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Close-up image of the internal functions of a jet engine oil system

What is a Jet Engine Oil System?

A jet engine oil system is vital to any plane as it is responsible for providing a continuous flow of oil to the engine of the aircraft. The recirculatory system is needed to store, cool, carry, and distribute oil necessary for lubricating and cooling every gear, spline, bearing and carbon seal.

Under international air regulations, all planes are required to be equipped with a jet engine oil system for the engine and aircraft to function properly in all conditions. ExxonMobil oils comfortably operate within the temperature bracket of -40°C and 250°C, the scale required of jet oils. These products are Mobil Jet Oil 387, Mobil Jet Oil II, and Mobil Jet Oil 254.


Oil Flow

The filtered fresh oil is supplied to the various engine components through a series of pipes and/or internal flow passages.

The implementation of an antisiphon system prevents tank draining due to the siphoning effect created upon engine shutdown through the supply network when the tank is located above a supply nozzle. A pressure relief valve protecting the supply pump prevents abnormal output pressure during cold starts. 

Jet oils have different functions, of which ExxonMobil products offer to a premium standard.


Monitoring System

The engine oil system contains a monitoring capability that provides information to the cockpit engine health by measuring oil parameters such as oil supply pressure and temperature. In more advanced on-board computerised systems, additional factors are recorded and analysed either in real time or after landing. These can include scavenge temperatures, oil quantity in the tank and quantity of debris released by the sumps. 

All bearings and gears that are enclosed inside sumps and protected by a labyrinth of carbon seals, require lubrication. The lubricant acts as another form of protection in that it helps reduce friction between bearings and gears, thus minimising wear. It is important to note that in order to be leak free, the pressure inside the sumps must always remain lower than outside the sumps. Should a leakage occur outside the oil system, air bleeds could become polluted or there could be an engine fire. Hence, it is always best to regularly check and ensure the oil system is operating correctly. ExxonMobil provide a number of lubricants to help ensure the proper and safe working of your aircraft engines. To discover more about these lubricants, click here to speak with an expert.


Sump Lubrication

The oil sumps within an engine oil system require a minimum of two oil sumps distributed along the main shaft line, and sometimes more than four. To ensure the oil is retained within the oil circuit, each oil sump is pressurised and sealed. However, it is vital that the pressure inside the oil sump remains lower than the pressure outside the sump.

Understanding the basic methods and procedures of oil sump lubrication is beneficial as it can result in a very low cost, low maintenance, and a reliable system of equipment lubrication. Although simple in design, complexity arises around the application. Knowledge of the relationships between oil type, oil level maintenance, shaft speed and bearing housing design are important to determine the correct application. Moove Aviation offers products such as Mobil Jet Oil 387, Mobil Jet Oil II and Mobil Jet Oil 254 from ExxonMobil’s Jet Oil range. To request a quote on any of these products, click here, or you can speak to an expert regarding these products by clicking here.

If the level of lubricant is either too high or too low, excessive heat can be generated, in turn accelerating the degradation of the oil and shortening the life of the bearing. If the oil level is too high, a condition often referred to as ‘churning’ can occur. In this situation, air is whipped into the oil, which along with the induced heat raises the oxidation rate, shortening the effective life of the oil. Too little oil means there is not sufficient contact to lubricate the bearing and act as a heat sink to carry away the normal levels of heat generated by the bearing.

If you are experiencing problems with the sump, it could be due to poor oil sump lubrication. One of the most common causes of this is contamination of the particles within the oil. When the oil becomes contaminated, it can often result in wear of component parts, making aircraft less efficient and more costly, as these parts need to be replaced to maintain the safety of the aircraft. ExxonMobil aviation lubricants undergo strenuous testing, manufacturing and packaging processes in order to ensure all products avoid contamination and thus help your aircraft to operate at its maximum potential.

Moove Lubricants are a dedicated and authorised ExxonMobil European distributor, operating extensively throughout South America, Europe and Asia; representing Mobil lubricants in the automotive, industrial, marine and aviation sectors.

For more information visit our product pages or email aviation@moovelub.com for a quote.