Rule 14(a) of the Fed. R. Civ. P. provides, in relevant part, that: 'At any time after commencement of the action a defending party, as a third-party plaintiff, may cause a summons and complaint to be served upon a person not a party to the action who is or may be liable to the third-party plaintiff for all or party of the plaintiff's claim against the third-party plaintiff.' Unless the third-party plaintiff files the third-party complaint within ten days of serving the original answer, the third-party plaintiff must seek leave from the court to file the third-party complaint. Id. Impleader is appropriate when the third-party defendant's liability to the third-party plaintiff is 'dependent upon the outcome of the main claim' or the third-party defendant is 'potentially secondarily liable as a contributor to the defendant.' Kenneth Leventhal & Co. v. Joyner Wholesale Co., 736 F.2d 29, 31 (2d Cir. 1984)(citing 6 Charles Alan Wright & Arthur R. Miller, Federal Practice and Procedure, § 1446 (1971)); Rodolico v. Unisys Corp., 189 F.R.D. 245, 249 (E.D.N.Y. 1999). The purpose of this rule is to promote judicial efficiency by eliminating the necessity for the defendant to bring a separate cause of ...