The Transportation Security Administration is cutting the cost of TSA PreCheck for younger travelers in a new limited-time promotion timed to the start of the summer travel rush. Through May 31, first-time applicants age 30 and under can receive $20 off a new five-year TSA PreCheck membership, lowering the enrollment cost to as little as $57 depending on which enrollment provider they use. TSA is calling the promotion “$20 Take Off,” and it marks the first broad age-based discount the agency has offered for the trusted traveler program. The discount applies only to new enrollments completed by May 31 and is available through all three TSA-authorized enrollment providers: CLEAR , IDEMIA , and Telos Corporation . Travelers must complete both the online application and in-person interview before the deadline to qualify. The deal comes as airports brace for another record-breaking summer.…