Hairline crack at wing root

[neongoby]

Just noticed a hairline crack on the upper surface of the left wing at the trailing edge of wing root. I estimate to be about 10inches long.

My mechanic looked at it and said that it is not through the thickness (yet), and that that's what I can expect from composite airframe. He didn't think it is a airworthiness issue. I tend to agree with him, but would also like a second opinion.

I suspect it may be due to stepping too close to the trailing edge.

Secondly, is there a procedure to stop the crack from continuing to propagate?

[BlackMammoth]

My mechanic looked at it and said that it is not through the thickness (yet), and that that's what I can expect from composite airframe.

Through what thickness? Is this in the paint, in the outer surface of the laminate? I believe that all DA40s are painted with LPU paint and NOT with Gel Coat (which sometimes suffers surface cracks).

We don't have any cracks in our DA40 and I disagree with your mechanic's opinion on "this is what you can expect".

[Rich]

I've had one like this in the same place for years, though it is shorter. It hasn't grown any larger. It's just in the paint. Like you, I suspect some not-particularly-svelt individual mounting/dismounting the wing by stepping on the trailing edge causing the structure to flex and the paint cracked. I know this improper operation has occurred when the telltale black streak appears on said trailing edge. There is no such crack on the right-side wing.

A similar thing happened when my seriously overweight son dismounted heavily onto the passenger step. The composite flexed and the paint cracked all around it. In this case, Diamond repaired it and thickened up the structure in the area.

[Lance Murray]

I have a similar crack. It is a non-structural area and the crack is likely only in the body filler used to fare in the area to the fuselage. No big deal, it is just a cosmetic area.

The only problem I see here is that might be challenging to get a good blend in the paint when you fix it. It might not be too noticeable since the area often has a shadow in that area.

[Lance Murray]

I am not sure what LPU means but the airplane is not "gel coated" and it is standard aircraft paint. There is an anti-static paint coating above the filler and below the primer.

My mechanic looked at it and said that it is not through the thickness (yet), and that that's what I can expect from composite airframe.

Through what thickness? Is this in the paint, in the outer surface of the laminate? I believe that all DA40s are painted with LPU paint and NOT with Gel Coat (which sometimes suffers surface cracks).

We don't have any cracks in our DA40 and I disagree with your mechanic's opinion on "this is what you can expect".

[Steve]

My aircraft has one of these (pilot side only). It has been there for 9 years with no change. It is in the paint coat only (you can actually inspect the underside of the faired wing root). When it initially appeared I sent some pictures to the factory and they said it was not a problem. Apparently, they were correct...

Steve

[Charles]

I have the same thing, about 4-6 inches long at the trailing edge on the pilot's side. Diamond Service Center mechanic had a look at it and deemed it superficial and inconsequential.

[carym]

I have it on the passenger side of my wing root. Sent pictures to the factory and they thought it was just in the paint and not significant. It is being looked at more carefully now as it is in annual.

[Kai]

Same thing here:

http://www.flightglobal.com/news/articl ... ss-367116/

[Tim]

I had a crack found in my 2000 hour inspection that had to be ground out, new composite applied and painted. It was in the wing root also.