(b) The investigation may include one or more of the following, at the sole discretion of the FAA:
(1) A review of the written submissions or pleadings of the parties, as supplemented by any informal investigation the FAA considers necessary and by additional information furnished by the parties at FAA request. In rendering its initial determination, the FAA may rely entirely on the complaint and the responsive pleadings provided under this subpart. Each party shall file documents that it considers sufficient to present all relevant facts and argument necessary for the FAA to determine whether the sponsor is in compliance.
(2) Obtaining additional oral and documentary evidence by use of the agency's authority to compel production of such evidence under section 313 Aviation Act, 49 U.S.C. 40113 and 46104, and section 519 of the Airport and Airway Improvement Act, 49 U.S.C. 47122. The Administrator's statutory authority to issue compulsory process has been delegated to the Chief Counsel, the Deputy Chief Counsel, the Assistant Chief Counsel for Airports and Environmental Law, and each Assistant Chief Counsel for a region or center.
(3) Conducting or requiring that a sponsor conduct an audit of airport financial records and transactions as provided in 49 U.S.C. 47107 and 47121.