How and Why: Aircraft Engine Preheating

Posted on January 23, 2020 Joe Aircraft Bearings

If it's cold enough, shortly after take off, a single cold start can cause severe aircraft engine problems. The degree to which a cold start will damage an engine depends upon factors like the type of engine, the engine’s age and condition, whether the engine has steel or chrome cylinders, and what kind of engine oil is being used. As a general rule, a “cold start” occurs when the engine is at a temperature below freezing (32F or 0C). Any start below 20F or -7C is very dangerous to a power plant.

The cause of “cold-start” damage is due to dissimilar metals used in aircraft engines and their reaction to cold weather. When cooled, aluminum alloy parts like the crankcase, pistons and cylinder heads, contract twice as much, as the contraction of steel parts like the crankshaft, camshaft, connecting rods and cylinder barrels. When these parts contract at the same time, there is no room left between metals for oil to lubricate and avoid friction and therein is a recipe for disaster. This point is why the myth of warming up the engine oil to avoid “cold start” damage is a false hope. Even with warm oil, if there is no clearance between metal parts for oil to go, it doesn’t matter how warm the oil is. With this being said, it is absolutely essential that preheating occur prior to the start of the engine.

The best way to preheat an aircraft engine is to leave the aircraft overnight in a heated hangar. 8 to 12 hours in a 40F hangar will heat every part of the airplane at an even temperature and ensure a safe start and proper functionality. Currently, most Fixed Base Operators (FBOs) charge anywhere between $20 to $50 to store a 310 aircraft overnight. An alternative to overnight hanger heating is multipoint electric heaters. These heaters attach directly to the oil pan, the crankcase, and each cylinder. A few hours plugged into a 115V or 230V power supply and you can at least be assured to have warm cylinders, a warm case, and warm oil when you start up.

In extreme cold, or if you have to preheat outside - particularly if its windy - engine and prop covers are a great way to insulate the engine compartment and keep most of the heat generated by your multipoint electric heater from escaping. One compelling advantage of insulated engine and prop covers is you may be able to get away with not preheating at all. Covering the engines right after landing and only staying on the ground for four hours or less, the covers can retain the natural heat from the engine. Lastly, some FBOs use large forced-air preheating units that are readily accessible for use to preheat an aircraft before departure.  

At ASAP Parts 360, owned and operated by ASAP Semiconductor, we can help you find the aircraft engine solutions you need, new or obsolete. As a premier supplier of parts for the aerospace, civil aviation, and defense industries, we're always available and ready to help you find all the parts and equipment you need, 24/7x365. For a quick and competitive quote, email us at or call us at +1-708-387-7800.

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