Northrop Grumman has delivered its 200,000th FMU-139D/B electronic fuze, marking a major production milestone for one of the US military’s most widely used bomb components.
Used in MK-80 and BLU-100 series bombs operated by the US Navy and Air Force, the FMU-139D/B controls how and when a munition detonates, including impact bursts and delayed explosions designed to penetrate hardened targets.
Northrop said the fuze has been fielded across multiple US and allied aircraft and weapons platforms over decades of service.
Production takes place at the Allegany Ballistics Laboratory in West Virginia, where the company said it can manufacture up to 85,000 units annually using a production line that is nearly 70 percent automated.
Unlike older mechanical designs, the FMU-139D/B uses an electronic architecture that allows operators to tailor detonation settings for different mission profiles. Northrop added that the system has achieved a 100 percent lot acceptance rate during production.
“There’s no room for error when a weapon is deployed, and that reality drives how we design, test and manufacture our fuzes,” Tanya Santers, director of bombs and missiles at Northrop Grumman’s Fuze & Warheads operating unit, said.
Procuring FMU-139 Fuze
Several US allies have procured the FMU-139D/B fuze in recent years as part of broader guided munitions and aircraft packages.
In May, the US State Department approved a $373.6-million sale to Ukraine covering FMU-139 fuze systems, support equipment, and spare parts.
Japan received approval for an $82-million package in November 2025 that also included the fuzes, while the US cleared in August 2025 a potential $3.46-billion sale to Nigeria that likewise featured the system among other weapons.
