Boeing completes PDM of Chilean planes SAN ANTONIO, March 28 (UPI) -- Boeing announced completion of programmed depot maintenance of three KC-135E Stratotankers operated by the Chilean air force. Work on the final plane, which arrived at the company facility in Texas, was completed this month and returned to Chile by a crew from the U.S. Defense Contract Management Agency. Work on the aircraft included a variety of depot-level inspections, repairs, maintenance, modification and repainting, Boeing said. "Boeing worked with the Chilean air force to incorporate lessons learned on the first and second aircraft to deliver the final KC-135 and return it to doing what it does best," said Mike Wright, Boeing KC-135 program director. This highly dependable aircraft is a critical resource to Chile for refueling missions and humanitarian assistance. Boeing said KC-135s receive programmed depot maintenance after five years of service or 20,000 hours of flight time. The Chilean government purchased the three KC-135 E-model aircraft in 2009 through a U.S. Foreign Military Sale arrangement.