In the late 1980s, a hugely valuable tool for fighting corrosion was developed by Lear Chemical Research of Ontario, Canada--fluid thin-film coating (FTFC).
If you have corrosion around rivets that is temporarily holding them tightly in place, it is not uncommon for the FTFC to break that corrosion loose and the underlying loss of metal to manifest itself in smoking rivets.
ACF-50 and CorrosionX effectively own the FTFC field.
All said that fogging an airplane with an FTFC is most inexpensively done when it's opened up and the interior is out--such as during an annual or 100-hour inspection.
Derrick DeRuiter, owner of Northwoods Aviation in Cadillac, Michigan, cautioned about overspray when applying an FTFC, noting that it doesn't do brakes any good at all.
Based on what I learned preparing this article, if your airplane is older than 15 years and it has not had an FTFC treatment in at least five years, it would be wise to seriously consider fogging it at the next annual.
After talking to application shops, we're convinced this is due to poor application rather than something intrinsic in using FTFCs. Lear Chemical's original equipment would pump about a gallon of AFC-50 into a Cessna 172.
The thin of FTFCs means they spread out to about 3/10,000 of an inch thick.
FTFCs are fogged into the airframe in a uniform mist, settling on all the interior surfaces, and then flowing into small spaces, between skins and ribs, between lap joints and even along rivet shanks.
When we last looked at FTFC products in 1997, there was some question about methylene chloride and the role of organic fatty acids in promoting fungal growth.
CorrosionX is the only commercially available FTFC that meets the new Milspec PRF-81309F, which replaced MIL C-81309F covering these types of products.
+ Modern FTFC products work and add negligible weight to the aircraft.