LOWER BUSHING, SCISSORS, YAK 52 MAIN GEAR
In developing this bushing to be retrofitted in the field, we had to make a few choices.
Neither the stock OD of 16mm nor an ID of 12mm would be much use.
The bushing OD needs to be slightly oversized to provide a good press fit into lower end of the arm (which has probably worn slightly large.)
The bushing ID needs to have a sliding fit with the steel pin which after a few years has now almost certainly worn to a smaller outside diameter.
And you need to be able to install it using available hand tools in your hangar.
With the plane on jacks and the arm removed from the airframe, start by pressing the new bushing into the arm.
Then if you find the steel pin a little tighter than needed for a good sliding fit, a piece of Emory cloth on a wooden stick can be used to gently relieve the bushing ID.
We’re curious why the grease is fed inward from the Zerk fitting in the arm into the grooves on the outside of the bushing.
(This would seem to lubricate the interface not intended to slide).
From here the grease finds its way through the interlinked channels to the 2mm through-hole onto the surface of the steel pin.
Customers who have installed TYC's Yak 52 Nose Gear bushing and axle kit will see the reverse- where grease is fed into the grooved bushing ID via a hole through the axle bore.
Probably something to contemplate over a refreshing malted beverage, we reckon
Huge thanks to the customers who helped TYC develop these dimensions!