Airbus is pushing its suppliers to incorporate advanced metallic coatings on the landing gear of its A380 ultra-large aircraft. The manufacturer "has advised vendors to avoid chrome plating" due to environmental issues and operational experience with chrome-induced cracking.
Messier Dowty, which is building the nose landing gear (NLG), and Goodrich, which is developing the body and wing main landing gears, are being encouraged to develop their High Velocity Oxy-Fuel (HVOF) coatings to replace chrome plating on the landing gear sliding tubes and hydraulic pistons.
Patrick Monclar, Messier Dowty's research and technology director, says HVOF coating will be incorporated on the A380's Messier Dowty NLG slider and hydraulic pistons, where chrome plating would traditionally have been used. The chrome plating application process produces highly toxic hexavalent chromium compounds and chromic acid - which are carcinogenic, and subject to US Environmental Protection Agency controls.
HVOF coating consists of particles of tungsten carbide, cobalt and small amounts of chromium applied at high velocity to the base material to produce a 0.1mm (0.004in) thick coating. Messier Dowty has had a HVOF-coated slider in service on a Lufthansa Airbus A320 NLG for two years. Boeing is using HVOF coatings on its 767-400ER landing gears.
Messier Dowty is building a large plasma-spraying installation, and aims to demon-strate HVOF coating on A380-size components by the end of the year, says Monclar (Flight International 14-20 May). The components will undergo testing on the effect of the coatings on static and fatigue strength and surface friction characteristics.
Source: Flight International
