KC-135 Design Innovation Could Save $583M
After years of development, a new wheel and brake system on the KC-135 “Stratotanker” is ready for installation by Oklahoma City Air Logistics Center personnel at Tinker Air Force Base, OK. The system replaces the steel brakes currently used on the KC-135 with carbon brakes (the KC-135 is based on the Boeing 707, but the planes have been heavily modified over the years). Other changes include the brakes operating on three rotors instead of five, a pressure of 3,000 pounds per square inch (psi) instead of 965 psi and different wheels used on the aircraft.
At a time cost of 16 hours for initial installation, the new system allows the aircraft to complete 1,000 landings as compared to 100 landings before needing replacement, which means the new system could last up to 10 years instead of the average one-year lifespan of the old brakes. The changes could save the Air Force $583 million throughout the life of the program, said Cathy Klea, 327th TSG KC-135 program manager.
The Wheel and Brake System Improvement (WBSI) Program originated from the invention of the carbon brake, in 1968, by the French aerospace company Messier-Bugatti, but, according to the Messier-Bugatti Web site, the brakes did not appear on aircraft until 1985. Since then, carbon brakes generally have been found on commercial U. S. aircraft as opposed to military. With a $144 million spending allotment, the new system marks the largest Improved Item Replacement Program that Air Force Material Command has ever approved.
According to Ms. Klea, the OC-ALC began working on the WBSI in 2002. The Ogden Air Logistics Center (OO-ALC) in Hill Air Force Base, UT developed the preliminary design, and then handed the system off to OC-ALC personnel to integrate it with the aircraft. Ms. Klea said OC-ALC’s job consisted of [making] sure that what they design works on our aircraft.” The brakes also tested well in high- and medium- risk conditions, exceeding expectations.
Although logistics service tests using an Alaska Air National Guard KC-135R will continue, the OC-ALC equips all incoming KC-135s with the new system. The field tests will not end until July 2006, but Mr. Couch said some KC-135s with the new wheel and brake system have already been delivered.
“One of the reasons we do the logistics service tests is to collect raw data faster than if we waited for the aircraft to have the system installed in PDM, go back into the field, and then collect data, ” Ms. Klea said. After flight tests showed a 45% reduction in stopping distance under certain dry runway conditions, for instance, officials wanted to improve the new system. This was not an original goal of the program because officials were not sure how much the new wheel and brake system would improve KC-135 performance, but once it was shown to have improved, efforts were made to capture it and include it in relevant manuals, etc.
- Air Force Link: KC-135 Stratotanker
- Air Force Technology.com – KC-135 Stratotanker Air-To-Air Refuelling Aircraft, USA