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-   -   Don't make this mistake installing the wheel fairings! (https://vansairforce.net/community/showthread.php?t=160754)

psalys 05-24-2018 08:36 PM

Don't make this mistake installing the wheel fairings!
 
Page 36A-06. When installing the left outboard main gear fairing bracket (U-00002 and U-00004) with the long AN3-40A bolts, I broke off both bolts in the holes in the axle. Sounds pretty dumb but here's how it happened.

As I screwed the bolts in they became tight with about 1/8" left to go. I was puzzled so I turned the small 1/4" socket wrench carefully and then, snap, the bolt broke off. I thought I had a bad bolt so I carefully tightened the other bolt and it snapped off as well.

I tried to drill out the bolt shanks but was unsuccessful. I believe the problem is that the holes in the end of the axle were not tapped deep enough for the bolt. I bought a 10-32 tap and tapped the other axle until the tap reached the bottom and the AN3 bolts worked perfectly.

I spoke with Van's a couple time and they will send me replacement bolts but for the axle, they referred me to Matco. Matco asked me to send the axle back and I don't know if they will charge be for a replacement ($71 + shipping on their website).

So this is an easy mistake to make that could cost you $100 and a couple weeks to fix so the moral of the story is: if your bolt gets tight before it should, STOP! Go buy the correct tap and tap it deeper. That solution would have cost me $5.77 and an hour of time.

Just because it's a machined part doesn't mean it's right.

BigJohn 05-25-2018 04:41 AM

I have had two of those bolts break off. Once when I hit a ridge of ice pushing into my hangar, the other time one was just broken when I took the wheel pants off. Both times I was able to extract the broken bolts using a drill press, left hand drill, and an easy-out. Has to be done carefully but it can be done. And, an excuse to buy a few more tools!

benfra 05-25-2018 10:02 AM

Wheel pant bolts
 
Did same thing, dosent appear to be enough threading in axel. Next time I was careful and used a good amount of blue thread lock. Good Luck

RFSchaller 05-25-2018 07:58 PM

I have had fairings on my plane since it was licensed in 2012, and they look great, but it?s a pain to check pressure or add air, so I plan on removing them at next oil change when I usually go through the rigamaroll of topping off tire pressure.

EXflyer 05-28-2018 06:43 PM

Bolt Lenght
 
Quote:

Originally Posted by benfra (Post 1262465)
Did same thing, dosent appear to be enough threading in axel. Next time I was careful and used a good amount of blue thread lock. Good Luck

Its very easy to bottom a bolt out, but to over tighten it and have it break is another thing. There are torque limits for a reason, just because its not all the way down, item its supposed to hold and has a space under the head does not mean keep wrenching. It means, find out why the bolt is not going to tighten against the item. Real easy take a wire and use it to find out what the problem is. Use it to measure from the surface of the item to the bottom of the hole. Happens quite often that the bolt is too long or hole needs to be threaded more or drilled deeper. More than just a little force was exerted to break it off.

Snowflake 05-29-2018 07:25 AM

Quote:

Originally Posted by EXflyer (Post 1263142)
Real easy take a wire and use it to find out what the problem is. Use it to measure from the surface of the item to the bottom of the hole. Happens quite often that the bolt is too long or hole needs to be threaded more or drilled deeper.

A wire can easily check for hole depth, but it can't easily confirm thread depth.

EXflyer 05-29-2018 08:12 AM

Quote:

Originally Posted by Snowflake (Post 1263231)
A wire can easily check for hole depth, but it can't easily confirm thread depth.

Didn't say it could but by running bolt in by hand will tell how far threads go. Then check with a tap will confirm it as to take out a small piece of material can be done with little force. That will tell if there is any hole left to tap other wise one could do damage by forcing a tape against the bottom of the hole. Been there done it many times that way during my years as a heavy duty mechanic.

And will add another thing that many don't do, blow the hole out with air as some times they are not cleaned after drilling and tapping, just an FYI for those who have never done this.

rvbuilder2002 05-29-2018 10:25 AM

There has been communications with Matco in an attempt to gain an understanding of what the problem might be.

It seems that occasionally an axle doesn't have fully cleaned up threads at the bottom of the hole.

Light clean-up of the threads can be done using a 10-32 tap if the threads of an AN3 bolt wont easily thread in full depth. Just be sure not to bottom out the tap and break it off in the hole.

As already mentioned, never exceed the max. torque value for a fastener.
An AN3 bolt begins to yield in torsion at something in the neighborhood of 60 inch pounds (only a bit more than 3X the normal torque value).


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