Order, Supreme Court, New York County (Michael D. Stall-man, J.), entered April 4, 2005, which denied the petition brought pursuant to CPLR article 78 seeking to annul respondent’s determination dismissing petitioner from his position as principal, and dismissed this proceeding, unanimously affirmed, without costs.
Petitioner failed to establish that respondents’ determination regarding the calculation of his probationary service was either irrational or arbitrary and capricious. To the contrary, the record demonstrates that respondents began crediting the time petitioner served as principal of Sheepshead Bay High School at the start of the school year, when he officially assumed that position.
Petitioner’s three-year probationary period was frozen from September 2000 through the summer of 2003, while serving as a “principal assigned” at the Brooklyn High School Superintendent’s Office and during the final summer at South Shore High School. On August 23, 2003, he was assigned as principal at Sheepshead Bay, with still five months to go in his probationary status. Any work he voluntarily performed in preparation for that position while serving temporarily as principal assigned at South Shore, which was part of his frozen period, would not have been in furtherance of his probationary period, which is designed “to determine if appointees are ‘competent, efficient and satisfactory’ for purposes of recommending tenure” (Matter of McManus v Board of Educ. of Hempstead Union Free School Dish, 87 NY2d 183, 188 [1995]). Petitioner has failed to establish that he achieved tenure by estoppel. Concur—Mazzarelli, J.E, Saxe, Marlow, Sullivan and Williams, JJ.