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ALC-30: Multi-Engine Safety Review
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Course Review, Notes, Resources

Chapter 1 - Critical Concepts

In a light twin, loss of power on one engine results in:  

Yaw toward the failed engine (from asymmetric thrust).
Roll toward the failed engine (from loss of airflow over the wing).
Drag on the failed engine side.  

Asymmetric thrust is a key consideration in flying light twins, because loss of an engine results in yaw toward the dead engine.  In a conventional light twin (both engines turning clockwise), P-factor on the right engine is a major factor.  Because the right engine's greatest thrusting moment is to the right of the airplane's center of gravity, it produces significant yaw toward the left if the left engine fails.  The left engine is thus considered the critical engine because its failure has a greater adverse impact on aircraft control and performance.   

Chapter 2 - Control Considerations

The effectiveness of the rudder and ailerons is related to airflow – the greater the airflow, the more effective they are.  Airflow depends on airspeed, so it is necessary to establish and maintain an airspeed that will provide enough control authority to counter yaw and roll after engine failure.   The published minimum control airspeed – Vmc -- is designated by a red radial line near the low speed end on most airspeed indicator.  

Chapter 3 - Basic Performance

Vmc varies, and many light twins will not maintain level flight near Vmc with one engine inoperative.  Establish and maintain a higher speed – Vyse (“best rate of climb with a single engine”).  Vyse is designated on the airspeed indicator with a blue radial line and generally known as “blueline.”  Vyse does not guarantee ability to climb with one engine inoperative.
Sideslip significantly increases drag, which is bad for both aircraft control and performance.   To achieve zero sideslip with one engine inoperative, the pilot must use rudder and ailerons to bank toward the good engine.  The inclinometer will be deflected toward the good engine by about one-half of its diameter.
Chapter 4 - Takeoff Performance 

Takeoff planning is essential.  Never try to fly before reaching Vmc, since an engine failure below that speed would leave you without enough rudder effectiveness to control the airplane.  Review emergency procedures, so you will be fully prepared to act promptly (and correctly) if you lose an engine on liftoff, or just after takeoff.  
Accelerate-Stop Distance is the runway required to accelerate to Vr and bring the aircraft to a complete stop if you experience an engine failure right at Vr.
Accelerate-Go Distance is the runway required to accelerate to either Vr and, assuming an engine failure at that instant, continue the takeoff on the remaining engine and climb to a height of 50 feet.  Not all manufacturers specify an accelerate-go distance.

Chapter 5 - Climb Performance

Climb performance depends on an excess of thrust (power) over what is required for level flight.  Losing power on one engine represents a 50 percent loss of thrust, but it often results in an 80 to 90 percent loss of climb performance - sometimes even more.  

Chapter 6 - Cruise Performance
The single engine service ceiling is the altitude at which a twin-engine aircraft can no longer climb at 50 feet per minute in smooth air, with one engine feathered, at maximum certificated takeoff weight.  
If you lose an engine at an altitude above single engine service ceiling, you can expect to drift down to the single engine service ceiling.  Review the single engine service ceiling before each flight to determine if the airplane can maintain appropriate minimum altitudes and remain clear of terrain and obstacles. 
Chapter 7 - Approach and Landing Performance
If you have to land a light twin with just one good engine, fly the approach and landing as near to normally as possible.  Execute the approach and landing successfully the first time; your airplane may lack the power to make a successful go-around on just one engine.
Chapter 8 - Light Twin Training and Proficiency
Know key airspeeds and be thoroughly familiar with the AFM/POH recommended procedures. Know the basic one-engine-inoperative (OEI) emergency procedures common to all conventional light twins: 

  • Control . Maintain directional control with rudder and aileron. Assume the pitch attitude for Vyse.
  • Configure . Execute the memory items from the "Engine Failure After Takeoff" checklist.
  • Climb . Assume the bank angle and ball position for zero sideslip and maintain the best climb rate at Vyse.
  • Checklist . Review and accomplish any remaining checklist items appropriate to the situation.  

Practice with a qualified flight instructor at regular intervals.  Thoroughly brief all training activities, especially simulated engine failures, in advance.

For a copy of the course notes, please download the document below.


Related Media for this Section
View the file Multi-Engine Safety Review Course Notes.pdf
Multi-Engine Safety Review Course Notes
Multi-Engine Safety Review Course Notes.pdf (934.64 KB)

For more detailed information, download the document below, which is the multi-engine flying chapter of the FAA's Airplane Flying Handbook.  You might also find it helpful to visit the Learning Center Library for a copy of the safety pamphlet on Flying Light Twins Safely (P-8740-66).

Related Media for this Section
View the file FAA-H-8083-3a Chapter 12.pdf
Transition to Multiengine Airplanes (Airplane Flying Handbook Chapter 12)
FAA-H-8083-3a Chapter 12.pdf (1.03 MB)
View the file FlyingLightTwinsSafely.pdf
FAA - P - 8740-66 "Flying Light Twins Safely"
FlyingLightTwinsSafely.pdf (292.33 KB)

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