Thorp Air Command - T18.net

So after re-doing the wiring and having my plane down for about 6 months I had an inspection before flying. Here are a list of the things I was told needed to be fixed and I will need some advice on procedure as I'm not the builder.

Aileron bell cranks have play in them. I think taking off the gap cover I can gain access to it but i'm not sure what it will take to tighten things up. Maybe a bearing or bushing in there?

The wire that goes through the piano hinge on my stabilator has broken on the safety wire end and worked it's way outbound. In order to pull it out it appears I will have to remove the rudder and vertical fin. Where can I get that replacement rod to fix this issue?

Movement in my stabilator at the ends. It's at about 1/4" so the AP wants me to fix the bushings. It appears that vert fin and rudder must again come off to reach those. Where can I buy those bushings? I think it's the same thing as this person did in the thread: viewtopic.php?f=2&t=8027

The attachment points for my trim between the stabilator and the fuselage has some slop in it so I need to replace those bolts and re-torque.

Is there anywhere online with pictures or a description on removing the vertical fin and rudder so I can get to all these things?

Is there a list of nut torque values for assembly?


Thanks for all the help. These are the last things I need to do before I have my plane back in the air after 6 months. I'm ready to get it going but I want it to be safe as well.

Hard to tell about the bell cranks w/o getting in there ? The T-18 bell aileron bell cranks are a little more difficult to access than the S-18 so a T-18 guy would/might have knowledge to access/remove them . Spruce sells the stainless steel hinge rod in 6ft lengths . I would check with Jim at Thorp Central about the bushings for the stab and rudder . Removing the rudder and stab is so easy a politician can do it ! Remove the rudder cables from the bottom of the rudder . One bolt on top of the rudder hinge , one bolt on the bottom of the rudder . Fin removal...once the rudder is off you have access to the bolts on the back of the fin . At the very front of the fin where it meets the fus. there is an access point for that bolt . The attachment points for the trim have very small bushings in the "links" so a look at those may be helpful . A set of plans will detail the bushing requirements .

RB

Thank you so much! That is exactly the info I was looking for. I didn't know about the front bolt on the fin so that would have got me.

Are there different sizes of that hinge rod?

I have a set of plans with my plane but they are microfishe and I don't have a viewer or even know anywhere that has one. Our library no longer has them and I suspect being out in the mid west I would have to drive to indianapolis to find one. I don't really have time for that. I'll see if i can use a magnifying glass to look at it but I doubt that will be effective.

I'll pull those trim bolts and see if there are bushings that can be replaced. I guess I can just get them all from thorpcentral.

I buy piano wire from the hobby stores. I have found that off the shelf bushing's generally do not fit,because of wear or the builder used a drill instead of reamers , the holes are not to specs.

What do you recommend for the bushings then? obviously find the size of them and order some but this is new to me so I don't know where to get custom sized bushings.

Thanks!

Ebay has some microfische readers . I would buy one that I could at least get spare bulbs for ?

RB

Ah, dang. not what I was hoping to hear. From the info I've gained I'll get into this without the microfische at this time. Don't want to be down for another week for that to ship then a week after that while I order parts.

HI Jeff,

I know you're looking for ways to gain some knowledge and fix these problems ASAP. They all sound like important items, and the stabilator/anti-servo tab ones are especially important safety of flight issues. One general comment - you really need to have a set of readable plans if you are going to maintain and service your airplane safely and properly. The bushing material is specified in the plans, and for the T-18 they are generally made of "mild" steel tubing. There are some non-metallic bushings used on the flaps.

As Bill said, the bushings are many times custom-fitted by the builders of these airplanes. You start out with a very tight or oversized bushing and carefully machine,file, and/or polish it down until you get a good fit. If you have access to a lathe it's easy, or you can use a mandrel and a drill press. From a flutter standpoint, the hinge points on the stabilator are less critical than the anti-servo tab system. You want everything tight, but free and smooth. The lubricant is important.

The cadmium plated steel AN or MS structural bolts on your airplane should be tightened to the torque values specified on standard aircraft torque value charts. Just Google "aircraft bolt torque values" for instant access to charts. Be sure to measure and add the additional "running" or rotational torque caused by friction from locking nuts, etc. to the chart values when you are tightening bolt/nut assemblies. Propeller bolts are a different matter, and should be tightened to the prop manufacturers' specs.

_________________
John Evens
Arvada, Colorado
T-18 N71JE (sold)
Kitfox 7 SS N27JE

Do you have County or City offices ? They may have an old reader stored in the basement with the preserved bodies of past politicians ? Maybe one of your schools has one inturned with the ever popular mimeograph machine ! For sure the FAA has one as they are still using vacuum tubes and slide rules !

RB

Small town so I don't think our offices would still have them. The courthouse is a 45 minute drive for me so that might be my best bet. I know the motorcycle shop I used to work for had them so I might see if they have the old viewers in the back since they have switched to all computers now.

It just might be easier to buy a new set of real paper plans ? Keep the film as a back up , but I hear unless that film is kept under the proper conditions it will deteriorate with age much like some of us !

RB

Excellent info. Thank you for taking time out to post it. I have access to all the shop tools at the airport so custom sized bushings shouldn't be any issue if they need to be "fit". I'll try to find a way to view my plans. Maybe they have one in the back of the maintenance shop I haven't seen.

I might have to do that. Is thorp central who I need to contact about the plans?

Well, yes and no. We sell S-18 plans and parts. The T-18 plans and design rights were recently purchased by someone else. I made contact with them several weeks ago WRT another owner wanting T plans. I'm not sure if anything became of that. I'll ask.
Cubes

Jeff check your pm's.

Dave