Horn inspection

[T210DRVR]

Thanks Hans. Some while back before much of the prior forum discussions were lost there was an extensive discussion about the torque tube inspection that I cannot find. I need to give something to my A&P so he knows exactly what/where he is looking for. Can you post the link where I can find this information?

Thanks.

[Hansmeister]

Take it apart, except leave the counterbalance weight tube in place. Dye penetrant, or eddy current test.

Radius edge of bores where the counterbalance tube meets the torque tube bore using sandpaper. .125 radius ideal, ending up using 600 grit paper.

[T210DRVR]

OK, but where are we looking for cracks?

[9089P]

Hi 210,

There was an article by Denny Haskins in March or April of 2007 I believe that first raised this issue. You can search for it on this site and it gives a very good descrition of what to look for on the inspection. As I recall the cracks seem to most often radiate from(between) the attachment bolt holes on the balance arm side of the horn and the balance arm hole.

Good luck, Don

[T210DRVR]

Thanks Don, that's exactly what I was looking for.

Jim

[Kristin Winter]

Matt Kurke has the Haskins article posted on his website as well. Click on the stabilator tab on the left, and you will find a link to the article.

I just did mine this weekend. I used a dye penetrant and a 10X magnifying glass. No cracks. Now I have radiused the inside, and have got all the parts zinc chromated. Dissassembly, to the point that I had the counterweight tube and the attached horn in my hand, took about 6-7 hours. Doing the dye penetrant, cleaning and inspecting the bearings, radiusing the inside, and the primer paint, took about 5 hours. I probably have that to go again.

[Zach Grant L1011jock]

Jim,
Don't try to pull the ballance arm out of the tube as is shown in article. It is not necessary to inspect and can cause serious damage to the horn if done improperly. Only the torque tube needs to come out of the horn.
-Zach

[Kristin Winter]

A good technique to get the horn and balance arm off the torque tube is to stick the torque tube in a vise (wrapped of course), with the balance arm out horizontal. You will also want to clean up the torque tube itself so there is no impediment, like paint, to sliding the horn off. With the arm out horizontal, set a heat gun on the horn, several inches away from it. When the horn heats up enough, after a few minutes, the arm will drop down as the hot horn loses its grip on the torque tube. You should then be able to slide the arm and the horn off the torque tube.

[T210DRVR]

Thanks to all. I'm having my Comanche 180 checked next week.

[Hansmeister]

Kristen, re-assembly of the counterbalance arm to the horn should be done with extreme care. One can do more harm if improperly done. I would suggest placing the horn in boiling water or oil, and the counterbalance tube in the freezer. Have a long tapered bolt ready for the alignment.

[Kristin Winter]

Not to worry Hans, I did not take the counterbalance arm off the horn. I was referring to getting the horn and the arm off the torque tube. I would seriously not want to have to separate a horn from its balance tube.

[Chris Elgar_DUP]

I have removed the horn from the 1960 180 that I am rebuilding and will have it checked by Eddy Current tomorrow. John at Webco advised that this method can be done and the torque tube does not have to be removed. He said you do have to remove the bolts though. I will advise the outcome and send in the report. Unfortunately I then have to do the 59 250 that we are flying, which is not in pieces like the rebuild and in the hanger not my shop. Oh well that's Flying.

Chris.Elgar

P.S. How do you get picture sizes small enough to post on here? I have had no success

[T210DRVR]

Google IrfanView. This is a photo editor you can obtain free from the web. Others will work, but I'm assuming you don't have a photo editor.

Once installed, open the program, select the photo you wish to edit, select the image tab, select resize, then lower the size of the image until it fits.

There are other methods, but that's how I do it.

[Chris Elgar_DUP]

Just reporting that my 1960 PA180 with 3200hrs. TTSN was Eddy Current tested today and no cracks. Renewed the bolts, washed and repacked the bearings, primed and repainted everything and it back together. I will fill out report and mail it in as requested.

Chris Elgar.

[Chris Elgar_DUP]