Hi folks,
The reissue of L.Dv.521 in November 1941 stipulated that all cockpit areas or crew areas visible through a glazed covering were to be painted BlackGray 66, principally as an antiglare measure.
The remainder of the interior, including weapons bays and undercarriage housings, were to be finished in Green-Gray 02. Instrument panels were to be Gray 41 with individual instrument locations identified
by a letter/number combination, usually hand painted, in either 04 or 21. Certain equipment packs
were painted in other shades of 12 gray, e.g., battery housing in Gray 42.
Internal piping was color coded for maintenance purposes, using the colors yellow (04), white (21), black
(22), red (23), blue (24), green (25) and brown (26). Where 04 Yellow 04 Gelb
23 Red 23 Rot 26 Brown 26 Braun services terminated at an external point, the relevant coloring was
used to identify the specific service.
Additionally, instructions and symbols relating to maintenance were painted externally on the airframe.
Maybe this helps ( Source : Monogram German Aircraft Interiors)
Thomas