Flying Twin-Engine Aircraft
Double the fun and challenge

Two Approaches to Twin-Engine Flying in Flight Simulator
Takeoff Planning
Engine Failures in Flight Simulator
What to Do When an Engine Fails
Securing a Dead Engine
Climb Rate
P-Factor and the Critical Engine
The Dangers of Falling Below Vmc
Restarting the Engine
Approach and Landing with an Engine Out
Differential Thrust: Controlling Engines Independently
Twin-Engine Flying Tips
Suggested Reading

Related Links
Controlling the Engine
Setting Up Failures
Flying Jets
Cockpit Basics
Using the Mouse
Expanding Your Hobby
Beechcraft Baron 58

Flying twin-engine aircraft opens the door to many exciting challenges, both in real-world flying and in Flight Simulator. In a twin-engine aircraft, you can fly faster than in a single-engine aircraft, carry a heavier payload, and benefit from more backup systems. Twin-engine aircraft are the choice of pilots who routinely fly over mountains and water, travel long distances, fly at night, and cruise at high altitudes. Having more than one engine to keep you airborne brings a new safety factor into play. It also emphasizes the need to keep special piloting skills polished in case an engine fails.

Transitioning to a twin-engine aircraft, you will acquire new flying skills and perform different procedures than in a single-engine aircraft. Not only does a twin-engine airplane have two engines to control, but the aircraft usually is equipped with more complex features, such as retractable landing gear and variable pitch propellers. There's just more to learn: more instruments and more systems, more procedures that help you control a larger and more powerful aircraft on longer and often higher flights. That's the exciting challenge of twin-engine flying.

Two Approaches to Twin-Engine Flying in Flight Simulator

In general terms, flying twin-engine aircraft is not much different than flying single-engine aircraft in Flight Simulator. That is, if you only want to hop in the Flight Simulator cockpit and fly, all you have to do is throttle up and take off. Throttles and engines are synchronized by default. But Flight Simulator offers the virtual pilot the chance to learn twin-engine technique—and that includes what to do if you lose an engine.

Basically, there are two ways to approach twin-engine flying in Flight Simulator:

  1. Just throttle up and fly.
  2. Let twin-engine flying change your approach to flying. Once you do this, you'll begin to calculate what you will do if an engine fails on takeoff, soon thereafter, or somewhere during flight. And all this extra thought makes you a better pilot—and a better-prepared pilot—no matter how many engines your aircraft may have.

Takeoff Planning

Real-world twin-engine pilots review engine-out procedures before every flight, even if they've already made several flights that day. It's a good idea for Flight Simulator pilots to review engine-out procedures, too.

Here's an easy pre-takeoff twin-engine review. Speak these to yourself before every twin-engine flight:

  • "If an engine fails before V1: Close both throttles and use the brakes to stop on the remaining runway."
  • "If an engine fails after V1: Take off and deal with the problem as per the engine-out procedure."

Just saying these sentences aloud provides an instant review of what to do and reminds you that an engine could fail at any time. Remember, if an engine does fail on takeoff, you'll only have an instant to decide what to do.

Engine Failures in Flight Simulator

Of course, engine failures won't happen in Flight Simulator unless you make some errors, such as running out of fuel, forgetting to switch fuel tanks, or forgetting to lean the mixture. But you can also plan to have an engine failure. (For information, see Setting Up Failures.)

Saving Flights with Engine Failures

Saving flights with engine failures will help keep you in practice for engine-out procedures. Perhaps you'll want to select a few engine-out scenarios, such as having an engine fail on takeoff or during flight.

What to Do When an Engine Fails

Flying on one engine: The Beechcraft Baron 58 with a feathered propeller.

When an engine fails, you've got to do everything possible to:

  • Control the aircraft (airspeed, pitch, and yaw).
  • Achieve maximum power possible.
  • Reduce drag as much as possible.

A set procedure will help you compensate for the lost power and the effects of asymmetrical thrust. Today's twin-engine aircraft must be able to fly after losing an engine. This requirement, however, does not mean that that the airplane must be able to keep climbing.

Once you recover from losing an engine, the goal is to get the most power from the remaining engine(s) you have left, and reduce your aircraft's drag as much as possible.

Before you try to memorize the particulars of a procedure, here's the big picture of what you must do when an engine fails:

  1. Take care of the bad engine.
  2. Take care of the good engine.
  3. Find a place to land.
  4. Go there.

To perform a standard engine-out procedure

  1. Control the aircraft using the rudder.
    When an engine fails in real-world flying, the aircraft's directional control will be compromised. Your first task is to control the airplane, and you'll begin this process with the rudder because the power imbalance makes the aircraft yaw. Ruddering toward the good engine will help counteract asymmetrical thrust. If your joystick twists, twist the joystick toward the good engine, or, if you have rudder pedals (see Expanding Your Hobby), you will be able to physically kick in and hold the rudder that turns the aircraft toward the good engine. Use whatever rudder it takes to maintain heading.
  2. Make sure mixture controls, propeller controls, and throttles (in that order) are set at maximum power.
    • Push mixture and propeller controls full forward, but take care to adjust the mixture controls for maximum power. This will assure your good engine is getting plenty of fuel. At high altitudes, for instance, your engine runs best with a lean mixture.
    • Push both throttles forward to full power. Since you may not yet be sure which engine failed, this assures that you have your good engine at full power.
  3. Maintain Vyse.
    Remember, Vyse is the best single-engine climb speed when flying with one engine dead and the other operating at full power. Vyse is shown on the airspeed indicator by a blue line. It may be tempting, especially at low altitudes, to try to achieve a better rate of climb, but this is not possible and could ultimately cause you to drop below Vmc, the minimum controllable airspeed while flying on one engine. To recover from the resulting loss of control, you'll have to not only reduce your power to help stop the roll, but pitch the nose down to increase airspeed, again losing altitude. Again, Vyse is your best rate of climb when flying with just one engine. If you're flying at Vyse, you're doing the best you can.
  4. Reduce drag: set flaps up, gear up.
    Your goal at first is to maintain or achieve Vyse, so you've got to decrease drag.
  5. Identify which engine is out.
    • "Dead foot, dead engine" refers to the rudder pedal pressure. You will feel less pressure on the rudder pedal on the side of the dead engine.
    • Gradually decrease the throttle on the suspect engine.
  6. Verify which engine is out.
    If you decrease the throttle of the identified failed engine, the airplane should not be affected. If you notice a slight thrust decrease, the engine may be only partially failed.
  7. Feather the propeller of the dead engine.
    A propeller of a dead engine that rotates, or windmills, due to the force of the airflow is an enormous drag on the aircraft. Feather the propeller to stop it from windmilling and decrease drag. Make sure you feather the bad engine; this is the wrong time to accidentally feather the propeller on the good engine.
  8. Bank 5 degrees toward the good engine.
    When you are operating on only one engine and using the rudder to counteract the effects of asymmetric thrust, you will be sideslipping toward the side of the dead engine. To counteract the sideslipping, raise the wing with the dead engine, or "raise the dead," as the memorable phrase goes. Because lift acts perpendicular to the wing, banking about 5 degrees toward the good engine gives the aircraft a slight horizontal component of lift, which corrects for the sideslipping.
  9. Close the dead engine's cowl flaps.
    Since the engine is out, it doesn't need to be cooled with cowl flaps, so close them. Open cowl flaps cause extra drag.

Securing a Dead Engine

Once you have completed the engine-out procedure and you are sure that you will not be able to restart the engine, you'll want to secure the dead engine.

To secure the dead engine

  1. Close the throttle.
  2. Set mixture to idle cut-off.
  3. Feather the propeller, if you have not already done so.
  4. Set the fuel selector to Off.
  5. Set the auxiliary fuel pump to Off.
  6. Set the magneto switches to Off.
  7. Set the alternator switch to Off.
  8. Close cowl flaps, if you have not already done so.

Climb Rate

In a twin-engine aircraft, it may seem that if you lose one engine, then you'll have half the usual amount of power. But that's not the case. The power available in excess of the power required to maintain level flight determines aircraft climb performance. With an engine out, your aircraft is now a single-engine aircraft that is carrying the dead weight of the nonfunctioning engine, as well as any excess drag from the nonoperating engine and propeller. Under normal operating conditions, you need roughly 40 percent of your total power for level flight. When you lose an engine, you lose 50 percent of your aircraft's power, but 80 percent of your aircraft's performance. If you lose an engine on takeoff, a go-around will be difficult or impossible.

P-Factor and the Critical Engine

The most critical engine is the engine that affects directional control the most—it's the engine you don't want to fail because when the critical engine fails, directional control is often difficult to regain.

The P-factor (or asymmetric propeller thrust) and the rotation of the engines determine which engine is the critical engine. The P-factor is caused by the different thrust of rotating propeller blades at certain flight attitudes. Because the downward moving blade has a greater angle of attack than the upward moving blade whenever the aircraft is flying in attitudes which are not parallel to thrust line—especially when the aircraft is pitched up, or flying at slow airspeeds or high-power conditions—the propeller produces more thrust on the downward rotating side than the upward rotating side. This effect is especially noticeable during takeoff.

On twin-engine aircraft where the propellers rotate the same direction (usually clockwise when viewed from the pilot's seat of the aircraft on many light twins), the center of thrust is actually at the right side of each engine. The turning (or yawing) force of the right engine is greater than the left engine because the center of thrust for that engine is farther from the centerline of the fuselage. Thus, when the right engine is running and the left engine is not, the yawing force is greater than if the left engine were the only engine running. Directional control may be difficult when the left engine (the critical engine, in this example) fails. In summary, the critical engine is the engine that requires the most rudder force to correct the yaw when that engine fails.

Some aircraft have counter-rotating propellers, which both rotate toward the fuselage. In this case, there is no critical engine because the yawing force is the same for each propeller.

The Dangers of Falling Below Vmc

Vmc is the minimum speed at which the aircraft can maintain directional control with one engine producing full power. Below Vmc, by definition, you do not have enough rudder to counteract the turning moment, but the pilot still has some control of the aircraft. For example, pitch control is still available and will be needed in the recovery from flight below Vmc.

This means that when a twin-engine aircraft operating on only one engine falls below Vmc, the asymmetric force of one operating engine will cause the aircraft to yaw. The instant a directional change in the aircraft is noted at or near Vmc, the pilot must take steps to attain a speed at or greater than Vmc and control the aircraft.

To regain control of the aircraft below Vmc

  1. If you begin to roll below Vmc, decrease power on the good engine.
    This may at first seem counterintuitive, as everything you've done so far during an engine failure has been designed to achieve maximum power. But reducing your power on the good engine will reduce the asymmetric force, and therefore decrease the aircraft's yawing tendency.
  2. Point the nose down and decrease your angle of attack by applying forward pressure on the stick.
  3. Your descent will increase your airspeed above Vmc, where the aircraft can once again be controlled.
  4. Once you're airspeed is higher than Vmc, slowly increase the throttle on the good engine.
    Note: Never fly at or below Vmc, except for training.

Remember, however, that below Vmc you have no directional control of the aircraft. The recovery procedure above works in many sub-Vmc conditions, but without directional control below Vmc, you may end up in an unusual attitude, perhaps inverted, and the exact recovery procedure may depend more on the particulars of the situation than on any one procedure. The main thing to remember in a sub-Vmc situation is that to regain control, you must reduce power on the good engine as well as get the aircraft moving faster than Vmc. This latter objective usually means getting the nose pitched down. If you have plenty of altitude, recovery from such an "upset" is possible, perhaps likely. But if you are flying low and encounter such a situation, the results can ruin your day.

Restarting the Engine

The following procedure is adapted from the Beechcraft Baron 58 Pilot Operating Handbook.

To restart the engine

  1. Determine the reason for engine failure before attempting an airstart.
  2. Set the fuel selector valve to On. (Feel for detent and visually check.)
  3. Set the throttle approximately one quarter of the way in.
  4. Set the mixture control to Full Rich below 5,000 feet.
    Set the mixture control to halfway in above 5,000 feet.
  5. Set the Fuel Boost Pump to Low.
  6. Set the Magnetos to Check On.
  7. Move the propeller control forward of feathering detent until the engine reaches 600 rpm, then back to detent to avoid overspeeding. Use starter momentarily if necessary to accomplish unfeathering.

Approach and Landing with an Engine Out

Landing with an engine out is not much different from a normal approach and landing. Until you are sure to make the runway, the final approach speed should be greater than Vyse. This is so you will maintain maximum single-engine climbing speed if you need to abort the landing. Also, when lowering flaps be aware that most light twin-engine aircraft cannot make a go-around on a single engine with full flaps.

Differential Thrust: Controlling Engines Independently

When executing the engine-out procedures or when using differential thrust during taxiing or crosswind landings in twin-engine aircraft, you need independent engine control. Watch the King Kwik Tips Video above to learn how to control engines independently.

When you increase/decrease the throttle on your joystick or keyboard, both throttles are synchronized by default. The same is true when you change the mixture and propeller controls.

To control the engines independently

  1. To control the left engine, press E, 1.
    To control the right engine, press E, 2.
  2. To resume the synchronized default control on both (all) engines, press the sequence E, 1, 2.
  3. Once you have selected an engine, the throttle, mixture, and propeller feathering commands will only affect the selected engine.
  • Click the throttle, mixture, propeller control panel icon on the main control panel and drag the knob to its desired position.
    To move both levers at once, click and drag in the area between the throttles, as if grabbing both with one hand.

Twin-Engine Flying Tips

To feather the propeller

  1. Select the engine to control by pressing E+1 or E+2.
  2. Click the propeller control knob and drag all knobs back.
    Use keyboard shortcuts to control the propeller:
    - Feather propeller: CTRL+F1
    - Increase propeller rpm to high (unfeather): CTRL+F4
    - Decrease propeller rpm (in increments): CTRL+F2
    - Increase propeller rpm (in increments): CTRL+F3

To control the throttle

  1. Select the engine to control by pressing E+1 or E+2.
  2. Click the throttle knob and drag it to the desired position.
    Use keyboard shortcuts to control the throttle:
    - Increase throttle: F3 or Num Pad 9
    - Decrease throttle: F2 or Num Pad 3
    - Full Throttle: F4

To control the mixture

  1. Select the engine to control by pressing E+1 or E+2.
  2. Click mixture knob and drag it to the desired position.
    Use keyboard shortcuts to control the throttle:
    - Lean Mixture: CTRL+SHIFT+F2
    - Enrich Mixture: CTRL+SHIFT+F3
    - Set Mixture to Rich: CTRL+SHIFT+F4
    - Mixture Idle Cutoff> CTRL+SHIFT+F1

To control the cowl flaps

  • Open the flaps by pressing CTRL+SHIFT+V.
    Close the flaps by pressing CTRL+SHIFT+C.

To control magnetos

  • Press M and then + (PLUS) or - (MINUS).

Moving Up to Jets

Now that you've mastered twin-engine flying in light twin-engine piston aircraft, it's time to move up to turbine aircraft, such as the Beechcraft King Air 350, Bombardier Learjet 45, and modern jet airliners. To get you started, here are a few tips:

  • Turbine aircraft are the natural next step up from light twin flying. In a jet you will fly higher, farther, and faster. You'll explore skies and terrain beyond your familiar airports. This means that you'll learn about pressurization, instrument flight plans (which are required above 18,000 feet), flight and fuel planning, as well as new ways to plan descents. And in the sky, you'll move up from victor airways to jet airways.
  • The notion of a critical engine changes in jets. Because P-factor is not an issue with turbine engines, neither engine is critical in the same sense as with propeller-driven aircraft. But this doesn't let jet pilots relax too much: experienced pilots like to say that jets have "equally critical" engines.
  • When it comes to losing an engine, what if you have four engines rather than two? Remember that with many engines your aircraft must carry a lot of fuel, which means a heavy aircraft. So, losing an engine while fully loaded is always a concern. Inside engines have a smaller effect on aircraft directional control than outside engines because inside engines have less mechanical leverage against the counteracting rudder than outside engines. See Flying Jets to learn more.

Suggested Reading

To learn more about flying the Beechcraft Baron 58, see the Beechcraft Baron 58 Aircraft Information article.

You may also want to read Multi-Engine Flying by Paul A. Craig, McGraw Hill, 1997.