Document ID: chunk:federal_register_of_legislation:F2025C00187:reg:3:p7
Version: federal_register_of_legislation:F2025C00187
Segment Type: reg
Provision Reference: reg 3 (pt 7/7)
Character Range: 405005–406920

matter that may affect safety.
(d) in the case of replacement of NVG image intensifier tubes with tubes that are sourced from other than an official source — as follows:
           (i) replaced as a pair;
           (ii) of the same form, fit and function as the tubes being replaced;
           (iii) such that the replacement does not to involve modification of the NVIS mounting frame or optical components;
           (iv) compliant with paragraph (1) (a).
Note   For guidance only, US AN/AVS 9 NVIS, although manufactured by different manufacturers, are produced to the same US Department of Defense specification and, therefore, these tubes are interchangeable.
       (3) If 2 or more NVIS pilots on an NVIS flight use dissimilar NVG image intensifier tubes and equipment, the pilot in command must use the highest level of NVIS tubes and equipment in terms of resolution, gain and acuity.
Note   Use of dissimilar NVIS does not remove the requirement that the minimum standard of any set used must be in accordance with subsections (1) and (2).
       (4) An NVIS pilot who occupies a control seat of an aircraft during an NVIS flight must use the NVIS manufacturer's approved helmet mounted attachment device for the NVIS.
       (5) For paragraph (1) (a), column 3 of each item of Table 26.77 (5) shows how a relevant operational performance specification in the paragraph of RTCA/DO-275 mentioned in column 1 of the item, and summarised (if any) in column 2 of the item, is modified.

              Table 26.77 (5) — Modifications of RTCA/DO 275
      Column 1                                                    Column 2                                                                                     Column 3
Item  RTCA/DO-275 (as in force from time to time)                 Summary                                                                                      Amended performance requirement