(b) The sponsor or planning agency shall allow appropriate FAA or DOT representatives to make progress audits at any time during the project, upon reasonable notice to the sponsor or planning agency.
(c) It audit findings have not been resolved, the applicable records shall be retained by the sponsor or planning agency until those findings have been resolved.
(d) Records for nonexpendable property that was acquired with Federal funds shall be retained for three years after final disposition of the property.
(e) Microfilm copies of original records may be substituted for original records with the approval of the FAA.
(f) If the FAA determines that certain records have long-term retention value, the FAA may require transfer of custody of those records to the FAA.