What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Torquing Ourboard gear bolts????

Y

yankee-flyer

Well Known Member
OK, guys, unless I'm missing something there's no way I can get a torque wrench on the outboard gear attach bolts after the skin panel has been riveted in place. Brake line is in the way of the rear bolt from the bottom and you can't get a socket on from the top. Best I could do was use a stubby wrench and pull for all my aging fingers were worth.

120241/N143WM: 23 months, 134 hours, probably 200 landings, less than a dozen on grass. Outboard attach bolts were loose enough to turn easily without one end being held. Could only tighten one flat at a time so I don't know how loose they were or how much torque it took. Right side bolts took more turns than left side. No cracks in channel.

1) where do I find the "official form" to report to Van's

2) how in blazes are you guys getting a torque wrench on the outboard bolts without removing brake lines?????


Thanks Wayne
 
i-XC9NctM-M.jpg


If necessary, the brake line can be carefully bent enough to get the socket on the bolt.
 
Tony and group,
I'm no engineer, but I know a lot of the members on this forum are.
Question: when you put on a ratchet extension, not to mention the crow's foot adapter, wouldn't this cause an 'false' reading on the torque wrench? I know I have some ratchet extensions that flex a LOT more than others, so I am just curious if anyone knows? In other words, if I have a socket directly on the torque wrench, it would seem I would get a true reading, versus extensions and adapters downstream to the bolt/nut from the torque wrench?

Thanks.
 
Extension/adapter has no effect.

Crows foot does so follow the formula that came with your torque wrench.
 
szicree said:
Keep the crow's foot perpendicular to the wrench handle and no formula is needed.
Click to expand...

I beg to differ, the crowfoot extends the arm of the wrench by about 1 inch, the torque wrench instructions have a formula to take this into account. As there is a tolerance on torques to apply, it is likely that the difference involved is within this tolerance if your torque wrench is more than 10 inch long but it is wise to make the calculation of the correction to be on the safe side.
 
WingedFrog said:
I beg to differ, the crowfoot extends the arm of the wrench by about 1 inch, the torque wrench instructions have a formula to take this into account. As there is a tolerance on torques to apply, it is likely that the difference involved is within this tolerance if your torque wrench is more than 10 inch long but it is wise to make the calculation of the correction to be on the safe side.
Click to expand...

Steve is right!! If the crow's foot is perpendicular to the arm or handle of the torque wrench, no calculation is necessary. The change in torque applied is very small, it is insignificant. If the crow foot is in-line and extends the distance to the bolt, then a calculation would be necessary.
 
Last edited:
Even more clarification!

You can go to AC 43.13-1b, chapter 7, and look up information about torquing nuts and when and how to do an extension calculation.
Additional clarification to the above (correct) posts would include:
The extension from the wrench down to the crows foot is not a factor. It can be as long or short as you need it to be, since it is just extending the attach point of the socket to the wrench. (No calculation required if you use a regular socket or any other extended wrench or crows foot set at 90 degrees to the wrench handle, see below.)
Using a crows foot may or may not require a calculation, depending on the orientation. Looking at AC 43.13-1b, Figure 7-2, the illustration shows that if the attachment extends the arm of the torque wrench by any amount, then you must do the calculation to get a correction for the torque value. So, if the crows foot is in line with the center line of the wrench handle, whether it lengthens or shortens the length of the handle, or at any angle from the center line of the wrench handle, except 90 degrees, you need to do a calculation. (90 degrees is the only angle that does not change the length of the torque wrench arm.)
There are many calculators for the conversion on the web, just google torque wrench conversion calculaters.
But, to make it easy, just orient the crows foot at 90 degrees to the torque wrench!
Good luck.
 
Possible Mod?

I also posted this on the loose langing gear thread today:

I did a check on my RV today. After 29 Hours and 26 landings I found no cracks in the bulkhead channel. My inboard bolts were all tight. I got a little less than one turn on each outboard bolt. All landings were on concrete, and no hard landings. I had one brief brake over application causing a shudder on the left side early on right after certification.

I am thinking about two mods I might make to the outboard attachments:

1. Fashion an anti-rotation device that keeps the nut from turning. The bolt might still creep out, but at least it would make it easier to retighten if the nut couldn't rotate.

2. Drill a 5/8" diameter hole under each outboard bolt head so I can get a straight shot with an extension on a socket to retighten the bolts.

Any thoughts about these mods?
 
RFSchaller said:
I also posted this on the loose langing gear thread today:

I did a check on my RV today. After 29 Hours and 26 landings I found no cracks in the bulkhead channel. My inboard bolts were all tight. I got a little less than one turn on each outboard bolt. All landings were on concrete, and no hard landings. I had one brief brake over application causing a shudder on the left side early on right after certification.

I am thinking about two mods I might make to the outboard attachments:

1. Fashion an anti-rotation device that keeps the nut from turning. The bolt might still creep out, but at least it would make it easier to retighten if the nut couldn't rotate.

2. Drill a 5/8" diameter hole under each outboard bolt head so I can get a straight shot with an extension on a socket to retighten the bolts.

Any thoughts about these mods?
Click to expand...

#1. IMHO the nuts is not rotating, rather the dissimilar materials are "settling in". The powder coating is wearing, and the wear plate is wearing into the beam. I'll bet you a cold one after a few retorques
the bolts will stay tight..

#2. That is a great idea. :D
 
N412BR. 40 Hours. About 70 landings.
No skin wrinkles, brake lines fine, no cracks.
Inboard bolts all tight.
Outboard bolts took about a half turn to get up to the high end of the torque spec, but note that THE TORQUE PAINT HAD NOT MOVED since I originally torqued them and applied the paint.

As Larry is saying, and based on the looseness without the paint moving, it looks like the parts are settling in. I'm going to check those every 10 landings or so for awhile.

I did have to get a set of crows feet to torque the outboard nuts from above. It was not necessary to hold the bolt from below. If that stays the case, it obviates the need for a hole from below to grab the bolt head.

70 inch-pounds uses the smaller (1/4 drive) of my 2 torque wrenches, and the crows feet were 3/8 drive not 1/4 drive. But I had previously purchased a 1/4 FEMALE to 3/8 MALE adapter (an unusual tool) in order to use the small torque wrench on something where I needed a 3/8 drive socket.
 
I don't really see the mechanism that could account for settling in, but it really doesn't matter as the end result is the same: tighten as needed. The anti-rotation device will simplify tightening by eliminating the need for a crow's foot and making it a one person job.

Rich
 
In my case neither the nut or bolt had rotated based on the torque seal paint - which had been applied on both ends. So either the bolt had stretched (UNLIKELY) or the collection of bolted materials have become thinner through wear or settling in.

It is better practice to tighten the nut, not to secure the nut with an antirotation device and tighten the bolt. A crows foot bit is pretty cheap - I see a whole set on Amazon for $12.

I have submitted my case data to Vans.
 
Bill,

I agree torquing the nut is the optimum. Unfortunately working alone with this access and geometry makes torquing the bolt the most practical approach.

Several indicated they have torque values. I didn't see any In the plans, so I'm assuming they are using the torque table value from the standard handbook. Personally I've had to rely on the feel method due to the limitations described above.

Rich
 
Section 5V in the plans gives torque values. These are used unless something else is specified in the plans.
 
More holes?

I really like the idea of access holes to make tightening the bolts a one-man (sorry, person) job but I don't think I's want to frill more holes in an area of the fuselage that already may be having structural problems. Let's wait and hope Van's chimes in on this idea quickly. I'd though about drilling out the rivets that attach the covers above the landing gear and making them into access panels with nutplates and screws but there's a LOT of rivets there and I couldn't get that many screws in there. We really DO need access to the attach bolts!

Wayne 120241/143WM
 
Access hole impact on strength

I haven't cut holes yet. Short of a finite element analysis all I have is what we engineers like to call "good engineering practice". Which sounds so much better than a SWAG (scientific wild *** guess)! :)
 
Yeah...

I'm with you, Rich. I could do the aero on the -12 but my structural analysis classes are way too far back in the murky past to be of any practical use. Gut feeling is that we're going to wind up with some external stiffeners to stop whatever is causing the rotation and access panels to those outer bolts, which is going to mess up all our paint jobs!

Wayne
 
Well ...

As long as we're guessing, my SWAG money is on an internal doubler in the bay above the channel and a diagonal panel stiffener, or maybe two, aft of the channel ... but I'll be very interested to see what Van's decide, or whether they decide to do anything at all.
I also don't think a couple of 5/8" bolt access holes underneath would be a problem, but I'll wait to see what the factory has to say.
 
Inspection

Just checked my gear. No cracks, outboard bolts needed ? turn.
Used duct tape to tape box wrench to bolt heads making it a one person job.
67 flight hours and approx. same number of landings.

Gary Krause
 
We should really see if a moderator could 'merge' this thread with the other RV-12 'loose gear leg' thread. The other thread already has over 20,000 views, and if merged, we would be certain that everyone is reading ALL the inbound RV-12 gear leg data.

Mod's?
 
Good analysis. The adjustment is infrequent enough that it's not a hardship to wait for Vans' conclusion before drilling access holes. My annual is due in March. If there is no fix by then I'll drill the holes and possibly put doubles on them.
 
You must log in or register to reply here.
Back
Top