Possible spar crack holding up annual

astrahm · Post by **astrahm** » Tue Jul 21, 2009 12:57

Hi all, I'm new to the forum but at first look seem to have come to the right place. My Champ is getting an annual right now and the A&P has come across some dark lines running lateraly just to the right of the fuselage on the right rear spar (back side of the spar). No one that has looked at it has a definitive diagnosis but it's enough of a question that he won't sign off on it at this point without more info. Apparently it is tough to find experts on 65 yr old wood! Here are some pics taken through the inspection plate, starting at the end closest to the fuselage and going outward. There are no visible lines on the front of the spar. Sorry for the graininess. Any thoughts? We're at an impasse.

Andy

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Roger Anderson · Post by **Roger Anderson** » Tue Jul 21, 2009 13:06

Hi Andy. Yep. You're at the right place. From your photos, those look very similar to the lines in mine and most I've seen. However, wait for an expert opinion that I'm sure will be on here shortly.
The cracks that the AD reference are up at the butt area and compression of fittings points. I had an A&P once panic over the grain he saw in mine. It is hard to find someone that is familar with the issues. roger

astrahm · Post by **astrahm** » Tue Jul 21, 2009 14:36

Thanks Roger, what did you end up deciding on your spar (or the others you mentioned seeing?) Here's a little more info I left out originally: It's a '46 7AC, A65.

Obviously I would love to make a good case that it is not a problem but want to be safe as well. I don't have any plans to do aerobatics in this plane and am still a student but this is definitely holding me up.

Andy

james gevay · Post by **james gevay** » Tue Jul 21, 2009 15:02

Probable being 1000 miles away from the real thing and from only looking at your pictures on a computer screen. I'll make a guess, but it's possible those are glue lines from when the factory used bits and pieces glued together to make up the full thickness and length for the spars. One of my spars is like that, two half thickness pieces glued together to make the front and rear of the spar, and other smaller depth pieces to make the height for the spar. You can see the glue line all the way down the middle of the top and bottom face of my old spar, and other glue lines on the front and rear face.

Here's a couple of pictures to show you what I mean.

MikeB · Post by **MikeB** » Tue Jul 21, 2009 17:40

Thought I posted this before but I must have 'wiped it out'. Anyway, this is a picture of the horizonal crack on my L16 wing. Interestingly, an AP/AI (not mine) inspected the wing and said it was 'airworthy'

. Apparently he was blind as it was uncovered. Anyway, one way to test if it's actually a crack is to put some kind of fluid on the suspected surface and then work it back and forth. I used a wrench but should have a couple of pieces of card board to prevent damage to the wing in case it's not a crack. Jim makes a good point as a lot of wings have been condemned because of a glue line from the laminated wood surfaces. Also, very often spars get scratched as ribs are dragged down them on installation. Vertical cracks (compression type) usually occur at the outboard edge of the reinforcement plate over the spar attach point. Generally from 'ground looping and dragging a wing'. Also, have seen
cracks under the plate at the wing attach point. Anyway, make darn sure the spar is actually cracked before condemning it. Get a 'second opinion' if necessary. If they are original spars with laminations, you could well be looking at a glue line. Kind of hard to tell from the photos.

I'm hardly an expert, though.
MikeB

Paul Agaliotis · Post by **Paul Agaliotis** » Tue Jul 21, 2009 18:12

Andy,
This computer I,m at won,t load the images. If it is a crack in the grain the 43.13 covers longitudinal cracks and end grain splitting.
Paul

jkvincent · Post by **jkvincent** » Tue Jul 21, 2009 21:43

Andy,
There's a chance they could be "old rib nail dimple" scratches from removing old
ribs (to be replaced during 60 years of recovering), but they would be on the inside of the spars, not the outside (as you stated).
If not on the nail side of the spar, it could also be that when removing and replacing old ribs, the part of the rib
(opposite the nail side) that rests against the spar is kinked or bent slightly and scratches the spar when ribs are slid in or out.

The lines are not straight/parallel to be glued seams.
good luck, Jim

Post by **joea** » Tue Jul 21, 2009 22:13

Andy,

Any chance you can get some more photos that are in a bit better focus?

Right off the bat I do not see "a smoking gun" that I could point to immediately and say "thats 100% a crack" but then with better photos could be a bit easier to tell.

Joe A

astrahm · Post by **astrahm** » Tue Jul 21, 2009 23:45

Thanks for the input, I will get better photos and see what you guys think at that point. From looking over the 43.13-1b it sounded like probing the line with a sharp instrument (with a little prying to look for movement) would be the way to inspect it while still covered. I'm confident that won't show any movement though, we have already put up and down pressure from the end of the wing while eyeballing the line and seen nothing move. Any other ideas on inspection methods while it's still covered and while I'm out there?

Andy

Post by **joea** » Wed Jul 22, 2009 01:43

Andy,

More light the better and go over it with a fine tooth comb.

The factory did splice spars right and left, and in ways not allowed in AC43, but then they are the factory and can do that. Just because it does not look like new or like splices in the AC does not mean that its not right nor legal.

Joe A

Roger Anderson · Post by **Roger Anderson** » Wed Jul 22, 2009 08:53

astrahm wrote:Thanks Roger, what did you end up deciding on your spar (or the others you mentioned seeing?) Here's a little more info I left out originally: It's a '46 7AC, A65.

Andy

Andy. Obviously it will ultimately rest on the opinion of that or another A&P. However, although the pictures are fuzzy, the lines just look too wide to be cracks, and it's too unusual for multiple cracks to have appeared and for such length. They look like shallow indentations to me, caused by who knows what through the years. A crack is like the picture Mike B posted, very narrow, defined, and originating at a point causing it...such as the drilled hole and probably compression.

On my wing, the A&P became more familar with the many unique appearances of these old spars and has now accepted the various lines...grain, splice lines, etc, as normal. Of course my guy also had great concern by the aileron hinges being wiggly...until I explained that they indeed do "float" and showed him some information on that. He's becoming a pretty good Aeoronca guy now, finally.

You certainly don't want to ignore a possible safety issue, but at the same time if you and the A&P have put plenty of stress movement on the wing and have seen nothing happen in those areas, I personally wouldn't think they're cracks. I'm certainly not an expert here, but like Joe or somebody said, the unusual appearances and marks these old spars have been seen with, has caused many a good spar to be thrown away needlessly. roger

Andy. Another thought. Assuming this plane has stayed in annual, I will assume that it had the very detailed spar inspection as required by the AD a few years ago, and determined to be crack free.

Additionally, if it has been annualed as recently as last year, then absence of some accident and damage to the wing, lines like that would not have developed suddenly, and having already been present would have been obviously seen during the last inspections.

Maybe you can track down the previous A&Ps/IA and get their opinion of what did NOT concern them when previously looking at the wing and share those ideas with the current A&P.

MikeB · Post by **MikeB** » Wed Jul 22, 2009 10:35

One other thing, the horizonal cracks usually occur from "something". In my case is was a nail hole which opened up after years of flexing. Another spot would be around bolt holes and, as I mentioned before, at the outboard edges of the strut attach reinforcement plate. Loose nails are a common problem when the wood shrinks away after 50-60+ years. Mostly it allows the ribs to rub on the spar as wing loading changes. I think the newer ring shank nails will help it that regard.

MikeB

flyingfool · Post by **flyingfool** » Wed Jul 22, 2009 12:38

For what its worth.

If in the end it is determined that these areas are in fact NOT cracks and are instead splices or wood grain characteristics. I would recommend that you keep the photo's and also specifically document exactly where these areas are found.

This will help you or another future owner of the airplane document the baseline condition and establish a finding. Hate to have you, or another future owner go through this again and have to reinvent the wheel.

Jody Wittmeyer · Post by **Jody Wittmeyer** » Wed Jul 22, 2009 12:55

From a distance, it appears to be the laminations, but like others said, it is tough to tell from the pictures. Had this question come up on mine. It was indeed just the lamination joint glue line. It was not separating. Just visible as the varnish discolored different on the glue line.

DC Krog · Post by **DC Krog** » Thu Jul 23, 2009 08:15

I think people (mostly pilot's who are not mechanics) jump the gun with this spar AD not without good reason since their butts in the seat of these 60 year old airplanes but with that said I think these false claim of cracks have cost many owners A LOT OF MONEY.

Question: Has any Champ experienced any type of spar failure either on the ground or in flight? I believe the answer is no.

These spar cracks need to be examined with a grain of salt because as other posters stated are they scratches....mineral streaks.....laminations of glue .... pencil marks....whatever.

The only true way to FULLY examine the spar would be to strip it down completely and plane down the spar with a planer to remove all surface imperfections then look for cracks. However this is cost prohibitive. I fully understand why mechanics will not sign off an annual with "possible cracks" in the spar due to the liability. This AD is a small pebble in the shoe of all Champ owners. This AD quite suggestive and lets the inspector opinion deterimine what is airworthy or not. Ofcourse every inspector will have a different opinion. Maybe (just maybe....) the AD needs to conform similar to the Beech Bonanza spar web AD which says if there is a crack to mark the crack and inspect every annual to see if the crack grows. I feel this might be a better insight for all inspectors to use. However the Feds don't agree. I guess ABS has a better lobbist in Washington DC than the National Aeronca Association.

DC Krog

National Aeronca Association Bulletin Board

Possible spar crack holding up annual

Possible spar crack holding up annual

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