Corrosion.

[33alfa]

Anyone else find corrosion or here of it after tank removal inside, behind front attach point inner spar. Both wings same spot. 170 A model.

[dacker]

33A, that general vicinity is a common corrosion area. I found mine on the forward spar, probably the result of a poor groundloop repair where the spar was spliced. It was the intergranular corrosion type (where the structure was peeling away like shale)... only a matter of time before it would have failed. The end result was a rebuilt wing and an airplane refurbishment. Luckily for me my mechanic was sharp-eyed and found it.
If I would have thought that the previous owner or mechanics knew about it I would have had charges brought against them (or tried).
It is too bad that you have to deal with that. If you opt for rebuilt wings you might try Williams, I was very happy with the quality of their work.
David

[33alfa]

Thanks again for your input and i know what you mean. Just glad i decided to tear into the old girl when i did. Just to bad i had to locate this. Makes the last two guys i paid to check it out look pretty bad. I have since found a guy who knows cessnas and im going to stick with him. This Guy, after looking my wings over let me know just how lucky i am. I would tell everyone who is not sure if the wing tank panels have been removed to have it done. If you find what i did and your guy missed it,(More than Once) at first you will be discouraged, then Pissed takes over, Then You will realize how lucky you are. Have it checked if you have not please. 33alfa soon to have some pretty new wings.

[GAHorn]

It's difficult to understand how this area could be overlooked as often as it is during inspections. (I once spent a lot of money to go look at a 170 for purchase in So. TX. Despite my having hired the local shop to do an annual for me prior to my expenditure of travel expenses....the shop gave me a glowing report on their corrosion inspection I even talked to the previous owner's shop who'd performed an annual only 3 mos earlier, and who gave me a good report. But when I spent the money to travel 300 miles down there and look at it... I was appalled that the wings didn't fall on me right there in the hangar! The rusted wing-attach bolts were suffering from intragranular corrosion themselves! They were so bad they could not even be identified as aircraft hardware. The corroded wings had been bombed/painted internally with silver paint! Doh!) I was so disgusted. My "shop" shouldn't have been paid at all for that kind of work, but I paid them $400 for 5 hours "work" they invoiced me to remove a few fairings and inspection hole covers. (They also claimed to have already inspected the engine despite my instructions not to do that until the corrosion inspection was complete. This airplane had pretty paint on it and looked good from a distance. Imagine my difficulty when a new member contacted me a year later to ask for some mx advice on his proud new bird!)

(The PM sent to me by 33alfa described the problem to me and , if you don't mind,....since it's being discussed here...I'll make teh response here.)

Well....anyway.... Yes, this is an important area to inspect during "prebuy" and each annual. Most of the fleet has spent a good portion of it's life sitting outside tied down at uncontrolled fields. Rain will seep into the structure and corrosion will have an ample opportunity to exist at the wing root/forward spar attach area, and in the vicinity of the fuel tanks. That area can hold water/dampness a long time, and that's all it takes.....water and dirt....to provide an electrolyte to promote corrosion.

It's likely a spar repair will be able to repair this area. Some good information is available in the "structural repair" section of the 100 Series Service Manual. This area has the appearance of a laminated spar and will have to be disassembled to make the repair. If your mechanic is uncomfortable doing this work, you might consider Williams Airmotive, Inc. 9838 N. 1100 East Kendallville, IN 46755 (260/347-0807) who does excellent wing overhaul work and repairs.