Captain Donald A. Heine

In Phase I of the Cleveland Fire Tests, June 30 and July 1, 1966, a control burn of an aircraft was done to determine the free burn characteristics of an average aircraft cabin interior. Full instrumentation and gas analysis was accomplished to give baseline data for comparison with future tests.

Also, in Phase I, a second aircraft was accomplished to determine whether high expansion foam could be used successfully to extend survival time in an aircraft cabin beyond previously known limits. This test was not successful since it was determined that ingestion of air contaminated with products of combustion/pyrolysis into foam generator prevented formation of the foam. This has been further documented by research done by Williams and reported in Fire Journal (September 1968).

R. Byron Fisher, Paul M. Rich

An acoustic locator beacon was developed and tested in an underwater environment simulating the conditions that might exist when an aircraft crashes into water. The beacons were self-contained, battery-powered, and produced a 10- to 20-millisecond pulse of 35 to 40 kHz at a rate Of I to 4 pulses per second. The locator beacons were designed to be attached to airborne flight data recorders to assist in the recovery of the recorded records for use in aircraft accident investigations following a crash.

The crash environmental tests were conducted using a section of an aircraft fuselage that 8till contained the cabin pressure-bulkhead. The beacons tested were placed in two different representative locations; (1) inside the cabin pressure area, and (2) aft of the pressure bulkhead in the unpressurized area. . The fuselage section was lowered into seawater at depths of 50, 100, and 200 feet off the coast of the Florida Keys. Search run8 were made using a motor powered craft equipped with an acoustic locator receiver. The results indicate that the signals of a fuselage encapsulated locator beacon can be detected at reasonable surface distances (up to 3000 yards) and at depths as low a8 200 feet.

Federal Aviation Administration, Department of Transportation

Advance copy pending issuance of changes to FAR parts 25 and 121

J. Reed Welker

A mathematical model was formulated which permits calculation of the time required for damage of the aluminum skin covering an aircraft fuselage when exposed to fire. The damage time was defined as the time required for melting of the aluminum skin.

The model was developed through consideration of the heat transfer rates by conviction and radiation. The resulting differential equation was solved using a numerical technique. The results indicate that the minimum time for skin damage for the largest commercial aircraft now in service is less than 40 seconds. The predictions made through the use of the model correspond closely to measurements made by FAA on full-size aircraft models.

Gerald Slusher

The engine and exhaust system vibration and exhaust gas and metal temperature levels were determined for flight and ground conditions on several single-engine aircraft for purposes of establishing exhaust system and heat exchanger design and test criteria. The temperature data were presented as a function of engine compression ration and the vibration data were plotted against engine horsepower to foster the general utilization of the information.

Method of data presentation permits the estimation of exhaust gas temperatures for horizontally reciprocating engines. Temperature measurements indicated uneven heating of the muffler outer wall (heat exchanger surface) reflecting uneven flow of the exhaust gases through and around the baffles and diffusers probably producing thermal stresses and contributing to failure. Baffles and diffusers within the mufflers of engines with compression ratios of 8.5:l of higher are exposed to exhaust gas temperature levels under which standard construction materials (AISI 321 and AISI 347 stainless steels) become marginal with respect to high temperature oxidation, carbonization, and attack by lead compounds.

Vibration of general aviation aircraft engines was noted to increase with increased power rating and reached maximum intensities under takeoff conditions. The acceleration level of mufflers on engines of high power compared favorably with the MIL-STD-810A Vibration Test Specification for equipment mounted directly on aircraft engines. Recommended procedure for development of new exhaust system designs involved random vibration testing under operating thermal conditions.