30 CFR § 57.8534 Shutdown or failure of auxiliary fans.
(a) Auxiliary fans installed and used to ventilate the active
workings of the mine shall be operated continuously while persons are
underground in the active workings, except for scheduled production-cycle
shutdowns or planned or scheduled fan maintenance or fan adjustments where
air quality is maintained in compliance with the applicable standards of
subpart D of this part, and all persons underground in the affected areas
are advised in advance of such scheduled or planned fan shutdowns,
maintenance, or adjustments.
(b) In the event of auxiliary fan failure due to malfunction,
accident, power failure, or other such unplanned or unscheduled event:
(1) The air quality in the affected active workings shall
be tested at least within 2 hours of the discovery of the fan failure, and
at least every 4 hours thereafter by a competent person for compliance with
the requirements of the applicable standards of subpart D of this part until
normal ventilation is restored, or
(2) All persons, except those working on the fan, shall be
withdrawn, the ventilation shall be restored to normal and the air quality in
the affected active workings shall be tested by a competent person to assure
that the air quality meets the requirements of the standards in subpart D of
this part, before any other persons are permitted to enter the affected
active workings.
