# US 2019/0315495 A1 · Devices and Methods to Verify Tail Rotor Cross-Head Positioning

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- Number: US 2019/0315495 A1
- Document ID: US20190315495A1
- Status: Published application
- Kind: A1
- Application number: 16/183,385
- Filed: 2018-11-07
- Published: 2019-10-17
- Earliest claimed: 2018-04-16
- Assignees: Bell Helicopter Textron Inc.
- Applicants: Bell Helicopter Textron Inc.
- Inventors: Chad R. Haugeberg; Bradley D. Linton
- Web page: https://patentgrep.com/patent/US20190315495A1

## CPC

- B64F 5/60: Testing or inspecting aircraft components or systems
- B64C 27/008: {Rotors tracking or balancing devices}
- B64F 5/50: Handling or transporting aircraft components
- G01B 5/14: for measuring distance or clearance between spaced objects or spaced apertures (G01B5/24 takes precedence)
- G01B 5/25: for testing the alignment of axes
- B64C 27/82: characterised by the provision of an auxiliary rotor or fluid-jet device for counter-balancing lifting rotor torque or changing direction of rotorcraft
- B64F: GROUND OR AIRCRAFT-CARRIER-DECK INSTALLATIONS SPECIALLY ADAPTED FOR USE IN CONNECTION WITH AIRCRAFT; DESIGNING, MANUFACTURING, ASSEMBLING, CLEANING, MAINTAINING OR REPAIRING AIRCRAFT, NOT OTHERWISE PROVIDED FOR; HANDLING, TRANSPORTING, TESTING OR INSPECTING AIRCRAFT COMPONENTS, NOT OTHERWISE PROVIDED FOR
- B64C: AEROPLANES; HELICOPTERS
- G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS

## Abstract

A device to verify tail rotor cross-head positioning is disclosed. The device comprises a first portion and a second portion. The second portion may be adjoined to the first portion and comprises maximum and minimum surfaces configured to determine whether a yoke-measuring surface of a tail rotor yoke may be positioned between respective geometric planes of the maximum and minimum surfaces.

## Claims

### Claim 1

A device to verify tail rotor cross-head positioning comprising:
a first portion; and
a second portion adjoined to the first portion and comprising maximum and minimum surfaces configured to determine whether a yoke-measuring surface of a tail rotor yoke is positioned between respective geometric planes of the maximum and minimum surfaces.

### Claim 2 (depends on 1)

The device of claim 1, wherein the first portion is adjoined to the second portion on a first end of the second portion, and the maximum and minimum surfaces are arranged on a second end of the second portion.

### Claim 3 (depends on 2)

The device of claim 2, wherein the first and second ends are on opposing ends of the second portion.

### Claim 4 (depends on 1)

The device of claim 1, wherein the first portion and the maximum and minimum surfaces are substantially parallel.

### Claim 5 (depends on 1)

The device of claim 1, wherein the maximum and minimum surfaces are substantially parallel to a positioning surface located on the first portion.

### Claim 6 (depends on 1)

The device of claim 1, wherein the first portion comprises a positioning surface and a concave curvature located proximate to a first end of the first portion.

### Claim 7 (depends on 6)

The device of claim 6, wherein the concave curvature is configured to be aligned with a convex curvature of a tail rotor cross-head, the positioning surface is configured to be aligned with a mating surface of the tail rotor cross-head, and wherein the first portion is adjoined to the second portion on a second end of the first portion.

### Claim 8 (depends on 1)

The device of claim 1, wherein the second portion defines maximum and minimum lengths, respectively, between a tail rotor cross-head and the tail rotor yoke.

### Claim 9 (depends on 8)

The device of claim 8, wherein the maximum surface defines the maximum length between a mating surface of the tail rotor cross-head and the yoke-measuring surface of the tail rotor yoke, and the minimum surface defines the minimum length between the mating surface of the tail rotor cross-head and the yoke-measuring surface of the tail rotor yoke.

### Claim 10 (depends on 1)

The device of claim 1, wherein an upper surface of the second portion is flat, and wherein a lower surface of the second portion comprises a convex curvature.

### Claim 11 (depends on 1)

The device of claim 1, wherein an upper surface of the second portion is configured to align substantially perpendicular to a tail rotor cross-head and a tail rotor yoke, and wherein a lower surface of the second portion is configured to align to the tail rotor yoke.

### Claim 12 (depends on 11)

The device of claim 11, wherein the first portion is substantially perpendicular to at least one of the upper and lower surfaces of the second portion.

### Claim 13 (depends on 11)

The device of claim 11, wherein the maximum and minimum surfaces are substantially perpendicular to at least one of the upper and lower surfaces of the second portion.

### Claim 14 (depends on 11)

The device of claim 11, wherein the maximum and minimum surfaces are positioned between the upper and lower surfaces of the second portion.

### Claim 15 (depends on 11)

The device of claim 11, wherein the maximum surface is located on an overlap feature, wherein the overlap feature extends the maximum surface beyond the lower surface of the second portion.

### Claim 16 (depends on 1)

The device of claim 1, wherein the maximum surface is located on an overlap feature, and wherein the maximum surface is configured to overhang the yoke-measuring surface of the tail rotor yoke.

### Claim 17

A method of verifying tail rotor rigging of a rotorcraft, comprising:
determining, using a verification tool, whether a yoke-measuring surface of a tail rotor yoke that is coupled to an actuator using a control tube is positioned between respective geometric planes of maximum and minimum surfaces of the verification tool;
adjusting the control tube; and
determining, using the verification tool, whether the yoke-measuring surface of the tail rotor yoke is positioned between the respective geometric planes of the maximum and minimum surfaces of the verification tool.

### Claim 18 (depends on 17)

The method of claim 17, wherein the determination of the positioning of the yoke-measuring surface further comprises:
positioning a concave curvature of the verification tool on a convex curvature of a tail rotor cross-head;
positioning a positioning surface of the verification tool on a mating surface of the tail rotor cross-head;
positioning a convex curvature of the verification tool on a concave curvature of the tail rotor yoke; and
evaluating whether the yoke-measuring surface of the tail rotor yoke is positioned between the respective geometric planes of the maximum and minimum surfaces of the verification tool.

### Claim 19 (depends on 17)

The method of claim 17, wherein the adjustment of the control tube is performed by rotating wrenching flats of the control tube.

### Claim 20 (depends on 19)

The method of claim 19, wherein a revolution of the control tube corresponds to a 0.083-inch displacement of a tail rotor cross-head coupled to the tail rotor yoke.