Five Jet Engine Tips to Lower Maintenance Costs

One common theme when managing aircraft maintenance costs is whether to spend a little more now or to pay more later, highlights John Terpstra, Jet Support Services, Inc. Following are some key tips to help lower your overall jet engine maintenance expenses.

Over the following paragraphs, we present lessons learned from real life that will help you answer questions on whether to spend a little more now or pay more later when it comes to your business aircraft’s engine maintenance…

Tip 1: Life Limited Component Replacement

Installing a Life Limited Component (LLC) with low-time remaining may seem like a great way to save out-of-pocket expense at the time of a maintenance event, but if the component has insufficient time or cycles remaining to get you to the next major inspection, it can quickly lead to added expense.

We sometimes see operators considering a lower-cost, low-time LLC part, but it is possible their decision will mean additional downtime later, along with additional expenses related to engine removal, reinstallation and consumables. Ultimately, this could also diminish the overall value of the aircraft.

Be sure to carefully calculate the time needed from the LLC to get you to the next event.

 Tip 2: Engine Performance Issues

Trend monitoring provides valuable insight into the overall condition of the engine. Monitoring these trend data can reveal shifts in the performance that are indicative of potential issues. Although most shifts are subtle, due to the expected degradation of the hot section of an engine over time, some changes point to a serious problem.

Don’t wait until later. Investigating the condition at an early stage could result in saving hot section components from further damage.

Failing to address issues with the combustion chamber, turbine nozzle or turbine blades (for example) over time could result in an expensive, unscheduled shop visit, or much higher than average costs at the next scheduled shop visit.

 Tip 3: Engine Preservation

My JSSI colleagues have all addressed this recommendation in past articles, but engine preservation is a crucial lesson to learn with regard to saving on maintenance expense.

There are typically periods of high utilization with business aircraft - and, likewise, there will be periods of low utilization. For a myriad of reasons, your aircraft may be parked outside for extended periods of time. Too often, the need to preserve the engines during this time is overlooked.

In many instances, preservation goes well beyond installing inlet and exhaust covers.

Almost every engine OEM has set requirements for preserving engines, based on the expected period of inactivity and whether the engine is installed or removed from the aircraft during that time. 

These may include:

• Monthly to bi-monthly engine runs;
• Disconnecting electrical power to the engines;
• Full preservation of the fuel system;
• Routine oil samples; and
• Occasionally dry-motoring the engine.

The above requirements are not only limited to aircraft parked on a ramp, however. Many engines stored in a controlled environment still require some form of preservation. It is therefore important to discuss the need for this process with any facility where you plan to leave your aircraft for an extended period.

Regardless of the method and how involved it is, the consequences of not following the OEM’s guidelines can be very costly in the longer-term. Depending on the length of inactivity, a full engine teardown could be required to return the engine to service (at a minimum cost of $100,000).

Tip 4: Unscheduled Event = Opportunity for Scheduled Inspection

Many business jet operators miss the excellent opportunity to accomplish a scheduled event while the engine is disassembled for an unscheduled repair…

If you are in the unfortunate situation of needing to access an internal engine component outside of one of your regular scheduled shop visits, it will be in your best interests to inquire about the additional costs to complete the sign-off for the next major inspection.

You could be pleasantly surprised; in some instances the additional costs are minimal. By performing the inspection now, you will not incur the extra expense for the same access just a short time later, thereby turning your misfortune into opportunity.

There’s an additional silver lining of savings here too: you may have access to certain components that are repairable now but would require more costly replacement down the road with continued engine operation.

Tip 5: Auxiliary Power Unit

Replacing the Auxiliary Power Unit’s fuel nozzle(s) and ignitor(s) - even when the requirement is only to inspect and replace when necessary - could save you expense and unexpected downtime later.

Operators have seen increased reliability by implementing this maintenance action. In particular, they lower their risk of damaged hot section components related to poor fuel nozzle spray patterns, which lead to streaking and hot spots. They also avoid unscheduled downtime related to a faulty ignitor.

With certain APUs, the cost to replace ignitors and fuel nozzles at each routine inspection, regardless of condition, could range from $10,000-$20,000 over a period of 1,000+ operating hours. It is better to spend this amount than be faced with a $150,000–$200,000 repair later due to hot section damage that could have been avoided.

Though this approach would be considered elective maintenance and not a guaranteed means of eliminating performance issues, it’s certainly justifiable given the potential cost avoidance.

Bonus Tip: Don’t Skip the Pre-Purchase Inspection

It is hard to address the issue of maintenance costs and not mention how critical a Pre-Purchase Inspection (PPI) is when acquiring an aircraft or engine. As part of your due diligence, it is highly recommended that you include a PPI performed by a service facility with which you are comfortable. In addition, hiring an experienced individual who will look out for your best interests is never a bad thing.

From a technical standpoint, no pre-purchase is complete without a thorough review of the logbooks.

 The value of an engine varies greatly depending on Service Bulletin and Airworthiness Directive compliance as well as inspection status and time remaining on LLCs.

There is no better way to assess the overall condition of an engine than through a borescope inspection. If damage is found, either the seller or their hull insurance (depending on damage type) should be responsible for the costs to remedy. Alternatively, this can be negotiated into the purchase price.

By accomplishing these two items—logbook review and borescope inspection—you will come away with a good understanding of the overall status and condition of the engine and have a much better feel for anticipated costs going forward.

In Summary

The above lessons point to taking a proactive approach to managing your jet engine’s maintenance costs. It is worth spending a little more now rather than taking the risk of paying much more later!

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