Aircraft Drawings — practice questions

4% of the exam ≈2 real questions 2 free questions here

A small subject at 4%, but the points are easy once the vocabulary is automatic: line types, title and revision blocks, dash numbers for left- and right-hand parts, zone numbers, orthographic views, and how tolerance is calculated.

Where people lose points

• Tolerance is the SUM of the plus and minus allowances, not either one alone.
• A phantom line (one long, two short dashes) shows an alternate position or a missing adjacent part; hidden edges are short dashes.
• Zone numbers read from right to left.
• The left-hand part is usually the one drawn; the right-hand part is called out by its dash number as 'opposite'.

Questions and answers, explained

All 2 questions above, with the correct answer and why it is correct. Everything here is on aircraft drawings.

1. On an aircraft drawing, a line made of one long and two short evenly spaced dashes is a phantom line. It shows

   • Aan edge hidden behind another surface
   • Bthe alternate position of a part or a missing adjacent partCorrect
   • Cthe center of a hole or symmetrical part
   • Dwhere an imaginary cut is taken for a section view

   Why: The handbook: phantom lines indicate the alternate position of parts of the object or the relative position of a missing part, drawn as one long and two short evenly spaced dashes. Hidden edges use short dashes; center lines alternate long and short dashes.

   Reference AM.I.B.K1 · FAA-H-8083-30B, Ch. 4 (Phantom Lines)

2. A drawing note reads 470204-1LH shown; 470204-2RH opposite. What distinguishes the two parts?

   • ATheir materials, listed in the revision block
   • BThe scale at which each part is drawn
   • CThe dash number, for the left- and right-hand partsCorrect
   • DThe zone number where each part is located

   Why: Both parts carry the same drawing number; the dash number calls out which one. Only the left-hand part is drawn, and the right-hand part is its mirror image. The handbook notes some prints use odd dash numbers for left-hand parts and even for right-hand.

   Reference AM.I.B.K4 · FAA-H-8083-30B, Ch. 4 (Title Blocks; Dash Numbers)

Drill other domains

• Electricity and Electronics (16%)
• Weight and Balance (6%)
• Fluid Lines and Fittings (4%)
• Materials, Hardware and Processes (8%)
• Ground Operations and Servicing (9%)
• Cleaning, Corrosion and Finishes (14%)

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