; I MIGHT HAVE BEEN ABLE TO AVOID THIS INCIDENT.