Jack Stantons corroded lower spar cap in center spar
Exfoliation corrosion is a particular form of intergranular corrosion associated with high strength aluminum alloys. Alloys that have been extruded or otherwise worked heavily, with a microstructure of elongated, flattened grains, are particularly prone to this damage.
Corrosion products building up along these grain boundaries exert pressure between the grains and the end result is a lifting or leafing effect. The damage often initiates at end grains encountered in machined edges, holes or grooves and can subsequently progress through an entire section.
source: http://www.corrosionsource.com
![](http://www.ercoupe.info/images/centerSection/corrosion1.jpg)
A sight none of us hopes to see.
![](http://www.ercoupe.info/images/centerSection/corrosion2.jpg)
Exfoliation corrosion in the lower spar cap.
![](http://www.ercoupe.info/images/centerSection/corrosion3.jpg)