Front Gear Leg Bolt Hole Wear

[Fred.Stucklen]

Hi All,

I just got done repairing the front gear leg mount bolt hole on my RV-7A a while back. There was a slight bit of wear due to the bolt either loosening and/or the front fork being too tight, causing excessive torque on the gear leg during turns. In any case, there was a slight amount of rotation in the gear leg with the bolt loose, indicating that the bolt holes were slightly oblong...
Here's what I did to fix the problem. First I tied down the tail, and removed the front gear leg. Next, I cleaned both the top mount area and the lower mount area of any grease. I did the same to the gear leg, but re-greased the lower mount area where it comes into contact with the mount. Then I applied permanent Lock-Tight to the inside of the upper mount area, and also coated the top mount area of the gear leg. The gear leg was then inserted back into the mount and the bolt partially re-inserted. (My bolt inserts from the top. The firewall has an indentation for the nut. There is no hole in the firewall for the bolt...).
Next I used a small amount of "Liquid Steel" into the worn areas of the gear leg mounting bolt holes. (Since there was very little wear, I did this instead of drilling out the mount/gear to a larger size bolt, or inserting a taper pin.) The bolt was then torqued normally. I let the assembly dry before testing it for any movement. Solid....
I've flown over 100 Hours after that fix was performed, and still have no movement in the front gear leg upper mount area. I have checked it at every oil change for any signs of movement....
With the history of issues in this are, it would seem prudent to do the final front gear leg assembly with Lock-Tight on the upper mount area. This would prevent the re-occurring issue that we've seen in this area on the -A RV models.... And I've seen it happen to every RV-XA that I've owned....

[swisseagle]

Dear Fred

Thank you for this interesting information.

Can you give us a more preceise answer which type of loctite you where using?

Loctite are usualy choosen by numbers like 222 is a low friction screw safer, 638 is a more permanent glue to put gears and shafts thogether forever (heat it up to 120?C and there is a chance to take it apart again) and so on. do you have a exact number?

Regards, Dominik

[Mark Burns]

Originally Posted by swisseagle

Dear Fred

Thank you for this interesting information.

Can you give us a more preceise answer which type of loctite you where using?

Loctite are usualy choosen by numbers like 222 is a low friction screw safer, 638 is a more permanent glue to put gears and shafts thogether forever (heat it up to 120?C and there is a chance to take it apart again) and so on. do you have a exact number?

Regards, Dominik

Dominik,
I'm not trying to answer for Fred, but for another data point I did almost exactly what Fred did and used Loctite 609. It's labled as "Secures Gears" also.

That was about 150 hours ago an the nosegear leg is still tight.
I noticed mine being loose when I was parking the airplane by hand the nose gear would have a little "pop" sound when given a side load.
Not anymore

I used this stuff back when I worked in industrial maintenance. It really works.

Mark

[Captain Avgas]

Originally Posted by Fred.Stucklen

Hi All,

With the history of issues in this are, it would seem prudent to do the final front gear leg assembly with Lock-Tight on the upper mount area. This would prevent the re-occurring issue that we've seen in this area on the -A RV models.... And I've seen it happen to every RV-XA that I've owned....

Fred, is there any chance that you might not be able to remove the gear leg in the event that you need to for some reason.

[PCHunt]

Wondering the same thing.......

[Mark Burns]

Originally Posted by Captain Avgas

Fred, is there any chance that you might not be able to remove the gear leg in the event that you need to for some reason.

Guys,
It just takes a little heat to "unstick" the loctite. Just enough heat to ruin the powder coat but not adversely affect the engine mount steel.
Seriously, I'd just warm it up slowly and you might not have to compromise the powder coat before the loctite would loosen up.

I couldn't think of a reason I'd want to remove it anyway. Unless Van's comes out with a new style again.

Mark

[GrayHawk]

I think the builder of my RV-6A went one 'better' than loctite on the main gear legs. I could be wrong but it looks to me like the top of the tubes and the legs are spot welded.

Guess I'll find out as I'm currently gearing up to transform the 6A into a 6.

[Fred.Stucklen]

I think the stuff I used was the 609, but not sure. The container label is gone. The idea is to make the gear leg very difficult to move under loose bolt conditions.
And as others have stated, heating up the gear leg where the locktite was used will allow one to remove the gear leg. At least in theory... I haven't had to remove it yet, and don't plan to in the near future.....
It's interesting that there haven't been any reported instances of the main gear legs having the bolt hole wear problem.....

Fred

Originally Posted by Mark Burns

Dominik,
I'm not trying to answer for Fred, but for another data point I did almost exactly what Fred did and used Loctite 609. It's labled as "Secures Gears" also.

That was about 150 hours ago an the nosegear leg is still tight.
I noticed mine being loose when I was parking the airplane by hand the nose gear would have a little "pop" sound when given a side load.
Not anymore

I used this stuff back when I worked in industrial maintenance. It really works.

Mark

[Noah]

Hi Fred, are you still going strong with the loctite solution? Any issues? How many hours has it been now?

I am thinking of doing this. Latest condition inspection reveals nosegear rotation in the mount resulting in about .25" lateral free play measured at the nosegear axle after 320 hours on the Hobbs. I can't be sure whether this has gotten worse, I think there has always been a little free play but I never measured it before. I have used the Loctite/Henkel retaining compounds in other applications and it seemed to work pretty well.

Here is their catalog with a flowchart (on pp.121-125) for selecting the proper adhesive and the 609 looks like the correct stuff if you want to be able to remove it later on.
http://www.henkelna.com/us/content_d...2013__F_LR.pdf

[Vlad]

I was tired seeing this two-three times a year.






Last year I put loctite per Fred and it stays frozen. No wear on bolt/hole observed at almost 1K hours. I don't use nosegear on landings anymore.