Blueprint Reading & Interpretation Flashcards

On an aircraft wiring diagram, what does a circle with an 'X' inside typically represent?

Answer: A lamp or light bulb

In aircraft wiring diagrams, a circle with an X inside is the standard symbol for a lamp or light bulb.

What is the meaning of the abbreviation 'REF' placed next to a dimension on an engineering drawing?

Answer: The dimension is for reference only and does not control manufacturing

A REF dimension is provided for information only; it is not used to inspect the part or control manufacturing tolerances.

In aircraft blueprint reading, what does the term 'DATUM' refer to?

Answer: A fixed reference plane or point from which measurements are taken

A datum is an exact theoretical reference plane, axis, or point established on a drawing from which all feature locations are measured.

An aircraft hydraulic schematic shows a triangle pointing toward a line. What does this symbol represent?

Answer: A check valve allowing flow in one direction only

A solid triangle (arrowhead) pointing in the direction of permitted flow represents a check valve in hydraulic and pneumatic schematics.

What does 'CRES' stand for in aircraft material callouts on drawings?

Answer: Corrosion Resistant Steel

CRES is the abbreviation for Corrosion Resistant Steel, commonly used in aircraft structural and fluid system components.

On a multi-view drawing, what is the standard arrangement of views in third-angle projection (used in the US)?

Answer: Front view center, top view above, right side view to the right

In US third-angle projection, the top view appears above the front view and the right side view appears to the right of the front view.

A drawing callout reads '4X Ø.250 ±.005'. What does this specify?

Answer: Four holes each with a diameter of .250 inches with a tolerance of ±.005 inches

The '4X' multiplier means the feature is repeated four times; Ø.250 ±.005 specifies a diameter of .245 to .255 inches for each hole.