Parker Aerospace’s Fluid Systems Division has developed critical fuel-vent and line static dissipating tubes in collaboration with OEM customers to safeguard today’s modern composite aircraft from the risk of fuel-tank ignition and serious safety incidents.
Why composites for aircraft?
Once used only for light structural pieces or cabin components, carbon composites are now being utilized for wing and fuselage skins, engine components, and landing gear. Lightweight and strong, composites reduce weight and increase fuel efficiency while being easy to handle, design, shape, and repair. They also offer improved reliability and durability while reducing the number of heavy fasteners and joints in an aircraft, which are potential failure points.1
Aircraft manufacturers have been attracted by the advantages of composites. New aircraft using composite wings provide lower fuel use per passenger than comparable aircraft.2 Carbon composites have been portrayed as the perfect aircraft material – except for in the way that they handle lightning strikes.
The impact of lightning on aircraft
According to an article in Scientific American, “What happens when lightning strikes an airplane,” each U.S. commercial aircraft is struck by lightning more than once every year, usually attaching first to an extremity like nose or wing tip3.
Aircraft with an aluminum fuselage and wings can readily conduct the charge from a lightning strike, allowing the current to move along the skin and pass back into the atmosphere. However, composites are significantly less conductive than aluminum.
On composite structures, the current from a lightning strike does not have a highly conductive pathway that allows the electricity to transfer back into the atmosphere. Without dissipation, the lightning currents could ignite the fuel in the fuel tanks, fuel lines, and fuel vents. That’s why our fuel vent and line static isolating tubes are so valuable.
Our fuel vent and line static isolating tubes
Composite wings need isolating and dissipating tubes to slowly dispel the static charge from a lightning strike, thereby preventing arcing in the system. Installed in-line with the fuel lines and fuel vents, the tubes resist electrical energy and eliminate its transfer across the tube. This protects the fuel lines and the rest of the fuel system from possible combustion.
Proven in the air
Our fuel and vent line static isolating tubes are tested and proven. The components are currently installed on all HondaJet business aircraft as well as Northrop Grumman Global Hawk unmanned aerial vehicles. Available in multiple diameters, including 1/2-, 3/4-, 1.0-, 1.25-, 1.5-, 1.75-, 2.0-, 2.5-, 3.0-, 3.5-, and 4.0-inch inner diameter, the tubes are available with ferrules on each end and tubes with a flange mid span to meet most installation requirements.
The growing use of composites in aircraft manufacturing will increase the need for technologies that maximize the advantages of composites while minimizing their limitations. Our fuel-vent and line static isolating tubes will continue to play a critical role in keeping more-composite aircraft safe from ever-present lightning strikes.
For additional information, download these white papers from the division.
This post was contributed by Glen Kukla, engineering team leader, Parker Aerospace, Fluid Systems Division