Engine Preservation And Storage; Engine Corrosion And Prevention - Lycoming IO-360-N1A Installation And Operation Manual

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IO-360-N1A Engine Installation and Operation Manual

Engine Corrosion and Prevention

The life expectancy of engines in aircraft that are not in flight frequently (flown for 1 hour within 30

days) can decrease because of engine corrosion. Engine corrosion occurs when moisture from the air

and products of combustion mix to cause corrosion on cylinder walls and bearing surfaces when the

aircraft is not used.

Corrosion rates can increase because of variable factors such as environmental conditions (humidity,

salt air in ocean areas), seasonal changes, and engine usage.

Since conditions can change, the corrosion rate can change. Aircraft operated close to oceans, lakes,

and rivers and in humid regions have a greater need for engine preservation than engines operated in

arid regions. In regions of high humidity, corrosion can be found on cylinder walls of new

inoperative engines in as little as 2 days. Whereas in less humid environments, cylinder walls on

engines that have 50 hours or more time in service within weeks, can have a varnish coating that will

protect them from corrosive action. Such engines under these atmospheric conditions can be inactive

for several weeks without evidence of damage from corrosion. Engines that are in flight only

occasionally (less than one time per week) are more at risk for corrosion.

NOTICE: The best way to decrease the risk of engine corrosion is for the aircraft to be in

flight at least every 30 days for at least 1 continuous hour at oil temperatures

between 180°F to 200°F (80°C to 93°C), depending on location and storage

conditions. This continuous 1 hour of operation does not include taxi, take-off and

landing time. If the engine cannot be operated at the recommended oil temperatures,

speak with the aircraft manufacturer about the use of oil cooler winterization plates.

NOTICE: The Lycoming warranty does not include corrosion unless otherwise identified on the

notice tag for new, rebuilt, or overhauled engines sent from Lycoming Engines.

Because climate conditions are different in various geographic areas, Lycoming Engines only can

give general recommendations for corrosion prevention. The owner and operator must take into

account the following factors for setting a rust and corrosion prevention maintenance schedule for

the engine:

 Environmental conditions, especially humidity

 Salt spray from the ocean

 Size of the oil cooler system for the engine and airframe installation. (If the oil cooler system

is not the correct size, it can cause the engine to overheat or operate below the minimum

temperatures.) Low temperature operation can cause a build-up of water and acids.

For operation at the correct temperature:

 Make sure the aircraft temperature gages are correct.

 Examine the condition of cooling air baffles. There must not be any blockage.

 Make sure the baffles are the correct fit for maximum cooling air flow.

 Complete oil and oil filter changes per the recommended intervals in Chapter 12-10 of the IO-

360-N1A Engine Service Manual.

 Complete a monthly inspection of engines stored in humid conditions and/or in flight less than

once a week.

February 2016