Practically the only aircraft not using chrome plating is the Wright Flyer.  Every aircraft in the skies today uses chrome plating on hundreds, if not thousands, of parts large and small.  In fact, hard chrome plating is specified for almost every component likely to be subject to wear.  Even components that are not chrome plated by the OEM are often rebuilt with chrome during maintenance cycles, because hard chrome plating is one of the simplest means of adding material back to worn shafts and flanges.

 Hard chrome is used all over the aircraft
  • Landing gear cylinders
  • Axles
  • Pins
  • Engine shafts
  • Ball screw actuators
  • Flap and slat tracks
  • Lugs

 

The hundreds of hydraulic actuators used throughout the aircraft:

  • Hydraulic utility actuators (for landing gear, doors, etc.)
  • Hydraulic flight surface actuators
  • Engine actuators
  • Thrust reversers

Hard chrome plating is also used in internal diameters, such the IDs of hydraulic outer cylinders, IDs of lugs, position sensor holes in actuator rods, bearing holders, and other locations where wear is a problem.  Since IDs generally do not see the sort of abuse seen on ODs, ID coatings are often thinner, and thin dense chrome or flash chrome are often used instead.

Hard chrome has its limitations, of course

  • It can rebuild only up to about 0.015” thickness
  • Any part to be chrome plated must be stripped of other coatings, including paints
  • Areas that are not to be coated must be carefully masked
  • Any high strength steel component (such as hydraulic or landing gear) must be baked to remove hydrogen and prevent embrittlement, which is otherwise likely to cause complete failure of the part.
  • Since hard chrome cracks when it is thicker than about 0.001”, it must be sealed or its thickness restricted in high pressure hydraulic applications.


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