United Dynamics Inc

United States

Since the beginning of C-5 service, the C-5 community was plagued by a mean time between failure (MTBF) problem with the emergency gear extension motor. The problem was significant. About 75% of these motors failed at Programmed Depot Maintenance (PDM) due to environmental intrusions and other factors. The potential for failure put the aircraft at risk if a landing gear emergency occurred. The C-5 Emergency Gear Actuation Motor was United Dynamics’ ground-up design to solve this problem. Our mechanical and electrical engineers worked closely with the Air Force cognizant engineers and the C-5 SPO office to design and develop a new motor that would increase the MTBF by order of magnitude. The design required careful analysis of the mechanical and electrical requirements in order to match and surpass the performance of the existing motor. Full up qualification and flight test proved our design approach, assembly and manufacturing techniques. The success of the program can be measured by the U.S. Air Force’s decision to retrofit the entire fleet with our new motor rather than change by attrition.

During ground maintenance, a F-16 Compressor Vane Positioning Tester (Hydraulic Tester) moves the compressor vanes working through the hydraulic actuators on the Pratt & Whitney F-100 engines series. United Dynamics was asked to look at the existing design and formulate changes to improve the mean time between failures (MTBF) of the existing unit. Our due diligence path led us back to the drawing board After performing a thorough investigation that included numerous hours of speaking with end users, we discovered a stark reality: Improving the MTBF would require starting over again. Our engineering department designed and developed the hydraulic tester from ground up. To add value, we engaged with the end user to discover what features should be included that were not part of the original design. A new breed of hydraulic tester When our team finished, we delivered a robust new hydraulic tester. The tester met the physical and technical requirements of the Air Force with much more versatile capabilities. It even surpassed the requested performance requirements. The Hydraulic System delivers hydraulic controlled pressures between 0 and 250 pounds per square inch gauge (psig). It controls pressure within ± 2 pounds per square inch (psi). It has five main elements: filtration, pumping, control, monitoring and direction. The improvements we made proved so significant that the Air Force assigned a new National Stock Number to our part and made it a preferred unit.