Multi-Engine aircraft offer a potential safety advantage through redundancy, but only if the pilot has the knowledge and skill to manage their greater complexity and differing flight characteristics.

Induced Airflow

Wing-mounted engines create additional lift from the induced airflow of the propeller slipstream. This accelerated slipstream allows twin-engine aircraft to carry more weight without significantly increasing the wing surface area, but higher wing loading results in higher stall speeds and faster approach speeds. A sudden power reduction will cause an immediate loss of lift and a high sink rate. Pilots should remember to carry sufficient power throughout the approach to landing and smoothly reduce the throttles during the flare and touchdown rather than chopping the power over the approach end of the runway.

Torque

In a conventional twin-engine airplane both propellers rotate clockwise when viewed from behind. The torque produced by both propellers spinning toward the right causes a greater rolling tendency to the left than in a single engine airplane. Twin-engine aircraft equipped with counter-rotating propellers eliminate this effect, since the torque from the left engine cancels out the torque from the right engine.

P-Factor

A left-turning tendency is created at high angles of attack when the descending propeller blade produces more thrust than the ascending blade. This asymmetrical propeller loading causes an even greater yawing tendency to the left in a twin engine airplane because there are now two descending propeller blades. In twin-engine aircraft equipped with counter-rotating propellers the P-Factor of the left engine cancels out the P-Factor of the right engine.

Flight Controls

Multi-engine aircraft typically utilize a larger rudder in order to provide greater control over the yawing movement that occurs when one of the engines fails. Rudder effectiveness can be increased by enlarging the surface area, increasing deflection, increasing airflow around the rudder, or increasing the lever arm by placing the rudder further from the center of gravity. All of these measures will tend to make the rudder harder to move than in a single engine aircraft. Some of the pressure can be alleviated by utilizing rudder trim, a normal feature of twins. Pilots should remember to remove any rudder trim before landing in order to prevent directional control problems once the power is reduced on the operative engine.