Looking after your engine and propeller

Looking after your engine

The Rotax 912 series engine has an enviable reputation for reliability. Many, many thousands have been made and used in aircraft. However, just because it has a reputation for reliability doesn't mean you can take it for granted.

Foxbat Australia strongly recommends you register your Rotax engine serial number with the Rotax owner website - you will then receive by email any service bulletins which affect your engine.

Apart from the mandated pre- and post-flight checks and regular maintenance, there are a few other steps you can take to help your engine stay reliable:

  • wait until the oil temperature reaches 30º C before taxiing
  • wait until the oil temperature reaches at least 50º C before engine run-ups
  • on long descents, warm the engine every 1,000 feet with at least 30 seconds of power
  • if the oil temperature will not stay in at least the yellow arc, consider fitting an oil thermostat (standard on A22LS as recommended by Rotax)
  • if the coolant temperature varies a lot, consider using a waterless coolant (only on older engines, as recommended by Rotax)
  • change the spark plugs regularly as per Rotax maintenance schedule
  • keep the carburetors dynamically balanced (check every 200 hours or so)
  • based on type of fuel used, change the oil and filter at least as often as Rotax recommends
  • try to maintain at least 4,800 rpm in the cruise and better 5,000 or more. Rotax engines thrive on revs!

NB - WATERLESS COOLANT - it is important to note that the latest Rotax 912 series engines - including the 912iS Sport fuel injection engine - are NOT cleared for use with waterless coolant!


Looking after your propeller

Aeroprakt aircraft may be fitted with one of several different types of propeller, all 3-blade, on-ground adjustable for blade pitch:

  • KievProp; composite with brass leading edge inserts (supplied and recommended by the Foxbat factory)
  • WarpDrive; carbon fibre with nickel leading edge additions (tapered or broad blade)
  • Bolly; carbon fibre with Kevlar leading edge inserts

There are pro's and con's to each of these but whichever one you prefer, here are some general tips to look after your propeller:

  • ensure all three blades are pitched exactly the same; even ¼º difference can induce vibration, which will eventually damage the exhaust system and maybe even the engine gearbox
  • closely inspect the blades during pre- and post-flight checks to ensure any stone damage is quickly identified and rectified
  • when taking off, apply power slowly and lift the nose off the ground as soon as possible before applying full power. This will minimise stone damage
  • avoid flying through rain. The metal (or Kevlar) edges of the blades will help to protect them but the blade inner leading edges and backs will erode with frequent flying in rain
  • if you find vibration is a constant problem (even after balancing the carburetors and checking the blades are pitched identically), it may be that the cylinder firing order is synchronized with one of the prop blades. Try removing the propeller from the gearbox flange, turn it through one bolt hole, and re-mount to the engine
  • keep your propeller clean and free from dead insects
  • only use recommended cleaning agents


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