June 1976
From The Space Library
Prompted by the crash of an Overseas National Airways DC-10 at Kennedy International Airport in Nov. 1975, when a General Electric CF6 engine on the plane disintegrated after a massive encounter with seagulls, Webster B. Todd, Jr., chairman of the National Transportation Safety Board, wrote to Federal Aviation Administrator John McLucas that the GE engine was the only one in operation that had disintegrated completely on several occasions after bird ingestion. Todd asked that the CF6 engine be modified and that bird patrols be set up where known problems existed at airports served by CF6-powered aircraft.
FAA bird-ingestion tests allowed certification of engines that could absorb the impact of only 10 birds weighing 0.67 kg each (1.5 lb); Todd said that the FAA's birds were too light and that they should have been fired into the engine simultaneously instead of one at a time. The gulls that caused the ONA crash weighed more than 2.2 kg each (5 lb). Although CE immediately protested the letter, only the CF6 had been implicated in a massive bird-strike explosion, whereas Pratt & Whitney and Rolls Royce engines in similar occurrences did not explode.
GE said it was planning to use aluminum honeycomb to replace the phenolic-resin shroud on the abradable seal around the compressor booster stages; fan blades detached by bird ingestion had scraped off the resin, which accumulated in the combustion chamber and mixed with the fuel, creating overpressure and ultimately an explosion. Aircraft using the CF6 included the USAF's C-5A Galaxy, 190 DC-10s, 6 B-747s, and the A300 Airbus. ONA had decided on CF6 engines for a recent order of 3 DC-10s. (Interavia, June 76, 502)
The 50th anniversary of scheduled airline service in the U.S. had brought little or no traffic growth in a declining economy, the Air Transport Association reported in its yearly review for 1975. When airline passenger travel began in 1926, no more than 6000 persons were carried between a handful of markets. In 1975, the nation's scheduled airlines carried more than 205 million passengers over, a network of 58 000 city-pairs (pairs of cities between which a scheduled service carries people, mail, or freight on more than 13 000 daily flights). The passenger total in 1975 was 2 million less than for 1974, although miles flown remained constant; increased traffic during the last quarter of 1975 had brightened the outlook for the Bicentennial year, ATA said. Freight service in 1975 totaled more than 4.7 billion ton-miles, down 2.5% from 1974. Airline safety improved, with only 3 fatal accidents in 1975 (fewest recorded since records began in 1949) and 124 fatalities, lowest number since 1957. Scheduled airline travel was statistically 10 times safer than by private automobile; in the early 1930s, it was considered 8 times as dangerous. (ATA report, 1976)
Symphonic 2, the Franco-German telecommunications satellite that drifted out of its normal geostationary orbit late last month, was gradually repositioned by using its cold-gas stabilization system, Aviation Week and Space Technology magazine reported. French and German space technicians determined that the malfunction was caused by a still unidentified defect in one of 4 valves feeding the exhaust nozzles of the satellite's hot-gas stabilization system. Transmissions normally handled by Symphonic 2 were shifted to Symphonie 1 while the repositioning went on; both satellites were reported working normally again. (Av Wk, 28 June 76, 11)
The USAF announced that use of a new tool made of a graphite-epoxy composite material in fabricating 3 YF-16 fuselages of the same material had exceeded design requirements and saved both time and money. Materials and processes used to make the 227-kg 18.5-m composite tool replaced a multiple-step method used to construct large, complex, highly contoured aircraft fuselage skins or structural shells of graphite epoxy materials; the new concept eliminated 2 steps in fabrication, saving up to 50% of total tool cost. Steel curing tools used for smaller, less complex components were extremely expensive and could damage a contoured part because of incompatible thermal expansion; parts made with the new tool had mechanical properties and dimensional tolerances that exceeded those made with conventional tools. Whereas 23.5 man hours per 0.09m` were needed to make the previous tool, only 9.7 man-hours were needed for the new tools, for a total saving of 2660 man-hours. Elimination of materials used in the multiple-step procedure meant additional savings, (OIP Release 096.76)
Articles in 2 successive issues of Aviation Week & Space Technology magazine reviewed progress in changing to the international metric system of units, and concluded that industry would look to the U.S. government for the spur required to convert, and the funds to defray expenses of converting. The Department of Defense, which was preparing a directive that would "fall short of ... a substantive push to the industry" by stating that DOD's aim was to keep pace with industry, was said to be reluctant to take the lead-and be presented with a bill for the costs-in converting to metrics for a major new weapons system. The magazine had surveyed a dozen firms in the aerospace industry, none of which had plans to "metricate on their own without a requirement by their government or commercial customers." Most industry spokesmen said metrication was inevitable, although a mixed system with metric English capabilities would probably be in effect for the period during which tools and supplies' would be used up or replaced with the new measurements. (Av Wk, 7 June 76, 44; 14 June 76, 100)
Interavia magazine printed a photograph of Dora, a solar. generator being manufactured by AEG-Telefunken under contract to the German Institute for Space Research to provide power for 1980s communications satellites. Dora was designed as a "variably deployable array," meaning that it could begin its service life partially deployed; unfurled gradually at intervals, it could maintain a constant output over the years. It could also be folded down and brought back to earth at the end of a Spacelab mission. It consisted of two 22- by 2.8-m array panels carrying 46 000 solar cells. (Interavia, June 26, 504)
The government of Nigeria awarded a $150-million contract to TCOM Corp., a subsidiary of Westinghouse Electric, for a balloon-borne telecommunications and broadcast system to be installed by the end of 1979, and for training of Nigerian personnel. Ten tethered balloons supporting transmitting and receiving equipment at altitudes of 3 to 5 km would provide an expanded telephone, television, and radio service for the whole of Nigeria. (Interavia, June 1976, 573)
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