AERO ENGINE OIL FILTERS [Main Title]

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  • Title: AERO ENGINE OIL FILTERS [Main Title]
  • Film Number: AMY 161
  • Other titles:
  • Summary: An instructional film for RAF Tradesmen, presenting the different types of filter used with an aero-engine. The purpose of a filter is explained, both for a variety of liquids and air, that find application to the operation of an aero-engine. Failure to follow a strict schedule of maintenance for all types of filter can have disastrous consequences for the entire aircraft.
  • Description: Reel one: Film opens by defining the purpose of a filter. Cut to a water works where multiple filter beds remove heavy impurities from the water. Demonstration of domestic filters at home, tea strainer, coffee strainer and conical filter paper. These represent coarse, medium and fine grades of filtration. For all grades, the mesh size needs to be smaller than the particles to be removed. The finer the mesh, the longer the time taken to remove the particle. “Lubricating oil filters”: Use of filters in an aero-engine. One filter between oil tank and engine, another between engine pump and scavenge pump, both are cartridge (mesh) types. Cut to a clogged filter showing the sludge removed from the sump, demonstrating the necessity for a frequent maintenance schedule to protect the engine. Tradesman seen cleaning a mesh type filter. Explanation of the cleaning procedure. An examination of the filtrate collected during cleaning gives a good guide to the internal condition of the engine. To ensure every particle is removed from the oil, the mesh type filter is supplemented with propriety commercial filters containing a porous membrane within a cartridge housing such as Volks, Tecalamit and Cunoo. Reel two: The efficiency of an oil filter for aero-engines is determined by a large enough surface so the flow of the oil is not impeded, and will not allow harmful particles to pass through. A close examination of the filtrate under a microscope reveals the variation in particle size; a particle of grit less than 5 microns (1/20th thickness of human hair) is large enough to damage pistons/cylinder walls. Film shows tradesmen cleaning and servicing several types of filter. Propriety commercial filters are replaced with new ones. This type of filter incorporates a relief valve; cold oil is too thick to pass through the membrane, so the open valve allows the oil to by-pass and lubricate the engine. As the oil warms up it passes through the membrane, the valve gradually closes as normal oil flow pressure is achieved. The Cunoo filter, fitted to some types of American aircraft operates in a very different way. Reel three: “Hydraulic fluid filters”: The degree of filtering required for oil used in the hydraulic system is much higher than for engine oil. The size of the trapped particle must be smaller. Cut to view of a sectionalised jack; they have no packing at all, and the metal to metal contact of piston/cylinder wall will soon break down without adequate filtering. Such a failure will lead to disaster, operation of the under-carriage, gun turrets, flaps, bomb doors are dependent on hydraulic jacks. Cut to Spitfire landing with under-carriage up and the resultant damage to the aircraft’s underside and propeller. A rigorous cleaning and inspection routine (preventative maintenance) must always be adhered to. “Fuel filters”: Fuel is filtered as it enters the aircraft tanks. Mesh type wire gauze used, stopping the passage of medium size particles, and any water. Cut to Tradesman cleaning a filter. “Air filters”: Air filters present a different problem from the filtration of liquids. Their use is essential in sandy dessert conditions. Sand comprises silica, a fierce abrasive, and if ingested by the carburettor will soon ruin the engine. Example shown of sludge from an engine without air filters. Oil is burnt off to reveal a residue of sand which has damaged the pistons/cylinder walls during it’s passage through the engine. Two types of filter are available; the dry type and the oil wetted type. Explained. Both are constructed in similar manner except the wet type is dipped in low viscosity oil before installation; the particles adhering to the oil rather than collecting together in the base as for the dry type. Cut to explanation of the maintenance procedures for both types. Film closes with example of damage to a crankshaft and bearing shells; for want of an efficient filter, an aero-engine may be lost.
  • Alternative Title:
  • Colour: B&W
  • Digitised:
  • Object_Number: AMY 161
  • Sound: Sound
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  • Featured Period:
  • Production Date: 1944
  • Production Country: GB
  • Production Details: ROYAL AIR FORCE (Production sponsor) Brent Productions (Production company)
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  • Link to IWM Collections page:

    AMY 161

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