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Aviation History
1969
1969 - 0160.PDF
FLIGHT International, 23 January 1969 Light-aircraft Maintenance: the ARB Replies SIR,—We cannot allow Mr Stratton's letter (January 9) to go unchallenged. In March 1966 the ARB published proposals which included, inter alia, the adoption of the American system of maintenance for light aircraft which Mr Stratton holds in such high esteem. This proposal received a very mixed reception and, as the ARB is most anxious to adopt a maintenance system acceptable to the majority of those concerned, it has waited patiently for nearly three years in order to find out what is really wanted. Owing to the fact that there is no one organisation representative of the various interests involved it has been difficult to get the "feel" of the light-aircraft com munity; but to date the general consensus of opinion based on many individual representations to the ARB. both by telephone and by letter, indicates a slight pre ference towards a basic maintenance schedule produced by the ARB. It is very misleading to speak of FAA-approved main tenance schedules. The system towards which Mr Stratton leans so heavily is not based on any approved schedule but solely on the manufacturers' recommenda tions. These recommendations, and the way in which they are published, vary considerably according to the manufacturer; they rely, to a very large extent, on a vast output of service letters, service bulletins and the like, and on a highly organised system of approved repair stations throughout the USA. This is why a con siderable number of owners and operators in this country prefer an ARB approved schedule of a type which has worked very satisfactorily over a long period of time, and which may well prove more economical in the long run. We in the ARB know that we cannot possibly please all the people all the time; but, as soon as we know the majority opinion for or against the American system of maintenance for light aircraft, we will go ahead with out delay. Redhill, L. s. WHICHER. Surrey Air Registration Board SIR,—I should like to take up the points made by Dr Macpherson in his letter on maintenance shortcomings. As a director of two engineering organisations respon sible for light-aircraft overhaul and maintenance work, no one can be more conscious and concerned about the rising cost of aircraft maintenance than myself, and I know that this view is shared by all my associates in the trade. What Dr Macpherson must take into account if he is to get a fair view of the problem, and not make unfair comparisons with other trades, is the fact that the aircraft maintenance body, be it that of a single licensed engineer or an approved organisation, has not only to try and satisfy the customer on all points but also has to safeguard its licence or approval as the case may be. If too little is done, and a running fault or failure is experienced, then the accusation is raised of "danger ously incompetent work." If too much is done the phrase "putting the boot in" applies. I believe that the only answer for the private owner is that he should find the best possible maintenance source in his area and, having established a happy relationship with a suitable engineer or approved company, then he should stick to this source and work as closely as passible with the body responsible, so that the engineer knows exactly how far he should go. All too often does one see private owners flying around the countryside attempting to bring a competitive element into an extremely difficult engineering problem. As a result the final charge inevitably bears little relation to the original quotation, and this invariably gives rise to criticisms between one company's work and another's. Once an engineer is familiar with a customer and his aeroplane, and knows the exact work that he himself has carried out in the past, there is no need for him to spend additional time checking previous work over which he has had no control and for which he will now become responsible by virtue of his signature. In closing, I would point out that the labour rate charged by most people in this country, including my own two companies, is less than that charged by most garages. If, therefore, a comparison must be made (and I think that the garage trade is a most unfortunate instance, since we aviators are, in the main, also motorists and know of the shortcomings of the motor trade too) Dr Macpherson should reflect on the differ ence in garage overheads. In doing so he should bear in mind the size of the average aircraft relative to that of a motor car, the equipment needed to obtain ARB approval today, and the salary of a licensed engineer or approved inspector compared with that of the unsuper vised garage mechanic. Look after your maintenance firm, doctor, and they will look after you! Portsmouth, Hants A. E. HAWES Gatwick Runway Extension SIR,—The Daily Telegraph for January 9 exaggerated the difficulty of lengthening the runway for the BAC- One-Eleven-500 and for big jet aircraft. More than one pilot has suggested a simple expedient which would not touch the railway, the trunk road or Russ Hill. Extend the take-off runs backwards as far as the downwind obstructions. Heavy aircraft would not lift off on take off, nor touch down on landing, any closer to the obstructions than they do now. Since the extensions would be used only for the start of the take-off (and as stopways), they need be no wider or stronger than a taxiway—thus preserving their cost-effectiveness compared with normal runway exten sions. This method is used abroad. Reigate, Surrey j. w. PROCTOR, Captain QFE or QNH? SIR,—The arguments for or against QFE in your maga zine interest me, since I have used both in Service and civilian flying. Mike Conry makes rather a boob, how ever, when he states that "we add the difference to the QFE," and here I think lies the crux of the matter. If one is on QFE at any but an airfield below sea level, and one uses this, not QNH, to give safety height over terrain, then one is on the safe side, because the QFE setting will give height of terrain plus airfield height. Accidents occur on misreading QNH for QFE, so why bother with QNH at all? All aircraft today use 1013.2mb for flight levels on airways. On letting down one is invariably under control by the destination airfield and is interested in height above that airfield. If QFE is set at the transition alti tude, or before if necessary, then one knows that the height to which one is cleared is safe, and there is no need to change to another setting whilst the workload is heavy on the approach. Unless the field is below sea level (and how many are there in the world?) one is at a safe height above terrain on QNH levels, whereas the reverse applies if QFE levels are used and QNH set. The Services went over to QFE with the advent of the jet age for this very reason, and accidents due to wrongly set altimeters fell considerably. In my opinion QNH is only of use away from a destination field to
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