HR2 rear spar trim for pushrod

floridawing · #1 08-28-2012, 08:55 PM

Hello, I have a purchased HR2. During the conditional inspection I noticed the rear spar had alot of material removed so that the push rod would have full range of movement. I worry that too much metal has been removed. The area had not been smoothed or primed. I also noticed that the rod end bearing was set to its lowest setting and not adjusted higher which would give more clearance maybe not requiring so much metal having to be removed from the rear spar. I could smooth out the trimmed aera and prime it and leave it alone. I also could put in a reinforcement to the center section. I have included pics of this area. I would very much appreciate sugestons for this repair. Thanks alot.

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floridawing · #2 08-28-2012, 08:59 PM

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DanH · #3 08-29-2012, 03:46 AM

Remove the pushrod, lay a straightedge on top of the spar bars and across the hole, and measure how much material has been removed.

floridawing · #4 08-29-2012, 05:54 AM

Ok, thanks!

F1Boss · #5 08-29-2012, 07:58 AM

I have seen this before. The trick is to raise the torque tube, not trim the spar carrythru. Oh well - the deed is done; damage is minimal.

The 230XX foil, as is used on the HR2, does not put much stress on the aft spar. Flap loads might stress this part, but there is still quite a bit of the original part left. I would not worry about this 'trimming'.
But, I WOULD smooth out the edges a bit. Workmanship here is kinda rough.
If you want to, you could span the area between the inner floor ribs with another layer of 1/8" material, after you raise the aft pivot so the pushrod will clear the carrythru. Use the original rivet holes to install this additional layer; taper the new part from the center to the outer holes so there is a smaller stress rise at the outer fasteners. You could use AN525 #8 fasteners for this repair, but in any case keep your holes as tight as possible.

The castle nut on the rod end is supposed to be a std AN365...change this fastener out, along with any others done this way. Lube the rod ends at the same time.

Make sure the castle nuts on the cable-to-rudder pedal attach area are secured with .040 wire, not cotter pins. This applies to ALL of the RV series too.

Carry on!
Mark

Ironflight · #6 08-29-2012, 08:16 AM

Everything tat Mark said!

FYI - the RV-3 has a curved "saddle" like that in the plans, so conceptually, it is not unusual. Certainly could be executed more elegantly than in your case....

JonJay · #7 08-29-2012, 09:28 AM

Quote:

Originally Posted by F1Boss

Make sure the castle nuts on the cable-to-rudder pedal attach area are secured with .040 wire, not cotter pins. This applies to ALL of the RV series too.
Mark

Curious as to why. I know on my machine there is some interference with the side wall insulation that can catch a cotter pin. I "massaged" (bent) my pins over so that they would not catch. However, if there is no insulation there, what would be the issue with cotter pins?

s10sakota · #8 08-29-2012, 10:57 AM

Paul (Dye) no wonder you are a writer! You are very elegant in your choice of words. "Certianly could be executed more elegeantly than in your case...."

I was going to say, "It looks like they hacked at it with a dull chainsaw!"

Oh well, I'll stick to my day job...

floridawing · #9 08-29-2012, 10:20 PM

Thankyou everyone for your help! Dan, I enclosed some pics of the damage with a straight edge across the spar. I used a 1/8 dill bit to measure the depth of the removed material. On the rear side of the spar the 1/8 bit would not fit. The front of the spar had alittle more material removed. Mark, I cleaned up the area today and will prime it. Thankyou for the information on the spar mod to make it stronger! I hope to not need to do this mod but will if you feel it is needed to retain the required strength. I will also raise the rodend bearing and put the correct nut on it. I agree, it was pretty hacked up!

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Flying Scotsman · #10 08-29-2012, 10:24 PM

Quote:

Originally Posted by JonJay

Curious as to why. I know on my machine there is some interference with the side wall insulation that can catch a cotter pin. I "massaged" (bent) my pins over so that they would not catch. However, if there is no insulation there, what would be the issue with cotter pins?

I'd like to know this, too. Since I just finished hooking up the rudder pedals to the links and the links to the cable on my -7A, I'm loath to crawl up in there again and pull out the cotter pins and replace with safety wire unless there's a good reason. Also, the plans call for cotter pins...?