TM 1-410. Technical Manual, Airplane Structures 1941: Section 17 - Cleaning

SECTION XVII: CLEANING

64. General.-a. The necessity for keeping airplanes clean at all times both inside and out cannot be overemphasized. During cleaning operations those so engaged should watch carefully for and report all evidence of faulty maintenance, or apparent need for inspection adjustment, or repair of any part or parts.

b. Cleaners are divided into two groups, aqueous and volatile. Due to the lower cost and nonimflammability of aqueous cleaners, those listed in paragraph 65 below are used wherever practicable. Volatile cleaning fluids are used only where aqueous cleaners are found unsuitable.

65. Aqueous cleaners.-a. The noninflammable water solution cleaners listed below are available for use as indicated.

(1) A soft soap solution is used wherever practical for routine cleaning of painted and unpainted airplane surfaces, fuselages, etc. A suggested method of preparing the soap solution is to place 50 pounds of the soft soap in a steel drum or other suitable container and add 20 gallons of water. The soap is allowed to dissolve for 24 hours and is then mixed thoroughly. The soap solution for cleaning purposes is prepared by adding 1 pint of this concentrated soap solution, to 5 gallons of water. The solution may be applied with brushes, sponges, rags, or mops after which the parts being cleaned are thoroughly rinsed with clear water.

(2) Where grease spots, exhaust stains, etc., are difficult to remove with the soap solution, use of a liquid cleaner and polisher, scouring powder or dope thinner is recommended. Dope, thinner is used for this purpose only on unfinished metal surfaces.

(3) The liquid cleaner and polisher is a cleaning compound consisting of a mild abrasive in a naptha water emulsion. It is intended for removal of light scratches and polishing transparent sheet cleaning and polishing unpainted aluminum alloy surfaces of airplanes, and other purposes where a mild abrasive is required for cleaning. Most satisfactory results are usually obtained with this material by applying a small quantity of the liquid to the surface to be cleaned and then working it over a small area, using a brush or rag with a light rubbing or scrubbing action so that a thin even coating is obtained. The wet coating of cleaner and polisher is allowed to dry and the resulting white powder brushed or wiped off.

b. Liquid automobile polish or wax may be used for polishing doped or painted surfaces if desired.

66. Volatile cleaning fluids.-a. The following volatile materials are available for cleaning parts and surfaces of airplanes and equipment:

(1) Gasoline, unleaded. Under no circumstances will leaded (ethyl) gasoline be used for cleaning.

(2) Alcohol, denatured.

(3) Kerosene.

(4) Carbon tetrachloride-naphtha mixture.

b. Gasoline and alcohol are highly inflammable and it is necessary that the utmost precautions be exercised in their use. Kerosene burns rapidly if ignited but is moderately noninflammable. Carbon tetrachloride-naphtha mixture is also moderately noninflammable and is used only where a serious fire hazard might result from use of one of above cleaners. This mixture consists of equal parts by volume of naphtha, and carbon tetrachloride. The solvents should be mixed as required in quantities sufficient to meet daily requirements only.

c. In order to fix responsibility cleaning with inflammable cleaning fluids is done under the personal supervision of a commissioned officer, a crew chief, or a qualified civilian employee. The individual supervising such cleaning is held responsible for compliance with all instructions on cleaning. The following safety measures are absolutely necessary in use of inflammable cleaners:

(1) Adequate fire-fighting equipment will be readily available while cleaning.

(2) Inflammable solvents will be stored in small safety type containers, and kept covered when not in use. All safety type containers will be painted red and have the name of the contents marked on the outside.

(3) All sources of fire hazards such as smoking, open flames, or operations of any electrical equipment that may give off sparks is prohibited in vicinity of cleaning. Warning signs to this effect will be conspicuously posted during such cleaning.

d. While all the volatile cleaners listed above are more or less toxic, carbon tetrachloride and carbon tetrachloride-naphtha mixtures are dangerously so and the following precautions must be observed when they are used:

(1) Avoid breathing vapors. Carbon tetrachloride solutions should not be applied to heated parts, as carbon tetrachloride when heated gives off phosgene gas which is very poisonous.

(2) Keep containers tightly covered when not in use to prevent evaporation and reduce concentration of vapor.

(3) Do not place bare hands in solution.

67. Methods.-a. Use of suitable, spray gun provides a very efficient cleaning method, especially for large parts; however, due to the extreme fire hazard resulting from high vapor concentration  produced by spraying inflammable liquids, when this method is used every possible precaution against fire must be observed. Gasoline or kerosene may be used for spray cleaning in the open air provided the equipment to be cleaned is located at a safe distance from buildings or any source of fire hazard. The equipment being cleaned must be thoroughly grounded to eliminate collection of static charges. Personnel performing the work should always stay on the windward side of the work to avoid breathing fumes. Carbon tetrachloride and carbon tetrachloride-naphtha mixtures will not be used for open air spray cleaning. The volatile fluids will not be used for indoor spraying except where special approved equipment and conditions have been provided.

b. Where portable steam pressure cleaning machines are available, routine cleaning of engines installed in aircraft and aircraft surfaces may be accomplished insofar as possible with this equipment. Care will be exercised that electrical equipment such as magnetos, generators, starters, etc., are adequately protected against moisture during cleaning procedure. This work will be accomplished by experienced personnel only.

c. The following instructions apply to airplanes operating in salt water. The treatment prescribed is applied as soon as practicable after removal of aircraft from water at close of each day's flying during which salt water take-offs and landings have been made.

(1) All traces of salt water are removed by thoroughly rinsing exterior of airplane with fresh water.

(2) A light coat of rust-preventive compound is applied to all exposed fittings on which corrosion is likely to occur such as exposed portions of landing gear, retracting pistons, control surface hinges, control cables, exposed rivets and bolts, and similar parts not protected from corrosion.

(3) Draining and flushing interior of hull compartments is accomplished at the time intervals and in the manner prescribed in the airplane handbook of instructions.