The Pentagon has finalized a substantial approximately $6.6 billion agreement with Pratt & Whitney for the next batches of F-35 engines, critical powerplants for its stealth fighter fleet. This complex transaction secures propulsion for upcoming production Lots 18 and 19 as the United States continues to modernize its air forces.
Powering the Stealth Fleet Forward
The official contract cements negotiations for the F135 engines, the heart of every F-35, with deliveries for Lot 18 set to commence this fall, followed by Lot 19 next year. Jill Albertelli, Pratt & Whitney’s president of military engines, highlighted that the F135 is „the most advanced military engine in the world,” delivering unmatched thrust, reliability, and mission readiness. The company is significantly increasing its investments across its global production base and supply chain to meet the growing global demand for the F-35 program.
Initially an undefinitized deal, the Lot 18 contract, estimated at nearly $2.9 billion for 141 powerplants, has now been formally „definitized,” incorporating the additional award for Lot 19 engines. The Defense Department specified that Lot 18 funds approximately 140 production engines, along with spare engine modules and other equipment, totaling $3 billion. Lot 19 will contribute approximately 150 production engines, plus spares and equipment, at a cost of $3.6 billion. In total, F-35 manufacturer Lockheed Martin anticipates delivering 296 F-35s across Lots 18 and 19.
Technical Roadblocks and Operational Delays
Despite the massive influx of funding, the F-35 program faces notable challenges. The Pentagon plans to upgrade the F135 engine through a program known as the Engine Core Upgrade (ECU) to address rising power and cooling demands from new capabilities. However, a recent watchdog report indicates that ECU production will not begin until at least 2031, although Pratt & Whitney has stated it can be retrofitted into existing aircraft. A parallel effort is also underway to overhaul the jet’s power and cooling system.
A significant issue concerns the US military’s Lot 18 F-35s. These aircraft will be delivered with an unusual feature: weight ballasts in place of where a radar would normally go. While the new Lot 18 planes boast a modified bulkhead designed for the new APG-85 radar, the radar itself is not yet ready. Consequently, for a period, these aircraft will fly without the radar, using ballasts to ensure airworthiness and availability for limited training until the APG-85 is operational, possibly as early as next year.
Furthermore, since July 2024, and following a year-long freeze, new F-35s delivered by Lockheed have already been exclusively designated for training due to delays with a modernized software suite known as Technology Refresh 3 (TR3). It remains unclear when the Pentagon intends to certify this software as combat-capable, adding a layer of uncertainty to the F-35 program’s immediate operational readiness.
