WESTOVER AIR RESERVE BASE, Mass. -- The C-5 - one of the most complex aircraft in the inventory - challenged Westover's renowned aircraft maintainers recently, as Airmen salvaged parts from the former fleet to help with restoring the remaining operational jets.
Tech Sgt. Nathan Staples, a 439th Maintenance Squadron aero repair technician, explained how the two ball-screw drive assemblies in the nose-landing gear operate and how the problem arose.
"The ball screw drive assemblies have two internal bearings and a gear which works in conjunction with a spline shaft, a 90-degree gear box, and a hydraulic motor to drive the gear up and down," Staples said. "The upper most bearing in the ball screw drive, on some aircraft, as well as the two aircraft that had nose-landing-gear malfunctions, wears overtime and breaks up inside the housing. When the bearing breaks, the metal chunks from the bearing get lodged in the gear within the ball screw drive housing. This prevents the internal gear from spinning which prevents the nose-landing-gear from extending and/or retracting."
Here at Westover, our maintenance squadron has been hard at work replacing the parts for several of the fleet's Galaxies.
A portion of the parts were pulled from retired C-5s at Davis-Monthan AFB, Arizona. Staples and Master. Sgt. Eric Jancaitis, both assigned to the 439th Maintenance Squadron, went to Arizona from August 8-12, to assist in removing the needed parts from some of the boneyard aircraft.
"We prepped for removal and/or removed 22 left-hand ball screw drive assemblies and 21 right-hand ballscrew drive assemblies," Staples said.
While some of the parts were already in the inventory, others came from the boneyard at Davis-Monthan or were refurbished BSD assemblies, which were pulled from other operational aircraft.
Replacement of the parts is no easy feat.
It takes about nine to eighteen hours to complete the whole process, Staples said. The process includes the removal of the left-hand and right-hand ball screws, ball screw drives and nose-landing gimbals. This is followed by the installation of the new BSD assemblies, the re-installation of the ball screws (which were removed in order to replace the defective BSD assemblies) and the re-installation of the nose-landing gimbals. At the conclusion, an extensive operational checkout is conducted to ensure that the nose-landing gear functions properly in both normal and emergency modes.
The 439th MXS is the largest squadron within the Patriot Wing, with a combined workforce (reservists, civilians, and active duty) of more than 250 men and women including reservists, civilians and active-duty Airmen from Dover Air Force Base, Delaware.