## Troubleshooting and Abnormal Operation 

The information in this section is for training purposes and should never be used for maintenance on the actual aircraft. Only qualified personnel (experienced two-stroke technicians) trained on this particular type of engine are allowed to carry out maintenance and repair work. If the following information regarding the remedy of the malfunction does not solve the malfunction, contact an authorized facility. The engine must not be returned to service until the malfunction is rectified. As described earlier in the text, engines require basically two essentials to run: spark and correct fuel/air mixture. The majority of problems quite often are a simple lack of one or the other. 

## Troubleshooting 

Follow an organized method of troubleshooting. This facilitates the identification of discrepancies or malfunctions. 

• Fuel—start by checking the supply (tank), fittings (loose), filter (plugged), and float chamber (fouled). 

• Spark—check for spark at the spark plugs. 

Problems of a more complex nature are best left to an engine technician. The following are examples of engine troubles and potential fixes. 

## Engine Keeps Running With Ignition OFF 

Possible cause: Overheating of engine. Remedy: Let engine cool down at idling at approximately 2,000 engine rpm. 

## Knocking Under Load 

Possible cause: Octane rating of fuel too low. Remedy: Use fuel with higher octane rating. Possible cause: Fuel starvation, lean mixture. Remedy: Check fuel supply. 

## Abnormal Operating 

## Exceeding the Maximum Admissible Engine Speed 

Reduce engine speed. Any overage of the maximum admissible engine speed must be entered by the pilot into the logbook, stating duration and extent of over-speed. 

## Exceeding of Maximum Admissible Cylinder Head Temperature 

Reduce engine power, setting to the minimum necessary, and carry out precautionary landing. Any exceeding of the maximum admissible cylinder head temperature must be entered by the pilot into the logbook, stating duration and extent of excess-temperature condition. 

## Exceeding of Maximum Admissible Exhaust Gas Temperature 

Reduce engine power, setting to the minimum necessary, and carry out precautionary landing. Any exceedence of the maximum admissible exhaust gas temperature must be entered by the pilot into the logbook, stating duration and extent of excess-temperature condition. 

## Engine Preservation 

If the engine is not going to be used for an extended period of time, certain measures must be taken to protect engine against heat, direct sun light, corrosion, and formation of residues. In particular, the water bonded by the alcohol in the fuel causes increased corrosion problems during storage. After each flight, activate choke for a moment before stopping engine. Close all engine openings like exhaust pipe, venting tube, and air filter to prevent entry of contamination and humidity. For engine storage of one to four weeks, proceed with preservation prior to engine stop or on the engine at operating temperature. Let the engine run at increased idle speed. Shut the engine down and secure against inadvertent engine start. Remove air filters and inject approximately 3 cubic cm of preservation oil or equivalent oil into the air intake of each carburetor. Restart the engine and run at increased idle speed for 10–15 seconds. Shut engine down and secure against inadvertent engine start. Close all engine openings, such as exhaust pipe, venting tube, and air filter, to prevent entry of contamination and humidity. 

For engine storage of engine for longer than four weeks and up to one year, proceed with preservation prior to engine stop and on the engine at operating temperature. Let the engine run at increased idle speed. Remove air filters and inject approximately 6 cubic cm of preservative oil or equivalent oil into the air intake of each carburetor. Stop the engine. Remove spark plugs and inject approximately 6 cubic cm preservation oil or equivalent oil into each cylinder and slowly turn crankshaft 2 to 3 turns by hand to lubricate top end parts. Replace and re-torque the spark plugs. Drain gasoline from float chambers, fuel tank, and fuel lines. Drain coolant on liquid cooled engines to prevent any damage by freezing. Lubricate all carburetor linkages using the proper lubricates. Close all openings of the engine, such as exhaust pipe openings, venting tube, and air intake, to prevent entry of any foreign material and humidity. Protect all external steel parts by spraying with engine oil. 

