Section 50.40 - Maintenance of records(a) Each operator of a mine shall maintain a copy of each investigation report required to be prepared under § 50.11 at the mine office closest to the mine for five years after the concurrence.(b) Each operator shall maintain a copy of each report submitted under § 50.20 or § 50.30 at the mine office closest to the mine for five years after submission. Upon request by the Mine Safety and Health Administration, an operator shall make a copy of any report submitted under § 50.20 or § 50.30 available to MSHA for inspection or copying.42 FR 65535, Dec. 30, 1977, as amended at 43 FR 12318, Mar. 24, 1978