D-501A Lang Tailwheel Trouble shooting

The Lang Tailwheel is an durable reliable unit. Many units have been in operation for over 30 plus years. We have made improvements over the years to what we thought could use updating. Below are some issues that some older Langs have experienced. We are always here for help if you run into a problem.

Wire coming out of tire sidewall.

ACS does not manufacture the tire that is used on the Lang. There is a “wire core” molded into the tire itself. This core, gives the tire more stability over a plain solid rubber tire. On occasion a wire from the wire core will break and will migrate to the outside of the tire. We have been working with the vendor about this problem and believe they have resolved it.

The tailwheel will only release to the left or right not both ways.

This could be several things. More than likely the Cam washer is damaged and needs to be replaced. The problem could be the plunger in the driving cap is damaged. Usually it is a combination of both. If something such as a hard landing, heavy sideload etc it can nick or crack the cam washer. Once this happens the plunger rides over it and now it is damaged. The best solution is to replace the driving cap assembly (Cap, plunger and spring) and also replace the cam washer. Both the Driving cap assembly and the Cam washer have been redesigned about 6-7 years ago for more durability. If you turn the driving cap over and the hole the plunger rides in has a stainless steel sleeve pressed in, it is the new design. The cam washer used to be a “stamped steel” part. It is now made from billet 4130 and heat treated. The driving washer could also have been damaged and should be replaced.

Driving Cap, Plunger, Spring & pin P/N is 06-01570 (Aircraft Spruce)

Cam washer P/N is  06-13625 (Aircraft Spruce)

Driving Washer P/N is  06-13608 (Aircraft Spruce)

Tire Shimmy

Worn tire, loose steering arm springs, worn driving washer or worn flat on the vertical shaft. All the above are replace to fix items. The springs are either tighten or replace with a different style (compression or tension). Another thing to check would be worn wheel bearings.

Excessive amount of grease coming from the assembly.

In high temperature areas such as Arizona, Nevada where temps can stay at 100 degress or more it is not unusual to lose some grease from assembly. This is more than likely coming from under the hub cap. The quickest fix is to replace the felt washer under the hubcap. It is a easily replaced item and while the cap if off that’s a good time to regrease the bearings.