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Commentary on Likely Increase in JSF Engine Costs to Increase - Part 1

Air power discourse is The Central Blue’s core focus. In this two-part series, Gary Waters provides an in depth commentary on likely increases to the F-35 Joint Strike Fighter engine costs. This discussion continues the conversation of a recent Breaking Defense article, providing an Australian perspective around important air domain elements of sustainment. In Part 1, Waters takes us through the Breaking Defense article and highlights some of the challenges the F-35 faces.


This Commentary below refers to likely cost increases in the Joint Strike Fighter engine. A recent article in Breaking Defense noted that scheduled maintenance for the F-35's engine in the mid-2020s will drive up the price of engine sustainment, just as the Pentagon expects cost reduction goals to be achieved.

While the Breaking Defence article describes the challenges around engine cost containment, and offers a number of observations, the experience of a number of ex-RAAF engineers is worth noting. This Commentary below, therefore, outlines the key observations from the Breaking Defence article before discussing the key messages that provide insights into broader maintenance approaches and other options that could lead to improved engine performance and affordability.

The Breaking Defence Article

The Breaking Defence article indicated that the first F135 engines used by the F-35 will reach 2,000 hours and will be sent to the depot for a scheduled overhaul in the mid-2020s. While Pratt & Whitney, the engine manufacturer, is taking steps to minimise the cost of that maintenance work as much as possible, it’s unavoidable that engine sustainment costs will increase during the mid-2020s, according to the engine manufacturer.

This will make it more difficult for the F-35 program to meet a long-time goal: reducing the cost per flight hour to $25,000 by 2025. This difficulty should not be surprising; after all, sustainment is the largest portion of the life-cycle cost of platforms, and scheduled maintenance is the largest portion of sustainment cost.

Pratt & Whitney has been at pains to point out that there are several factors at play here that are not the company’s fault: unexpected wear and tear due to operational usage; inconsistent funding of spare parts; repeated delays in standing up maintenance depots; and the normal churn of engine overhauls, which typically ebb and flow as engines meet usage milestones.

The Pentagon noted in early 2021 that the F-35 was facing an engine shortage, which resulted in arguments to open a competition for more advanced engines to replace the F135. However, the engine shortage issues are multifaceted and not easily resolved.

As the Breaking Defense article indicates, the F135 Heavy Maintenance Centre at Tinker Air Force Base, Okla., has not been able to repair power modules as quickly as projected, creating a backlog of work. Furthermore, some aircraft that frequently operated in hot, sandy environments were grounded after the coating on engine rotor blades cracked and degraded. While Pratt & Whitney developed a new coating that has now been incorporated on about 25 percent of the F-35 fleet, it could take until 2030 for all fielded F-35s to be retrofitted.

In July, reports from the Joint Program Office indicated that 41 F-35As flown by the US Air Force were grounded and awaiting engine repairs, with an additional five other F-35s also inoperable due to engine-related problems. Fast forward to October, and we see little improvement, with reports indicating that there were 42 F-35As grounded due to propulsion issues.

Notwithstanding these affordability challenges, Pratt & Whitney is meeting program requirements in terms of the number of F-35s grounded for engine issues. The current contract obliges Pratt & Whitney to ensure that no more than 10% of F-35s are grounded due to engine issues, with 6% being the objective number. Historically, only 4% of the fleet has been typically non-mission capable because of engine problems. With about 9% of F-35s currently grounded due to engines, Pratt & Whitney is still technically within the levels of its agreement with the Pentagon.

Increased funding to expedite work at the F135 depot at Tinker, standing up additional maintenance hubs elsewhere, buying additional engines, and changing the F135 sustainment architecture, will take time to flow through to reduce the current backlog in engine maintenance and availability.

Pratt & Whitney has indicated that the depot network is about five years behind, largely because funds were diverted earlier in the program to meet other needs. In other words, sustainment did not receive the budget required in a timely manner.

There are some signs of improvement at the Tinker depot, which only produced 14 power modules last year, but is on track to exceed its target of 40 modules in 2021. Furthermore, while it took more than 200 days on average to repair a power module in 2020, that has been reduced to 120 days, and this will remain the goal for the future. However, the pressure on the depot will be even higher once engines begin coming in for scheduled overhauls in 2023.

The biggest drivers of cost during maintenance events are parts and materials, so Pratt & Whitney’s focus has been on conducting engineering work and developing repairs that enable maintainers to replace fewer parts during overhauls. Another long-term effort is making continual improvements to parts and managing the fleet so that engines can be installed for longer periods of time without having to be sent to the depot for scheduled or unscheduled repair work.

However, even if the company finds ways to reduce maintenance expenses, Pratt & Whitney anticipates added costs in the mid-2020s.

Join us for Part 2 and Water’s insights into maintenance and alternative options for improved engine performance and affordability.

Gary Waters spent 33 years in the RAAF, resigning as an air commodore and joining the Australian Public Service at the Senior Executive level. After four years in the public service, Gary became head of strategy for the Australian arm of a global defence company, retiring seven years later. He now consults on a part-time basis. He has a PhD in political science and international relations and has written extensively on defence, air power and cyber issues.


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