43 CFR § 3175.90
Mechanical recorder (secondary device)
June 11, 2020
(a) The operator may use a mechanical recorder as a secondary device only on very-low-volume and low-volume FMPs.
(b) Table 1 to this section lists the standards that the operator must follow to install, operate, and maintain mechanical recorders. A requirement applies when a column is marked with an “x” or a number.