Lock nut vs. castle nut & cotter pin on throttle linkage

[avi8tor50]

Hi all-

Getting read to complete the throttle and mixture linkages to the carb. Vans instructions call for a steel lock nut on the bolt of each of the two. Somehow, I kind of think I might feel better with a drilled bolt, castle nut, and cotter pin. Was wondering what others have done.

Peter K
9A

[Sam Buchanan]

Originally Posted by avi8tor50

Hi all-

Getting read to complete the throttle and mixture linkages to the carb. Vans instructions call for a steel lock nut on the bolt of each of the two. Somehow, I kind of think I might feel better with a drilled bolt, castle nut, and cotter pin. Was wondering what others have done.

Peter K
9A

Either will work just make sure the nut is fully torqued to spec. You don't want the bearing ball to rotate on the bolt and cause wear that might weaken the bolt. The bearing should rotate around the ball, not the ball around the bolt.

Be sure you use a large area washer on the outside of the rod end bearing to prevent the linkage from disconnecting in the unlikely event of a bearing failure.

[az_gila]

Originally Posted by Sam Buchanan

Either will work just make sure the nut is fully torqued to spec. You don't want the bearing ball to rotate on the bolt and cause wear that might weaken the bolt. The bearing should rotate around the ball, not the ball around the bolt.

Be sure you use a large area washer on the outside of the rod end bearing to prevent the linkage from disconnecting in the unlikely event of a bearing failure.

...that the self-locking nut would be a little easier to install.

As Sam says, you don't want the bearing to rotate about the ball, and since it is not a fork, the bolt woud also wiggle in it's hole if it's not tight - wearing out the hole in the expensive carb. arm before the cheap bolt would wear...

However, having said that, I looked up FAA AC 20-143 that deals specifically with this area...

...and it definitely calls for a castle nut and cotter pin...

So - I'd go the cotter pin route....

[Jeff R]

Thanks for the reference, Gil. Reading it raised a question that I had not yet thought of too much yet, and that is the lubrication of cables and connections. Actually, I just came in from the shop after connecting my rudder cables for the first time, and I was wondering about lubrication. I thought I might rub in a little greese that I use pack the wheel bearings (i.e. Aeroshell #5 or similiar), and AC 20-143 refers to using that or Lubriplate for the initial application of lubricant, but something like LPS #2 for periodic lubrication. I looked up LPS #2 and that is a spray can lubricant, however.

So, is there a reason to not use a greese for subsequent lube'ing and to instead use a spray lube? I am refering to cable connections like the rudder cables, and well as other control cables such as that being discussed here.

[az_gila]

Originally Posted by Jeff R

Thanks for the reference, Gil. ......
I thought I might rub in a little greese that I use pack the wheel bearings (i.e. Aeroshell #5 or similiar), and AC 20-143 refers to using that or Lubriplate for the initial application of lubricant, but something like LPS #2 for periodic lubrication. I looked up LPS #2 and that is a spray can lubricant, however.

So, is there a reason to not use a greese for subsequent lube'ing and to instead use a spray lube? I am refering to cable connections like the rudder cables, and well as other control cables such as that being discussed here.

...talking about the rod end bearing and pivot points here, not the actual cables....

e. In the absence of specific lubrication information from the manufacturer, it is acceptable to apply LPS 2?, Permatex ?Maintain?? Lubricant, or equivalent, to each pivot point, including throttle shaft bushings. If parts such as a lever or link rod are to be replaced or reassembled, initial lubrication may be accomplished by using Shell Number 5 grease, or LUBRIPLATE?, Number 630AA, or equivalent.