An Overview of Aircraft Rigging
When constructing an aircraft and installing the various airframe components needed for performance, safety, and stability, rigging serves as the installation and adjustment method for such components. Whether attaching wings, tail surfaces, ailerons, or similar airframe structures, a number of procedures are carried out to ensure proper travel stops, cable tension, and more. Beyond airframe components, rigging and rigging gear can also be used for the attachment of flight deck controls, landing gear, engine controls, and other such components.
When conducting the rigging process, it is crucial that one always follows rigging specifications and guidelines that are provided by various sources such as the manufacturer. Without proper rigging, the operation of an aircraft can be very unsafe as flight characteristics change and optimal control is lost. To conduct standard rigging operations, the most common procedure is to install fixed tail surfaces first, then move on to movable tail surfaces & trim tabs and wing panels before finishing with the installation of movable surfaces that are attached to wing panels.
Before beginning the rigging process, the aircraft must have its fuselage leveled out and then secured and blocked. By setting out blocks, tackle rigging, and slings, the rigging process can be safely conducted as the aircraft is held in place. When beginning the installation of fixed tailed surfaces, personnel will check to see if horizontal and vertical surfaces are strut or wire braced, as this will allow further rigging adjustments. For aircraft that feature strut based surfaces, strut adjustments may be conducted to level horizontal surfaces. For wire braced surfaces, on the other hand, manufacturer specifications should be followed to ensure proper tension of all wires.
When moving on to the installation of movable tail surfaces and trim tabs, it is often recommended that one first installs the elevators. This is due to the fact that attaching the rudder can make mating elevators and their related components more difficult. After finalizing the elevator and its tabs, the rudder can then be secured alongside its control cables. With manufacturer specifications, the travel of the rudder should be checked, and toe brakes should not be applied during the process. As this is a common but problematic issue with rigging brakes, one should always check before finalizing the entire procedure.
During the installation of the wings, rigging will often depend upon the type present for the particular model. If an aircraft is constructed with cantilevered wings, tool rigging may not be required once installation is finished. For wire and strut based wings, rigging and rigging gear can be used much easier for conducting adjustments. Once the wings have been attached to the fuselage, a dihedral should be always be set. With a dihedral board, one can follow specifications to conduct tool kit rigging for wing dihedrals, wing twist, and horizontal stabilizer dihedrals. For strut based aircraft in particular, rigging twist into the wings can be done by adjusting the eccentric at the rear wing attach fitting. For aircraft with two lift struts, on the other hand, an adjustment can be located on either the upper or lower end of the rear lift strut.
As the last major part of installation and rigging, movable surfaces must be attached to wing panels. While similar to the other rigging processes, ailerons in particular may need to be adjusted as necessary to ensure their differential travel to equalize resistance. Based on manufacturer specifications, one can find the recommended drooping lengths for ailerons assembly to ensure that they normally rise and operate during cruise flight.
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