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Old 19th September 2004 | 08:53
  #7 (permalink)  
mono
 
Joined: Feb 2002
Posts: 554
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From: The Sandpit
Noisy,

The simple treatment of corrosion with deoxidine and/or alochrom (at least in aviation) is not a sufficient treatment for corrosion.

Firstly minute traces, etc may be left behind which will continue to corrode.

Secondly and more importantly, the corrosion pits create stresses within the material which can reduce the structural integrity of the componant.

To this end, when treating corrosion, all evidence of corrosion must be removed, plus a little extra for good measure. The depth of material removed is then checked against the maintenace manual (actually called a structural repair manual) to check it is within limits. Some form of NDT will be carried out to confirm there are no undetected cracks, pits or other damage. The damaged area is blended to ensure there are no sharp edges or gouges where further stresses may develop. the blended area will have a contour which is within the limits stated in the manual.

If after the NDT there is no sign of further damage and the depth and contour are within limits the area is reprotected and released to service.

If, however, the damage is out of limits or NDT detects damage within the componant then it is replaced. I am not aware of ANY aviation practice which allows the damaged area to be removed and a repair "riveted" in.

Certain types of corrosion will almost always require componant relacement. A good example is intergranular corrosion, as by the time this form of corrosion is visible at the material surface, the damage is done.

Perhaps if you explain what your specific problem is someone may be better able to help.
mono is offline