Aircraft fluid system pressure variation attenuation

A fluid system of an aircraft engine, comprising:

• a first fluid conduit fluidly connected to at least one part of the aircraft engine;
• a pump fluidly connected to the first fluid conduit, during at least part of operation of the fluid system, the pump moving a fluid via the first fluid conduit and imparting an excitation frequency to the fluid;
• a second fluid conduit at a first end thereof fluidly connected to the first fluid conduit and at a second end thereof fluidly connected to a sensor;
• and
• a plunger disposed in the second fluid conduit and slidably movable between a first position and a second position within the second fluid conduit,
• the plunger being closer to the first end of the second fluid conduit in the first position than in the second position,
• wherein a liquid capacitance of the second fluid conduit is defined by a volume within the second fluid conduit between the plunger and the second end of the second fluid conduit,
• a mass of the plunger and the liquid capacitance of the second fluid conduit defining a resonance frequency of the second fluid conduit, the mass of the plunger and the liquid capacitance selected to maintain the resonance frequency less than the excitation frequency;
• and
• a third fluid conduit at one end of the third fluid conduit fluidly connecting into the second fluid conduit at a first location and at another end of the third fluid conduit connecting into the first fluid conduit, the first location being open to the second fluid conduit when the plunger is in the first position and being blocked by the plunger when the plunger is in the second position.