Controls and input devices should be sufficiently rugged to withstand normal and emergency use.
Additional Information:
Each device should retain its appearance, "feel," and functional characteristics during its service life. Broken, chipped, or crumbled control surfaces should not ordinarily occur. Control knobs or handles should not rotate, slip, or move loosely on their shafts. No internal wear or breakage should occur which alters the "feel" or other sensory feedback of a control. Controls should not develop internal looseness, binding, or backlash.