An Am Law 50 firm was among the law firms that hit aircraft engine manufacturer Pratt & Whitney with an antitrust lawsuit Friday in a federal district court in Pennsylvania, accusing the company of trying to monopolize the U.S. market for two types of widely used turboprop engines.

Plaintiff Universal Turbine Parts LLC, a used aircraft engine supplier, claimed in the lawsuit that Pratt has worked to cut off the supply of used engines and parts in its PT6 and PW100 families of products in order to drive its competitors out of business.