Rotax 912 aircraft engine storage, how to properly store your Rotax 912 ultralight engine for winter.

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Getting your 912 Rotax light sport or ultralight aircraft ready for storage.

A lot of ultralight pilots do not use their aircraft for several months at a time, especially during the winter season. So here are some tips on proper storage of Rotax 912 engines.

Like anything else in life, preventative maintenance, is just what it implies. If you do this now, then that certain something shouldn't happen later.

Parts required:

  • gasoline stabilizer
  • enough synthetic oil to do an oil change
  • a new oil filter brand name preferred
  • moth balls
  • rags
  • tie raps or elastic bands
  • distilled water
  • silicate free antifreeze
  • carb intake sockets
  • spark plugs
  • silicone paste for spark plug threads

Tools required:

  • gas can if you are draining the fuel
  • siphoning hose  - for information on the Super siphon click here!
  • container if you are draining anti freeze
  • 13 mm socket
  • ratchet
  • feeler gauges
  • 17 mm socket or wrench
  • 5/8 inch spark plug socket
  • inch pound torque wrench

Getting the 912  ready for periods of storage - there are two ways of doing this. The first is with a fuel stabilizer. The second is by draining the fuel system.

1. To properly store the engine you first want to get it up to operating temperature. Add gas stabilizer to half a tank of fuel, take the plane up for one last flight, land with about 1/4 tank of fuel.

Stabilizing the gas is probably the most important thing to do when storing your 912 engine. Gasoline is a blend of dozens of different compounds. Over time, the more volatile compounds will evaporate, leaving a hard sludge that will plug up your carburetor's needle and seats as well as your high and low speed jets, preventing them from working. Gasoline stabilizer helps prevents this from happening.  AGAIN make sure the fuel tank(s) are NOT full when you put your craft in storage!

Why? Because when you next go flying you HAVE to fill it up with FRESH fuel!

2. The second way is to get the engine up to operating temperature by taking the plane up for one last flight, after you land change the oil and filter, and then drain the fuel from the tanks, fuel lines, fuel filter or gascalator and carburetor bowls.

Oil Change:

Now that you've gotten your engine up to operating temperature we need change the oil and oil filter, by doing this we remove all of the contaminants in the engine and engine oil. If the engine were stored without doing this these contaminates would form into sludge in the engine, oil lines, oil cooler or oil tank.

After you have changed the oil and filter, with the ignition turned OFF turn the engine over with the electric start making sure you have oil pressure, NEVER START a Rotax 912 engine after an oil change UNLESS you have oil pressure! Now crank the engine over on the starter in two, 15 to 20 second bursts.   This will ensure that any remaining contaminates are diluted and moved into the oil filter.

Do Not START the engine, if you start it any time during the storage period you will cause condensation to form and will contaminate the oil. You can turn the engine over by hand, turning it ALWAYS in the direction of rotation, or with the electric starter if you can turn it over with the ignition turned off.

Oiling the cylinders

Our next step is to oil the pistons and cylinders. To do this we have to remove the top 4 spark plugs, which may mean removing the engine cowl. Before removing the spark plugs use a bit of compresses air to remove any dirt or debris from around the spark plug holes. Now remove the spark plugs. With the plugs removed, spray a bit of "fogging oil" into each cylinder. DO NOT use WD 40 it will evaporate AND will remove any oil that is on the cylinder walls! When you have about a tablespoon  of oil in each cylinder with the TOP plugs OUT turn the engine over by hand 4 or 5 revolutions.

Re-install the spark plugs putting a little  silicone grease on the threads.

Carburetor and exhaust:

After your exhaust has cooled take a little of the "fogging oil" and spray it into the exhaust pipes,  I like to put a moth ball in each outlet and then cover the pipe ends with a rag or canvas cover secured by an elastic band or tie wrap. The moth balls will keep your friendly neighborhood mice from taking up residence.

It is also a good idea to do this in the cabin, wings, storage areas etc. ANYWHERE mice or squirrels may think of nesting.

If you have an air intake box or airfilter it is also a good idea to cover them, putting a moth ball inside the cover.


One of the most frequently forgotten items during storage is the battery. Your plane doesn't need it's battery over the winter, and leaving it in the plane in the cold can cause it to freeze. Batteries contain water, and water expands when it freezes. If it gets cold enough, the water/acid solution in your battery could freeze, cracking the battery when it expands. Then during a thaw the battery acid will be all over your plane! Take it out of the plane and bring it inside, remembering to keep it charged, the best method of doing this is with a "smart charger" this only charges it as much as needed and won't boil it dry.

  • If you can't afford or don't want to buy a smart charger, buy a cheap 12v trickle-charger ($10 or so) and hook it up to an automatic timer, so the battery gets about 30 minutes of trickle-charging a day.
  • Unless you have a maintenance-free battery, check the battery's fluid levels regularly to make sure the charger isn't boiling away the electrolyte. If the levels are low, add distilled water only to bring the levels back up.
  • Charge the battery in a well-ventilated area, particularly if your battery isn't "maintenance free." Batteries can emit hydrogen gas while charging, which is fairly explosive. (This is why wires get hooked up in a specific order when hooking up booster cables.)
  • All batteries: clean the terminals with a wire brush and lube them with a dielectric grease before returning the battery to service.
  • Do not start the engine over the winter! You'll  create condensation in the engine and combustion by products (acids, etc) in the oil. But you can turn the engine over by hand - or with the electric start if your battery it is installed.
  • When turning a 912 Rotax engine over by hand NEVER turn it over backwards!

    Winter is an excellent time to do other routine maintenance -- you'll miss flying, and it's a good way to spend time with your plane as you wait for the flying season to start.

    Read through your owner's manual, and perform any service that gets done once a year or more frequently, even if it isn't quite time yet.

    At the very least:

    • check the 912 intake sockets for cracking
    • inspect/replace/clean air filter
    • disassemble/clean/reassemble carburetors
    • gap and install new spark plugs, using silicon paste on the threads,  on new engines these should be gapped to .027 thou. - on older engines .022 thou. Torque on the spark plugs is 177 INCH LBS.
    • check your motor mount and rubber mounts
    • clean your windshield and prop with PLEDGE - you wife uses it for polishing furniture, it will fill in scratches and remove bugs etc.
    • check the exhaust for cracks, and springs for damage and proper tension
    • lubricate control cables and periodically move all of the control systems
    • check brake pads/ drums/rotors
    • check all bolts to make sure nothing is loose or worn
    • inspect tires for cuts, uneven wear, side wall cracking, proper inflation
    • change coolant, remember to use a silicate free anti-freeze with distilled water

Rotax 912 aircraft engine storage, how to properly store your Rotax 912 ultralight engine for winter.

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