Engine Oil System. Is It Important?
What Does The Oil System Do?
There are an array of functions that an oil system provides to an engine. The key functions are to provide lubrication to moving parts within the engine, cool down the engine through minimising of friction between those moving parts, transferring of heat away from moving parts, generating a barrier between cylinder walls and and pistons, and lastly transporting contaminants away from the moving parts (FAA, n.d., p7-16). Take for example, the joints in your body. If not properly lubricated (synovial fluid), can lead to stiffness of joints. Drawing comparison from that, if engine rotating parts are not properly lubricated, it can lead to many severe consequences. But, we will dwell more on that later.
What Does The Oil System Consists Of?
Generally, there are two types of engine oil system. Mainly, a wet sump type which consists of a sump and a pump, and a dry sump type which consists of an oil pump as well, but instead of a sump it has an external oil tank (FAA, n.d., p7-16). To further elaborate, a wet sump usually draws oil from the sump through an oil pump which sprays on moving parts. The oil falls back down in to the sump, and the cycle is repeated. For the dry sump, the oil is drawn through an oil pump from the external oil tank to lubricate moving parts. The oil is then returned to the oil tank through scavenge pumps in the engine. Besides the pump, sump, oil tanks, scavenge pumps that are mentioned before, the oil system also consists of a pressure gauge that detects the oil pressure supplied to the engine to ensure sufficient lubrication (FAA, n.d., p7-16).
Is It Important?
Oil systems are primarily present to lubricate bearings and other moving parts within the engine. If lubrication is not adequately supplied to these moving parts, it could lead to catastrophic failures within the engine such as overheating, bearing failure, and total mechanical failure. Take for example this failure analysis of bearings by Roy (2019), whereby most bearing failures were resultant from improper or lack of lubrication as evaluated by wear or rub marks on bearing surface. All these are evidence of metal to metal contact due to the absence of barrier provided by the oil on moving surfaces. As time progresses, the failure to lubricate moving parts led to wear and deformation due to excessive heat generated from rubbing, ultimately leading to bearing failures. Therefore, it is very important that oil systems are present within the engine as most parts are mechanical which are rotating or moving all the time. The oil can help prolong the life of the engine by ensuring smooth operations throughout.
References
Federal Aviation Authority (FAA). (n.d.-a). Chapter 7 - Aircraft Systems. FAA. https://www.faa.gov/sites/faa.gov/files/regulations_policies/handbooks_manuals/aviation/phak/09_phak_ch7.pdf
Federal Aviation Authority (FAA). (n.d.-b). Wet Sump oil system [Illustration]. FAA. https://www.faa.gov/sites/faa.gov/files/regulations_policies/handbooks_manuals/aviation/phak/09_phak_ch7.pdf
Roy, M. (2019). Failure Analysis of Bearings of Aero-Engine. Journal of Failure Analysis and Prevention, 19(6), 1615–1629. https://doi.org/10.1007/s11668-019-00746-3
Radu, C. (2020, March 17). Bearing Failure due to improper lubrication [Photograph]. Bearing-News. https://www.bearing-news.com/the-most-common-causes-of-bearing-failure-and-the-importance-of-bearing-lubrication/
Saif, M. (n.d.). Dry sump oil system [Illustration]. The Engineers Post. https://www.theengineerspost.com/types-of-lubrication-system/
Hey Thaddeus, I feel like most people would skip over the oil system when looking at aircraft systems. I believe its super important, up there with fuel systems. As we all know without oil the engine cannot lubricate itself which can cause a major failure in flight. I’ve always wondered and thought about ways to try to make the oil system more reliable but can never think of any. Besides regular maintenance, oil systems are pretty solid. I’ve never heard of an oil pump just stop working suddenly without external factors playing a role. With my background in fighter maintenance, I have wondered but never really thought of how the engines can pump oil with the aircraft inverted and such. I for some reason never thought of a dry sump oil system, guess its not really my job to worry about it but its cool none the less. Overall was a very good read and now you have me looking into all types of oil systems.
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