Manual (Item) - RAF Navigation Instrument Repair Manual, Navigation Instruments: Repair and Reconditioning Instructions Historical information Air Publication 1275B, Volume 6.On front cover: "Note.- on all leaves issued with A.L.s I to 19, for "Vol 2 Part 3" read "Vol. 6". Any referenes to "A.P. 1275B., Vol. 2, Part 3" are also to be read as "A.P. 1275B, Vol. 6"