Three pump fuel systems with selectable main and augmentor pumps

A fuel system comprising:

• a main fuel pump sub-system (MFP) with an inlet for receiving a supply of fuel from an inlet line, wherein the MFP has a main outlet line configured to supply fuel to a main fuel throttle valve assembly (MFTV), and a cross-over outlet line;
• an augmentor fuel pump sub-system (ABFP) with an inlet connected in fluid communication with the cross-over outlet line, and an outlet connected in fluid communication with a main augmentor supply line;
• and
• an actuation fuel pump sub-system (AFP) with an inlet connected in fluid communication with a branch of the main outlet line, an outlet line with a first outlet line branch configured to connect to supply fuel to the MFTV, and a second outlet line branch configured to connect to supply fuel to an actuation system, wherein the AFP includes a positive displacement pump, with a pump inlet connected in fluid communication with the branch of the main outlet line, and an outlet connected in fluid communication with a main AFP pump outlet line, and wherein the AFP includes a check valve (CV) in the main AFP pump outlet line, configured to prevent backflow through the main AFP outlet line into the positive displacement pump.

A fuel system comprising:

• a main fuel pump sub-system (MFP) with an inlet for receiving a supply of fuel from an inlet line, wherein the MFP has a main outlet line configured to supply fuel to a main fuel throttle valve assembly (MFTV), and a cross-over outlet line;
• an augmentor fuel pump sub-system (ABFP) with an inlet connected in fluid communication with the cross-over outlet line, and an outlet connected in fluid communication with a main augmentor supply line;
• and
• an actuation fuel pump sub-system (AFP) with an inlet connected in fluid communication with a branch of the main outlet line, an outlet line with a first outlet line branch configured to connect to supply fuel to the MFTV, and a second outlet line branch configured to connect to supply fuel to an actuation system, wherein the MFTV includes an MFTV check valve (CV) connected in fluid communication between the main outlet line and the first outlet line branch of the AFP, configured to prevent flow from the main outlet line to the first outlet line branch of the AFP, and to allow flow from the first outlet line branch of the AFP to the main outlet line.

A fuel system comprising:

• a main fuel pump sub-system (MFP) with an inlet for receiving a supply of fuel from an inlet line, wherein the MFP has a main outlet line configured to supply fuel to a main fuel throttle valve assembly (MFTV), and a cross-over outlet line;
• an augmentor fuel pump sub-system (ABFP) with an inlet connected in fluid communication with the cross-over outlet line, and an outlet connected in fluid communication with a main augmentor supply line;
• and
• an actuation fuel pump sub-system (AFP) with an inlet connected in fluid communication with a branch of the main outlet line, an outlet line with a first outlet line branch configured to connect to supply fuel to the MFTV, and a second outlet line branch configured to connect to supply fuel to an actuation system;
• wherein the ABFP includes:
• an inlet shut off valve (ISOV) in a centrifugal pump feed line that is in fluid communication with the inlet of the ABFP and the cross-over outlet line, wherein the ISOV is configured to switch between a first state blocking supply of fuel through the centrifugal pump feed line and a second state supplying fuel through the centrifugal pump feed line;
• a centrifugal pump connected in fluid communication with the centrifugal pump feed line downstream of the ISOV to be supplied with fuel from the ISOV in the second state, wherein the centrifugal pump has centrifugal pump outlet in fluid communication with the main augmentor supply line;
• a stabilizing check valve (SCV) in the main augmentor supply line configured to allow flow from the centrifugal pump through the main augmentor supply line, and to prevent backflow from the main augmentor supply line into the centrifugal pump;
• an ejector having a drain inlet connected in fluid communication with a branch of the main augmentor supply line that is upstream of the SCV, an ejection inlet connected in fluid communication with a return line from the MFTV, and an outlet connected in fluid communication with a return line configured to be connected to an inlet of a boost pump, wherein the ejector is configured to drain the centrifugal pump using flow from the AFP through the MFTV;
• and
• a pump transfer valve (PTV) connected in fluid communication with a return line connected in fluid communication between the ABFP and the inlet line, in fluid communication with a branch of the main augmentor supply line upstream of the SCV, and with a return branch of the main augmentor supply line downstream of the SCV, wherein the PTV is configured to switch between returning flow from either downstream or upstream of the SCV to the return line.