C-17 treads into new territory

by Jet Fabara
412th Test Wing Public Affairs

9/10/2014 - EDWARDS AIR FORCE BASE, Calif. -- As important as ailerons, rudders and elevators are to the fundamental movement of any aircraft in flight, its tires are equally important while moving on the ground.

Since August, the C-17 Global Reach Integrated Test Team at Edwards AFB has been putting the C-17's new Dunlop tires through the rigors of testing to ensure the aircraft's capability remains intact well into the future.

"The original tires for the C-17A were Michelins and they were tested and approved in the mid-90s. These first tires had no capability to retread a worn tire casing. Basically, they were a one-time only tire," said Michael Quinton, 773rd Test Squadron project engineer. "Now, the C-17A is testing new Dunlop tires in place of the current legacy Michelin tires. No performance increases to the aircraft are expected as a result of the new tires, but increased number of retreads to a single tire casing and corresponding cost savings are anticipated."

Since Dunlop Tire was selected as the supplier for the C-17 as the replacement tire, the tires still had to be tested thoroughly, according to Patrick Terry, 412th Test Support Squadron C-17 project manager.

"While structural integrity and load capability are tested in a laboratory, parameters such as wet-runway stopping distance and minimum aircraft turning radius have to be tested in the real world with a wet runway," Quinton said.

"Although the current testing does not include semi-prepared runways or terrain, the test involves a collection of vibration, skid, stability, structural and wet-and-dry runway takeoff and landing performance data, which will be provided to Boeing to assist in their certification effort," added Terry.

Quinton also noted that the biggest difference between both tires is the new tires incorporate tighter geometric tolerances that are designed to increase retreadability and have a new internal casing design.

In order to fulfill the tire test requirements, the C-17 team depended on the support of personnel from the 412th Operations Group, 412th Maintenance Group, the Wheel and Tire Shop, various engineers, pilots, loadmasters from the 418th Flight Test Squadron, Fire and Safety, Audio Visual support, including both Boeing and Dunlop personnel.

"The biggest challenges have been logistics and coordination of this large team, wind and temperature limitations, as well as scheduling exclusive use of the runway at early hours so we do not interfere with other flight test projects or programs executing simultaneously," Terry said. "In all, this requires an amazing team effort, which is typical of our work here at Edwards in order to execute a flawless test project."

So far the team has executed 27 of 50, or 54 percent, of the test points, according to Terry. Approximately 10 wet runway tests, several more landings and maintenance tow tests are on schedule until the end of September.