George A. Coffinberry, Thomas M. Tucker

This report summarizes results from a 20-month technical effort involving the design, fabrication and evaluation of an Antimisting Kerosene (AMK) degrader. The principal objective was to demonstrate the feasibility of employing a high-speed centrifugal pump to condition AMK fuel fqr use in an aircraft turbine engine. The effects of AMK fuel on the engine/airframe fuel system as well as any effect the flight environment might have had on the fire-preventive characteristics of the AMK were also investigated.

Five functionally identical degrader systems were produced. The first system was installed on the No.3 engine of a CV880 aircraft with a dedicated AMK fuel tank. This system accumulated about 45 hours of engine operation on AMK, 30 of which were in-flight. The remaining four degrader systems were installed on a B720 aircraft that was used in the Full-Scal'e Transport Controlled Impact Demonstration (CID).

The degrader systems performed well and met the objectives of both the CV880 and the CID programs. In the early phases of the CV880 flight test program, gelling was observed on a number of the engine fuel filters. Three distinct types of gel subsequently were identified. The mechanisms involved in the formation of all the gels were not fully understood by the end of the program. Aside from the intermittent occurrence of gel, little difference in performance could be distinguished between the No.3 engine, operating on AMK, and the No.2 reference engine, operating on Jet A.

Ludwig Benner, Jr., Richard Clarke, Russell Lawton

This report describes a study of fires and interior materials in General Aviation (GA) aircraft during 1974-1983. The purpose of the study was to learn trends in. GA fires and the materials used in aircraft interiors. The study covered aircraft of less than 12.501 pounds gross weight, hot in commercial or agricultural operations.

Fires are a minor part of GA accident experience. Accident data yielded 2,351 most impact fires having 798, fatalities. These accidents were 6 percent of the total of 36,130 GA accidents. Only 153 in flight fires occurred during the period from 1974-1983. The GA fire population closely resembled the entire GA aircraft population. One difference was that fatalities and aircraft damage increased with higher approach speeds and gross weights up to 10,500 pounds. Also, the proportion of fire accidents and fatalities was greater in low than in the more common high wing aircraft. For inflight fires, the aircraft engine was the major fire origin for twin- and single-engine aircraft. Only in single-engine aircraft was the instrument panel a source of inflight fires.

Data on the 20 most common GA aircraft disclosed conventional materials, similar to those used in the home. Polyurethane foam cushioning, wool and nylon fabrics, ARS plastic and aluminum typify the materials used in these aircraft.

DOT

Hazardous Materials Incidents

S. Wayne Stiefel

Fire risk assessment and decision analysis methodologies were developed for the case of major aircraft fires. This document reports on the final phase of the project, which concerned refining the model specifically for the in-flight fie, scenario. A step-by-step approach has been suggested for use in the evaluation of the risk reduction potential of specific mitigation strategies available to the FAA; prevention, early detection, extinguishment and smoke control. To demonstrate the approach one scenario was examined – gasoline fire in the cabin. The discussion includes the type of information required by the model and the potential sources (test results, mathematical models, accident experience and expert judgment) for obtaining such information.

G.R. Slusher, J. A. Wright & L. C. Speitel

Hand-held Halon 1211 and Halon 1301 fire extinguishers of 2.5-pound and 3-pound capacity, respectively, were discharged to determine their effectiveness on instrument panel fires in a small aircraft. The fires consisted of aircraft wire insulation and hydraulic fluid located below and behind the instrument panel in a Piper Model PA-30 Twin Comanche fuselage.

The extinguishers were discharged using two methods; (1) by directing agent upward under the instrument panel, and (2) by directing agent behind the instrument panel by discharging through Fireports mounted on the instrument panel.

Except for one test, the fires were extinguished rapidly upon discharge of the Halon extinguishers. The two methods of discharge were equally effective in extinguishing the fires. Extinguishers charged with Halon 1211 and Halon 1301 were both effective for the fire extinguishment. In the test where the fire was not extinguished, the fire was located under the instrument panel on the copilot's side and the extinguisher was discharged through a Fireport located on the extreme opposite side (pilot's side). In this test, the fire was knocked down but continued to burn.

Measurements of the decomposition products of the Halon agents demonstrated toxic gas concentrations significantly below levels considered dangerous.