If your Airstream is being exposed to coastal or road salt environment, you must treat bare metal areas with corrosion preventive products such as CorrosionX and repair any corroded areas promptly to keep corrosion under control. There are many threads on the process here, search filiform corrosion.
Your grab handle corrosion is probably not filiform but probably is corrosion, That is a good indicator the other areas such as panel rivet holes and panel edges need ongoing corrosion protection.
We have had no corrosion anywhere on our 4 1/2 year old Airstream, but it has not been exposed to salt environments and we have a periodic inspection and treatment schedule. Takes about an hour a four times a year.
Doug and Cheryl
2012 FC RB, Michelin 16, ProPride 1400
2016 Ram 1500 Laramie Crew Cab 4X4 Ecodiesel 3.92 axles
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