Messier-Dowty Canada is testing a new coating to eliminate chrome plating on undercarriage legs and other components. Chrome plating causes environmental and health hazards and several governments are trying to eliminate it.

A High Velocity Oxy-Fuel (HVOF) applied coating is being tested on a Boeing F/A-18 Hornet nose-gear leg on a rig at Messier-Dowty's Toronto factory. The tests will run for nine months.

Chrome plating is used on the shock absorber and other undercarriage components, and HVOF, while being non-hazardous, can apply surface coatings with greater integrity (chrome-plating can leak) and with improved surface finishes. The coating can also be used on propeller hubs, actuators, helicopter rotor head components and jet engine components.

Allan Harvey, group vice-president, business and regional aircraft business unit, says the company can apply the technique to exterior surfaces and is aiming to extend the capability to interior surfaces as well.

Tests of the aircraft carrier operations-capable Hornet gear follows in-service trials using an Air Canada Bombardier CRJ regional jet, which has been flying since 1999 with the shock absorber on one leg treated using the system. The leg has been back to Messier-Dowty for strip down and subsequently been returned to service.

A Canadian-US body, the Hard Chrome Alternative Team, has been considering the elimination of chrome plating for some time and both governments and Messier-Dowty have contributed study funding.

Harvey says Messier-Dowty plans to have an HVOF facility running by the end of this year. There will then be a gradual switch to HVOF coatings.

"Realistically" it could be 10 years before chrome plating is eliminated from new production, says Richard Evans, Messier-Dowty Canada director business development. Evans says the US Air Force is using a similar system on landing gear repairs.

HVOF is a form of plasma coating with liquid fuel and oxygen used to accelerate metal powder - such as cobalt-cemented tungsten carbide - to high speed, melting the powder, which forms a dense, strong, low residual stress coating.

Source: Flight International