Thorp Air Command - T18.net

Hello everyone...

I've been spending the winter making some small improvements (I hope!) to my T18. New backup / aux alternator (Monkworkz,) slightly bigger battery, etc. In my recent avionics retrofit, I had a net shed of 27+ lbs. So, adding back a bit of weight for some electrical redundancy and capacity is acceptable, in my mind. The Monkworkz generator is like, 2.7 lbs including the external regulator. 30 amps!

I pulled the prop spinner because there was a very slight resonance or rattle when it was tapped by hand. I thought I'd find the front bulkhead was loose or something. Instead, I found there was no front bulkhead (yikes!) and even worse, some of the spinner mounting holes were wallowed out, such that the screws were doing nothing in those locations. Ugh!

Cubes is going to send a forward bulkhead / plate, so that will address one issue. But now this spinner needs the wallowed holes welded up and re-drilled. I found a shop that can do that, to the tune of several hundred bucks. That's fine, and I'll move in that direction. Unless...

Any chance anyone has a ready-to-bolt on spinner the fits an IO360 and Hartzell extended hub c/s prop? I'd rather not go through the process of a new, blank spinner! This is the eddy current AD prop. Id be open to a B hub / prop if one turns up at a reasonable price. Otherwise, I'll continue with the inspections. (Are those required for Experimental applications?)

Any thoughts?

Peter

I am of no help to you, but i understand not wanting to start the spinner from a blank. I goofed up my spinner trying to drill the holes in the correct spots for the bulkheads and had to reorder a new spinner. Ouch! On a separate note, I wonder if you will be able to notice any improved flight characteristics after shedding 27 pounds?

I can't say I noticed much change in performance. It's like 5 or 6 gallons of gas, in terms of weight. Noticeable? I guess, if you're really looking. This airplane already has fantastic performance. But knowing it's lighter makes me happy!

At the time, I knew it was lighter, but didn't really know how much lighter. Since then, I've weighed what was removed, vs what was installed. I really need to get it on scales, and do a formal W&B.

But now this dang spinner! Ugh! I guess I can still fly it, without spinner (Cubes, et al suggest that's not a problem.) But the looks!

I plan to polish this (currently painted) spinner when it comes back from the welding repair shop. I love the look of a good-fitting polished spinner, like those I see elsewhere on this forum!

So...

My spinner had to be sent out to have the wallowed backplate screw holes welded up. I sent it to Kim Weckerly at K&K Precision Welding. They have an FAA approved process for this type of repair- and it worked out great!

Cubes supplied a forward bulkhead (my setup didn't have one previously- which probably explains the hole damage.) Fitting that forward bulkhead required some spacing changes- which seemed to work out well. I moved the spinner aft by 1/4" and spaced the forward bulkhead toward the front by 3/16". So now the spinner has about 1/4" of clearance from the cowl, and fits very snugly over the forward bulkhead.

What I don't know is if there's enough clearance for the constant speed prop to cycle without touching the spinner prop cutouts. Can I just twist the blades by hand (one guy on each blade) to check the clearance? Or do I need to disconnect the oil line from the governor and inject air pressure? Or?

Thanks for any suggestions...

Peter

Call Hartzell and ask them what the actual degree of rotation is.

_________________
Bob Highley
N711SH
SN 835
KLAL

while your talking to them, ask them if they have a spinner cutout template. There maybe one on their website available for download.

Yes you can twist it. A better way to do that is to “C” clamp two 2/4’s on each side. Do not do it over the decal. Then you can rotate the blades. The return spring is very strong.. it will take about 2’ of board to get enough leverage.
Cubes

Thanks guys!

I read on another forum that gave the same advice as what Cubes suggested- although that post didn't specify where to clamp the "handle."

I was able to twist the blades, and found I did have a clearance issue. So the spinner is off (for the umpteenth time!) and will require a bit of dremel / file work. Man, I'm looking forward to flying again!

did you unplug any fittings to do that, or just brute force twist it? Just curious in case I ever need to use this technique.

Just brute force. It's not too hard...