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Inspection hatches in forward deck?

A

ao.frog

Well Known Member
Hi and merry Christmas to all!

I'm wondering wether or not to install four "inspection hatches" across the forward deck, just aft of the upper cowling.

These four hatches will greatly improve access underneath the forward deck once the forward deck is riveted on.

I've seen a few builders have installed these, but by far not all.

I'm wondering what you guys with flying RVs out there would recommend?
Schould I install those or not?

It doesn't seem to be so much work or weight. And it schould be possible to make them so they won't leak either.

Soooo.... please chime in RV'ers and let me hear what you think?

Christmas wishes from Alf Olav Frog / Norway
RV-7/ wiring-finishing
 
Hi Alf and Merry Christmas to you as well!!

I installed two of these access panels just aft of the top cowl on my RV9a tipper. I did this because my LS PIII control box and my AFS 2500 control box are mounted high between the subpanel and the firewall. These panels gave me easy access for service---which I used several times while "dialing in" the aircraft. If I had not had avionics in this location I would not have gone to the trouble. I made permanent gaskets "in place" using proseal for a leak free panel.

Best Wishes for a Happy New Year!!

Cheers,

db
 
ao.frog said:
Hi and merry Christmas to all!

I'm wondering wether or not to install four "inspection hatches" across the forward deck, just aft of the upper cowling.

These four hatches will greatly improve access underneath the forward deck once the forward deck is riveted on.

I've seen a few builders have installed these, but by far not all.

I'm wondering what you guys with flying RVs out there would recommend?
Schould I install those or not?

It doesn't seem to be so much work or weight. And it schould be possible to make them so they won't leak either.

Soooo.... please chime in RV'ers and let me hear what you think?

Christmas wishes from Alf Olav Frog / Norway
RV-7/ wiring-finishing
Click to expand...


This is a question regarding a major mod to the airframe. It will be difficult for you to evaluate whether any advise given to you on this forum will be based on sound engineering principles or not (including this one). I recommend you go directly to the aircraft engineer (Vans). My guess is they will advise you against it.

Many builders who do this mod mistakenly believe that if they use heavier guage aluminium, and edge reinforcement, and many fasteners, the mod will be structurally equal to or even superior to the original design. That is an intuitive and dangerous assumption.....in fact making the mod "stiffer" than the original skin can attract loads and increase stresses.

Quite often the problem with intuitive mods is that while the plane might fly OK...it might not crash OK. In the event of a prang you do not want to be leaving an imprint of your face in the rear of your engine block.
 
I found the access panel mod valuable

I can't speak to the structural issues. I took the chance and followed a few other builders by installing two access panels. I have a Word document spelling out the process (with photos) if you are interested and email me offline. I have found them invaluable in accessing the workings behind a complex panel. In fact, I am not sure I could have wired the panel as well, and certainly not as conveniently or quickly, without them. I guess these opportunities are why "experimental" is really "experimental".
 
ao.frog said:
Hi and merry Christmas to all!

I'm wondering wether or not to install four "inspection hatches" across the forward deck, just aft of the upper cowling.
I'm wondering what you guys with flying RVs out there would recommend?
Should I install those or not?
Click to expand...
Structurally I would advise against it without specific approval from the designer. Since I believe he has not tested this modification, I suspect he also will advise against it.
 
I did it as well . . .

I did mine similar to what Dan Checkoway did on his plane. I find the access they provide invaluable. I don't think they represent any compromise to the structure if done properly. The openings are essentially lightening holes in a shear web (I'm a AE and designed structures for McDonnell Douglas a while back). Use large radius corners (I used the wing access plates as templates) and proper edge distance for the fasteners when you install the backing plate and I'll bet Van's would approve. Enough folks have done this that if it was a problem, we'd know about it by now.
 
I asked Van about it.

I put in two access panels and have used them many times. Would do it again!

I flew my plane to Vans factory and Van himself came out with a few other folks. They mentioned the access panels and I asked why they did not put this in the plans. They said that they were worried about rain leaking through the holes.

Haven't crash tested mine yet, but if I ever do I will let you guys know how they fare!!!!!!!!
 
Planning

If you plan your panel carefully with all of the brain boxes accessible you won't need the access panels. The only thing I would ever need access to would be the grounding tree. I can get to that fairly easily the old fashioned way, on my back on the passenger side.

I looked over several planes that had these and even the best ones didn't look that good. Just personal preference, but I think the top of the cowl and forward deck are the focal point for the canopy transition. The panels detract from this. As noted, there is the ever present possibility for leakage. Tough to get them perfectly flat.

BS factor exceeded, leave as is and move on:)
 
access panels

I put in four. I followed Dave Nickolson's drawings. I found a local person with a plasma cutter to cut the spacers and panels. I had to do the skin by hand as I had already bent it to shape. Lots of rivits and lots of screws. It was an invalualble aid to riviting the skin on as well as having access to installed goodies later.
Regards,


I contacted Van's - the answer they gave was that they had no objection.
 
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I didn't put the access panels in. However, at first start my battery wasn't charging. The problem was at the voltage regulator, mounted high up under the skin behind bundles of wire. It took 2 1/2 hours of work to get it out and put in the jumper I missed. Now I know I can reach everything...it just takes patience and work.
Dekky111
RV7A
Ready to fly
 
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