Apparatus to eliminate back drive in push pull system of rotor aircraft and related methods

An apparatus for eliminating back drive in a push pull type control system, the apparatus comprising:

• a control rod including a rod end assembly comprising a pair of spaced apart piston displacement members, each piston displacement member having a check valve aperture configured to receive a check valve;
• a piston located within a chamber of a piston housing, the piston comprising a piston head and a piston body having inner surface portions defining a piston chamber configured to receive hydraulic fluid, the piston head including a first aperture for receiving a portion of the control rod, a first of the pair of piston displacement members located within the piston chamber and a second of the pair of piston engagement members located outside the piston chamber, the piston head further including a second aperture for passing portions of the hydraulic fluid into the piston chamber and for passing portions of the hydraulic fluid out of the piston chamber;
• a first check valve of a pair of opposite-facing check valves having a body connected to the first of the pair of piston displacement members and having an aperture extending through a piston-facing surface of the first check valve for receiving hydraulic fluid, the first check valve body oriented so that when the first of the pair of piston displacement members is retracted into a direction of the piston head and the piston-facing surface of the first check valve lands upon an opposing surface of the piston head, the aperture of the first check valve forms a sealed pathway through the second aperture in the piston head;
• and
• a second check valve of the pair of opposite-facing check valves having a body connected to the second of the pair of piston displacement members and having an aperture extending through a piston-facing surface of the second check valve for receiving hydraulic fluid, the second check valve body oriented so that when the second of the pair of piston displacement members is extended into a direction of the piston head and the piston-facing surface of the second check valve lands upon an opposing surface of the piston head, the aperture in the second check valve forms a sealed pathway through the second aperture in the piston head.

An apparatus for eliminating back drive in a push pull type flight control system for an aircraft, the apparatus comprising:

• a cylindrical housing having a first end portion, a second end portion, and a medial body portion extending therebetween, the medial body portion having an inner body surface defining a housing chamber containing hydraulic fluid, the first end portion configured to connect to a main aircraft structure;
• a first control rod extending from the first end portion of the housing and configured to operably interface with a rotor control head;
• a second control rod extending from the second end of the housing and configured to be operably controlled by a user, the second control rod including a rod end assembly comprising a pair of spaced apart piston displacement plates, each piston displacement plate having a check valve aperture configured to support a check valve;
• a piston slidably positioned within the chamber of the cylindrical housing and having an outer surface in sealed contact with inner surface portions of the medial body portion of the cylindrical housing, the piston comprising a first end portion, a second end portion defining a piston head, and a medial body portion extending therebetween, the medial body portion defining a piston chamber containing portions of the hydraulic fluid, the piston head including a first aperture for receiving a portion of the second control rod, a first of the pair of piston displacement plates located within the piston chamber and a second of the pair of piston displacement plates located outside the piston chamber and inside the chamber of the cylindrical housing, the piston head further including a second aperture for passing portions of the hydraulic fluid into the piston chamber and for passing portions of the hydraulic fluid out of the piston chamber;
• a first check valve of a pair of opposing check valves having a body connected to the first of the pair of piston displacement plates and having an aperture extending through a piston-facing surface of the check valve for receiving hydraulic fluid, the first check valve body oriented so that when the first of the pair of piston displacement plates is retracted into a direction of the piston head and the piston-facing surface of the first check valve lands upon an opposing surface of the piston head, the aperture of the first check valve forms a sealed pathway through the second aperture in the piston head;
• and a second check valve of the pair of opposing check valves having a body connected to the second of the pair of piston displacement plates and having an aperture extending through a piston-facing surface of the check valve for receiving hydraulic fluid, the second check valve body oriented so that when the second of the pair of piston displacement plates is extended into a direction of the piston head and the piston-facing surface of the second check valve lands upon an opposing surface of the piston head, the aperture in the second check valve forms a sealed pathway through the second aperture in the piston head,
• the first and the second check valves being separated a sufficient distance so that when the respective piston-facing surface of one of the pair of opposing check valves is in sealing contact with the piston head, the piston-facing surface of the other of the pair of opposing check valves is separated from the piston head.