Apparatus and associated methods relate to simultaneously pumping and measuring density of an aircraft fuel. The aircraft fuel is pumped by a centrifugal pump having an impeller. A rotational frequency of the impeller is determined while the centrifugal pump is pumping the aircraft fuel. Flow rate of the aircraft fuel through the centrifugal pump is sensed. Pressure of the aircraft fuel is measured at two different points within or across the centrifugal pump or a differential pressure is measured between the two different points while the centrifugal pump is pumping the aircraft fuel. Density of the aircraft fuel is determined based on a head-curve relation characterizing the centrifugal pump. The head-curve relation relates the fuel density to the rotational frequency, the flow rate, and pressures at the two different points or the differential pressure between the two different points.

On board an aircraft, a method is perform in which the following steps are implemented in the following order: measuring a first density value, a first dielectric constant value and a first temperature value of the fuel at a first time, measuring a second density value, a second dielectric constant value and a second temperature value of the fuel, determining parameters of a function for calculating a density from a temperature or a dielectric constant, measuring a volume flow rate value and at least one of a third temperature value and a third dielectric constant value of the fuel in a fuel injection duct in the engine, and determining a density value of the fuel and a mass flow rate of the fuel in the injection line.

A system and method for supplementing fuel feed pressure and flow within an aircraft fuel system. The fuel system includes boost and override fuel pumps delivering fuel from the tanks to a fuel manifold, and a jettison fuel pump. The method includes the steps of: (a) sensing whether the aircraft engine is operating near maximum power; (b) upon sensing the condition, operating the jettison fuel pump in fluid interconnection with the override fuel pump to deliver fuel to the fuel manifold; and (c) upon sensing the cessation of the condition, deactivating the jettison fuel pump. The system includes a monitoring circuit signaling when the aircraft engine speed is greater than a predetermined threshold, and a fuel system control circuit operating a jettison fuel pump enable circuit portion in response to the signal while omitting other jettisoning operations. The jettison fuel pump consequently functions as an override fuel pump assist.

A system and method for supplementing fuel feed pressure and flow within an aircraft fuel system. The fuel system includes boost and override fuel pumps delivering fuel from the tanks to a fuel manifold, and a jettison fuel pump. The method includes the steps of: (a) sensing whether the aircraft engine is operating near maximum power; (b) upon sensing the condition, operating the jettison fuel pump in fluid interconnection with the override fuel pump to deliver fuel to the fuel manifold; and (c) upon sensing the cessation of the condition, deactivating the jettison fuel pump. The system includes a monitoring circuit signaling when the aircraft engine speed is greater than a predetermined threshold, and a fuel system control circuit operating a jettison fuel pump enable circuit portion in response to the signal while omitting other jettisoning operations. The jettison fuel pump consequently functions as an override fuel pump assist.

Fuel systems, apparatus and associated methods for preventing or hindering unwanted fuel transfer between fuel tanks of aircraft are described. An exemplary apparatus comprises a conduit portion disposed inside a fuel tank for receiving fuel in the first fuel tank. The conduit portion includes an orifice through a wall of the conduit. The orifice permits venting an interior of the conduit portion to an interior of the fuel tank to prevent unwanted fuel transfer due to siphoning. A deflector is disposed and configured to deflect a stream of fuel discharged from the orifice during fuel transfer.

Fuel systems, apparatus and associated methods for preventing or hindering unwanted fuel transfer between fuel tanks of aircraft are described. An exemplary apparatus comprises a conduit portion disposed inside a fuel tank for receiving fuel in the first fuel tank. The conduit portion includes an orifice through a wall of the conduit. The orifice permits venting an interior of the conduit portion to an interior of the fuel tank to prevent unwanted fuel transfer due to siphoning. A deflector is disposed and configured to deflect a stream of fuel discharged from the orifice during fuel transfer.

A fuel drain engagement tool and a method for draining fuel from a fuel tank are provided. In one example, a fuel drain engagement tool includes a housing. An engagement mechanism is coupled with the housing and extending upward therefrom. The engagement mechanism is configured to engage a fuel drain valve and to move between a contracted state and an expanded state. A compression applicator is coupled with the housing and is positioned to engage the engagement mechanism when the compression applicator is compressed to apply a force to the engagement mechanism that causes the engagement mechanism to move from the expanded state to the contracted state.

A fuel drain engagement tool and a method for draining fuel from a fuel tank are provided. In one example, a fuel drain engagement tool includes a housing. An engagement mechanism is coupled with the housing and extending upward therefrom. The engagement mechanism is configured to engage a fuel drain valve and to move between a contracted state and an expanded state. A compression applicator is coupled with the housing and is positioned to engage the engagement mechanism when the compression applicator is compressed to apply a force to the engagement mechanism that causes the engagement mechanism to move from the expanded state to the contracted state.

Apparatus and associated methods relate to simultaneously pumping and measuring density of an aircraft fuel. The aircraft fuel is pumped by a centrifugal pump having an impeller. A rotational frequency of the impeller is determined while the centrifugal pump is pumping the aircraft fuel. Flow rate of the aircraft fuel through the centrifugal pump is sensed. Pressure of the aircraft fuel is measured at two different points within or across the centrifugal pump or a differential pressure is measured between the two different points while the centrifugal pump is pumping the aircraft fuel. Density of the aircraft fuel is determined based on a head-curve relation characterizing the centrifugal pump. The head-curve relation relates the fuel density to the rotational frequency, the flow rate, and pressures at the two different points or the differential pressure between the two different points.

Apparatus and associated methods relate to simultaneously pumping and measuring density of an aircraft fuel. The aircraft fuel is pumped by a centrifugal pump having an impeller. A rotational frequency of the impeller is determined while the centrifugal pump is pumping the aircraft fuel. Flow rate of the aircraft fuel through the centrifugal pump is sensed. Pressure of the aircraft fuel is measured at two different points within or across the centrifugal pump or a differential pressure is measured between the two different points while the centrifugal pump is pumping the aircraft fuel. Density of the aircraft fuel is determined based on a head-curve relation characterizing the centrifugal pump. The head-curve relation relates the fuel density to the rotational frequency, the flow rate, and pressures at the two different points or the differential pressure between the two different points.