Elevator trim

[waltermrich]

During the annual inspection on my BC12d my mechanic noticed that when I turned the trim crank in the cabin, the entier bolt truned back at the trim pullely , the bolt that holds the trim pulley to the elevator horn and holds the two halves of the elevator together and goes thru the trim pulley, that bolt, and also when you try to turn the pulley by hand by grasping it and rotating it, the bolt, castelated nut and all truns . Is that normal, any help with the experts out there

[3Dreaming]

Re: Elwvator trim

The only bolts holding the 2 halves together are the 2 that attach the control cables. The nut you are talking about is the one that holds the pulley on the Left half. There is a big hole in the Right elevator for the nut to stick through. The nut should turn with the pulley because it is holding the pulley on the end of the trim screw shaft. Tom

[waltermrich]

Re: Elwvator trim

Thats a great answer ,and your right about that bolt ,it does not appear to structurally hold the two halves together, but why is it such a large bolt for just such a small pulley and how does it or way does it rotate,? thanks for your response

[3Dreaming]

Re: Elwvator trim

That nut holds the pulley on the end of the jack screw that makes the trim tab go up and down. It is locked to the jack screw with a cotter pin. The nut is more related to the size of the jack screw rather than the size of the pulley. Tom

[cvavon]

Re: Elwvator trim

Go to page two of this forum and look for a post on trim assembly there are some good photos from robert lee on the trim assembly

[Robert Lees]

Re: Elwvator trim

To save everyone the search, here's the post-war B model trim mechanism:





A reminder to all post-war B model owners: there's a requirement to lube the trim mechanism at this hole:



And in the photo below, it's the 2nd-largest diameter bronze portion (about 1-1/2 inches long) that gets lubed through this hole. It sits in a steel tube in the left stabiliser. The split pin hole on the far left is the split pin passing through the castellated nut to which waltermrich refers.

[waltermrich]

Re: Elevator trim

Thanks for all the responses to my enquiry its very helpfull to go to the forum and ask for help

[3Dreaming]

Re: Elevator trim

I'm a little worried that you have someone who is going to sign off an annual on your airplane that doesn't understand how it works.

[Robert Lees]

Re: Elevator trim

Lots of folk do not understand, Tom, (mechanics & IA's and owners too), but it's good that someone takes the trouble to ask, even on behalf of their mechanic.

I'm glad that the mechanic asked the owner to turn the trim so that he could see what goes on at the aft end. That showed some initiative, which is often lacking.

The "old knowledge" needs furthering as far as we can send it, so it's a learning curve for all.

[cvavon]

Re: Elevator trim

Thank you rob as always grate info better photos we appreciate you very much chuck

[waltermrich]

Re: Elevator trim

Again thanks for your response ,as for having an AI signing off on something he does not understand I would not worry to much about that , its nice to have a place to ask

[magman]

Re: Elevator trim

I'm a little worried that you have someone who is going to sign off an annual on your airplane that doesn't understand how it works.

This is EXACTLY the type of data that should be included in the Taylorcraft Inspection Manual.

Similar to this is the methods used to lube the M/L/G atach points.

On a Taylorcraft there are"Lube Holes".

Piper; while similar in appearance, requires you to remove the bolt for lubrication.

My thought is there are very few A & P
Taylorcraft SPECIALISTS .

Dealing with Piper,Mooney, Boeing , Airbus,
Rockwell, Cessna, Lycoming,Franklin, Continental,Slick,Bendix,Eiseman,Case, MarvelSchebler, Stewart,Cleveland,Hartzell, GE, McCauley, etc, etc, can be demanding.

Doctors have only had to deal with 2 models ( M & F ). Until recently at least.