What is the minimum letter height used to mark certified static and power grounds?

What is the minimum letter height used to mark certified static and power grounds?

• A. 1/2 inch
• B. 1 inch
• C. 2 inches
• D. 3 inches

Answer: (B)

Ensuring legibility of safety-critical markings is the key idea here. For certified static and power grounds, the marking must be easy to read at typical inspection and maintenance distances, under various lighting and conditions you’d encounter on an aircraft. Standards specify a minimum letter height of 1 inch for these grounding marks to guarantee readability and reduce the chance of misreading or confusion during preflight checks or troubleshooting. A half-inch would often be too small to read quickly or from a distance, while two or three inches, though legible, are usually unnecessary and may not fit on smaller panels. So the standard minimum keeps markings clearly readable without imposing excessive labeling on equipment.

Ensuring legibility of safety-critical markings is the key idea here. For certified static and power grounds, the marking must be easy to read at typical inspection and maintenance distances, under various lighting and conditions you’d encounter on an aircraft. Standards specify a minimum letter height of 1 inch for these grounding marks to guarantee readability and reduce the chance of misreading or confusion during preflight checks or troubleshooting. A half-inch would often be too small to read quickly or from a distance, while two or three inches, though legible, are usually unnecessary and may not fit on smaller panels. So the standard minimum keeps markings clearly readable without imposing excessive labeling on equipment.