RV10 SV42T Installation Questions.

[plhamilton]

Hi There,

I am in the process of installing a SV42T pitch servo in the tailcone of my RV-10. I acquired the correct installation kit from my supplier, but there are a couple of questions that I can not answer.

1. The Dynon Autopilot Servo Installation Guide. There seems to be nowhere in the document that actually describes the drilling of the bellcrank. It's location is described in the diagram on page 8 as 2.5" from the axis of the main bearing, but nowhere does it state the actual diameter to be drilled. I am guessing it is drilled #19 to provide a clearance fit, and that the 2 remaining AN960-10s are used between the two sections of the bellcrank to ensure rigidity when tightening. Can someone confirm this is correct pls?

2. The Aluminium Spacer that I have been provided has been drilled slightly off axis. Does it matter? Is this normal, or is this a defect?

Any and all thoughts would be appreciated...

cheers

Paul

 

[davedubb]

1. The hole in the bellcrank for AN3H-14A bolt should be drilled using a #12 drill bit (.189 dia) and the bolt should fit snugly into the hole.

2. The hole in the spacer is just fine as it was shipped.

 

[plhamilton]

Thanks David. Can I also confirm that the spare washers should be used to pack between the bellcrank sides to avoid compression of the parts when tightening.

One other question: From the instructions, I note that the star washers will be used against the actual servo bracket. This is not normal practice as the star washer will cut into the bracket (through priming and chemical treatment creating an opportunity for subsequent corrosion. Is there any reason why I shouldnt use an AN960 between the bracket and the star washer?

 

[davedubb]

The extra washers are there in case you need to shim the standoff in order to align the rail of the SV-42T. The rail should move parallel to the elevator bellcrank. There should be no visible angle between the bellcrank and the rail of the SV-42T. Refer to the first detail on page 8. Be careful that you have enough thread engagement through the AN365-1032A nut if you need to add washers. At least one thread should be projecting through.

I would suggest that you safety tie the bolts that hold the servo to the bracket and not use the lock washers. As you may realize this is not an easy thing to accomplish with the SV-42T because the rail/pulley assembly should not be removed from the servo motor. .020 diameter safety wire should work just fine to accomplish this. The AN960-10 washers were omitted because of potential interference between the bolt head and SV-42T rail if they are installed.

Hope this helps.

 

[plhamilton]

Hi David,

Thank you for your reply. My interpretation of your email is that Dynon is recommending that the bolts holding the servo to the bracket are installed without a AN960-10 washer and without the lock washers, and that in this configuration, it is mandatory to install the safety wiring.

I assume that the lock washers are not installed so as to again minimise the risk of binding with the mechanism.

cheers

Paul

 

[davedubb]

Correct.