FAA Aviation Mechanic Airframe (AMA)Airframe StructuresEasy
A technician is identifying bolts during an inventory check and finds a bolt head marked with a single raised dash. According to standard AN bolt head marking conventions, what does this marking indicate?
- AAn NAS close-tolerance bolt
- BA corrosion-resistant steel bolt
- CAn AN standard steel bolt
- DAn aluminum alloy bolt
Show answer & explanationAnswer & explanation
Correct answer: C. An AN standard steel bolt
A single raised dash on a bolt head identifies it as an AN standard steel bolt. NAS close-tolerance bolts typically use a recessed triangle or asterisk marking, corrosion-resistant steel bolts are marked with a cross or X, and aluminum alloy bolts are marked with two raised dashes.
Why the other options are wrong
- A. NAS close-tolerance bolts use a different marking, typically a recessed triangle or asterisk.
- B. Corrosion-resistant steel bolts are marked with a cross or X, not a single dash.
- D. Aluminum alloy bolts are marked with two raised dashes, not one.
AN Bolt Head Markings
Standardized markings stamped on AN bolt heads that identify the bolt's material and specification.
- Single raised dash = AN standard steel bolt
- Cross/X = corrosion-resistant steel bolt
- Two raised dashes = aluminum alloy bolt
- Asterisk or recessed triangle = NAS close-tolerance bolt
Memory trick: 'One dash, one common steel bolt.'