Aeronautics and astronautics – Aircraft – heavier-than-air – Helicopter or auto-rotating wing sustained – i.e. – gyroplanes
Reexamination Certificate
2003-04-01
2004-04-06
Poon, Peter M. (Department: 3644)
Aeronautics and astronautics
Aircraft, heavier-than-air
Helicopter or auto-rotating wing sustained, i.e., gyroplanes
C244S00100R
Reexamination Certificate
active
06715711
ABSTRACT:
BACKGROUND OF THE INVENTION
A typical helicopter includes a fuselage having a forward section and a tail boom section, a main rotor assembly extending out from the forward section of the fuselage, a plurality of main rotor blades coupled to the main rotor assembly, a tail rotor assembly extending out from the tail boom section of the fuselage, and a plurality of tail rotor blades coupled to the tail rotor assembly. An Apache helicopter has four tail rotor blades detachably connected to the tail rotor assembly.
SUMMARY OF THE INVENTION
A method of the present invention comprises providing a helicopter and providing a hub-protecting cap. The helicopter has a fuselage, a tail rotor assembly operatively coupled to the fuselage for rotation relative to the fuselage about a tail rotor axis, and at least one tail rotor blade detachably connected to the tail rotor assembly. The tail rotor assembly comprises a hub portion having a pitch change bearing surface. The tail rotor blade has a hub socket. The pitch change bearing surface of the hub portion is within the hub socket of the tail rotor blade. The pitch change bearing surface engages the tail rotor blade in a manner to permit movement of the tail rotor blade relative to the hub portion about a blade pitch change axis. The hub-protecting cap has a cap body portion. The cap body portion has a hub socket. The method further comprises removing the tail rotor blade from the tail rotor assembly and attaching the hub-protecting cap to the tail rotor assembly in a manner such that the pitch change bearing surface of the hub portion is within the hub socket of the hub-protecting cap. The attachment of the hub-protecting cap to the tail rotor assembly occurs after removal of the tail rotor blade from the tail rotor assembly.
Another aspect of the present invention is an assembly comprising a helicopter and a hub-protecting cap. The helicopter has a fuselage, a tail rotor assembly operatively coupled to the fuselage for rotation relative to the fuselage about a tail rotor axis, and a first tail rotor blade detachably connected to the tail rotor assembly. The tail rotor assembly comprises a first hub portion and a second hub portion. Each of the first and second hub portions is adapted to receive a tail rotor blade. The first hub portion has a pitch change bearing surface. The second hub portion has a pitch change bearing surface. The first tail rotor blade has a hub socket. The pitch change bearing surface of the first hub portion is within the hub socket of the first tail rotor blade and engages the first tail rotor blade in a manner to permit movement of the first tail rotor blade relative to the hub portion about a first blade pitch change axis. The pitch change bearing surface of the second hub portion is adapted to be within a hub socket of a second tail rotor blade. The helicopter is in a tail rotor blade removed configuration in which the second hub portion is free of any tail rotor blade. The hub-protecting cap includes a cap body portion having a hub socket. The pitch change bearing surface of the second hub portion is within the hub socket of the hub-protecting cap.
Another aspect of the present invention is a hub-protecting cap for use with a helicopter. The helicopter has a fuselage, a tail rotor assembly operatively coupled to the fuselage for rotation relative to the fuselage about a tail rotor axis, at least one tail rotor blade detachably connected to the tail rotor assembly, a retention pin, and a pitch control link mechanism. The tail rotor assembly includes a hub portion and a portion of a retention strap assembly extending out from the hub portion. The hub portion has a pitch change bearing surface. The tail rotor blade has a hub socket. The hub portion is adapted to receive the tail rotor blade. The pitch change bearing surface of the hub portion is within the hub socket of the tail rotor blade when the hub portion is in receipt of the tail rotor blade. The pitch change bearing surface is adapted to engage the tail rotor blade in a manner to permit movement of the tail rotor blade relative to the hub portion about a blade pitch change axis. The retention pin is adapted to extend from the tail rotor blade to the portion of the retention strap in a manner to detachably secure the tail rotor blade to the portion of the retention strap. The pitch control link mechanism is adapted to move the tail rotor blade about the blade pitch change axis. The hub-protecting cap comprises a cap body portion, a pin-receiving aperture, and a link-attaching portion. The cap body portion is adapted to be attached to the hub portion in a manner to cover the hub portion when the tail rotor blade is detached from the tail rotor assembly. The cap body portion has a hub socket adapted such that the pitch change bearing surface of the hub portion is within the hub socket of the cap body portion when the cap body portion is attached to the hub portion. The pin-receiving aperture is through the cap body portion. The pin-receiving aperture is sized and located to align with the portion of the retention strap and to receive the retention pin when the cap body portion is attached to the hub portion. The link-attaching portion extends from the cap body portion. The link-attaching portion is sized and adapted for attachment to the pitch control link mechanism when the cap body portion is attached to the hub portion.
Other features and advantages will be in part apparent and in part pointed out hereinafter.
REFERENCES:
http://www.b-domke.de/AviationImages/Apache/3968.html and 5323.html.*
http://www.b-domke.de/AviationImages/Rotorhead/1077.html and 1079.html.*
http://www.bearingbuddy.com/bra.html.
Duffield Christopher T.
Muylaert Neal W.
Collins Timothy D.
Poon Peter M.
Thompson & Coburn LLP
LandOfFree
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