The gravity refuel adapter is the primary fueling and defueling connection point on the aircraft. The adapter is a normally-closed valve designed to minimize back-flow in the event of a failure of the poppet. The adapter has a MS24484-4 adapter configuration and is MS29520 nozzle compatible. The adapter opens and closes with a refuel nozzle control lever and has aircraft structure break-away protection.
This device mates up with the ground refueling nozzle and has pins for indexing for proper installation. Once the nozzle is correctly installed, the poppet within the refuel adapter is opened by the poppet inside the ground refueling nozzle. The refueling cap is attached to the refuel adapter when not in use; however, the cap serves as a secondary level of protection to keep the interface clean.
The defueling suction is limited up to -8 psig at refuel/defuel adapter (with an assumption of typical ground refueling equipment), without assistance from onboard electric pumps. At this suction pressure, the refuel/defuel system has the capability to defuel the aircraft from maximum capacity to minimum fuel level.
The suction defuel requirement is used to establish operating conditions for defueling, including the maximum suction pressure to be applied by the refuel equipment, -8 psig. Note that this is not a limit imposed by the refuel adapter itself; the suction pressure is set by the refueling equipment. The requirement imposed on the refuel adapter itself requires defueling capability at an inlet pressure of
-8 psig.
The concerns associated with effective and safe defueling are two-fold. First, pressure drop within the refuel adapter must be small enough to transmit pressure beyond the adapter to provide a motive force for the fuel within the aircraft fuel tanks and plumbing. Second, the refuel adapter must be sufficiently strong to withstand structural stress caused by the negative pressure.
The refuel adapter is also capable of surviving a breakaway load of 1,200 lbs. applied 12 inches from the mounting lug plane at 90 degrees. If this scenario should occur, Parker has designed significant margins of safety into the design.
APPLICATIONS: Commercial aircraft
FEATURES AND ATTRIBUTES:
• Mating end conforms to international standards
• RTCA DO-160F certified
• Proven history of reliability
• Design is used on several aerospace platforms (Embraer, Boeing, etc.)
