J.J. Gassmann

The relative ignitability of various hydraulic fluids has been determined qualitatively under simulated flight and crash conditions. The ignition characteristics of the fluids, under practical aircraft conditions, were the only properties investigated in this test program.

Flight conditions were simulated in a full-scale operating B-29 engine installation in which the fluids, released at pressures of 1,000 and 3,000 psi, were exposed to four typical sources of ignition: (1) exhaust flame, (2) hot exhaust stack, (3) ignition spark and (4) burning gasoline.

Crash conditions were simulated by bench tests in which the fluids were ejected at 3,000 psi through a strong electric arc and an oxy-acetylene flame. Wick fires were simulated by using horizontal and vertical wick test conditions

H.A. Watson

The introduction and use of synthetic materials in various applications may lead to potential hazards from toxic, gaseous, decomposition products if these materials are subjected to conditions abnormal to their intended use, such as high temperatures or burning from accidental causes. This report covers an investigation of such possible hazards from toxic gases produced by the burning or thermal decomposition of some low-density expanded, synthetic materials, three of which consisted of polyvinyl chloride and one of acrylonitrile.

H.A. Watson, H.J. Stark

Fluorine-containing polymers are comparatively new materials that exhibit very desirable characteristics not usually found in many non-fluorine containing polymers. Among these characteristics are heat and flame resistance desirable electrical properties and chemical inertness. Polytetrafluoroethylene and polymonochlorotrifluoroethylene are examples of such polymers commercially available.

In practical applications it is reasonable to expect thermal decomposition of these materials if they' are subject to high enough temperatures. The temperatures at which thermal decomposition takes place and the nature of the gaseous products of decomposition are considered pertinent data in intelligent use of these materials.

The purpose of the tests discussed herein was to detemine:(1) The . temperatures at which gases were produced when small Specimens of the two' polymers were heated and (2) determine the identity of the major constituents -of the gaseous products.

No attempt is made to draw conclusions concerning the relative merits of one, material over the other.. Also, no attempt is made to express the result's in terms of hazards relating to toxicity of any of the products. of thermal decomposition. The matter of possible toxic hazards in connection with the use of organic polymers must be studied carefully in terms of operating requirements and conditions involved in each specific applications.

J.J. Gassmann

Aircraft fires originating within faulty vacuum systems have been investigated in the laboratory.

Bench test and tests in full-scale engine installations of an operating vacuum system have been conducted to determine conditions within the system resulting from blockage of suction and/or pressure lines combined with malfunctioning of the suction and/or reassure relief valves.

A simple bench test was developed to duplicate the internal fire conditions which were obtained in earlier tests, but without destroying a vacuum pump in each investigation as occurred in those tests. Control of conditions was refined until tests could be easily and accurately duplicated. Various vacuum piping systems, including systems in use and those proposed for future use, were compared to determine the relative abilities of the systems to withstand internal fire.

Lyle Tarbell

One type of fire which occurs rather frequently in air carrier aircraft is the landing gear fire which usually results from excessive braking or from hydraulic fluid leaks or a combination of both.