T

tinman

Well Known Member
Is there a structural reason to not use a lexan cover over the aft fuselage elevator inspection ports? Seems like this is an important area and not inspected due to the difficulty of getting the covers off.
 
plastics expert needed

I asked the same a while back after seeing all the clear covers on the acros. Didnt really get any good answers. Needs to be strong, then etc but that should not be a problem with the polycarbonates etc available. It would look great, be very easy to inspect quickly and i am in if someone can suggest a suitable material.
 
YMMV but ...

I've been flying with lexan inspection covers since day one (July 4 2004) without any problems what so ever. I got the idea to do this from the DA20 Katana aircraft that I first learned to fly.
 
Pictures?

N520TX said:
I've been flying with lexan inspection covers since day one (July 4 2004) without any problems what so ever. I got the idea to do this from the DA20 Katana aircraft that I first learned to fly.
Click to expand...

Can you post some pictures of this?
 
The inspection covers on RV's should be considered a structural component (as well as the baggage bulkhead panel and tunnel covers).

I'm not saying that a clear cover can not be made that is equal to the aluminum ones, but "mine have been ok since day one" is not a good reason that everyone should do it.

If someone makes a mod that reduces their wing strength to 2.5 g"s (I'm not saying that this one does that), then in all of their flying they never pull more than two G's, does that make it appropriate to say "the mod has worked fine on my airplane"....I don't think so.

My suggestion...Think very carefully about what the true value of a mod like this will be...and what the consequences might be.
 
Inspection covers

My concern is that just looking at a component isn't an inspection. On my last condition inspection I found a questionable rod end only because I did a "tactile inspection," tough to do through lexan.

John Clark
RV8 N18U "Sunshine"
KSBA
 
I don't have a picture of them, but a guy I know has approx 2" round plexi windows in the elevator inspection covers. It looks great and is easy to look through. I plan on doing the same thing.
 
I believe some of the polycarbonates are way stronger then thin aluminum. I do agree that viewing is not as good as touching, but the point is that a quick inspection as part of the walk around would provide much more info then waiting for the annual and removing the panels. At annual, certainly remove and inspect fully(metal or lexan). Finding a thin strong and transparent plastic that would not scratch easily is the issue i believe.
 
FWIW, our CT uses 3" diameter plexi inspection ports at pushrod joints on the underside of the wings. Works great for making sure that the nyloc nuts are still snug and witness marks still line up. It's only used during preflight to make sure that nothing bad has happened; it's still removed for the annual and 100 hr inspection (we are required to perform a 100 hr even though we're not operating for hire....).

TODR
 
Numbers...

RickWoodall said:
I believe some of the polycarbonates are way stronger then thin aluminum. I do agree that viewing is not as good as touching, but the point is that a quick inspection as part of the walk around would provide much more info then waiting for the annual and removing the panels. At annual, certainly remove and inspect fully(metal or lexan). Finding a thin strong and transparent plastic that would not scratch easily is the issue i believe.
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The tensile strength of aluminum is around 70,000 PSI, the tensile strength of polycarbonate (Lexan) is 9,500 PSI. Engineer carefully. I really like the idea of a "window" in an existing aluminum cover. With a little thought, that could be just as strong as the original plate and easier to make aerodynamically correct.

John Clark
RV8 N18U "Sunshine"
KSBA
 
Digging up an old thread...

I put a "window" in my wing inspection panel to allow for a quick visual check of the bellcrank assembly.

I cut a doubler ring to go on the opposite side of the lexan fron the panel. The rivets will pinch the lexan between the two sheets. The doubler is made of .025 2024-T3 Clad (same as the panel). I used CS 4-4 blind rivets to attach the window assembly. In my tests, the crush-force of the AD3 rivet was to great and distorted the assemble (I did that test on scrap). If the panel and double were made of a thicker material, then solid rivets may work. As it is, I am very happy with the results. I would have liked to put a single large window, but the bellcrank rib does not make the possible on the RV-6. However, I could put a second window on the right side to make both control rods visible...I'll think about it.

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Digging up an old thread - has anyone ever done this at the tail? I am used to this from acro planes, it's nice to be able to do a quick check there are no loose objects that may have worked their way back there.
 
We did that on our 7 - a 2" window and contact adhesived some clear perspex on.

Allows a good look at the elevator bolts and retains the strength of the cover.
 
Thanks, looks like a small window in the inspection plate may be the way to go. I'll research the structural issues a little more as well.
 
John Clark said:
The tensile strength of aluminum is around 70,000 PSI, the tensile strength of polycarbonate (Lexan) is 9,500 PSI. Engineer carefully. I really like the idea of a "window" in an existing aluminum cover. With a little thought, that could be just as strong as the original plate and easier to make aerodynamically correct.

John Clark
RV8 N18U "Sunshine"
KSBA
Click to expand...

So that would make the polycarbonate about 3/32 inch thick...
 
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