KC-10 Boom Nozzle vs. KC-135 Boom Nozzle
Shown here are the nozzles of the KC-10 and of the KC-135. The nozzle mates to the air refueling receptacle installed on the receiver aircraft. The nozzle incorporates a ball joint swivel and a universal joint. These two items provide flexibility to the nozzle assembly that is required when making contact and when the tanker and receiver are hooked up. The universal joint is used to transmit impact loads through the nozzle assembly to the shock absorber recoil assembly. The nozzle assembly is approximately two feet long.
A spring-activated check valve, referred to as the poppet valve, forms the fuel seal in the aft end of the nozzle when not in contact. The poppet valve is automatically depressed during the coupling operations by the receiver’s receptacle assembly. The spring in the poppet valve assembly, coupled with fuel pressure, exerts sufficient force on the poppet valve to close it rapidly, which results in very little fuel spillage. The resultant surges in fuel pressure are absorbed by the rubber surge boots.
The boom nozzle incorporates an induction coil at the 6 o’clock position that allows the tanker and receiver air refueling signal systems to transmit contact and disconnect signals. The induction coil also allows the two aircraft to share interphone communications.
At the 3 o’clock and 9 o’clock position on the nozzle are detents that the receiver’s latch toggles engage when contact is established. The detents on KC-10 nozzle can be retracted (IDS), this allows the tanker to disconnect from the receiver even if the receiver’s air refueling system malfunctions. The independent disconnect system (IDS) is an electrically controlled, pneumatically actuated system located in the nozzle assembly. Pneumatic pressure is supplied from a compressed air reservoir mounted on the telescope tube. The IDS is operated by depressing the disconnect switch through the second detent. When the system is activate, pneumatic pressure reacts the toggle latches on each side of the nozzle to a flush position. This allows the boom to be retracted from the receiver aircraft while its toggles are in the latched/extended position. The toggle latches have a holding circuit installed that retains them in the retracted position after IDS actuation, until the RESET TO READY button is pushed.