diamondaviators.net

Ok, I am in Florida and before I bought the airplane she lived outside.
However... It's a 2007 airplane with 1300 hours on it.
The item in question is the aluminum arm that holds the flap mass balance. Those iron chunks show rust the moment the paint is dinged, that's more or less to be expected.
I noticed that the arms started to disintegrate, and somehow that happened almost overnight. Ok, maybe it didn't, but I'm quite thorough on my preflights, and one day in sunny TN I noticed the paint was bubling a bit, tried the "fingernail test" - and chipped off a sizeable chunk of aluminum.
Come annual time, we've decided to replace those things and not wait for the flap balances to declare independence. Well... Here comes the problem - those things aren't in the IPC. Neither is the procedure to replace them in the Maintenance Manual.
Thanks to Brittany at Premier, eventually figured what we needed (I'll post the p/n's here for later use once we're done). Getting the parts from Diamond took a bit - don't think that's a commonly ordered part (although Premier did have one iron chunk in stock), and the Canada had them, but not painted, and they will only sell them painted.
Now for the procedure - if anyone figures how to replace them without removing the flaps, please let me know. Most evil part is a allen head screw on the leading edge of the flap, with a nut (a friggin' nut. Why not a nutplate or something??) inside the flap. Only access is through a tiny hole in the end rib of the flap (covered with a plug). You can access the nut (barely) when the flaps are down, and you can reach the bolt (again.. very barely) when the flaps are up. "Win-win"
Cost of hardware - someone here once said "If it's below $1000 it doesn't count" - that'd be one of those that just barely don't count

PS The only other place on the airplane having corrosion is the rudder trim tab - that thing bolted onto the rudder.

We have had several instances of corrosion like this on our DA-20-A1, which also sat outside in Florida most of it's life. My A&P son looked at your pictures and had the following comments - the corrosion is probably intragranular corrosion - which as I indicated, was the reason we had to replace a flap and aileron bellcrank on our DA-20. I've never done a 40, but I suspect the construction is similar and it does require that the flight control be pulled. Not only that, my son was adamant that you need to rebalance the flap after replacement - despite the parts all being the same P/N, rebalancing of flight controls is required after maintenance like this (as it would after repair, repainting, etc.).

Sorry, not a job legally performed by the owner, unless you have an A&P license.

Krea Ellis
DA-20-A1
DA-40-XLS

I really have a problem with Diamond's lack of corrosion protection on pretty much every part that is made of metal. I understand that Zinc Chromate may be banned in many places but they could be anodizing the aluminum at a minimum. Seems that they don't care if their airplanes last beyond 10 years.

krellis wrote:despite the parts all being the same P/N, rebalancing of flight controls is required after maintenance like this

Don't mess around with control surface balancing... flutter can be deadly.

Lance Murray wrote:I really have a problem with Diamond's lack of corrosion protection on pretty much every part that is made of metal. I understand that Zinc Chromate may be banned in many places but they could be anodizing the aluminum at a minimum. Seems that they don't care if their airplanes last beyond 10 years.

Me too. I spend a lot of time during each Annual doing corrosion prevention/treatment. Even though the airplane is in TX, I have had to replace attachment hardware on both trim tabs and several static wicks. I treat the wing root screws for the grounding straps a couple of times each year with LPS-3. As the airplane ages (its 11 now), this will become more of an issue.

Steve

Krea is right. Removal and balancing are mandatory

Don't have a problem with rebalancing
Trivia question though - how many airplanes with balanced flaps can you list?

Steve wrote:Me too. I spend a lot of time during each Annual doing corrosion prevention/treatment. Even though the airplane is in TX, I have had to replace attachment hardware on both trim tabs and several static wicks. I treat the wing root screws for the grounding straps a couple of times each year with LPS-3. As the airplane ages (its 11 now), this will become more of an issue.

Steve

Steve, you'd be surprised, but in my export business I get to see airplanes from all over the country. Texas is pretty high up on the "Corrosion list"
Florida - really depends. Some places are worse than the others. Have seen dramatic difference between airplanes based on airports 50 miles apart. Prevailing salty winds or swamps or god knows what might be the reason.

Looked mine over with a fine tooth comb today during pre flight. Not a scratch, dent or bubble in the paint. Everything solid. Defiantly another area to watch closely.