F-35 A Aircraft Hangar Fire Protection Systems

With the arrival of the F-35 fifth-generation fighter jets, the Belgian Ministry of Defence required advanced fire protection systems for new aircraft hangars at Florennes Air Base and Kleine-Brogel Air Base. Both sites play a critical role in Belgium’s air defence capabilities and are undergoing significant upgrades to support fifth-generation aircraft while meeting NATO operational standards. As part of this programme, the hangars were required to comply with the latest edition of NFPA 409, the internationally recognised benchmark for aircraft hangar fire safety. 

Jensen Hughes was appointed to provide fire safety expertise for the project, working closely with Arcadis and Jan De Nul.While NFPA 409 permits several prescriptive fire protection options, many of these rely on fire-fighting foam systems. In this case, however, the Belgian Ministry of Defence had prohibited the use of foam due to concerns regarding environmental impact and the potential risk to sensitive aircraft surfaces. This created a significant challenge, requiring an alternative solution that would deliver equivalent levels of protection using only clean water, while fully satisfying the intent of the standard. 

The team collaborated closely with the client and project partners to develop a hybrid fire protection concept that combines a traditional sprinkler system with a low-pressure water mist system. The mist nozzles were strategically installed at floor level beneath the aircraft and connected to highly sensitive flame detection technology. This configuration enables rapid fire suppression at the point of origin, particularly for fuel-related fires near the aircraft, while minimising water usage, avoiding environmental contamination, and preventing damage to high-value assets. To validate the proposed solution, Jensen Hughes conducted a detailed, performance-based risk analysis in accordance with the ICAO Safety Management Manual. Key fire scenarios, including fuel spills, electrical faults, hot work activities and arson, were identified and assessed to understand how fires develop with and without suppression. 

The analysis examined the effectiveness, reliability and availability of the system, focusing particularly on preventing unwanted activations while ensuring a rapid response to credible fire events. Techniques such as fault tree analysis, structured 'what if' scenario evaluation in accordance with SFPE guidance and success tree methodologies aligned with NFPA 550 were employed to demonstrate that the proposed system would meet all safety objectives. This risk-based, performance-driven approach allowed the project team to justify the selected fire protection strategy and achieve full regulatory acceptance without reliance on foam-based systems. The final solution is a robust, low-pressure water mist system that provides effective fire protection for fifth-generation aircraft and safeguards critical NATO infrastructure, while significantly reducing environmental impact. In recognition of the technical innovation and collaborative approach demonstrated on this project, the team was nominated for the 2025 FireForum Awards.