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Aviation History
1957
1957 - 1741.PDF
29 November 1957 831 British Air Safety Standards Stricter Rules for the Older Transports Typifying the older generation of transports which will be affected by new British airworthiness standards is the DC-3. About 100 are on the U.K. register, half of these being owned by the independent airlines. MEASURES which may substantially impair the economicaloperation of the older transport aircraft used by Britishoperators have, Flight understands, now reached an advanced stage. The Ministry of Transport and Civil Aviation have notified the British air transport industry of the proposed changes which will be made to tighten up the airworthiness stan- dards of aeroplanes such as the DC-3, Viking, Freighter, York, Solent, Hermes and so on. These involve (1) the introduction of weight, altitude and temperature (WAT) limitations for the DC-3, Viking and Freighter 21, and (2) amendment of the Air Navigation Regulations under which these and the other older transports at present operate. The provisional date fixed for these changes to become law is January 1, 1959. Obviously, the operators most affected by these changes will be die British independent airlines. The aircraft concerned* fall into the "unclassified" performance group of the British Civil Airwordiiness Regulations: were they to be operated to these regulations their use would of course be severely limited. As matters stand at present, the requirements to which these aircraft are in fact operated, particularly those require- ments affecting engine-out take-off performance, do not ensure a level of safety which comes within the accepted present-day definition of the term airworthiness. This does not mean that these older types are to be condemned as dangerous: it is recognized that for 12 post-war years some 200 of them have achieved a good record of safety and service. But it does mean that the law intends to secure a more uniform level of public air transport safety, and more effective control of that safety. The proposed airworthiness amendments have not been sprung as a surprise upon the airlines. The Government made known its intended policy three or four years ago, and circulated its pre- liminary proposals for comment two years ago. These were arrived at with the co-operation and guidance of die Air Registration Board, but not without considerable difficulty. This was mainly due to the lack of scheduled performance information about the aircraft concerned, which were designed, tested and brought into service in an era of unsophisticated airworthiness standards. But it is significant that all but one or two operators accepted the basic technical common sense of the proposals. The objections which were raised against the proposed amendments (and there were many) were directed mainly at their adverse commercial and economic effects. What is the likely effect of the new requirements on the economy of the industry? The requirements themselves may be briefly summarized as follows: — (1) The introduction of full temperature accountability for take-off. rv, -r .mtr°duction of one-engine-out flight-path obstacle clearance.(3) The introduction of a two-engine-out requirement on long over-water flights. (4) Strengthening of the existing one-engine-out en route requirement tomaintain minimum safe altitude while conducting a flight to a suitable *Anson, Argonaut, Chipmunk, Consul, DC-3, Dove, Freighter 21",™ 32> Gemini, Hermes 4 and 4 A, President, Prince 3 and 4, Rapide, °C-4, Solent 2, 3 and 4, Tudor 2, 4 and 5, Viking, York. OF special concern just now are the steps which the Governmenthave for a long time proposed to take in order to raise the airworthiness standards of the older transport aeroplanes still operating on the Britishregister. The new requirements, which may cause economic hardship —particularly to some of the independent airlines—are likely to comeinto force in little more than a year. aerodrome, and also to maintain an altitude of 1,500ft above thataerodrome. The aeroplane would also have to meet landing distance requirements on this aerodrome.(5) Strengthening of landing distance requirements by deleting the pro- vision for visual approach and landing.(6) The introduction of a limitation in the weather conditions in which an aeroplane which is unable to maintain altitude with one-engine-outcan operate. (7) Introduction of a requirement not to fly below the altitude calculatedas being necessary for compliance with the one-engine-out requirements.(8) Aircraft of U.S. manufacture to be operated to a code based on Part 40 of the American C.A.R.s, except for (a) the revision of thetake-off flight-path obstacle-clearance requirement by one calling for an increasing obstacle clearance with distance, and temperatureaccountability, and (b) the replacement of the two-engine-out en route climb requirement by a requirement calling for the ability to reachan aerodrome similar to that proposed for unclassified British aircraft. After comments had been received on these proposals, they were revised in the following manner: — (1) The one-engine-out obstacle-clearance at take-off to be a constant 35ftinstead of increasing with distance. (2) The criterion for the application of two-engine-out performancerequirements to be "90 minutes from shore," and the landing dis- tance requirements need not be met at the emergency aerodrome.(3) "Terrain clearance" prescribed for the engine-out en route case. (4) The requirement taking runway slope into account deleted.(5) The limiting weather minima of low-stalling-speed aeroplanes unable to achieve a one-engine-out climb gradient of \ per cent at 2,500ftabove mean sea level reduced to a 1,000ft cloud ceiling and one-mile visibility at the terminal and the alternative.(6) The requirements for aeroplanes with American flight manuals to correspond in all respects to C.A.B. rules except for the two-engine-out en route ease and take-off obstacle clearance case. The commercial effect of these requirements is not easily sum-marized, since operators employ the old aircraft concerned in such varying conditions. But, as a generalization, it may be said that inNorthern Europe, limitations of weight by altitude and temperature will put a small economic penalty on the DC-3 and, to a lesserdegree, on the Viking, but will seriously affect the early Mk 21 Freighters (though not so much the later 31s and 32s). In warmerclimates, however, and particularly in Africa, WAT limitations will be substantial. The two-engine-out en route requirement will of course rule outDC-3s and Vikings from long ("90 minutes from shore") over- water flights, though few such British services are flown with thesetypes. This requirement may restrict Yorks considerably, and continued on page 852) Two ways in which the economical penalties of the proposed new regu- lations might be reduced are by a modification to the power section of the Bristol Hercules 600, power- plant of the Viking, Freighter 21, Solent 3, etc. (a Viking engine is shown in the picture); and by incor- porating on DC-3s the undercar- riage fairing designed by the independent airline Transair, Ltd.
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