Slideshow "How helicopters fly"

Fasteners and connections

Because of the long lifespan of helicopters, all components need to be replaceable. For safety reasons, fasteners should not shake loose under the influence of vibrations. For those two reasons, nearly all components in a helicopter are fixed using locked nuts and bolts. Locking mechanisms used in the R44 are safety pins, safety wire, and adhesives. Plain bearings and ball bearings are either pressed into place, or held in place by a retainer ring and bolts.

Annoted drawings and photos

Pictures of components

The top picture shows the location of the PTFE plain bearings (shown in red) and the bolts which are used to attach the teetering hinge to the mast and the spindle to the teetering hinge (shown in blue). The plain bearings are attached to the teetering hinge by pressing them in. The bolts are 22mm in diameter, as they are effectively responsible for carrying the weight of the helicopter and keep the blades from being torn off by the centrifugal force. A variable amount of washers is added so that the friction of the flapping hinge can be changed. Because this bolt is such a critical component, the nut is locked in place using a safety pin.

The rotor blade spindle contains 6 angular contact ball bearings. The bearings are necessary to allow change of the angle of attack of the blade. Angular contact bearings are necessary because they have both an axial and a radial load: the centrifugal force and the lift force respectively. The order in which the bearings need to be assembled is printed on the outer ring: a number from 1 to 6 and two sloped lines indicate this. The bearings are heated and slid over the spindle. When the bearings need to be replaced, they are removed using a hydraulic press. The spindle with bearings is pushed into a socket in the helicopter blade, and are then fixed using 12 bolts.