Engine debris guard

1. An engine debris guard for preventing tire propelled debris striking an aircraft engine, the debris guard comprising a guard bar pivotably connected to an aircraft main landing gear having at least one wheel and tire assembly having an axle line, the guard bar being arranged to be movable between a first position wherein the guard bar is generally below the axle line and a second position arranged to prevent the guard bar from striking a runway during take-off and landing maneuvers of the aircraft, wherein in the first position the guard bar extends laterally across the wheel and tire assembly to intersect the possible trajectories between the wheel and tire assembly and an engine of the aircraft of any tire propelled debris, wherein the guard bar is at least one of adapted to be moved from the first position to the second position during take-off manoeuvres of the aircraft or adapted to be moved from the second position to the first position during landing manoevres of the aircraft, and wherein the engine debris guard is at least one of adapted to automatically move the guard bar from the first position to the second position or to automatically move the guard bar from the second position to the first position.

2. An engine debris guard according to claim 1 , wherein the debris guard is arranged to partially rotate with respect to the main landing gear.

3. An engine debris guard according to claim 1 , wherein the guard bar includes an attachment arm pivotably connected to the main landing gear.

4. An engine debris guard according to claim 3 further comprising an actuator connected between the attachment arm and the main landing gear, wherein operation of the actuator causes the guard bar to move between said first and second positions.

5. An engine debris guard according to claim 1 further comprising a resilient member arranged to bias the guard bar away from first position.

6. An engine debris guard according to claim 1 further comprising shock absorbing means arranged to permit movement of the engine debris guard away from the wheel and tire assembly when struck by a piece of debris.

7. An engine debris guard according to claim 6 , wherein the shock absorbing means comprises a resilient member connected between the engine debris guard and the main landing gear.

8. An engine debris guard according to claim 6 , wherein the shock absorbing means comprises an attachment arm connecting the guard bar to the main landing gear, the attachment arm including an hinged section resiliently biased to resist hinging movement.

9. An aircraft having at least one engine mounted at the rear of the fuselage and including an engine debris guard according to claim 1 .

10. An engine debris guard according to claim 1 , wherein in the first position the guard bar is located behind the axle line with respect to a longitudinal direction of the aircraft.

11. An engine debris guard according to claim 10 , wherein in the first position the guard bar is located behind the periphery of the tire with respect to a longitudinal direction of the aircraft.

12. An aircraft according to claim 10 , wherein the guard bar extends both laterally and longitudinally substantially across a trajectory cone in which an unimpeded piece of debris originating from the wheel and tire assembly will strike the aircraft engine.

13. An engine debris guard according to claim 1 , further comprising an actuator configured to move the guard bar from the first position to the second position.

14. An engine debris guard according to claim 1 , wherein in the first position the guard bar is located generally below the axle line and generally aft of the axle line with respect to the direction of forward movement of the aircraft.

15. An engine debris guard according to claim 1 , wherein the engine debris guard is adapted to enable manual movement of the guard bar from the first position to the second position, and wherein the engine debris guard is adapted to enable manual movement of the guard bar from the second position to the first position.

16. An aircraft including an engine debris guard according to claim 1 , wherein the engine debris guard is movable from the first position to the second position via an actuator.

17. An engine debris guard for preventing tire propelled debris striking an aircraft engine, the debris guard comprising a guard bar pivotably connected to an aircraft main landing gear having at least one wheel and tire assembly having an axle line, the guard bar being arranged to be movable between a first position wherein the guard bar is generally below the axle line and a second position arranged to prevent the guard bar from striking a runway during take-off and landing maneuvers of the aircraft, wherein in the first position the guard bar extends laterally across the wheel and tire assembly to intersect the possible trajectories between the wheel and tire assembly and an engine of the aircraft of any tire propelled debris; and wherein the guard bar is at least one of moved from the first position to the second position during take-off maneuvers or moved from the second position to the first position during landing maneuvers.

18. An engine debris guard according to claim 17 further comprising a resilient member arranged to bias the guard bar away from first position.

19. An engine debris guard according to claim 17 further comprising shock absorber arranged to permit movement of the engine debris guard away from the wheel and tire assembly when struck by a piece of debris.

20. An engine debris guard according to claim 19 , wherein the shock absorber comprises a resilient member connected between the engine debris guard and the main landing gear.

21. An engine debris guard according to claim 19 , wherein the shock absorber comprises an attachment arm connecting the guard bar to the main landing gear, the attachment arm including an hinged section resiliently biased to resist hinging movement.

22. An aircraft having at least one engine mounted at the rear of the fuselage and including an engine debris guard according to claim 17 .

23. An aircraft according to claim 22 , wherein the guard bar extends both laterally and longitudinally substantially across a trajectory cone in which an unimpeded piece of debris originating from the wheel and tire assembly will strike the aircraft engine.

24. An engine debris guard according to claim 17 , further comprising an actuator configured to move the guard bar from at least one of the first position to the second position or from the second position to the first position.

25. An engine debris guard according to claim 17 , wherein in the first position the guard bar is located generally below the axle line and generally aft of the axle line with respect to the direction of forward movement of the aircraft.

26. An engine debris guard according to claim 17 , wherein the engine debris guard is at least one of adapted to automatically move the guard bar from the first position to the second position or adapted to automatically move the guard bar from the second position to the first position.

27. An engine debris guard according to claim 26 , wherein the engine debris guard is adapted to enable manual movement of the guard bar from the first position to the second position, and wherein the engine debris guard is adapted to enable manual movement of the guard bar from the second position to the first position.

28. An engine debris guard according to claim 17 , wherein in the first position the guard bar is located behind the periphery of the tire with respect to a longitudinal direction of the aircraft.