Van's Air Force
Don't miss anything! Register now for full access to the definitive RV support community.
Avionics Access Panels?
- Thread starter gfb
- Start date
Carl Froehlich
Well Known Member
No longer very applicable if you are going with glass. Make the panel so it comes out in your lap after taking apart a few connectors.
Carl
Carl
I put four panels into the front deck in front of the tip up canopy. I also put a shelf over the rudder peddles so "Black Boxes" could be mounted there. They, and the two batteries, are all accessible via the access panels, as well as the rear side of the avionics stack.
My dual AHRS (GRT) box is on the shelf as is the NavWorx ADS600-EXP box....
Last edited:
Do your research
Before I created mine, I spent some time talking to the engineer at the Vans mothership, and here's what I learned regarding those access panels.
1) BLUF*, they did NOT recommend or endorse this sort of modification. They haven't conducted an engineering assessment on if/how the forward access panel mod strengthen or weakens the aircraft. That forward skin is structural.
2) Having said that, there is an engineering convention (don't ask me to ID the scripture, chapter, verse) that says basically if you're going to cut such a hole and install an inset panel:
a) it needs to sit on a doubler of the same or greater thickness of the surrounding skin material, and...
b) the area of the doubler needs to meet or exceed the area of the hole.
Take at look at the fuselage section of my Kitlog, starting on 1 Dec 2014. That'll show you how I went about applying this modification:
http://www.mykitlog.com/users/category.php?user=ScrollF4&project=879&category=6927
As you can see, I riveted the heck out of it, then used plenty of screws. I wanted it strong....period.
This mod has been an absolute moneymaker for work up front.
* BLUF = Bottom Line Up Front
Before I created mine, I spent some time talking to the engineer at the Vans mothership, and here's what I learned regarding those access panels.
1) BLUF*, they did NOT recommend or endorse this sort of modification. They haven't conducted an engineering assessment on if/how the forward access panel mod strengthen or weakens the aircraft. That forward skin is structural.
2) Having said that, there is an engineering convention (don't ask me to ID the scripture, chapter, verse) that says basically if you're going to cut such a hole and install an inset panel:
a) it needs to sit on a doubler of the same or greater thickness of the surrounding skin material, and...
b) the area of the doubler needs to meet or exceed the area of the hole.
Take at look at the fuselage section of my Kitlog, starting on 1 Dec 2014. That'll show you how I went about applying this modification:
http://www.mykitlog.com/users/category.php?user=ScrollF4&project=879&category=6927
As you can see, I riveted the heck out of it, then used plenty of screws. I wanted it strong....period.
This mod has been an absolute moneymaker for work up front.
* BLUF = Bottom Line Up Front
rv7charlie
Well Known Member
It's almost always fun to read the various opinions coming out of the mother ship.
I called (after consulting my mechanical engineer, a&p-a/i, builder of 3 or 4 scratch builts, an RV-8, & rebuilds of several a/c). Abbreviated answer from both: primary load path in that area is from the top longerons down. (Look at the RV-8 baggage door.)
I didn't need the two skinny openings between the ribs, but took a long look at brake pedal adjust bolts, motor mount firewall bolts, forest of tabs ground block on the firewall recess, etc etc. & decided I really wanted access. I did a screwed-on cover on the left side (engine controller, most of my FWF wiring & throttle cable runs are there), and a hidden-hinge door on the right side, anticipating a soft sided removable forward baggage compartment over the rudder pedals on that side for oil, tools, etc. I used hinge stock to make a continuous latch at the bottom; pin can be pulled by reaching in the oil access door. Mine look a lot like Fred's outer ones, but they are a bit bigger. I think I left ~2" of skin around each opening.
Not flying yet, but I'm loving the access they give. The -4 has a removable skin between canopy & firewall. I knew how nice it would be from working on my -4.
I'll send pics off list if anyone's interested.
Charlie
I called (after consulting my mechanical engineer, a&p-a/i, builder of 3 or 4 scratch builts, an RV-8, & rebuilds of several a/c). Abbreviated answer from both: primary load path in that area is from the top longerons down. (Look at the RV-8 baggage door.)
I didn't need the two skinny openings between the ribs, but took a long look at brake pedal adjust bolts, motor mount firewall bolts, forest of tabs ground block on the firewall recess, etc etc. & decided I really wanted access. I did a screwed-on cover on the left side (engine controller, most of my FWF wiring & throttle cable runs are there), and a hidden-hinge door on the right side, anticipating a soft sided removable forward baggage compartment over the rudder pedals on that side for oil, tools, etc. I used hinge stock to make a continuous latch at the bottom; pin can be pulled by reaching in the oil access door. Mine look a lot like Fred's outer ones, but they are a bit bigger. I think I left ~2" of skin around each opening.
Not flying yet, but I'm loving the access they give. The -4 has a removable skin between canopy & firewall. I knew how nice it would be from working on my -4.
I'll send pics off list if anyone's interested.
Charlie
I put four panels into the front deck in front of the tip up canopy. I also put a shelf over the rudder peddles so "Black Boxes" could be mounted there. They, and the two batteries, are all accessible via the access panels, as well as the rear side of the avionics stack.
My dual AHRS (GRT) box is on the shelf as is the NavWorx ADS600-EXP box....
How do you seal these access panel against rain?
Paul K
Well Known Member
I C&Ced two panels in my forward skin along with spacers and backers, all for a perfect fit. Check the link in my signature for about 500 build photos, the photos still display but without the captions. Sorry but I haven't upgraded or changed my Google photo site yet.
I love the additional access I get through the access covers for everything mounted between the fire wall and the sub panel. Yes access is good by removing the glass from the panel but that only gets you back to the sub panel, nothing behind it.
Do your engineering! This is a highly stressed skin supporting the firewall and engine! Do it right.
I love the additional access I get through the access covers for everything mounted between the fire wall and the sub panel. Yes access is good by removing the glass from the panel but that only gets you back to the sub panel, nothing behind it.
Do your engineering! This is a highly stressed skin supporting the firewall and engine! Do it right.
Charles in SC
Well Known Member
I did mine very similar to those pictured above. I used the pieces I cut out for the new cover panels. I do not have glass and I am not sure how I would have done some of the wiring without them.
Turbo69bird
Well Known Member
I'm not a builder, but wouldn't it be stronger to have a lip hanging down and riveted at the corners, all the way around the flange being riveted into the panel?
This is on my 9A. There are some tricks. I am still installing mine and learning. You can NOT lay the backing plate on the top and match drill. You need to have the cover clecoed to the backing plate when you mark the holes to match drill. I am lucky - my mentor here aluminum jugs made for the cover and backing plates for the side access panels. We rough cut them on a band saw, then finished the cutting on a router table with a trimmer bit. I will be working on them next week and will get a few more pictures.
Email me if you want a full size PDF scan of the backing and cover.
[/URL][/IMG]
Email me if you want a full size PDF scan of the backing and cover.
rv7charlie
Well Known Member
load path
Paul, look at the load paths. The only things that top skin supports is the two ribs, the forward bulkhead and the top of firewall (firewall itself is completely non-structural), meaning it's just stabilizing the structure that holds the canopy hinges (on the tipper style canopy). Think of a truss; there's nothing inside the triangles created by the tension/compression members. All the major loads (engine, landing gear loads, flight loads, etc) are between the top & bottom longerons. I suppose you could make a case for it helping with 'racking' of the top part of the fuselage, but there are some pretty hefty gussets on the top longerons at the forward bulkhead and the structure behind the firewall.
I worried about cutting into it, too, until I consulted an engineer. After than, and looking at an RV-8's baggage door (which is the entire skin on the right half) and got a lot more comfortable with the idea.
Charlie
Paul, look at the load paths. The only things that top skin supports is the two ribs, the forward bulkhead and the top of firewall (firewall itself is completely non-structural), meaning it's just stabilizing the structure that holds the canopy hinges (on the tipper style canopy). Think of a truss; there's nothing inside the triangles created by the tension/compression members. All the major loads (engine, landing gear loads, flight loads, etc) are between the top & bottom longerons. I suppose you could make a case for it helping with 'racking' of the top part of the fuselage, but there are some pretty hefty gussets on the top longerons at the forward bulkhead and the structure behind the firewall.
I worried about cutting into it, too, until I consulted an engineer. After than, and looking at an RV-8's baggage door (which is the entire skin on the right half) and got a lot more comfortable with the idea.
Charlie
Also think of a box....
A closed box adds torsional rigidity to a structure (example is a cardboard box with the flaps on one side open, vs taped closed.
The fwd top skin is adding torsional rigidity to the front of the fuselage.
Adding access covers should be done per AC43.13 a manner that would be used for any other structural skin.
I installed two access panels in the center of the front skin similar to those shown above. They provide access to several avionics components and two terminal strips. I'm VERY glad I did so .... Access to those items would be a nightmare from the bottom side, especially as I get older and the contortions required to get under the panel are more difficult than ever.
