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Understanding Jet Fuel System Maintenance

What owners need to know about ensuring fuel quality in their craft

Private jet owners know the paramount importance of protecting the aircraft’s value and ensuring the utmost safety and performance during operation. One crucial aspect of aircraft maintenance that often goes underappreciated is the maintenance of the jet fuel system.

The jet fuel system is a complex network of components designed to store, manage, and deliver fuel to the engines. These components include fuel tanks, lines, pumps, filters, valves, gauges, and the fuel management systems that use sensors, computers, and displays to provide the pilot with vital information about the fuel in the aircraft.

Global MX is particularly adept at servicing the inner workings of the fuel system. It’s just one of the many systems we inspect and maintain when you choose us as your maintenance partner.

Here are some of the most frequently asked questions we field from jet owners about fuel system maintenance:

Which fuel system components require the most regular maintenance or replacement?

This varies depending on the aircraft, but in any aircraft, fuel filters require regular inspection or replacement. We also find that electronically driven pumps and valves are subjected to stress during constant operation and often require repair.

Fuel nozzles also need regular maintenance and inspection. These nozzles distribute fuel to the combustion section of the engine and technicians must ensure the proper spray pattern.  If the spray is too concentrated, it can cause premature engine wear and operating difficulties.

What is the most common problem that occurs in the jet fuel system?

Leaks! There are several maintenance companies that have built their business solely around repairing fuel tank leaks.

Fuel is stored directly within the structure of the wings and sometimes fuselage of modern jets as opposed to within rubber bladders found in smaller aircraft.  An aircraft’s wings and fuselage tend to flex during takeoff and landing, placing stress on rivets and fasteners. This can lead to seeping seams and gaskets and wear on plumbing and valves. This is one of the primary reasons for regular inspections.

Other problems can actually arise during maintenance. A necessary evil – many fuel tanks may need to be opened to access the innermost areas during structural inspections. If not done properly, this can often induce leaking from the tanks.

How big of an issue is fuel contamination? What causes it?

It’s surprising how prevalent organic growth is in the fuel system, which is typically a symptom of the most common contaminant — water. Additionally, there have been several recent instances of DEF (diesel exhaust fluid) contamination that have caused in-flight shutdowns.

DEF has garnered such a spotlight that the FAA updated SAFO 18015 in 2023 to document cases of clogged fuel filters and fuel nozzle deposits from DEF (caused by contaminated refueling equipment) that led to service difficulties and emergency landings.

Frequent inspection of tanks, fuel nozzles and replacement of filters, along with regular sumping —  removing water through low-point drains, (as water is heavier than the fuel in the tanks) — are the primary measures to minimize the effects of contamination. Fuel testing kits are also a great method to spot potential hazards.

Should owners be doing anything to ensure the jet fuel quality? Should any testing and maintenance be left to their maintenance provider?

An owner operator can surely undertake sumping and testing. However, it’s important to note that no maintenance should ever be undertaken without a thorough familiarization of the procedure on that specific aircraft type. Countless sump drains have been stuck open or damaged due to improper execution, which can lead to gallons of fuel spilled and possible fines at certain airports.

Maintenance providers like Global MX spend years understanding the specifics of these procedures and how they vary between different aircraft types. If you are not an expert in these tests and repairs, the best thing you can do for the value and performance of your aircraft is to leave it up to the people that are!

How often should fuel systems be checked?

This depends entirely on the type of aircraft and how often it’s being operated. We aim to provide private jet owners with a comprehensive understanding of the importance of jet fuel system maintenance and equip them with the knowledge necessary to make informed decisions regarding their aircraft’s upkeep. Contact us to learn more about these routine jet maintenance services.