Q about Assymetric Ops

[Con-Trail]

The critical engine is the engine, which when it fails, generates the biggest yawing moment.

In other words: it has everything to do with the moment arm, not the thrust. (Apart from loosing 50% of it that is)

When you have a twin-prop aircraft with co-rotating propellers, (lets asume that they turn clockwise) the critical engine is the left engine.

Assymetric blade effect
The downgoing blade creates the greatest thrust. With an engine turning clockwise the arm on the right hand engine is greater.

Thus, when the left engine fails, the right engine creates a bigger yawing moment. If the right engine would fail, due to the assymetric blade effect, the yawing moment would not be so great because the moment arm is smaller.

On Jets
There are also critical engines on jets. They are the 2 inboard engines on a 4-engined aircraft: Again the longest arm creates the biggest yawing moment so if 1 inboard engine fails, a big yawing moment would be generated

So I would go for A).

Hope this helps

C-T