Could be an expensive mistake: using foam instead of water. Depends how corrosive the foam is on the RAM coating on the F-35. Another learning experience, I guess.
This foam is quite aggressive for the coating used on F35, which can cause rust. The fire trucks were deployed a few minutes before for an emergency landing of volkel this F16 had smoke in its cockpit during training mission. A few minutes later they were deployed for the arrival of the F35 but there was still some foam in the fire cannon instead of water.
