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Nose wheel pants mounts

D

Dorfie

Well Known Member
The cutout in the U-1013C-L and R mounting brackets that fits over the axle washers has some play in them (up and down play). Is this OK? Furthermore, the plans calls for three washers under the bolt head and nut. They are AN 960-616 and AN-960-616L, and outside to these washers is a larger diameter washer 062-25783054. The combined height of the 616 washers is greater than the thickness of the mounting bracket, with the result that there is up and down play from the mismatch of cutout and 616 washer diameters AS WELL as the bracket not held down by the larger washer. Does not seem right to me.
As a side, I have the MATCO nose wheel installed.
What did you guys do gain access to the nose wheel valve?
Thanks.
Johan
 
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What Plans revision / page are you looking at? Is the part in question number U-1013C-L/R.

Cheers,
Jay
N433RV RV10 - Flying

Dorfie said:
The cutout in the U-10123C-L and R mounting brackets that fits over the axle washers has some play in them (up and down play). Is this OK? Furthermore, the plans calls for three washers under the bolt head and nut. They are AN 960-616 and AN-960-616L, and outside to these washers is a larger diameter washer 062-25783054. The combined height of the 616 washers is greater than the thickness of the mounting bracket, with the result that there is up and down play from the mismatch of cutout and 616 washer diameters AS WELL as the bracket not held down by the larger washer. Does not seem right to me.
As a side, I have the MATCO nose wheel installed.
What did you guys do gain access to the nose wheel valve?
Thanks.
Johan
Click to expand...
 
As I recall, I used a thin and a standard washer to get a stackup that was just a few thousandths less than the bracket, then a large dia washer to capture things when the axle bolt is tightened up.

Works well.

For air, I remove the wheel pant----------pretty easy to do.
 
jaybob said:
What Plans revision / page are you looking at? Is the part in question number U-1013C-L/R.

Cheers,
Jay
N433RV RV10 - Flying
Click to expand...

Jay,
My fault. The 2 should not be in the part#. Your part numbers are the correct ones. I have corrected it in my original post. Page 46-06 Fig 2 calls the axle and washer/nut arrangement. Pages 48-18 and 19 shows bracket installation.
Johan
 
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Mike S said:
As I recall, I used a thin and a standard washer to get a stackup that was just a few thousandths less than the bracket, then a large dia washer to capture things when the axle bolt is tightened up.

Works well.

For air, I remove the wheel pant----------pretty easy to do.
Click to expand...

Mike,
The thickness of the bracket is 0.063. Thickness of -616 washer is 0.063, and -616L is 0.030. I am not sure why the plans call for the addition of the thinner washer, and was wondering if there is a reason for that. Maybe the mount is supposed to be "floating" a little, which seems unlikely to me. The larger washer seems to be there to clamp the bracket in place.
Can you recall if the "slot" in the mount that slides over the -616 washers was a tight fit around the washers? I have quite a few thousands play in mine.
Thanks.
Johan
 
Dorfie said:
Maybe the mount is supposed to be "floating" a little, which seems unlikely to me.
Click to expand...

Mine "floats" while sliding it on, but then is solid when the axle bolt, and the tow bar hookup bolts are tightened.

Dorfie said:
The larger washer seems to be there to clamp the bracket in place.
Click to expand...

That is how I have it setup.

Dorfie said:
Can you recall if the "slot" in the mount that slides over the -616 washers was a tight fit around the washers?
Click to expand...

Loose enough to make sliding the bracket/pant assembly on simple.

You do have the brackets and rear half of the pant assembled into a unit for installation, dont you?

Once you have the brackets installed in the rear half of the pant, there is no reason to take them out again unless something gets bent or broken.

Dorfie said:
I have quite a few thousands play in mine.
Thanks.
Johan
Click to expand...

Yep, same here.
 
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The design philosophy of this style of nose fairing and brackets (also used on the 7,8,and 9) is the washer stack-up to be such that there is just enough thickness clearance for the brackets to slid on and then be held in position by the fwd. bolts (tow bar attach points).
This allow the fairing to only need holes at the tow bar attach bolts. None are needed to access the axle bolt (because it is fully tightened before installing the fairing).
It has proven to hold up well in service.
 
Scott, I am not about to dispute your input on the design of the brackets, but I chose to do mine a bit different, and use the axle to clamp the assembly for a more secure setup------again, that is how I did it. I am willing to have the extra holes in my wheel pant. Of course, I could have used a couple end wrenches and not put in holes, but I tend to a bit of laziness at times;)

I felt that there was too much moment arm working against the tow bar mounts, and that the nose of the bracket would take excess punishment.

There have been failures.

http://www.vansairforce.com/community/showthread.php?t=101934&highlight=broken+bracket

http://www.vansairforce.com/community/showthread.php?t=85383&highlight=broken+bracket
 
I've set mine up exactly as per the plans. The bracket is a very tight fit sliding in behind the washers but does just go into place. Then the 2 set screws hold it in place. It means I could glass over the screws in the rear half and all that is required is to fit the front half to the rear. What is the issue?
 
paul330 said:
What is the issue?
Click to expand...

Some folks have had problems.

image_zps338c1706.jpg


http://www.vansairforce.com/community/showthread.php?t=101934&highlight=broken+bracket
 
I wasn't meaning to dis the way you did it Mike. Just mentioning that it doesn't necessarily require doing it that way an have good results.
N410RV now has about 1700 hrs with it this way, and no bracket problems.

More info needs to be known when there is a failure, to say whether a design is faulty.
Such as....
Investigate whether the parts were well deburred?
Investigate whether the fairing was attached in such a way that there wasn't a preload in the brackets?
Was there any past history of nose wheel shimmy?
Etc.
Etc.
And lastly, how many failures vs the number of airplanes in service.
Considering there are now more than 600 RV-10's flying, I haven't heard much about nose wheel fairing bracket failures, so I am inclined to think that the issues listed above could be a factor in at least some of those that have, but of course who knows for sure.
The great thing about building an RV, is that you can do what you think is best.
 
rvbuilder2002 said:
I wasn't meaning to dis the way you did it Mike.
Click to expand...

Scott, I took no offense at your statement at all.

I was trying to stress to other readers that the way I did the bracket mounting was my own idea, and was not something the factory had recommended.

I totally agree that the small number of failures vs. the total number of flying examples would support the idea the factory method is sound.
 
I sanded the thick washer down until I got fit I liked.

I get fore-aft shimmy at 14-18 kts gs, so I stay outside of this range. It will crack brackets or wheel pant at bulkhead.
 
I used a much larger diameter washer on the outside to lend more support to the bracket. I also used a smaller thickness washer under the large washer. In order for me to remove the wheel pant I have to loosen the axle and also the tow bar support. Having support in two areas is just insurance from a broken bracket due to vibration.
One thing to note. I was able to eliminate my nose wheel shimmy by using a Goodyear Flight Custom II tire on the nose wheel and running 40 psi. It went from really bad at 14 kts, to very little or no shimmy at all!
 
The shimmy I was talking about is lateral in the nose fork hinging axis (as in when a shopping cart castor Shimmy's). This is the destructive mode on an RV and is caused by lack of proper nose fork pivot friction. It is very similar to control surface flutter.
An up and down mode is likely caused by tire runout/out of round. It is not nearly as destructive (but still not good).
 
I hate to disagree with you, but the nose wheel shimmy (shopping cart type) is prevalent in an awful lot of 10"s. In fact, none that I have flown in do not exhibit this issue. It is not always caused by improper nose fork tension. I have had several conversations with Vans in regards to this. In fact, the Vans RV 10 exhibits this problem. I have never gotten an answer in regards to what causes this. Some have it and some do not. I have tried shaving the Vans provided tire, balancing the tire, various tensions, with and without wheel pants, and using the Matco designed bearing tensioner. Not one of these things helped. I finally was able to eliminate 95% of the issue by going with a two groove Goodyear tire and reducing pressure. The issue lies in the design of the nose fork assembly.
Apparently, this is what contributes to the nose pant bracket failures and further, I have seen cases where the entire wheel pant has fractured at the bulkhead. I personally would welcome Vans Aircraft to investigate the true cause and come up with a fix.
Don't get me started on the main gear shimmy issue!
 
Fitting pants, while on this topic

I started to fit the rear pants last night, and was amazed at how much I have to stretch (open up) the wheel pants and push the tabs in to get the pant to slide over the 4 bracket tabs that is on each side. Once in place, there is a big gap (1/2 inch about) between the bracket mounting tabs and the pant. Is this normal? If so, how did you guys get the bracket tabs to approximate the wheel pant? That is a large gap to fill. If I bend the tabs out, How will I get the pant off again? (I understand that once the pant is fitted, the bracket can stay in place in the pant. It is the on-and-off while fitting).
Thanks, as always.
Johan
 
Bill.Peyton said:
I hate to disagree with you, but the nose wheel shimmy (shopping cart type) is prevalent in an awful lot of 10"s. In fact, none that I have flown in do not exhibit this issue. It is not always caused by improper nose fork tension. I have had several conversations with Vans in regards to this. In fact, the Vans RV 10 exhibits this problem.
Click to expand...

Bill, I wrote " is caused by lack of proper nose fork pivot friction". I didn't say always. But I guess what I should have said was "is often caused by".

There are other factors as well. Tire pressure is a big one.
You say "none that I have flown in do not exhibit this issue". How many have you flown in (not being sarcastic... genuinely interested in how many you think have the problem)?

As of this moment N410RV (Van's Demonstrator RV-10), has 1808.6 hrs on it. It does not have a nose wheel shimmy problem (I know because I flew it last week on a post maint. test flight). Nor has it had a problem with cracking nose wheel pant brackets. If you say it had shimmy at some point when you flew in it, then it must have been a short term issue that got resolved (adjusted nose fork friction or tire pressure, etc.).

I am not trying to deny that some builders have had the problem. Just saying that I have seen no evidence to indicate that it is a chronic problem, and with N410RV being one of the highest time (if not the highest) 10's flying, and not have cracked the brackets, what approach to analyzing the problem would you suggest be taken?
 
Scott,
Ill give you a call @ work later this week to discuss, rather than hijack this thread.

Johan,
It is very difficult to remove the nose wheel pant rear section by removing the screws that hold it in place and sliding it out, or install it after the brackets are installed on the fork. You will have to really force it to expand over the bracket. Once you install the bracket on the rear pant, it should be left on to mount it on the fork. To remove the wheel pant you slide it off the axle, then you can remove the brackets if desired. Hope this helps
 
Bill.Peyton said:
Johan,
It is very difficult to remove the nose wheel pant rear section by removing the screws that hold it in place and sliding it out, or install it after the brackets are installed on the fork. You will have to really force it to expand over the bracket. Once you install the bracket on the rear pant, it should be left on to mount it on the fork. To remove the wheel pant you slide it off the axle, then you can remove the brackets if desired. Hope this helps
Click to expand...

Bill,
That is how I have it pictured. Just wanted to make sure that I am not the only one finding the initial fit be so tight.
Thanks.
Johan
 
While on this topic

With this cold weather I cannot work at the hanger. I have the nose wheel assembly at home, and have rigged a setup where I have the front pivot completely vertical. Do you think it is OK to use this to mount the front wheelpant (in the comfort of the basement!!) as per plans?
Seems OK to me.
Thanks.
Johan
 
Dorfie said:
With this cold weather I cannot work at the hanger. I have the nose wheel assembly at home, and have rigged a setup where I have the front pivot completely vertical. Do you think it is OK to use this to mount the front wheelpant (in the comfort of the basement!!) as per plans?
Seems OK to me.
Thanks.
Johan
Click to expand...

Not unless your gear legs are attached to your fuselage and are in your basement too. :eek:

Getting the alignment correct on the wheel pants is important. I would recommend following the process in the plans.

I ran into a similiar situation, while I can temporarily heat my hanger, unless it remains above 70 degrees, working with fiberglass and epoxy will be problematic. I basically had to wait until spring to start on all the fiberglass projects that I made the mistake of saving until the end of the build.
 
Dorfie said:
With this cold weather I cannot work at the hanger. I have the nose wheel assembly at home, and have rigged a setup where I have the front pivot completely vertical. Do you think it is OK to use this to mount the front wheelpant (in the comfort of the basement!!) as per plans?
Seems OK to me.
Thanks.
Johan
Click to expand...

I recall needing to have the plane on jacks with the nose wheel barely touching in level pitch attitude to do some steps. I just followed the plans other than adding a helicoil and longer hex bolt/spacer for towbar attachment. Enjoying our teen temps?
 
Dorfie said:
With this cold weather I cannot work at the hanger. I have the nose wheel assembly at home, and have rigged a setup where I have the front pivot completely vertical. Do you think it is OK to use this to mount the front wheelpant (in the comfort of the basement!!) as per plans?
Seems OK to me.
Thanks.
Johan
Click to expand...

Per plans would be with the airplane jacked to a level flight attitude (as already mentioned) so that you can get it proper aligned in the pitch attitude.
In level flight, the pivot axis of the nose fork is not vertical.
 
Nose wheel pant

Was hoping I could do it this way. Glad I asked!! Just to be clear, I understood the leveling of the plane as per plans with nose wheel just touching the surface, but was not sure if the nose wheel swivel is vertical in that position. Looking at the plans the drawing shows it as vertical.
Which raises another issue. Is the horizontal reference points per plans really horizontal in level flight (fore-aft axis)? I would think she flies with some degrees of nose-up. Just thinking.
Will find something else to do...in the warmth of basement.
Thanks for al the replies.
Johan
 
Dorfie said:
Was hoping I could do it this way. Glad I asked!! Just to be clear, I understood the leveling of the plane as per plans with nose wheel just touching the surface, but was not sure if the nose wheel swivel is vertical in that position. Looking at the plans the drawing shows it as vertical.
Which raises another issue. Is the horizontal reference points per plans really horizontal in level flight (fore-aft axis)? I would think she flies with some degrees of nose-up. Just thinking.
Will find something else to do...in the warmth of basement.
Thanks for al the replies.
Johan
Click to expand...

The fuse. is very close to level (longitudinally at the longerons) in cruise flight (will vary slightly depending on speed and load).
The wings have some positive angle of attack as mounted to the fuselage
 
Dorfie said:
Which raises another issue. Is the horizontal reference points per plans really horizontal in level flight (fore-aft axis)? I would think she flies with some degrees of nose-up. Just thinking.
Will find something else to do...in the warmth of basement.
Thanks for al the replies.
Johan
Click to expand...


As Scott mentioned, the longerons or the aluminum surface at the doors can be used.

You'll also have to do the same when you do your weight and balance. I actually had to let a little air out of the nose wheel to get the airframe level.
 
Dorfie said:
Was hoping I could do it this way. Glad I asked!! Just to be clear, I understood the leveling of the plane as per plans with nose wheel just touching the surface, but was not sure if the nose wheel swivel is vertical in that position. Looking at the plans the drawing shows it as vertical.
Which raises another issue. Is the horizontal reference points per plans really horizontal in level flight (fore-aft axis)? I would think she flies with some degrees of nose-up. Just thinking.
Will find something else to do...in the warmth of basement.
Thanks for al the replies.
Johan
Click to expand...

I did not measure the vertical on the nose fork pivot, so no idea.

On the ground taxiing, our bottom door opening/deck angle is +2 or 3 degrees. You will see that when doing wheel pants or weight & balance that our main wheels are off the ground about 2" in level attitude.

In cruise flight at lower altitudes, 150-160 kts and gross weight my deck angle is +1-2 degrees. We went up to 16,500' this summer, OAT= 32F, IAS= 105kts, TAS= 136 kts, 7.9 gph, 40 LOP(stock mags and unbalanced factory injectors), 16 mpg...our deck angle was +5-6 degrees. We also noted our CHT's 20-30F hotter than normal and my cowl outlet temp exceeded 225F for the first time since new. Sorry to get off topic, but very interesting.
 
Wayne Gillispie said:
I did not measure the vertical on the nose fork pivot, so no idea.

On the ground taxiing, our bottom door opening/deck angle is +2 or 3 degrees. You will see that when doing wheel pants or weight & balance that our main wheels are off the ground about 2" in level attitude.

In cruise flight at lower altitudes, 150-160 kts and gross weight my deck angle is +1-2 degrees. We went up to 16,500' this summer, OAT= 32F, IAS= 105kts, TAS= 136 kts, 7.9 gph, 40 LOP(stock mags and unbalanced factory injectors), 16 mpg...our deck angle was +5-6 degrees. We also noted our CHT's 20-30F hotter than normal and my cowl outlet temp exceeded 225F for the first time since new. Sorry to get off topic, but very interesting.
Click to expand...

Very interesting. Thanks for sharing. Do you measure deck angle continuously?
Thanks.
johan
 
I take pictures of EFIS screens on every flight once in cruise(Map, PFD and Engine). They come in handy if someone ask a question or I have a engine problem.
 
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