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Riveting success: 436th MXS saves time, money

  • Published
  • By Roland Balik
  • 436th Airlift Wing Public Affairs

Since mid-September 2021, the 436th Maintenance Squadron hydraulic shop has been saving the Air Force more than $1 million.

The 436 MXS employs an in-shop orbital riveter to locally repair loose caps on C-5M Super Galaxy brake torque tube assemblies and return brake assemblies to serviceability, saving on costs and time to service the aircraft.

“Due to our in-house capabilities, we don’t have to outsource our brake maintenance and be at the mercy of a vendor or contractor,” said Senior Master Sgt. Zwide Spencer, 436th MXS accessories flight superintendent. “We went from a six-day turnaround to a three-day turnaround, significantly increasing part availability for the C-5M fleet.”

Loose caps are discovered when brake pad wear renders a brake assembly unserviceable. The assembly is removed from the main landing gear axel and taken to the hydraulic shop for repair.

To prevent wear of the actual brake torque tube, 11 caps are riveted around the circumference of the torque tube with each cap held in place by two rivets. The orbital riveter, along with a special horn attachment, are needed to compress the rivets to a specific height and width that allows brake stators, similar to a vehicle brake pad, and rotors to easily slide over the caps during the rebuilding process.

The Super Galaxy has a total of 24 brake assemblies, six on each of the four main landing gear axle assemblies. Each of these brake assemblies costs more than $164,000. The 436th MXS, with the help of the 436th Contracting Squadron, purchased the orbital riveter for $41,675.

“A new torque tube from the manufacturer is $35,384,” said Tech. Sgt. Ryan Bailey, 436th MXS hydraulic section chief. “We now can repair them [with caps and rivets] in-shop with the new riveter for $1,881.”

Prior to using the orbital riveter, ordering a torque tube assembly from a supply shop initiated an average wait time between six months to a year.

“We had 20 C-5M main landing gear brake assemblies that were unserviceable due to brake pad wear,” said U.S. Air Force Air Reserve Technician Master Sgt. Matthew Tira, 512th MXS hydraulics craftsman. “Normally, when a piece of a component is unserviceable, we simply ordered a new one. The problem was there is a zero balance world-wide of these [brake] torque tubes.”

At one point, the hydraulic shop had 17 torque tubes on order with an estimated delivery date of more than a year out.

“We are the only entity in the U.S. that is currently performing the repair of these components,” Tira stated. “Outsourcing repairs was not a feasible option with a six-day turnaround at a cost of $2,130 per torque tube.”

In November 2021, there were 83 unserviceable brake assemblies in the global supply system valued at $13.6 million dollars. By the end of January 2022, that number was reduced to 50 as a result of hydraulic shop personnel using the orbital riveter.

“We do roughly 15 brakes per year which equals out to $500,000 in savings, on average, just for the brakes we do in our shop,” said Bailey. “We haven’t seen the numbers yet on how many standalone torque tubes we will receive in a year, but our estimate would be around an additional 15-20. That would bring the total yearly savings to around $1.1 million.”

Because Dover AFB was able to procure an orbital riveter, the 436th MXS is now servicing brake torque tube assemblies for the entire U.S. Air Force fleet of 52 C-5M aircraft.