AFRL Plays Key Role in Preventing Aircraft Towing Damage Published March 10, 2014 By Holly Jordan, AFRL/RQOB Aerospace Systems WRIGHT-PATTERSON AIR FORCE BASE, Ohio -- At the request of the Air Force Life Cycle Management Center (AFLCMC), the Air Force Research Laboratory tested a shear pin for use in a new tow bar adapter for the RQ-4B Global Hawk aircraft. The current tow bar uses an adapter that can be overloaded and fail, creating an unsafe condition for personnel and the potential for damage from a runaway aircraft. To help prevent this problem, the AFLCMC Rapid Development Integration Facility (RDIF) designed a new adapter that will be installed on the end of the standard MD-1 tow bar. This adapter includes a shear pin that prevents the transmission of excessive loads to the Global Hawk nose landing gear which, in turn, causes the adapter failure. Before field testing the new adapter design, RDIF requested assistance from AFRL in gathering shear pin failure data. AFRL's Facility for Innovative Research in Structures Technology (FIRST) was requested for the testing effort because of its well-suited test equipment, minimal setup and cost, and its ability to produce quality data under an aggressive test schedule. Researchers in the FIRST lab tested 23 shear pins, collecting load and deflection data for each pin. RDIF will use this baseline data to design a pin to be used for the field tests. If additional pin and hardware design changes are needed, RDIF may again request AFRL test support to further refine the design.