Bell, PhotonFirst to Mature Fiber Optic SHM for Rotorcraft
The collaboration will mature FBG-based sensing for condition-based maintenance on Bell rotorcraft, drawing on PhotonFirst’s experience embedding optical fibers in composite aerospace structures.
By Grace Stubbins
Bell Textron Inc. (Fort Worth, Texas, U.S.) and PhotonFirst Technologies B.V. (Alkmaar, The Netherlands) have signed a memorandum of understanding (MOU) to further explore and mature the use of fiber optic sensing technology for advanced structural health monitoring (SHM) applications on Bell aircraft.
Fiber optic sensing is increasingly being adopted as a next-generation sensing technology for SHM applications. Compared with conventional electrical sensors, optical sensors are inherently immune to electromagnetic interference, can withstand high temperatures and can significantly simplify installation. Multiple sensing points can be integrated into a single small, lightweight optical fiber, significantly reducing cabling, weight and installation complexity.
These characteristics make this technology particularly suited to monitoring structural integrity of aircraft structures and components throughout their service life. The collaboration between Bell and PhotonFirst will focus on maturing the technology and further advancing its integration into rotorcraft applications. The structural data generated can support the transition from scheduled inspections and preventive maintenance toward condition-based and predictive maintenance. This will help Bell’s customers increase fleet availability and reduce maintenance costs.
Composites are well established across Bell’s platforms. Bell is responsible for the wing, transmissions, empennage, rotor systems and engine installation of the Bell Boeing V-22 Osprey, which CW has described as a composites-intensive tiltrotor. Similarly, its next-generation tiltrotor, the MV-75 Cheyenne, uses carbon fiber-reinforced composites in the wing, fuselage and tail. On the commercial side, Aviation International News reports that the Bell 525 Relentless is driven by an all-composite five-blade main rotor system.
PhotonFirst develops fiber optic sensing systems for aerospace, defense and other harsh environments. The company embeds optical fibers containing Fiber Bragg Grating (FBG) sensors into structures and components to measure strain, temperature, pressure and shape.
PhotonFirst’s fiber optic sensing technology has already been applied in composites-focused aerospace development work. CW reported on a Netherlands consortium led by Toray Advanced Composites that is developing a composite liquid hydrogen (LH2) tank for commercial aircraft. In that project, PhotonFirst concentrated on interrogator technology and on embedding optical fibers into composites. It developed a miniaturized optical safety system intended for permanent tank integration and planned to undergo qualification for in-flight aerospace use. In the SuCoHS project, which addressed composite parts under high thermal and mechanical loads, PhotonFirst optical fibers containing multiple FBG sensors were laid into a composite skin during automated fiber placement (AFP). The sensors then monitored strain and temperature during cure and later impact testing.
“For 20 years, we have been developing fiber optic sensing technology for some of the world’s most demanding environments,” explains Leendert-Jan Nijstad, CEO of PhotonFirst. “An aircraft structure is one of those environments, and succeeding there takes more than a good sensor. It requires the right approach to integration, installation and reliability. We’re proud to bring that experience to Bell and work together to turn structural data into better maintenance decisions.”
