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USMC F-35Bs Delivered Without Radar: Ballast Fills Sensor Bay
3 Jul
Summary
- Six new F-35Bs received by USMC lack radar, carrying ballast instead.
- Lot 17 redesigns created incompatibility with older radar hardware.
- Radar delivery delayed until 2028, with full cooling by 2031.

Six F-35B stealth fighters have entered service with the US Marine Corps, notably lacking their AN/APG-85 radar systems. These aircraft were produced with ballast weights in the nose where the crucial sensor should be installed. The redesign of Lot 17 aircraft to accommodate the future AN/APG-85 radar made them incompatible with previous AN/APG-81 hardware, creating a gap in interim capability.
Marine Corps Lieutenant General Gregory Masiello confirmed six aircraft currently lack installed radars as of June 23, 2026. While these F-35Bs can support basic flight training, they are unsuitable for combat operations. This situation highlights broader F-35 readiness concerns, with a GAO assessment indicating only 25% mission-capable status in fiscal year 2025.
The delayed APG-85 radar is part of the Block 4 modernization, facing schedule challenges. The radar is expected around 2028, but necessary cooling system upgrades won't arrive until after 2031. This procurement reality underscores the complexities of modern defense acquisition.