Fuel System Failure

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Airplane Fuel System Failure


If propellant system pressurization is lost, a caution light ("LOX" or "NH3" [70, 66, fig. 5-1]) will come on. System pressure can be restored for continued low thrust engine operation or propellant jettisoning by moving the propellant emergency pressurization switch [70, 66, fig. 5-1] toward the illuminated light. The emergency pressurization helium supply will provide sufficient emergency pressure for one tank only.


Note: Failure of the propellant pressurization system is not simulated in this software version.



Engine Fuel System Failure


Failure of the engine fuel system would be the result of an engine turbopump allure. Refer to "Turbo­pump Failure Durlng Flight" above.



Fuel Line Pressure Low


In the event of a low fuel line pressure caution light [64, 66, fig. 5-1] during flight (above 40,000 feet),  proceed as follows:


  1. Throttle [12, fig. 5-4] – Reduce. Reduce engine thrust setting as necessary to maintain fuel inlet pressure [72, fig. 5-1] at 30 psi. If pressure returns to normal, full throttle operation can be resumed.


  1. Continue operation, or shut down. Operation can be continued at 50% thrust setting if fuel inlet pressure remains above 20 psi. If fuel inlet pressure cannot be maintained above 20 psi, even at 50% thrust, shut down engine immediately, provided a safe landing can be made. An engine restart is not to be attempted unless pilot or airplane safety necessitates resumption of power.



Turbopump Failure During Flight


A turbopump failure will in most cases be caused by pump cavitation, or incorrect governor supply pressure. The possibility of a mechanical malfunction of the relatively simple turbopump assembly is not considered likely. Turbopump failure or shutoff, caused by the overspeed caution light [2f, fig. 5-1] coming on. If the over­speed caution light comes on, the engine may be restarted in the following manner:


  1. Throttle [12, fig. 5-4] – OFF.


  1. Engine reset button [62, fig. 5-1] – Push.


  1. Engine precool switch [56, fig. 5-1] – PRECOOL.


  1. Engine prime switch [56, fig. 5-1] – PRIME. Move engine prime switch to PRIME for one second and check ignition-ready light [2a, fig. 5-1] ON.


  1. Throttle [12, fig. 5-4] – START, then AS DESIRED.



Propellant Jettisoning


In an emergency where the engine propellants must be jettisoned, recheck jettison test switches [59, fig. 5-1] at JETT; then move the vent, pressurization, and jettison lever [11, fig. 5-4] to JETTISON, which allows the propellants to flow overboard. Approximate time required to jettison a full propellant load is about 120 seconds.