Am I permitted a break in service during the three (3) years of TPE period?

YES, you can take whatever leave for which you are eligible (e.g., Family & Medical Leave Act leave). HOWEVER, you must complete the equivalent of three (3) service years as a TPE. Thus, if you were on FMLA leave for one semester during your third year as a TPE, you will not be eligible for tenure until after the first semester of your fourth year of service. [See Pookman v. Upper St. Clair Twp. School District, 483 A.2d 1371 (Pa. 1984)]