Pitch link with track adjustment indicators

A rotorcraft comprising:

• a mast configured to rotate around a principal axis, wherein the principal axis extends along a length of the mast;
• a yoke coupled to the mast, wherein a rotation of the mast rotates the yoke around the principal axis;
• a plurality of rotor blades coupled to the yoke around a circumference of the yoke, wherein a rotation of the yoke rotates the plurality of rotor blades around the principal axis, and wherein a tip of each of the plurality of rotor blades traces a tip path while the rotor blade is rotating around the principal axis;
• a rotating ring coupled to the mast or to the yoke, wherein a rotation of the mast rotates the rotating ring around the principal axis, either directly, or via a rotation of the yoke;
• a plurality of pitch links, wherein each pitch link has a first end and a second end opposite the first end, the first end coupled to one of the plurality of rotor blades, and the second end coupled to the rotating ring along a circumference of the rotating ring, with a rotation of the rotating ring rotating the plurality of pitch links around the principal axis;
• and
• a non-rotating ring disposed under the rotating ring, wherein the non-rotating ring changes a position or angle of the rotating ring relative to the principal axis while the rotating ring and the pitch links are in rotation around the principal axis;
• wherein a change in the positioning of either or both sides of the rotating ring is configured to displace each of the plurality of pitch links relative to the principal axis and change pitch of the rotor blades, while the pitch links are engaged in maintaining the tip paths of the plurality of rotor blades within a tolerable distance from a rotation track;
• wherein, for each pitch link in the plurality of pitch links, the pitch link comprises:
• a tube having a first portion extending towards the first end of the pitch link, and a second portion opposite the first portion, wherein the second portion extends towards the second end of the pitch link;
• a first rod comprising a first rod head and a first rod body extending therefrom along a vertical axis defined between the first end and the second end of the pitch link, wherein the first rod head is configured to couple the pitch link to the rotor blade, and the first rod body is threaded into the tube at the first portion of the tube;
• and
• a second rod comprising a second rod head and a second rod body extending therefrom along the vertical axis, wherein the second rod head is configured to couple the pitch link to the swash plate, and the second rod body is threaded into the tube at the second portion of the tube;
• and
• wherein, for each pitch link in the plurality of pitch links:
• the first rod head has an outer vertically planar surface marked with a reference indicator, and the tube has an outer surface marked with a plurality of track adjustment indicators at the first portion of the tube along a circumference of the tube, the track adjustment indicators being vertical and substantially perpendicular to the circumference;
• the pitch link has a pitch length from the first end to the second end that is adjustable from a nominal length;
• and
• the pitch length is adjustable by vertically displacing the tube relative to the first rod and the second rod while the pitch link is coupled to the rotor blade and the rotating ring by turning the tube relative to the first rod and the second rod in one of a first direction or a second direction around the vertical axis, the first direction increasing the pitch length, and the second direction decreasing the pitch length;
• wherein an amount of adjustment to the pitch length is configured to be determined in accordance with a number of track adjustment indicators in the plurality of track adjustment indicators that at least partly pass the reference indicator while the tube is turned in one of the first direction or the second direction;
• and
• wherein the first rod is an upper rod or a lower rod of the pitch link, wherein:
• when the first rod is the upper rod, the second rod is a lower rod, the first end of the pitch link is an upper end of the pitch link, the second end of the pitch link is a lower end of the pitch link, the first rod head is an upper rod head, the second rod head is a lower rod head, the first rod body is an upper rod body, the second rod body is a lower rod body, the first portion of the tube is an upper portion of the tube, and the second portion of the tube is a lower portion of the tube;
• and
• when the first rod is the lower rod, the second rod is the upper rod, the first end of the pitch link is the lower end of the pitch link, the second end of the pitch link is the upper end of the pitch link, the first rod head is the lower rod head, the second rod head is the upper rod head, the first rod body is the lower rod body, the second rod body is the upper rod body, the first portion of the tube is the lower portion of the tube, and the second portion of the tube is the upper portion of the tube.

A method comprising:

• installing a first rotor blade in a rotor assembly of a rotorcraft, wherein the first rotor blade is one of a plurality of rotor blades installed in the rotor assembly;
• starting a first operation of the rotor assembly with a first spooling up the rotor assembly while the rotorcraft remains grounded;
• measuring a first deviation of a tip path of the first rotor blade from a rotation track;
• stopping the first operation of the rotor assembly;
• based on the first deviation, making a first adjustment to a pitch length of a first pitch link that is coupled to the first rotor blade, wherein:
• the first pitch link has an upper end, a lower end opposite the upper end, and a vertical axis defined from the upper end to the lower end;
• the first pitch link comprises:
• a tube between the upper end and the lower end;
• an upper rod at the upper end threaded into an upper portion of the tube, the upper rod coupling the first pitch link to the first rotor blade;
• and
• a lower rod at the lower end threaded into a lower portion of the tube, the lower rod coupling the first pitch link to a swash plate of the rotor assembly,
• wherein making the first adjustment comprises:
• loosening an upper jam nut on the upper end of the first pitch link, and loosening a lower jam nut on the lower end of the first pitch link;
• and
• turning the tube around the vertical axis while the first pitch link remains coupled in position to the first rotor blade and the swash plate, the tube turning in a first direction for increasing the pitch length, or in a second direction opposite the first direction for decreasing the pitch length;
• determining an amount of the first adjustment to the pitch length by counting a first number of vertical track adjustment indicators on the tube that at least partly pass a vertical reference indicator on the upper rod or the lower rod, while the tube is turned in one of the first direction or the second direction, wherein a plurality of vertical track adjustment indicators, including the first number of vertical track adjustment indicators, are machined onto an outer surface of the upper portion or the lower portion of the tube, and the vertical reference indicator is machined onto a substantially vertical and substantially planar surface of the upper rod or the lower rod;
• and
• tightening the upper jam nut and tightening the lower jam nut;
• after making the first adjustment, starting a second operation of the rotor assembly;
• and
• based on the second operation, determining whether the first adjustment to the pitch length reduced a second deviation of the first rotor blade from the rotation track.