Methods and systems to facilitate over-speed protection

1. A method for assembling a gas turbine engine to prevent rotor over-speeding, said method comprising:

serially coupling in fluid flow communication a first fuel system interface to a second fuel system interface, such that at least one of the first fuel system interface and the second fuel system interface is coupled in fluid flow communication to the gas turbine engine;

communicatively coupling a control system to the first fuel system interface and to the second fuel system interface, wherein the control system is configured to identify an occurrence of an over-speed condition; and

programming the control system to discontinue fuel flow to the engine only when both the first fuel system interface and the second fuel system interface indicate an over-speed condition has occurred.

2. A method in accordance with claim 1 , wherein the gas turbine engine includes a fuel throttling/shutoff valve, wherein serially coupling the first fuel system interface to the second fuel system interface, such that at least one of the first fuel system interface and the second fuel system interface is coupled to the gas turbine engine further comprises, coupling one of the first fuel system interface and the second fuel system interface to the fuel throttling/shutoff valve.

3. A method in accordance with claim 2 , wherein programming the control system to discontinue fuel flow to the engine comprises configuring the fuel throttling/shutoff valve to stop engine fuel flow when both the first fuel system interface and the second fuel system interface indicate an over-speed condition as occurred.

4. A method in accordance with claim 1 , wherein serially coupling the first fuel system interface to the second fuel system interface comprises:

coupling a shutoff shuttle valve of the first fuel system interface to a shutoff shuttle valve of the second fuel system interface; and

coupling the shutoff shuttle valves to the gas turbine engine.

5. A method in accordance with claim 4 , wherein programming the control system to discontinue fuel flow to the engine when both the first fuel system interface and the second fuel system interface indicate an over-speed condition has occurred further comprises coupling at least one sensor to the control system, wherein the at least one sensor is configured to provide engine operating information to the control system.

6. An over-speed protection system for a gas turbine engine including a rotor, said over-speed protection system comprising:

a fuel throttling/shutoff valve coupled to a fuel supply coupled to said gas turbine engine;

a first fuel system interface coupled in flow communication to said fuel throttling/shutoff valve, said first fuel system interface configured to provide said throttling/shutoff valve with a control pressure indicative of an over-speed condition;

a second fuel system interface serially coupled in fluid flow communication to said first fuel system interface, said second fuel system interface configured to provide said throttling/shutoff valve with a control pressure indicative of an over-speed condition; and

a control system configured to identify an occurrence of an over-speed condition and to provide said first fuel system interface and said second fuel system interface with a signal corresponding to said over-speed occurrence, wherein said fuel throttling/shutoff valve is configured to discontinue the fuel supply being provided to said gas turbine engine only when said first fuel system interface and said second fuel system interface indicate an over-speed condition has occurred.

7. An over-speed protection system in accordance with claim 6 , further comprising sensors positioned within said engine and configured to provide engine operating information to said control system.

8. An over-speed protection system in accordance with claim 6 , wherein said first fuel system interface comprises a servovalve coupled to a shutoff shuttle valve.

9. An over-speed protection system in accordance with claim 8 , wherein said servovalve comprises an electro-hydraulic servovalve (EHSV).

10. An over-speed protection system in accordance with claim 6 , wherein said second fuel system interface comprises a servovalve coupled to a shutoff shuttle valve.

11. An over-speed protection system in accordance with claim 10 , wherein said servovalve comprises an EHSV.

12. A gas turbine engine comprising:

a rotor;

a fuel delivery system configured to supply fuel to said engine for operating said rotor; and

an over-speed protection system coupled to said fuel delivery system, said over-speed protection system comprising:

a fuel throttling/shutoff valve coupled to said fuel delivery system;

a first fuel system interface coupled in flow communication to said fuel throttling/shutoff valve, said first fuel system interface configured to provide said throttling/shutoff valve with a control pressure indicative of an occurrence of an over-speed condition;

a second fuel system interface serially coupled in fluid flow communication to said first fuel system interface, said second fuel system interface configured to provide said throttling/shutoff valve with a control pressure indicative of an occurrence of an over-speed condition; and

a control system configured to identify an occurrence of an over-speed condition and to provide said first fuel system interface and said second fuel system interface with a signal corresponding to said over-speed occurrence, wherein said fuel throttling/shutoff valve is configured to discontinue the fuel supply being provided to said gas turbine engine only when said first fuel system interface and said second fuel system interface indicate an over-speed condition has occurred.

13. A gas turbine engine in accordance with claim 12 , further comprising sensors positioned within said engine and configured to provide engine operating information to said control system.

14. A gas turbine engine in accordance with claim 12 , wherein said first fuel system interface comprises a servovalve coupled to a shutoff shuttle valve.

15. A gas turbine engine in accordance with claim 14 , wherein said servovalve comprises an electro-hydraulic servovalve (EHSV).

16. A gas turbine engine in accordance with claim 12 , wherein said second fuel system interface comprises a servovalve coupled to a shutoff shuttle valve.

17. A gas turbine engine in accordance with claim 16 , wherein said servovalve comprises an EHSV.