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Aviation History
1962
1962 - 0330.PDF
332 FLIGHT International, I March 1962 SAFETY, ECONOMY; COMFORT . . . HARDINOHAM: Because of the Board's peculiar set-up—it is not a Government department, it represents the whole aviation industry; and from that industry the executive, through its council, is able to request assistance from any branch. We also have consultants— people like Sir Alfred Pugsley. In addition we have airworthiness co-ordination committees; there are four of them—on aircraft, powerplants, rotorcraft and flight problems. These committees are chaired by ARB people, and we have serving on them the lead ing experts in the country—from constructors, operators, pilots and the research organizations. This is terrific backing for us in consider ing some of the problems which we shall have to meet. But is it not true that these experts are passing judgment on problems and products which they have themselves created? Is it not fair to say that they are bound to consider favourably the products which they hope eventually to sell? Moreover, with the rationalization of the industry we have a situation developing in which only one team of designers is fully informed of any given problem with which you are concerned. What do you say about that ? HARDINGHAM: Let me give you an example of what happens from our earlier experience with rotorcraft. There were no air worthiness requirements and very little experience. To the best of our ability we set down provisional requirements long before a certificate was sought. We then invited all the best experts to consider these provisional requirements. After they hud sat around a tabic and considered them, they themselves modified the require ments and made them tougher. This was before we were even asked for a certificate. This suggests that the requirements always provide an adequate margin for safety, but does not experience show that when a machine goes into operation it is often found necessary to toughen up still more? I am thinking, for example, of a recent aircraft which, after a year or more service, has had its landing speed increased. HARDINGHAM: One approaches this in many ways. We try to do all that is possible to ensure that an aircraft is airworthy. But its certificate is conditional, and one of our duties, which is not delegated, is to lay down the limitations within which it must be operated. These limitations are recorded in the Flight Manual for the particular aircraft type. TYE : Another part of the answer is this. After looking at each individual part of an aeroplane—its handling, engine reliability, and so on—we still have to consider the machine as a whole. One thing which we do before passenger-carrying certification is to get flying experience—usually around 1,000 to 2,000 hours, including specific tests and a great deal of flying abroad for the purpose of assessing performance in hot and humid climates. But in addition we usually have the help of the first operator who flies the aircraft up and down the routes with operational pilots and operational maintenance staff, all for the purpose of finding out possible snags of which we had not originally thought. You mention 1,000 to 2,000 hours of flying, but we had the instance I mentioned earlier of the aircraft in service over a year before it was decided that additional limitation was necessary. That machine must liave done 50,000 hours. Then we had another recent ease in which it was shown, after considerable operation, that just one loose screw could cause an accident. In this situation, with these more complicated high-speed aircraft, would you say that 1.000 to 2,000 hours of development and proving flying are adequate? TYE: They probably will now show up every potential weakness. We do not pretend that all the troubles are thrown up within that time, but the community at large could not afford to subsidize 50,000 hours of flying before an aircraft went into service. HARDINGHAM: It has been suggested that 100,000 hours of flying would be necessary before a supersonic transport could be put into passenger service with absolute confidence and, at a cost of at least £1,000 per flying hour, you can see the kind of expense involved. In any case that sort of thing is "out" on a time basis, let alone the cost. Even with ten supersonic aircraft on test, it could mean a matter of five years" flying. TYE: It would entail an enormous expenditure if an aircraft were to be 100 per cent proven before going into service. The 1,000 to 2,000 hours give us the best chance of proving an aircraft within a practicable time. You think that amount will be sufficient for supersonic transports? TYE: 100,000 hours have been mentioned, but I should have thought maybe something of the order of 10,000 will be accepted as a realistic figure. HARDINGHAM: We also have to bear in mind that after the first 100,000 hours' flying another set of problems can arise—with fatigue, wear and tear, and so forth. With problems of this scale confronting you, would it not be feasible to try for a halt in the present race in re-equipment ? Various operators and constructors have gone on the record as saying, rather wistfully, that it would be an excellent thing if we could delay the race towards the supersonic; but usually they confess that commercial competition will prevent this kind of rational approach. Is there any more likeli hood that the airworthiness authorities—yourselves and your counter parts abroad—could get together and call for something of a pause ? HARDINGHAM: It is certainly true that we are co-operating more with overseas organizations, particularly in this matter of super sonic aircraft, but the only organization able to call a halt in re-equipment would, perhaps, be IATA. TYE: Whatever the rate of development, I think it would still be feasible to keep pace; and, however nice it might be to have this quiet period, I cannot see that we could convince other air worthiness authorities that there are problems so intractable thai we need to call a halt in development. HARDINGHAM: It is also a fact that, despite all this alarm and despondency, every year we are carrying more passengers more miles at less risk. TYE: It is certainly true that the risk to passengers is not increasing. Can I put to you one or two specific questions about safety ? Firstly about landing speeds. You may have noticed that both Lord Brabazon and John Cunningham have suggested that more effort should be put into the problem of reducing landing speeds; is this something which you can lay down as a requirement ? TYE: There is no doubt that the high landing speeds are the reason why there are more accidents when landing than during other phases of flying. The feasibility of reducing landing speeds is dependent upon the designers' ingenuity in finding a fresh approach. So far, if one has wished to fly very fast over very long ranges, then high landing speeds have been inevitable. But round the corner there are technical developments—power-assisted lift, for example —which might make it possible to keep the virtues of high cruising speed without the high landing speed. This, of course, means a sizeable piece of technical development. HARDINGHAM: We do give benevolent encouragement to the reduction of landing speeds, but we think it impractical to demand such a thing by airworthiness requirements. Personally, I would like to see any further extensions in the speed range applied to the bottom as well as the top end of the range. I would like to see aircraft with the ability to fly slower as well as faster. It is not only the landing problem which would be made easier, but there are other advantages—avoiding storms and riding out turbulence, for example. I suppose the ideal to hope for is a supersonic aircraft plus VTOL. TYE: There is another influence on landing speeds. Governments are showing a very strong reluctance to lay down more concrete at airports, and there is also a necessity to conform to traffic control patterns. These influences will at least do something to ensure that we retain the present position until technical developments make a reduction of landing speed possible. There is a very strong plea in BALPA"s "The Log" this month calling for a flight recorder which, in the event of an accident, would preserve all the essential information about a flight. Is this the kind of thing which you can lay down as a requirement ? TYE: We have thought a good deal about this, but there is a division of responsibility between the ARB and the Ministry, who are responsible for accident investigation. The sort of flight recorder you are talking about is an aid to accident investigation and, although we are interested in the results, the next step lies with the Ministry. HARDINGHAM : We also have an interest, from the point of view of continuing airworthiness, in a recorder which can collect a great Concluded at foot of page 339
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