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Technical Paper

The Development of a Turbine Engine Maintenance Program from a New Reliability Model

1973-02-01
730374
In the last 12 years new conclusions have been reached concerning the traditional reliability model for turbine aircraft engines. The overhaul of engines at one point in time has been discarded. New maintenance processes called “On Condition” and “Condition Monitoring” have been defined. A simple decision diagram has been devised to determine the proper maintenance process for each part. The historical background for these new conclusions, the maintenance decision diagram, and a new maintenance program called Powerplant LIBRA are discussed in this paper.
Technical Paper

The Future Needs and Current Advances Within the Airlines

1967-02-01
670338
New systems and techniques in aircraft maintenance had to be developed to cope with the rapid increase in workload and the changing nature of aircraft systems, parts, and material. Some of those that developed were from the science of mathematics dealing with sampling and the improvement of performance reliability and maintenance costs. Science and industry developed new material fabrication and machining techniques that enable us to work with materials that did not exist 10 years ago. This paper deals with maintenance concepts developed since we acquired turbine aircraft. It mentions a few of the new shop techniques that meet demands of reliability, costs, and new types of materials. It lists some needs of our business in the near future that will enable us to continue moving toward greater dependability and better control of costs.
Technical Paper

An Airline View of the SST Powerplants

1967-02-01
670865
The purpose of this paper is to show how an airline sees the SST engines from the 1967 perspective. With the British-French Concorde only months away from first flight, and the major United States SST design decisions made, the age of commercial supersonic flight has practically arrived. Afterburning turbojets will provide the power for both transport airplanes. A review is made, therefore, of some of the technological and operational complications which face the users of this equipment. Among these are the questions of how to deal with the noise problem, what the new higher engine operating temperatures will mean, and what might need to be done in the event of a performance “bust” of the airplane-engine combination. An attempt is made to identify the real problems and separate them from the imaginary ones: finally, the review ends on an optimistic note considering the resources and creative problem solving abilities of the industry itself.
Technical Paper

United Air Lines’ Evaluation of the Hughes Pictorial Navigation System

1969-02-01
690393
This paper addresses itself to two basic questions which have been generated by the rapid increase in commercial aircraft complexity and in air traffic density now challenging the entire aviation industry. The on-board capability of general area navigation holds great promise for alleviating some of the difficulties brought about by each of these. In addition to being faced with the problem of how to quantify the advantages of this more flexible navigation capability, there is also a great concern with the question of how best to provide that capability in the cockpit. As a vehicle for examining these two related, but distinct subjects, a moving map display system, developed as a joint project by the Hughes Aircraft Company, United Air Lines, and Jeppesen Company, was installed in a Boeing 727 and operated for approximately 193 flight hours, primarily in the high traffic density environment between the Chicago and New York areas.
Technical Paper

Reengining Large Jet Transports in 1972? - Economics and Technology

1966-02-01
660321
The purpose of this paper is to explore one part of the 1972 commercial air transport picture. New jet engine and aircraft technology will be available which offers substantial advantages in operating economics. A major portion of the improvement will come by way of the engine redesigns. Higher bypass ratios, higher turbine inlet temperatures, and substantially advanced structural concepts point in the direction of lower direct operating costs. An analysis is made using these “new technology” engines on older fleets of large jet transports. Results show that the domestic operators have little to gain. Longer range, intercontinental operators may find the engine conversion attractive for some route segments where range is critical. Engine maintenance costs, among other costs, associated with reengining are considered. Finally, using these results, an estimate is made of an airplane size which will maximize the cost-reduction potential of the engines.
Technical Paper

Minimizing the Effects of Mountain Waves and Shear Generated Clear Air Turbulence in Airline Operations

1966-02-01
660195
The development of techniques employed by the airlines in overcoming the problem of clear air turbulence is outlined. Improvement in transport aircraft brought new sets of challenges in this area which were overcome by applied meteorological studies conducted by the airlines and assisted by military and government research. A distinction is made in the methods of bypassing the turbulence regions caused by wind shear and those caused by the mountain wave. A new study on mountain wave turbulence evasion showing considerable promise is discussed. Recommendations are made on methods for keeping pace with an increasing exposure to this important operational problem.
Technical Paper

1953 Paper Jet Operations in Retrospect with Connotations for the Supersonic Transport

1965-02-01
650231
A first attempt to study civil aircraft operations comprehensively, prior to having the airplane, occurred before the initial operation of U.S. subsonic jets. One airline carried out a manual-simulated “paper jet” operation lasting fifteen months. Today, computerized simulation of machines, methods, and operations has become commonplace, and replaces the slide rule and tedious day-by-day inputs of aircraft operational criteria. Computerized simulations are also applied to every aspect of the SST design and operations. These are important, but the results being should be used with caution and judgement.
Technical Paper

The Assessment of Supersonic Transport Operating Costs

1964-01-01
640831
The fixed plus variable cost concept is frequently employed in the analysis of productive industrial processes. This paper discusses application of this concept to the assessment of the direct operating costs of a proposed supersonic transport aircraft. It is shown that the unit variable cost is approximately the same for the proposed supersonic transport airplane as it is for current subsonic long range jet transports. The unit fixed cost, however, is four times as great for the supersonic transport as it is for subsonic transports. The factors which cause the increased fixed costs in the supersonic transport are identified.
Technical Paper

Simulated Jet Transport Operation

1955-01-01
550232
IN order to study the practicability of reliable cross-country commercial jet transport operation, a series of simulated jet flights are in progress. Flights for these hypothetical airplanes are handled by regular United Air Lines dispatchers and are subject to the same delays, traffic restrictions, and holding as other real aircraft in the area. This paper presents results of the first year of this study and answers questions about such items as: variations in cruising altitude to avoid unfavorable winds, special routing because of jet streams, fuel reserve policy, reliability of schedules, and adequacy of present-day weather reporting.
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