AUTHORIZED FINISHES

a. The exterior of metal fuselages and metal airfoils do not ordinarily require paint as a protection against corrosion (T. O, No. 01-1-2), However, where it is necessary to provide additional protective finish on any parts not made from chromium – coated sheet material, any such unprotected parts will be cleaned with phosphoric acid alcohol cleaner, finished with one coat of zinc chromate primer, Specification No. AN-TT-P-656, and two coats of aluminized lacquer. Aluminized lacquer consists of lacquer, cellulose nitrate, clear, Specification No. AN-TT-L-51, pigmented with 12 ounces per gallon of paste, aluminum pig­ment, Specification No. TT-A-468.

b. Antiglare camouflage olive drab or dull dark green paint is authorized, where necessary, to be applied to top of the fuselage in front of the cockpit and on the inside upper one fourth of the engine nacelle.

c. Exterior plywood surfaces will be finished with two coats of sealer, Specification No. AN-S-17, or on open grained woods, one coat of sealer followed by one coat of surfacer, Specification No. 14115, sanded down, before the final two coats of aluminized varnish. Use 16-20 ounces of pigment, aluminum paste, Specification No. TT-A-468, in each gallon of varnish. Specification No. AN-TT-V-116 or No. AN-TT-V-118.

d. All exterior fabric parts will have a minimum of two brush and two spray coats of clear nitrate dope, Specification No. AN-TT-D-514 (aluminized dope vehicle AN-TT~D-551 is not a suitable substitute, as it does not have the tautening quali­ties of AN-TT-D514), This will be followed by two or more coats of aluminized dope prepared by adding 8 ounces per gallon of paste, aluminum pigment, TT-A-468, to dope, cellulose nitrate, clear, Specification No. AN-TT-D551, before thinning.

e. Patching will be accomplished with clear dope, Specification No. AN-TT-D-514, applied in same manner as semipigmented dope previously used.

f. EMERGENCY REJUVENATOR FOR OLD FABRIC. – To one gallon of two to one mix of clear dope, Specifica­tion No. AN-TT-D-514, and blush retarding thinner, Specification No. AN-TT-T-258, add 1 fluid ounce each of tricrcsyl phos­phate and castor oil. Apply one coatby brush to clean surface, followed by one spray coat. After several hours drying, spray one coat aluminized dope, prepared as specified in paragraph 2,d.

g. For removal of all types of paint material from metal surfaces, use paint and varnish remover, Specification No. 14119, for removal. If not available, lacquer finishes may be removed with material compounded by the following formula: 3 gallons benzene, 2 gallons acetone, 1 pound paraffin wax. For removal of dope from fabric surfaces, use nitrate dope and lacquer thinner, Specification No. AN-TT-T-256.

1. MARKINGS.

Only such markings and identifying insignia as outlined herein will be used on AAF aircraft except as specifically authorized by the Commanding General, Army Air Forces.

a. Each part and assembly will be permanently and legibly marked the same number as the drawing number in such location, that it can be read after assembly in the unit.(See Specification No. 98-24105.)

b. Various detail and code markings for the cockpit, fuselage, oil lines, etc., as required in Specification No. 98-24105 will be maintained.

c. Radio call numbers of not less than four numbers will be maintained on all AAF aircraft, utilizing both sides or each outboard side, as applicable, of vertical stabilizer and rudder assembly; on all airplanes operating solely within the continental limits of the United States, the radio call numbers will also be placed on the lower surfaces of both wings. These are not required, however, on primary trainers not equipped with radio and which bear field identifying numbers. Wing numerals will be placed with the top forward on the right wing immediately inboard of the insignia and in a corresponding position on the left wing. Call numbers, or designators, will be of a size discernible at a distance of 150 yards. They will be derived by deletion of the first number of the serial number (4) and the hyphen, and the combination of the remaining four or more numerals. In case of serial numbers of type 41-7, use zero as necessary to make four numerals as 1007. Decalcomanias may be used where available.

d. Under no conditions will the letters “U. S. Army” be applied to any airplane lower wing surface,

e. American propeller blades, design Nos. A-2721107 add C-3821306, used in sets in Aeroproducts and Curtiss propel­lers, respectively, will be identified by a yellow stripe, 3/8 inch in width and 3/8 inch inboard of the yellow tip section, A. O. Smith propeller blades used in sets in Curtiss propellers will be identified by two 3/8-inch yellow stripes, one 3/8 inch inboard

of the yellow tip section and the second stripe 3/8 inch inboard from the first. These stripes will extend completely around the blade section.

CAUTION Care will be exercised to mask any angular graduations on the propeller hub or blades. The space between the blade shank and barrel will be masked-off to prevent paint from contacting the seals.

The stenciled markings between the 18- and 24-inch R stations on the cambered side of the propeller blades will be retained.