30 CFR § 18.96
Preparation of machines for inspection; requirements.
(a) Upon receipt of written notice from the Health and Safety
District Manager of the time and place at which a field approval
investigation will be conducted with respect to any machine, the applicant
will prepare the machine for inspection in the following manner:
(1) The machine shall be in fresh air out by the last open
crosscut and free from obstructions, or, if the machine is located on the
surface, moved to a clear area;
(2) All enclosure covers shall be removed;
(3) The flanges and interior of each enclosure, including
the cover, shall be cleaned thoroughly;
(4) All hoses, cables, cord, and conveyor belts shall be
wiped clean to expose surface markings;
(5) All electrical components shall be cleaned to reveal
all stampings, identification plates, certification numbers, or explosion
test markings.