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Aviation History
1921
1921 - 0102.PDF
FEBRUARY IO, 1921 GROUND ENGINEERING' By Lieut.-Col. H. W. S. OUTRAM IN his introduction the lecturer referred to the framing of theAir Navigation Regulations which came into force on April 30, 1919, and especially that part of the regulationsdealing with ground engineers. He pointed out the reasons which necessitate the creation of a new class of official, andwherein the inspection of aircraft must necessarily differ from that of other vehicles of locomotion. Examination of Ground EngineersCol. Outram outlined the procedure of examination of candidates by a Board composed of Air Ministry inspectors,and pointed out that any such examination can only guarantee to weed out those who are insufficiently qualified. TheBoard, he said, can do no more than state that in their opinion a candidate is reasonably likely to be an efficient groundengineer, and it would appear that the only way to deter- mine definitely whether a man is a properly qualified groundengineer is to watch him at his work, and in particular to note the results of such work. After pointing out that it is seldom that any one man iscalled upon to cover the whole range of a ground engineer's duties, the lecturer gave the following subdivision of licencesinto four categories :—" (a) Rigging and daily maintenance of aircraft at the aerodrome ; (b) overhaul and constructionof aircraft; (c) top overhaul and daily maintenance of the engine, and (d) overhaul and construction of aero engines."" The majority of candidates may be divided into two classes," the lecturer said. " One class has a sound knowledge of aerodrome practice,a fair knowledge of ordinary workshop methods, and a sur- prising ignorance of the qualities of the materials from whichan aircraft or aero engine is built, and even less of the many ways in which such materials may be spoilt by bad treatmentand ignorance of their peculiar properties. The other class consists of men whose experience has been limited to a largeextent to the construction of aircraft or aero engines, and who have gained the knowledge of materials referred to above,are expert in modern aeronautical workshop practice, but have only a very general or theoretical idea of what happenswhen the aircraft takes the air. Each of these classes is again sub-divided into the metal-worker and the wood-worker.Generally a candidate with good and sound knowledge of metal work has but an elementary knowledge of wood andnon-metallic materials, or his knowledge of the latter pre- dominates. Only a few men have shown equally soundknowledge of both branches of aircraft construction. " It hast>een found that in the majority of cases a candidatecan be placed in one of these classes within the first few minutes. The remainder of his examination is spent inascertaining whether his experience and knowledge in the other divisions are sufficient to warrant a recommendation. Supervision of Ground Engineers " The examination of a ground engineer is only completedwhen his work has been watched. In order, therefore, to supervise the work of the ground engineer, the power ofreinspection provided in paragraph 6 of Schedule 3 of the Regulations and paragraph 8 of Part IV of the ' Directions 'is exercised. It was decided to arrange for periodical rein- spection of all aircraft in use, and thereby supervise the workof the active ground engineers. The method adopted is as follows :—All certified aircraft must fly from licensed aero-dromes. The Air Ministry have a complete list of such aerodromes, which is kept up to date. Each is visited inturn, and the aircraft examined, the work done by the ground engineers responsible for the daily certificates for such aircraftbeing checked and noted. It has been found that this method gives a useful record of nearly every ground engineer who isoperating. Should any escape such supervision, the fact becomes apparent when they apply for renewal of theirlicence, and in such cases particulars of the work done are required. " The first two years' supervision has shown that operatorsmay be divided into two classes : those whose chief aim is to run a regular aj*rl reliable service ; who have a number ofmachines in operation, and employ an organised staff of ground engineers ; and the owner-operator or small syndicatewith one or two machines, whose main object is to obtain the biggest return for their outlay by " joy-flying," exhibitionflights, and the like, at sea-coast resorts or inland holiday centres. It is appreciated that at this stage the latter classof operator is important from the point of view of the public * Extracts from Paper read before the R.Ae.S. on February 3, 1941. education in flight. It is, however, this latter class ofoperator that requires the more careful supervision, and it is claimed that the small number of accidents which haveoccurred have proved that adequate and efficient supervision is possible without undue expense to the-State or such a degreeof State control as to seriously hamper the operator. The Duties of a Ground Engineer(1) A ground engineer is responsible for maintaining the validity of the certificate of airworthiness, and to do so isrequired to certify each day on which a flight is made that the aircraft is safe in every way for flight. The experienceduring the past two years has been that in some cases there has been a tendency to consider such certificates as merelya piece of formality which must be fulfilled. Sometimes the ground engineer hanHs over the machineto the pilot, and takes but little, if any, interest in what happens on its journey, although the pilot generally bases his certificateas to fitness for each flight on the ground engineer's daily certificate, and ma\ also rely on the ground engineer to seethat the petrol, oil and water in the tanks are sufficient for the proposed journey. The ground engineer is responsible for theairworthiness of the machine until the very moment when it takes the air, and the last few minutes on the ground and thefirst few in the air often provide evidence which should be carefully noted. " (2) Aircraft require continuous maintenance, and theground engineer is responsible that the machine to which the original certificate of airworthiness was granted isunaltered by such maintenance. He must also consider the conditions under which the machine is stored ; how theseare likely to affect the various parts of which the machine is composed. " The ground engineer must decide when it is necessaryto fit a spare part, whether this be a nut or a complete com- ponent. The mere fitting of the new part is but the smallestpart of this duty. He must satisfy himself that the part has been correctly made in accordance with the drawings onwhich the certificate of airworthiness was granted, and is of the material specified in these drawings. It must have beeninspected during construction (as laid down in detail in paragraph 21 of Section 3 of the ' Directions '), and he musthave actual evidence that it has passed such inspection, and further, must satisfy himself that the part has not beendamaged or deteriorated since such inspection was carried out. " (3) The certificate concerning the fitness of the engines isprobably one of the most difficult duties of a ground engineer. Obviously the airworthiness of the aircraft depends verylargely upon the engines. Records taken over a considerable period show that for every eight forced landings due to enginefailure, one is actually due to defect in the engine itself, the remainder being directly caused by some default in theinstallation of the engine. So long as the engine and the aircraft structure are designed as separate units, installationmust remain a weak point of the whole machine, so that the ground engineer must give his constant attention to the dailyroutine of cleaning petrol filters, checking petrol flows and water connections, etc., ensuring that all ignition leads,switches and contacts are in good order. He should verify each day that the engine runs up to its proper speed, see thatthe oil pressure builds up and is properly maintained, and that the radiator temperature is normal. He should alsomake a point of inquiring of the pilot as to any sign of exces- sive engine vibration in the air, the flexibility of the engineand any unusual circumstances which may have characterised its running during the daily trips. " The repairing of an engine requires on the part of theground engineer in charge of it almost a wider and more detailed knowledge than is needed in the building-up of anew engine, in that he must determine the safe limits to which crankshafts, cylinders and the like may be re-ground,and the extent to which part-worn components may be retained. A sound knowledge of materials and their heattreatment, too, is essential to justify his responsibility in the acceptance of new parts. This all-round knowledge isnot easily obtainable under normal conditions of works organisation and employment. " (4) One result of both Service and civil experience isthat various small points come into prominence which it is desirable to draw to the notice of all ground engineers.' Notices to Ground Engineers ' are therefore issued. They are published in the technical press and are sent to all regis- 102
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