If the FRA shops the engine it can be moved but only out of service and with non compliance tags to nearest shop.
Untill it is fixed and reported fixed to FRA it can not be used for any revenue moves.
see following FRA rule:
PART 229_RAILROAD LOCOMOTIVE SAFETY STANDARDS–Table of Contents
Subpart A_General
Sec. 229.9 Movement of non-complying locomotives.
(a) Except as provided in paragraphs (b), (c) and Sec. 229.125(h),
a locomotive with one or more conditions not in compliance with this
part may be moved only as a lite locomotive or a dead locomotive after
the carrier has complied with the following:
(1) A qualified person shall determine–
(i) That it is safe to move the locomotive; and
(ii) The maximum speed and other restrictions necessary for safely
conducting the movement;
(2)(i) The engineer in charge of the movement of the locomotive
shall be notified in writing and inform all other crew members in the
cab of the presence of the non-complying locomotive and the maximum
speed and other restrictions determined under paragraph (a)(1)(ii) of
this section.
(ii) A copy of the tag described in paragraph (a)(3) of this section
may be used to provide the notification required by paragraph (a)(2)(i)
of this section.
(3) A tag bearing the words ``non-complying locomotive’’ and
containing the following information, shall be securely attached to the
control stand on each MU or control cab locomotive and to