Final answer:
When pump #2 is the lead on a Type III hydrant system, the sequence of the other pumps is typically arranged for redundancy and to balance wear and tear, with pump #3 as the likely immediate backup.
Step-by-step explanation:
The Type III hydrant system refers to an aircraft refueling system commonly used at military airfields. When pump #2 is selected as the lead pump in this system, there is a predetermined sequence for the remaining pumps to engage in order to maintain pressure and flow rate within the system. If the demand increases or the lead pump fails, the sequence ensures that the system continues to operate efficiently without interruption.
Typically, the sequence will be designed based on redundancy and alternating usage to even out wear and tear. For example, if pump #2 is the lead, pump #3 might be designated as the immediate backup, followed by pump #1, and then pump #4, depending on the specific programming and operational protocols of the system. This sequence can vary, however, based on the specific design of the hydrant system at the airfield.