SAFETY PRECAUTIONS FOR PLANE ENGINES

Press, Volume XCV, Issue 28264, 30 April 1957, Page 11

SAFETY PRECAUTIONS FOR PLANE ENGINES

Occasionally an, engine of an aircraft in ttight may be voluntarily stopped and the propeller feathered” while the plane either returns to base or continues to jets destination. Because anxiety ‘Bxay be created by such, an event, I Tasman Empire Airways, Ltd., has supplied the following statement .of the circumstances which may' cause such a decision and the procedure for the safe completion of ! I the journey. ; There are two reasons why ar. ■aircraft captain may decide to feather an engine in flight: some ! part of the engine, propeller or i engine ancillaries has failed mechanically. or readings of any of the various instruments coupled to the engine indicate that its performance is below standard. Mechanical failures in flight are not common but when they do : occur the captain has only to press a button to feather the engine and the aircraft continues its flight with abundant power for any manoeuvre the pilot desires. Feathering an engine because instrument readings are not satisfactory is more common.. In modem aircraft a multitude of gauges is attached to each power plant. They show the temperature of the cylinder heads, off the oil going ;into_ the engine, and of the oil. coming out of the engine. They show the amount of power being used and the number of revolutions the engine is doing every ; minute. Other gauges show the I amount of petrol being consumed and an ingenious device known as an ignition analyser reveals whether the ignition system is properly functioning. It wril even show incipient failure of a single! spark plug. Constant Watch AU these instruments are con-1 stantly watched by the flight crew.! i Readings are recorded periodically and. if there is any variation from I i standard, the captain will im- j .mediately decide whether action! .is necessary. Customarily the cap-' tain will stop an engine if there; iis the slightest indication that it I jis not functioning well. If left to I operate the engine would probably not fail—the chances are | very much against it doing so—' (but it is obviously wiser to rest! rather than strain an engine if its' performance is suspicious. : Usually when an aircraft arrives 1 I:at its destination with one engine! i feathered only a small adjustmentJ to the carburettor system or the I jquick replacement of one of its) 136 spark plugs will restore per-' iformance to normal. In an emerg-l I ency an aircraft can land at its i [take-off weight but there is less, • strain on its under-carriage if the; [weight is redueed. When a four-engined airliner I arrives, at an airport on three | engines it does not mean that thej aircraft has been in danger. It I .means that its crew have used j important aids which have helped 1 commercial aviation to become in-! creasingly safe during the last 10 , years. Once it was hazardous to> complete flight on three engines I —before feathering propellers be[came standard passenger aircraft

equipment, before airliners had anything like the huge reserves of power they have today. Afrcraft like the DC.-S and DC-7, Constellation and Super Constellation airliners, on which most ! international passengers fly ta>I can stop an engine in flight j feather the paropeller (which i means locking it in position so it j wffEE not race) 1 and not lose altitude. For regular cruising they employ only per cent of the power generated by their four Flights 1 on Three Engines So three-engined flights have become quite common. Somettmes :they are undertaken for purely precautionary reasons, sometimes ■of necessity. If a pilot suspects that one engine is not performing satisfactorily he may cease it in che knowledge that it is better to rest it than continue working it ! if it is ” A popular belief among airline passengers, and airport by stand-! ers is that landing an aircraft on only three engines is difficult. Airline pilots refute this. It is no more difficult than landing with all four engines in operation. Airliners require comparatively little. power for the landing operation. . To take off, however, they take a great deal of power. Three engined take-offs are never wilfully undertaken with passenger aircraft. Some types of aircraft . are never taken off on three engines, although modern airliners are designed to perform satisfactorily in the event of an engine failure at the point of take-off—-j the moment when an aircraft re- . [quires more power than at any, I other time | Airline and civil aviation admin- : istration regulations prohibit airI craft from continuing flights on three engines unless they have/ ! passed their point of no return, | the. point, beyond which they 1 | would not necessarily have suffi- 1 [ cient fuel to return to their de- : ! parture point. 1 i Are all strictly 1 ! necessary? In the light of later ■ | investigation, most off them are 1 i not. But unlike a motor-car or; , ■railway engine driver, an airline [ Ip-ilot who suspects something ! wrong with hrs vehicle cannot • I stop and look at it. Most trouble • ■spots can be inspected only on , [the ground, so unless he has', ; passed his point of no return he < turns back at the first sign or • j suspicion of his aircraft not per- ; 'forming quite perfectly. Jettisonning Fuel i Turning back often necessitates.I jettisonning fuel When a four- | engined aircraft takes off on a I long-distance flight laden to, or i near, its permissible take-off i weight, its weight exceeds its nor- . . mal permissible landing weight. Normally this situation will have rectified itself before the aircraft reaches its destination through the consumption of fuel. On the occasion of a turnback in the early stages of a flight, the aircraft must jettison fuel before landing and airliners are fitted with safe and efficient equipment to rid the aircraft of parts of its fuel load. The fuel is ejected from the aircraft through small nozzles. Immediately it leaves the aircraft. ! the high octane fuel vapourises and in this form the greatest speed at which it is physically possible for it to travel is far below the speed of the aircraft. So the petrol vapour is left instantly behind. The nozzles through which the fuel is ejected are far ; to the rear of the aircraft engines j and exhausts. Airlines maintain a continuous effort to minimise passenger delays caused through turning back and mechanical faults, but when technical faults do occur safety is the factor governing all decisions. Neither expense nor convenience is considered.