Airfoilmod:
The Valve sleeve moves in two directions, with flow (and against a spring), and versus flow, with the aid of the spring and the "backflow" of the Fuel, when it closes and prevents Fuel return. The mechanical "stop" can stall in any position, while transiting in either direction, vibrate (resonate) and completely stop Fuel entry into the system. All that is required (unlikely) is sufficient tuned energy to overcome the normal working parameters of the device.
Got a picture (cross section) of these specific one way valves?
Is it correct that at BOTH ends of the travel of the "restricting device" that fuel is completely shut off?
I'm more familiar with valves (spherical ball on a conical seat etc) whereby only one end of the travel actual restricts the flow.The design specifically ensures that flow is unrestricted in the other direction.
Interesting (if correct).
Two INDEPENDENT valves responding at the same time to some form of resonance (both systems likely tuned differently)...Possible but WOW!
Worse odds than the lottery!