41 CFR § 102-33.415
When may we declassify a Federal aircraft and remove it from our Federal aircraft inventory?
June 9, 2020
When an aircraft is lost or destroyed, or is otherwise non-operational and you want to retain it, you may declassify it and remove it from your Federal aircraft inventory. For further details, see §§102-33.250 and 102-33.420. See §§102-33.265 and 102-33.270 for reporting excess Federal aircraft.