Thread: Wing inspection

Wayne Flemington, a highly experienced Rotax mechanic and experienced with annuals on many LSA aircraft, including the CT, came across something unusual during the wing inspection of one of the CT's undergoing its first bi-annual wing inspection. Attached are the photos of the left and right fuel tanks he asked me to post for any information others might have on this unusual condition.

As he has only seen something like this a long time ago in Velocity aircraft before they discovered the affect of alcohol on the type of epoxy used, and was only eliminated after the introduction of Jeffco epoxy, he is puzzled as to what could cause this in a CT. He told me that Flight Design USA seemed as puzzled as he was.

If anyone has any idea what could lead to this condition, he would appreciate any feedback.

I have been informed by Wayne that the tanks in question are undergoing special inspection by Flight Design, GmBh, and that an analysis and determination of repair will be forthcoming as per LAMA and ASTM requirements. If anyone else should encounter a condition like this, which is probably and hopefully, quite rare, Flight Design is on top of this.

Hi Navy,

This looks like it happened before fuel was in there. Look at the way the run marks are and the drips hanging in the one picture on the seem along the right side of the picture. Look at the run marks, the way they just stop like they ran out of meterial to flow and just stopped dry in their tracks. I'm only speculating here, but if it was fuel caused all the runs or drips wouldn't be so straight, stop in mid drip or be up on the top so much. It seems it should have run more down the sides to the bottom and been a more of a spread out pattern like if you throw water on something and it spreads it out, not to mention all the sloshing going on. The big round drip bubble looking marks look like adrip that just froze because it didn't have enough liquid to break the surface tension. I would think if fuel did this then they wouldn't look like that at all. It looks hard and not soft or fluid which again seems like the fuel would have not let it harden. Kreem Weiss should be impervious to our fuel with 10% and less alcohol. If this was a 91 oct. fuel with alcohol issue I would exspect to see a lot of us with this, but this seems like the first case and there should be thousands of hours now with our 91 oct with alcohol.
This is a hard coating on the top of the Kreem Weiss. The Kreem Weiss does not look penetrated. I know your wings were off the plane for a while and wonder if something could have gotten into the wings while they were off ????

Just my opinion, which could be wrong. It will be interesting to hear the final determination.

I would agree with Roger in that its been in the tanks from new if you look in photo 1 at the end panel the drips would have to defy gravity to form while on the plane ...Unless its got a better climb rate than mine :>)

Rgs Mike

Originally Posted by micromike

I would agree with Roger in that its been in the tanks from new if you look in photo 1 at the end panel the drips would have to defy gravity to form while on the plane ...Unless its got a better climb rate than mine :>)

Rgs Mike

The drip lines being both vertical and horizontal certainly indicate that the tank was turned at least 90 degrees while this substance was wet.

Do you think mabe this tank had a leak and this was done to cure it ?

Mike

Originally Posted by micromike

Do you think mabe this tank had a leak and this was done to cure it ?

Mike

Mike and Roger,

Thanks for your insights. I will pass this information on to Wayne.

There has never been a tank leak detected previously, and were it not for the small leak in the filler cap gasket, this condition would never have been discovered.

This condition was discovered while replacing the gasket to the filler cap, which showed signs of leakage around the filler cap gasket. The wings were removed and the ports on the side opened to take the photos, in order to comply with the Flight Design Maintenace manual, which requires a wing inspection every two years, or whenever there is any question of the cause of a wing stain.

There was only a matter of minutes between removal of the wings and the inspection photos being taken. There was no evidence while removing the filler cap plate or the ports on the side that they had been opened since manufacture. In fact, removal of the filler cap plate is very difficult because the bolts are epoxied in place, along with the gasket. It is the same expoxy as seen in the tank.

Wayne says that Flight Design USA determined that the condition originated in Europe, because the "slosh" material in question is controlled by Flight Design, and that two independent inspections have ruled out the possibility that this was done inside the USA. The material itself is very friable, and disintigrates upon being touched, and appears to have reacted with the gasoline. Another possibility offered by Flight Design, GmBh, is that the material foamed and became brittle when heated during the initial sealing of the tank at the time of manufacture, but further testing and analysis will be required to determine exactly how this occured.

Flight Design has their best engineer working on it.

Isn't the top photo the LEFT wing and the bottom the RIGHT?

Originally Posted by Sky Gazer

Isn't the top photo the LEFT wing and the bottom the RIGHT?

Right and Left as seen while sitting in the pilot's seat.

The small end is the leading edge of the wing.

The following photo shows the new interior of the right wing tank after repair by Flight Design's factory engineer. Compare with the original photo to see what the tank should look like.