Matronics Email Lists :: View topic

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

Inspection covers.
Goto page 1, 2 Next

Matronics Email Lists Forum Index -> Zenith-List

View previous topic :: View next topic

Author Message

pacificpainting(at)comcas
Guest

Posted: Tue Oct 17, 2006 3:36 pm Post subject: Inspection covers.

Hello Fellow Listers,

  

 Can anyone tell me why I would have to put doublers  on for inspection plates. I have the plates and skins drilled. I don't see why I  can't dimple and flush rivet nut plates to the skin. It's .025 and would hold a  small flush rivet OK. If the plates were riveted direct to the skin, wouldn't it  be about the same?

  

  

 Dave in Salem

   [quote][b]

dredmoody(at)cox.net
Guest

Posted: Tue Oct 17, 2006 4:14 pm Post subject: Inspection covers.

The only reason that comes to mind for the doublers is to make the rim of the inspection hole more trauma resistant when the hatch cover is off. Once the cover is screwed into place, it essentially is a doubler for the inspection hole in the skin, isn't it?



Ed Moody II

Rayne, LA

601XL / Jabiru / fuselage



---- Dave Ruddiman <pacificpainting(at)comcast.net> wrote: 

 	  Quote: 	
		   Hello Fellow Listers,

 

 Can anyone tell me why I would have to put doublers on for inspection plates. I have the plates and skins drilled. I don't see why I can't dimple and flush rivet nut plates to the skin. It's .025 and would hold a small flush rivet OK. If the plates were riveted direct to the skin, wouldn't it be about the same?

 

 

 Dave in Salem

p.mulwitz(at)worldnet.att
Guest

Posted: Tue Oct 17, 2006 4:46 pm Post subject: Inspection covers.

 	  Quote: 	
		  

One other reason for the doubler approach is it allows a flush 
	


mounted inspection plate.  This might be significant in a very fast 

airplane - definitely not a good description of the CH801.



Paul

XL fuselage

 	  Quote: 	
		  The only reason that comes to mind for the doublers is to make the 

rim of the inspection hole more trauma resistant when the hatch 

cover is off. Once the cover is screwed into place, it essentially 

is a doubler for the inspection hole in the skin, isn't it?



Ed Moody II

jhstarn(at)verizon.net
Guest

Posted: Tue Oct 17, 2006 5:37 pm Post subject: Inspection covers.

NO..... The doubler is to spread the "load" of flexing around the hole as a  whole. Individual nutplates DO NOT spread the flex and can be the cause for  cracks as they localize it. Besides if you use a doubler that leaves a  1/2" lip inside the hole & attach nut plates to the back of that flange the  inspection cover will fit flush and add addition strength to the area. Flush  rivet the doublers and make it part of the permanent structure. No square  corners, radius them & those of the removable panel. I would also use  .032 for the doubler and make it one piece. On the Rocket we used .040 on  the .032 skins.   KABONG  Do Not Archive

 [quote]   ---

Michael Valentine

Joined: 09 Jan 2006
Posts: 108

Posted: Tue Oct 17, 2006 5:59 pm Post subject: Inspection covers.

Perhaps I am just showing my ignorance here, but where does it call for doublers?  I haven't seen that on the inspection holes on the tail or wings.  Am I missing something or does this come later?



Michael

(in NH) 



do not archive



On 10/17/06, Dave Ruddiman <pacificpainting(at)comcast.net (pacificpainting(at)comcast.net)> wrote:[quote]        Hello Fellow Listers,

  

 Can anyone tell me why I would have to put doublers  on for inspection plates. I have the plates and skins drilled. I don't see why I  can't dimple and flush rivet nut plates to the skin. It's .025 and would hold a  small flush rivet OK. If the plates were riveted direct to the skin, wouldn't it  be about the same?

  

  

 Dave in Salem

   

 [b]

pacificpainting(at)comcas
Guest

Posted: Tue Oct 17, 2006 6:07 pm Post subject: Inspection covers.

I'm not challenging any of the advice about the  covers. I'm not concerned about drag. The 801 isn't exactly a low drag air  frame. I also considered whether the plates would become part of the structure  of the wing skin. The wing assembly manual says I can cut a 95mm access hole.  Mine is 100mm. It also says to make a 135mm round cover and use 6 A4 rivets. My  cover is 140mm and I have 8 holes which I have only pilot drilled. I was  originally going to use doublers and nut plates, then decided to just rivet the  plates to the skin. Now I have thought about using nut plates again. It seems  like I am making a big issue out of something that should be simple. Or maybe  not.

  

 Dave in Salem

  

  

 [quote]   ---

pacificpainting(at)comcas
Guest

Posted: Tue Oct 17, 2006 6:13 pm Post subject: Inspection covers.

Michael,

  

 They don't call for doublers that I know of. I was  just asking the question to see if they are necessary or not. ZAC says you don't  need them. It does add a step or two to the procedure but.....?

  

  

 [quote]   ---

gboothe(at)calply.com
Guest

Posted: Tue Oct 17, 2006 6:43 pm Post subject: Inspection covers.

Dave,  

   

Your question is worthy. Unfortunately, there are many different answers depending on one’s preference. Whether .016 needs a doubler is probably more relevant than .025. You just have to make the decision yourself….caffeine / no caffeine, Mac / PC, tri-cycle / taildragger, green scotchbrite / purple scotchbrite, center yoke / dual sticks….so many decisions…..  

   

Making a flush mount inspection plate is an easy task and looks real cool. Consider it. If you decide to make any kind of screw-on inspection cover, be sure to make the screw pattern an obvious indication of which direction the plate goes on. If you have multiple plates, mark them to show placement. Life will be better.  

   

Gary Boothe 

 Cool, CA 

 601 HDSTD, WW Conversion 90% done, 

 Tail done, wings done, working on c-section   

   

         

  

From: owner-zenith-list-server(at)matronics.com [mailto:owner-zenith-list-server(at)matronics.com] On Behalf Of Dave Ruddiman

 Sent: Tuesday, October 17, 2006 7:07 PM

 To: zenith-list(at)matronics.com

 Subject: Re: Zenith-List: Inspection covers.  

  

     

I'm not challenging any of the advice about the covers. I'm not concerned about drag. The 801 isn't exactly a low drag air frame. I also considered whether the plates would become part of the structure of the wing skin. The wing assembly manual says I can cut a 95mm access hole. Mine is 100mm. It also says to make a 135mm round cover and use 6 A4 rivets. My cover is 140mm and I have 8 holes which I have only pilot drilled. I was originally going to use doublers and nut plates, then decided to just rivet the plates to the skin. Now I have thought about using nut plates again. It seems like I am making a big issue out of something that should be simple. Or maybe not.  

    

   

    

Dave in Salem  

    

   

    

   

  [quote]    

---

pacificpainting(at)comcas
Guest

Posted: Tue Oct 17, 2006 7:04 pm Post subject: Inspection covers.

Gary,

  

 Caffeine, PC, tri-cycle, green scotchbrite,  (apparently it is Un-American to use any othe color), center yoke. Flush plates  look good, but I won't be able to see the top of the wing without a ladder. I  did make a tiny little notch towards the leading edge of the plates.  Another thing, hopefully these things never have to be taken off. I've got to  quit making things so difficult. I feel so much better now that I've made all  these decisions.

  

 Dave

  

  

 [quote]   ---

gboothe(at)calply.com
Guest

Posted: Tue Oct 17, 2006 7:14 pm Post subject: Inspection covers.

Dave,  

   

Now you’ve done it!! You just condemned yourself to multiple removals.  

   

Gary – Do not archive  

     

…..Another thing, hopefully these things never have to be taken off…..   

    

   

    

Dave  

    

   

    

   

  [quote]    

---

pacificpainting(at)comcas
Guest

Posted: Tue Oct 17, 2006 7:38 pm Post subject: Inspection covers.

Gary,

  

 You know, having my computer in the shop is almost  as bad as leaving the door open at the airport when you are trying to get  something done. I guess I don't have to stop and read the emails, but that part  of the fun of the whole process. I wouldn't want to be left out.

  

 Dave

 I keep forgetting the DO NOT ARCHIVE  part.

  

  

 [quote]   ---

doug kandle

Joined: 09 Jan 2006
Posts: 33
Location: Boise ID

Posted: Tue Oct 17, 2006 8:35 pm Post subject: Re: Inspection covers.

I believe that in a stressed skin design (like the 701 and 601) adding an inspection hole is the same as making a repair to the skin.  AC 43.13-1B covers procedures for repairs of damaged skins.  The repair that covers a 3" hole, using only material of the same thickness as the skin, requires two circles of rivets (24 rivets total).  That is a lot more rivets (or screws) than you would put into an inspection cover.  I don't know where the design data is for an inspection cover, but clearly it is not enough to repair a 3 or 4 inch hole with just 6 or 8 screws.  (see AC43.13-1B section 4-58 ).  

Remember that unlike a tube and fabric design, most of the strength of your aircraft is obtained from the skin.  Unless you know the stresses that will be applied to each particular part of the skin, you should probably assume that it is critical to not weaken it wherever an inspection opening is added.

Ron Lendon

Joined: 10 Jan 2006
Posts: 685
Location: Clinton Twp., MI

Posted: Tue Oct 17, 2006 8:52 pm Post subject: Re: Inspection covers.

Ahh there is light at the end of this tunnel, thanks Doug

_________________
Ron Lendon
WW Corvair with Roy's Garage 5th bearing
CH 601 XLB
N601LT - Flying
http://www.mykitlog.com/rlendon
Corvair Engine Prints:
https://sites.google.com/site/corvairenginedata/

pacificpainting(at)comcas
Guest

Posted: Tue Oct 17, 2006 9:37 pm Post subject: Inspection covers.

Not to complicate things any more, or keep this subject going, but what 

about the holes in the skin for the fuel tank caps? Would I be correct in 

assuming that there might be less stress because they are somewhat smaller 

and are fairly close to both the spar and a rib? Just curious. It's time to 

get this done and move on.

---

dredmoody(at)cox.net
Guest

Posted: Wed Oct 18, 2006 7:22 am Post subject: Inspection covers.

Radio Shack sells those little vibrating engraver tools (cheap and easy to use). I consider it a must for my project. When I have fitted and drilled a piece, it has to be removed, deburred, and primed (and sometimes painted) before it is ready for rivetting later. When I take the piece off to do all that stuff, the first step is to ID it with the little engraver. It does not lead to cracks or fraternization with green scotchbrite (I use a security camera to monitor the parts while I'm at work). I put the ID where it will not be seen once the part is installed. That allows me to positively ID the parts location and its orientation with arrows as needed. Even once the part is primed or painted the marks can still be seen. The same goes for my inspection hatch covers.... they all bear location and orientation marks on the inside.



Ed Moody II

Rayne, LA

601XL / Jabiru / fuselage

---- Gary Boothe <gboothe(at)calply.com> wrote: 

 	  Quote: 	
		   Dave,

 

If you decide to make any kind of screw-on inspection cover, be
	


 	  Quote: 	
		   sure to make the screw pattern an obvious indication of which direction the

 plate goes on. If you have multiple plates, mark them to show placement.

 Life will be better.

 

 Gary Boothe 

 Cool, CA 

 601 HDSTD, WW Conversion 90% done, 

 Tail done, wings done, working on c-section

dredmoody(at)cox.net
Guest

Posted: Wed Oct 18, 2006 7:28 am Post subject: Inspection covers.

Yep.... just as well convert them to Velcro now.



Ed



---- Gary Boothe <gboothe(at)calply.com> wrote: 

 	  Quote: 	
		   Dave,

 

  

 

 Now you've done it!! You just condemned yourself to multiple removals.

 

  

 

 Gary - Do not archive

 

  

 

 ...Another thing, hopefully these things never have to be taken off... 

 

  

 

 Dave

doug kandle

Joined: 09 Jan 2006
Posts: 33
Location: Boise ID

Posted: Wed Oct 18, 2006 8:02 am Post subject: Re: Inspection covers.

 	  pacificpainting(at)comcas wrote: 	
		   what 

about the holes in the skin for the fuel tank caps? Would I be correct in 

assuming that there might be less stress because they are somewhat smaller 

and are fairly close to both the spar and a rib? Just curious. 



--- 	


The fuel tank cap holes were designed in, not a builder add on.  I assume that the designer knows what he was doing.  But I don't have any easy way to determine how much stress must be supported in any particular location on the skin and therefore I assume the worst (that it must be full strength).  I have heard rules of thumb - like the farther out on the wing you go, the less stress the skin must withstand.  The FAA takes design changes very seriously and I think we all should too.

pacificpainting(at)comcas
Guest

Posted: Wed Oct 18, 2006 10:30 am Post subject: Inspection covers.

What is the rating for Velcro. Would it need to be higher in  shear or 

tension? Do I have to use industrial strength or just the regular household 

variety. Does it have to be "Velcro" brand or can I use after market 

products as long as they are approved. What about Color? I'm really confused 

now.

---

jhstarn(at)verizon.net
Guest

Posted: Wed Oct 18, 2006 12:03 pm Post subject: Inspection covers.

"I'm really confused  now."



You didn't to tell us that Dave, we already knew.   KABONG   8*) Do Not 

Archive

Subject: Re: Inspection covers.

 	  Quote: 	
		   

 <pacificpainting(at)comcast.net>



 What is the rating for Velcro. Would it need to be higher in  shear or 

 tension? Do I have to use industrial strength or just the regular 

 household variety. Does it have to be "Velcro" brand or can I use after 

 market products as long as they are approved. What about Color? I'm really 

 confused now.

gboothe(at)calply.com
Guest

Posted: Wed Oct 18, 2006 1:43 pm Post subject: Inspection covers.

Dave,



You raise relevant points. I think the shear rating is most important on

under-wing applications, while the tension rating would apply to

top-of-wing. It would not matter if it was "industrial" or "household" as

long as it was at the certified rating. Certainly, anything other than

"Velcro" would require an STC. As to color, my guess is that any color

except green would be certified (wouldn't want anyone to mistake the green

Velcro for scotchbrite).



What really concerns me, though, is the adhesive with which the Velcro is

applied. It'll take someone smarter than I to determine the required testing

for that (after all, I'm just a guy who travels too much for work with way

too much time on my hands in a motel!)



Gary Boothe 

Cool, CA 

601 HDSTD, WW Conversion 90% done, 

Tail done, wings done, working on c-section

DO NOT ARCHIVE

--

Display posts from previous:

	Matronics Email Lists Forum Index -> Zenith-List	All times are GMT - 8 Hours Goto page 1, 2 Next
Page 1 of 2

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum