Anyone know the detail about it? how we define the class of corrosion?
Do you mean in terms of process? Oxidation, galvanic corrosion, that kind of thing?
Sorry i din make it clear. I mean the degree of corrosion, the severity, as up to a certain level of corrosion it will be reportable to authority.
Inspection criteria for any aircraft component is usually spelled out in the inspection procedures by the manufacturer. I can't think of a general "catch all" type of corrosion spec that covers everything.
What exactly is the situation you are referring to?
This is out of my direct field, but the NRC or manufacturers/suppliers provide similar guidance in the nuclear industry, so -
Criteria would be set by the manfucturer or safety authority, and there is no catch all. It depends on the many factors such as whether or not the component is load bearing or safety related.
Limits might be set on remaining material thickness. But then there are also issue of stress corrosion cracking which require inspection and probably reporting based on the certification of the appropriate safety/regulatory authority. The FAA has a corrosion control program. See this newsletter - http://www.tc.faa.gov/aar400/news94-4.html#Corrosion [Broken]
Very likely any corrosion on critical pieces, e.g. rivets, is considered reportable. This could be an indication of a potential stress corrosion failure. Presumably there is a standard or airworthiness directive for whatever system/component is of concern.
As Fred and Mech_Engineer indicated, one must elaborate.
If you are concerned about a possible safety problem, then contact the appropriate regulatory authority (which in the case of the US is the FAA) or report the situation.
I would like to know more about the type of corrosion, eg. strees corr..., exfoliation.....Could anyone supply more material about it? Or any website contain useful information about it>? thank you
Well, one can use search engines like google to find sites on corrosion and use qualifiers to narrow down the responses.
However, http://www.corrosion-doctors.org/ is a pretty good site.
http://www.corrosionsource.com/ is another good site.
If one is interested or involved in the study of corrosion, then consider membership in the National Association of Corrosion Engineers - www.nace.org
There maybe some university courses with online notes.
A good source for this info could be found in the forum section of amtonline.com. It's for aircraft mechanics; many of whom deal with corrosion daily. A few members are even FAA inspectors.
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