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Aviation History
1957
1957 - 1829.PDF
919FLIGHT, 13 December 1957 Britannia in Service Statistics Tell the Story Right, subject of this story— the B.O.AC. Britannia 102. OPENING his paper with a summary of the Steps which ledto the design of the Britannia, Dr. Russell traced thehistory of the specification up to the time the formal contract with B.O.A.C. was signed in July 1949. The first flight,with Proteus 625 engines installed, was made in August 1952, and at the end of 1953 the second prototype, with Proteus 705s,made its first flight. Two months later, a forced landing as the result of an engine fire (due to a reduction gearing failure) causeda setback rendered more severe by the fact that the first prototype had then to be converted to production standard. Further delaysin delivery were caused by a B.O.A.C. decision not to accept any aircraft until a full C. of A. had been granted and later, iceaccumulations in the engine air intakes introduced a new and formidable problem. By the time the first Britannia 102s enteredservice, 4,150 hr of test flying had been performed. By the time [continued Dr. Russell] a civil aircraft has passedthrough its initial flight development programme, exceeding (in the case of the Britannia) four thousand hours in the air, it hasbeen handled by a considerable number of expert and critical crews. Many hundreds of thousands, if not millions, of figuresare stored in records, a large proportion of them extracted and plotted in a form to demonstrate compliance with the many detailsof the specification. The airworthiness authorities also have fretted and speculated with the greatest determination to foresee a com-bination of faults, overlooked by the designers, which might possibly lead to an emergency. In the final phase the aspect ofaircraft performance covering the recognized conditions of engine and component failure has been fully documented for the benefitand instruction of its future operational crews. Notwithstanding this care and attention to detail, it is certainthat the gruelling environment of operational service will show that certain presumed cures for previous maladies were incom-plete, while other dormant hazards become active. The early periods of passenger carrying operation are, therefore, the mosttesting of all. In this stage popular interest usually emphasizes aspects of glamour and prestige, so diverting attention from theengineers concentrating upon the task of setting and keeping the machinery in order.Statistics of the reliability of aircraft and their equipment in service are difficult to come by. Airlines are generally peculiarlyreticent on these matters. It would seem that they would prefer to have the casual passenger infer that his experience of delay isunique, and those who travel more frequently are made to feel grateful for the good care taken of them. Amongst this lattergroup one finds from personal experience that a fair proportion are themselves engaged in some branch of aviation and have thusbecome conditioned on their own airfields to waiting for something to happen. So if the unique occasion arises when an airline pub- NO other aircraft now in airline service has had to operate in thecontinued glare of limelight accorded to the Bristol Britannia 102. Introduced on to B.O.A.C. routes on February 1 this year after aseries of frustrating delays, it has since been the subject of some sharp criticism. How much of this has been justified and how muchtendered as the result of hypersensitivity about the prestige of British transport aircraft may be judged from this summary of a lecture byDr. A. E. Russell, a director and chief engineer of Bristol Aircraft, read to the Bristol Branch of die Royal Aeronautical Society onDecember 5. Supported by statistics provided by the operator, it pre- sents the most complete and balanced survey of the first eight monthsof Britannia operation yet published. licizes frequent service delays due to the unreliability of its latestaircraft—the consequence of which is in effect to advise its potential customers to travel with a rival operator—somethingsomewhere must be amiss. Now a fair judgment of reliability in service can only be reachedby making comparisons with the standards reached by other aircraft at a similar stage in their operational life. The gatheringof evidence is, however, made difficult by the limited amount of published information. Some is provided by a paper entitled"The Comet in Service," read by Campbell-Orde before the Fourth Anglo-American Conference in London, 1953; this has beenaugmented by information including all types in their fleet which B.O.A.C. has recently provided. Figs. 1, 2 and 3 are based uponthese sources, with Britannia curves added where required for purposes of comparison. Fig. 1 shows aircraft utilization obtained by dividing the totalnumber of hours flown by the total number of aircraft in the fleet and Fig. 2 shows the cumulative revenue miles flown per aircraft;in these two respects the Britannia appears to perform quite credit- ably. Fig. 3 gives a comparison of terminal punctuality betweenComet, Argonaut, Stratocruis;r and Britannia; this information suggests that punctuality is not a typical virtue of new aircraft.I don't know what impressions you get from these results, but I assure you that the curves have not been drawn upside "down. We now turn to America for some experience. After its firstyear of passenger operation, it was found that the Lockheed 1049C had reached an average daily utilization of 5.65 hours, less, infact, than the Britannia has achieved after only nine months. The same figures for the Douglas DC-7 at the completion of its first yearin service was 6.6 hours, approximately the same as the Britannia is expected to reach by the time it, too, has had twelve months inservice. This expectation seems justified by the fact that during the last two periods for which figures are available utilization hasaveraged nearly eight hours a day. An important point to bear in mind is that both these now well-established and highly suc-cessful American aircraft are developments of earlier types, and Fig. 7. Aircraft utilization during first years of service with B.O.A.C. tor Fig. 2. Cumulative revenue miles per aircraft—comparison over first ten months of B.O.A.C. service. AIRCRAF T r JE MILE S t ! x1 s • / > / / •y> / /BRITANNI/ / UO2 / OMET •^RGC3NAUT
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