Engine maintenance StandardAero

Cost-Saving Tips For Engine Maintenance

For airlines taking delivery of new or remarked aircraft, extensive due diligence is called for to establish an engine lifecycle management plan.

When airlines take delivery of new or remarketed aircraft, establishing an engine lifecycle management plan is essential to maximizing on-wing time and minimizing shop visits. To do so requires long-term due diligence.

“A strong fleet strategy takes into account how long the aircraft will be held, how many will be leased or owned and how they will be operated,” says Peter Requa, Southwest Airlines senior director for supply chain management. “The ability to make long-range forecasts greatly enhances being able to commit to volumes of work, providing for better cost control for both supplier and customer.”

In that regard, Peter Turner, StandardAero president for airlines and fleets, notes that some airlines fail to plan for high-dollar, long-term maintenance events. “For a new engine, nacelle and thrust reverser refurbishments, as examples, are usually 5-10 years into the future, so the airline may not want to plan that far ahead for an engine they may not even operate at that time.”

Jim Holmes, co-owner of Turbine Management Solutions in Boca Raton, Florida, reports that the biggest mistake airlines make is to craft a technical plan based on what is required from an airworthiness perspective, without cost-saving considerations.

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As engines exit power-by-the hour-type agreements, airlines are looking for ways to optimize those assets, in some cases through a tailored approach with an MRO or OEM.

“If you look at the plan commercially, there is always flexibility to do things differently, which can save money,” he says. “This, and not following through with the plan, are the two biggest problems. Many operators just let things happen.”

Fortunately, these and other difficulties with engine life-cycle management planning can be greatly reduced if not eliminated totally. For instance, according to Rudy Bryce, general manager, GE Aviation Materials and TrueChoice Transitions, desired reliability and daily usage must be the focus.

“It’s a balancing act to determine the return on investment the operator will achieve through greater reliability and utilization, compared to maintenance costs,” Bryce says. “For example, will an additional dollar of maintenance cost mean $20 worth of greater revenue-generating capability because of higher reliability and utilization?”

Engine life-cycle planning, Bryce stresses, also means incorporating the flexibility and degree of risk aversion the operator is willing to accept. To do that, he explains, the carrier should consider the estimated operational time horizon for the aircraft, where the engines are in their life span and the remaining life assumptions on the engines at the conclusion of the aircraft’s time in the fleet. “If it’s a leased aircraft, contractual redelivery conditions also need to be factored in,” he says.

Holmes says that an engine life-cycle management strategy should be predicated on whether the aircraft is owned or leased, citing end-of-life residual value as a factor. 

GE Aviation

“A leased asset can be almost at the end of its life at the return point, depending on the return conditions—due to the timing of the last shop visit,” he says. “The leasing company is fine with that as long as it has collected maintenance reserves since that shop visit. However, an owned asset, depending on how old it is, could have zero residual value on the airline’s books but be worth a considerable amount in the market” based on how much life remains before the next shop visit and life.

Holmes also says any engine life-cycle management plan should be structured on a total fleet planning concept, in which the operator views the fleet as a whole asset and not as individual aircraft. Depending on when leases terminate, this perspective can be advantageous because the airline can plan to have the engines’ remaining lives coincide with the leases’ end-of-life conditions. But he cautions that planning on that level is fluid and changes  as engine removals occur.

“The reliability of a modern engine is exceptional, but unscheduled removals can still happen,” Holmes says. “When they do, it’s important to look again at the total fleet plan to see how an unscheduled removal can be mitigated. For example, if it happens early in the lease, then it would be possible to keep the engine as a spare—and prevent a shop visit for another engine before the end of the term,” he says.

Aircraft leasing agreements normally require the aircraft operator to pursue an engine workscope that maximizes the exhaust gas temperature (EGT) margin, according to Shannon Ackert, vice president of commercial operations for Jackson Square Aviation, a San Francisco-based aircraft leasing firm. He explains that lessors will calculate the operator’s maintenance reserve rate on the assumption that the maintenance provider will maximize EGT margins to maximize time on wing. To achieve that, says Ackert, the operator should comply with the suggested levels of required maintenance on each of the engine’s modules and components.

“The key point here is the term ‘suggested,’ and it is up to the airline to decide what that will be for each of the modules,” he notes. “The level performed will be dictated by the engine’s performance. Very often, an airline will make a trade-off between investing more money in keeping the engine on wing longer, or it may decide to invest less with a shorter period between overhauls.”

In that regard, Ackert cautions that when an older, legacy powerplant is involved, the operator should exercise more discretion as to the level of work it is willing to put into that engine.

“Often, an airline may want to purchase an engine with ‘green time’ [meaning flying time] left on it, instead of investing in a more costly overhaul,” he says. “Generally, when you start to reach the end of the engine’s life, or the time period you plan to use it, the goal is to preserve cash—to minimize shop visit costs and not to maximize time on wing.”

GE Aviation’s Bryce agrees that a green-time engine may be an alternative to a major overhaul, but he stresses that under some circumstances it should be a seen as a bridge to when the aircraft is retired.

“When considering a green-time engine to save the cost of an overhaul, it’s generally an option, if there is less than one year of operation planned for the aircraft,” Bryce says. “Beyond a year, it’s a trade-off: Will the operational horizon be long enough to justify the cost of an overhaul?”

Bryce also points out that as engines mature, used serviceable material becomes an attractive maintenance option. “For many older engines, you have very active trading of used serviceable materials, which provides added value to the engine,” he says.

Southwest’s Requa, however, reports that legacy powerplants bring both opportunities and challenges.

“Generally, material and pricing goes down, often dramatically, in the latter part of an engine’s life cycle. The ability to leverage surplus, designated engineering repairs and third-party MRO facilities provides tremendous opportunity. But the downside can be waning interest in support by the OEM, less reliability, higher fuel burns and an inability to firmly predict when the costs for a legacy engine will begin to fall,” Requa says.

Turner, at StandardAero, says that as engines exit OEM power-by-the-hour-type agreements and enter into “the more mature stages of their maintenance cycles,” owners look at the available maintenance practices in the marketplace to optimize asset value. “For example, an airline may decide to negotiate a more limited power-by-the hour agreement with the OEM or look at other available options,” he notes. “Often, optimizing the maintenance plan will take the form of a tailored maintenance agreement with an OEM or MRO.”

Another alternative, of course, is a time and material (T&M) approach. However, as Holmes points out, selecting T&M as an alternative to an OEM plan can be tricky.

“If the OEM has been successful in capturing the market on its support plan, then the only time that T&M make sense is right at the end of the asset’s life,” he says. “In this way, once part of the fleet has been retired, the engines can either be used as spares or torn down for serviceable used material. Delta Air Lines did this very well over the last few years with its Boeing 747-400s. The problem with doing T&M earlier in the engine’s life is that the engine manuals will not be mature, due to it being cheaper for the OEM to replace with new material rather than develop repairs,” says Holmes.

As airlines take delivery of the new-generation aircraft, the engines will generate an abundance of data, enabling the operators to be more proactive with optimizing on-wing life. But at the same time, the engine OEMs have been pushing the technology envelope to achieve better performance and fuel efficiency, says Turner.

“This has meant using more exotic materials, enabling operation at increased temperatures compared to older powerplants,” Turner says. “The result is that airlines are seeing increased levels of unscheduled maintenance events, compared to previous generations of engines at the time they were introduced. This makes it essential for the airline to have an appropriate support plan in place with the OEMs as the new engines enter service.” 

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