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Landing gear mount

LettersFromFlyoverCountry

LettersFromFlyoverCountry

Well Known Member
Question. Van's says if you don't have a -- I think it was -- .311 size drill, to drill the mount to gear leg hole, to use a 5/16". How many of you have done that and is there any significant safety penalty to pay there? I assume a .311 hole will be a snug fit for the bolt (as snug as the bolts through the 704 and wings and munt?) but a 5/16" will not.

And if you used the .311 size drill bit, where'd you get it?
 
A 7.9mm bit is

7.9 / 25.4 = .3110"

7.9mm bits aren't too hard to find. I could probably dig up a link if you need it.
 
Bob Collins said:
Question. Van's says if you don't have a -- I think it was -- .311 size drill, to drill the mount to gear leg hole, to use a 5/16". How many of you have done that and is there any significant safety penalty to pay there? I assume a .311 hole will be a snug fit for the bolt (as snug as the bolts through the 704 and wings and munt?) but a 5/16" will not.

And if you used the .311 size drill bit, where'd you get it?
Click to expand...
Bob,
My plan is to bring the hole to size using one or two reamers on a slightly undersize drilled hole.

You can get reamers in nearly any size you would want.

Wholesale tool supply is one source.
This one is adjustable from 9/32 - 5/16.

http://wttool.com/p/1166-0010


-mike
 
If there was a "significant safety penalty" to using a 5/16" drill bit, I doubt Van's would recommend using it in the instructions. A difference of .0015" seems mighty small. I'll let you know if my gear legs fall off.
 
An Answer to the question

Bob, I just finished that phase of construction and used a 5/16 bit to ream both the holes in the gear leg and the mount although not at the same time.
The supplied bolts are still a light drive fit which is very reassuring.
In fact they were both such a tight fit that it scraped off some of the cad plating as they were being driven in.
I wouldnt waste your time and money on a .311 reamer.
Hope this helps.
Rick
 
I have a question about the 4-12A bolts (6 of them) that hold the landing gear mount to the F-704 (sans wings). Everything fits fine on my installation. The mount is absolutely flush with everything. Perfect.

But with the 4-12A, when it's all torqued down, I don't have any threads exposed aft of the lock-nut. Did other folks note that too. I can't find anything that says you should have any, but I usually do. Right now the end of the bolt is pretty much flush with the locking nut.

How 'bout you?
 
Bolts too short

On Greg Cameron's 7 he had to use -13's because of this. Looks like more stuff to order.

Darwin
 
I believe I used 13's as well. I have quite a collection of leftover bolts, probably due to have to substitue lengths for one reason or another. Kept ACS happy, though.

Roberta
 
IIRC, -12A was a little short, -13A was a little long, so I used -13A with an extra washer. Talk about trial and error. :)
 
Short Bolts On Tri Gear Main Landing Gear Weldments

I noticed the short(4-12a) bolts too on the main gear weldments for the 7A. I called Vans and they alluded it's a mistake. They should be 4-13A's. It's interesting that they shipped the 13a's along with thje 12a's with my hardware. They are in a bag called tri-gear hardware.

Why they don't simply revise the plans is a source of great frustration. :)
 
I'd love to see Van's start using RVAtor again for plans revisions and updates like these little "mistakes." I told them about 4 different mistakes on the rivet callouts for the fuselage and nothing's been printed in RVAtor.

It'd be great to have somewhere that all these mistakes could be documented.
 
Engineering Change Notices on Internet...a thought

Bob Collins said:
I'd love to see Van's start using RVAtor again for plans revisions and updates like these little "mistakes." I told them about 4 different mistakes on the rivet callouts for the fuselage and nothing's been printed in RVAtor.

It'd be great to have somewhere that all these mistakes could be documented.
Click to expand...

I would like to see Van's have a secure, password protected site for folks with a builder's number to check for revisions and maybe get a revised print. That way a builder could check periodically for changes to the model he was building. And what would really be cool is to get an "automated" email notifying a builder to check thus and such revision that affected his number series. :rolleyes:
What the heck am I thinkin' ! That'll never happen. This is an "experimental" aircraft. ;)
 
For me the most frustrating part of the gear leg mounts is the fact that there are two rivets that interfere with the mount and there's no mention of it anywhere. The first one is a little easier to spot:
2005-10-09.1084.jpeg

The red arrow points to the rivet that interferes.


The second is much less obvious and I only found it because I stumbled across it on someone else's website.
2005-10-19.1097.jpeg


You can see that I extended lines from the edges of the relief holes and sure enough, there should be a relief notch here. You can sort of see in the picture how the powder coat was disturbed a little by the rivet pressing against the weldment. If you don't notch this relief hole, your weldment will not sit perfectly flush against the center section web.

I called Van's to talk to them and they said they had never heard of it before. I'll be interested to see if they change the weldment design and/or make a note of it in the drawings or manual.
 
I hasn't noticed that when I was fitting it. It didn't cause any problem. but after your post I went out and looked, and sure enough.... the rivet is butting up against the weldment. And yet, everything aligns fine and the rest of it seems to be sitting flush to the 704.

Ugh.
 
Jamie said:
For me the most frustrating part of the gear leg mounts is the fact that there are two rivets that interfere with the mount and there's no mention of it anywhere.

Jamie: Look on drawing 23, area a3. It tells you to set that rivet with a flush bucktail on the inside. That solves the clearance problem. Steve.
Click to expand...
 
You can see that I extended lines from the edges of the relief holes and sure enough, there should be a relief notch here. You can sort of see in the picture how the powder coat was disturbed a little by the rivet pressing against the weldment. If you don't notch this relief hole, your weldment will not sit perfectly flush against the center section web.

I called Van's to talk to them and they said they had never heard of it before. I'll be interested to see if they change the weldment design and/or make a note of it in the drawings or manual.[/QUOTE]

I had to go look and sure enough, I see that I relieved the weldment in this area to fit around the rivet, so you aren't the only one to have had the problem. Steve
 
Stephen Lindberg said:
Jamie said:
For me the most frustrating part of the gear leg mounts is the fact that there are two rivets that interfere with the mount and there's no mention of it anywhere.

Jamie: Look on drawing 23, area a3. It tells you to set that rivet with a flush bucktail on the inside. That solves the clearance problem. Steve.
Click to expand...

Thanks, Steve. I'll take a look at it this afternoon when I get home from the day job.
Click to expand...
 
Now I'm confused. I know there are 5 (if I recall) rivets on the bottom flange of the 704 that are set flush. But I think we're talking about one on the WEB of the F-704 that's interfering, aren't we? (It was hard to tell with the picture). Did I miss a note that there's a flush rivet on the web?
 
Amazing. I sure skipped over that little note on drawing 23. I guess it pays to carefully read everything on the plans. The second rivet that Jamie pointed out isn't mentioned though.
 
Bob Collins said:
Now I'm confused. I know there are 5 (if I recall) rivets on the bottom flange of the 704 that are set flush. But I think we're talking about one on the WEB of the F-704 that's interfering, aren't we? (It was hard to tell with the picture). Did I miss a note that there's a flush rivet on the web?
Click to expand...

Bob: The first rivet I was referencing goes through the side skin, vertical flange of F-704 and the gear attach web. And I confirmed that my drawing has that rivet mentioned too. Guess I missed that note.
 
The diameter of a 5/16" drill is .312. All drills cut oversize .005-.010, more if they are dull or misaligned. If you really need .311, drill undersize and use a 5/16(-) dowel pin reamer. The case is ,usually, unless the bolt is a body bolt, the diameter of the bolt will be undersize, anyway. Just my $.02.
 
It's not so much the date that's the problem, as Bob keeps changing the topic in this thread. :D
 
I put my left landing gear mount in today (I had drilled the hole to the gear leg 1/64" too big so I bought another one) and, sure enough, this rivet IS interfering and causing the mount to be slightly out of alignment to the center. I didn't have the problem on the right gear, though.

I doublechecked the plans again and there is NO callout for a flush rivet in this lodation (those are called out for the flange beneath the 704).

So I guess I'll be filing away this weekend.
 
Davepar said:
It's not so much the date that's the problem, as Bob keeps changing the topic in this thread. :D
Click to expand...
All things "landing gear mount." You know, the more I think of it, the more it makes sense to have the topics broken down by the part. Why have to search through a bunch of threads like

"problem with landing gear mount"
"installing the landing gear mount"
"where's my landing geare mount"
"what does the landing gear mount do"

When there could an entire section slugged "landing gear mount."

In fact, the sections could be set up to match the kits.

Empenagge -- with subsections for HS, VS, rudder, Elevator
Wings - with subsection for mains, flaps, ailerons, fuel tanks
Fuselage - Aft section, center section, firewall, landing gear mount, interior
Finishing -- With sections that I have no clue what they would be since I'm not there yet.

There...now THERE'S a message that has nothing to do with landing gear mounts.
 
Jamie said:
Bob: The first rivet I was referencing goes through the side skin, vertical flange of F-704 and the gear attach web. And I confirmed that my drawing has that rivet mentioned too. Guess I missed that note.
Click to expand...
That explains why I didn't have a problem on the right side. I put that rivet in after the landing gear mount.

That note, byt he way, shouldn't be on drawing 23. It should be on DWG 28...the rivet callout drawing for the fuselage...and the same place the note for the flush head rivets for the flange is.

I think that's why people -- including me -- missed it.

so here's a question. How do you buck a shop head flush? The only way I can figure it out is to use an undersized rivet..or just beat the snot out of it..
 
Bob Collins said:
That explains why I didn't have a problem on the right side. I put that rivet in after the landing gear mount.

That note, byt he way, shouldn't be on drawing 23. It should be on DWG 28...the rivet callout drawing for the fuselage...and the same place the note for the flush head rivets for the flange is.

I think that's why people -- including me -- missed it.

so here's a question. How do you buck a shop head flush? The only way I can figure it out is to use an undersized rivet..or just beat the snot out of it..
Click to expand...

Same as on the rudder. Just countersink the shop head side and 'overdrive' the rivet a little, it'll set most of the way in there. I also like to give them a once-over with the scotchbrite wheel on the die grinder to smooth the rivet with the surrounding material if necessary.
 
I used AN4-13A's - that's my final answer

Tedtheflyer said:
I noticed the short(4-12a) bolts too on the main gear weldments for the 7A. I called Vans and they alluded it's a mistake. They should be 4-13A's. It's interesting that they shipped the 13a's along with thje 12a's with my hardware. They are in a bag called tri-gear hardware.

Why they don't simply revise the plans is a source of great frustration. :)
Click to expand...

I toyed with this for a good while the 12's were looking too short. Vans said if you can get a thread into the nylon they'd be okay. Hum. My local EAA Tech Advisor said to try a couple of things: the 12's with a flat "L" washer instead of the regular washer. I did and was able to get one thread to show barely. His other suggestion was to use the 13's with a regular washer and a flat "L" washer. That is what I ended up doing and have three threads.
 
Yeah, me too, I used a washer on both sides for the 13s and I'm MUCH more comfortable with the the 13s, than the 12. I think Van's is just flat out wrong about getting it to the elastic. I think you need to have a thread showing. And this is sort of an important part, as near as I can tell. ;)
 
Jamie said:
You can see that I extended lines from the edges of the relief holes and sure enough, there should be a relief notch here. You can sort of see in the picture how the powder coat was disturbed a little by the rivet pressing against the weldment. If you don't notch this relief hole, your weldment will not sit perfectly flush against the center section web.

I called Van's to talk to them and they said they had never heard of it before. I'll be interested to see if they change the weldment design and/or make a note of it in the drawings or manual.
Click to expand...

I had the same problem with that rivet on the 704 web hitting the gear leg mount. Took me a while to work out what the problem was. It strikes me that there might be people flying around with the mount not pulled up flush to the 704. Vans failure to update their drawings borders on irresponsible. At the very least it's commercially eccentric.

Incidentally there are a number of locations on the RV7 that really require snug bolts although they are not specified. For instance Vans suggests that the gear leg and mount bolt hole can be drilled with a 5/16" drill instead of a .311 drill. Personally I wouldn't use either, but I certainly wouldn't use 5/16. I would suggest that there are lots of RVs out there with slop in their gear legs due to an oversized hole in this location. Even a .002 oversize hole can result in up to 3/16" movement at the tip of the axle.

A good solution is to drill the hole 1/64" undersize and open it up progressively with an adjustable hand reamer. Then you can tweak it until the bolt is an interference fit. I would recommend doing the same with the hole that has to be drilled through the rear spar at the wing root.
 
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