WHITE PLAINS, N.Y. — Spirit Airlines is making “massive progress” to revitalize the airline, the carrier’s restructuring lawyer Marshall Huebner said in a court hearing Tuesday.

The struggling budget airline has reached an agreement with debtholders for up to $475 million in debtor-in-possession financing as well as $150 million from a major aircraft lessor, Huebner said. The agreements are subject to court approval.

Spirit last month filed for its second Chapter 11 bankruptcy protection in less than a year after high costs, weaker demand and a host of other lingering problems drove more than $250 million in losses from when it emerged from bankruptcy in March through June.

The carrier has been racing to cut costs, and recently announced plans to cut 40 routes and furlough about one-third of its flight attendants. The airline is in talks with its pilots’ union and is seeking about $100 million in cuts from that group.

Huebner, a partner at Davis Polk & Wardwell, said in U.S. Bankruptcy Court on Tuesday that people who are pessimistic about the struggling carrier’s turnaround prospects should “say less” and observe what it’s doing.

Spirit is planning to reject leases on 27 Airbus narrow-body aircraft from Ireland-based leasing giant AerCap, 25 of them airplanes that are grounded or will be grounded for inspection due to a Pratt & Whitney engine defect, Huebner said in court. AerCap will pay Spirit $150 million as part of the agreement, under which Spirit would still plan to take delivery of 30 more airplanes, the company said.

Spirit is also planning to reject 12 airport leases and 19 ground handling agreements as the carrier shrinks to cut costs.