Would fuel quantity indications be affected by extended flight at nonzero bank angles?
I don't know what fuel quantity indicating system is installed on the MH-53, but most aircraft use a capacitive indicating system. Basically, there are multiple probes spaced throughout the fuel tank(s). During a turn or bank, the fuel will accumulate to one side of the tank, which increases the capacitance on the respective probes on that side of the tank. Meanwhile, the capacitance decreases on the probes that aren't covered as much. Total capacitance of all the probes is then summed and processed. Basically, no matter how the aircraft is oriented, in a properly operating system, there should be no detectable change in fuel quantity.