FAA Aviation Mechanic Powerplant (AMP)Reciprocating EnginesMedium
A four-cylinder horizontally opposed engine has a firing order of 1-3-2-4. Immediately after cylinder number 3 fires, which cylinder fires next?
- ACylinder 1
- BCylinder 2
- CCylinder 4
- DCylinder 3 again
Show answer & explanationAnswer & explanation
Correct answer: B. Cylinder 2
The firing order 1-3-2-4 means the sequence repeats continuously; after cylinder 3 fires, cylinder 2 is next in the sequence.
Why the other options are wrong
- A. Cylinder 1 is the first in the sequence, not after 3.
- C. Cylinder 4 fires after cylinder 2, not directly after 3.
- D. A cylinder cannot fire twice in succession in a normal firing order.
Firing Order
The sequence in which cylinders receive their power stroke, designed to balance the engine and reduce vibration.
- Common four-cylinder opposed engine firing order is 1-3-2-4
- Firing order is determined by crankshaft throw arrangement
- Correct firing order minimizes vibration and uneven loading
Memory trick: One-Three-Two-Four, march the cylinders evermore