The distance required to accelerate to lift-off speed and, assuming failure to engine at the instant that lift-off speed is attained, to bring the airplane to a complete stop. It is CRITICAL to check this distance before every take-off. If you need more runway than you have, it is not advisable to take off under those conditions – go to a longer runway, reduce fuel or reduce passengers and baggage.
The distance required to accelerate to lift-off speed, and assuming failure of an engine at the instant lift-off speed is attained, to continue the take-off on the remaining engine to a height of 50 feet.
Critical engine is the engine whose failure would most adversely affect the performance or handling qualities of the airplane. Usually, in almost all American twins, the critical engine is the left engine on twins with props that rotate in the same direction. Twins, just like single engine airplanes, have left turning tendencies. These include torque and P-factor. Because the downward bite of the prop has a larger arm from the center of thrust on the right engine than it does on the left in conventional twins, when you lose the left engine the larger arm on the right engine causes more turning tendencies than when you lose the left engine the larger arm on the right engine causes more tuning tendencies than when you lose the right. Put this on top of the left-turning tendencies already existing on the airplane, and you have a severe rolling and yawing reaction of the airplane. On airplanes with counter-rotating props, the downward bite of the descending prop blades are the same on both engines. Thrust line is the distance from centerline of fuselage to downward bite of the propeller. Therefore, no matter which engine you lose it is not the critical engine. You could also consider both engines to be critical since the loss of either on would adversely affect the performance or handling qualities of the airplane.
Determining which engine has failed:
It may be difficult to determine which engine has failed. Trust your outside visual sights as well as your instruments. The airplane will roll and yaw in the direction of the dead engine. Your turn coordinator will show the ball on the side of the good engine. You may see an RPM drop, and your manifold pressure will go to ambient outside air pressure. You will also probably hear a change in the sound of the engines. Dead foot, Dead engine.
Loss of power when one engine fails:
When you lose one engine, you don’t just lose 50% of your horsepower. You will actually lose 80% of your power or more. For example: You have two engines at 200 hp each. This is a total of 400 hp. When you lose one engine, you automatically lose 200 hp. This leaves you with 200 hp. It takes around 160 hp to at least maintain straight and level flight. Now, instead of having 240 hp to climb with (400-160), you only have 40 excess hp to gain altitude with. If your density altitude is high, your performance will be even worse, and you may not even have that. At your single engine absolute ceiling, you will no longer be able to gain any altitude.
Engine Failure Procedures:
Maintain directional control and airspeed control at all times first and foremost.
- Throttles full forward
- Propellers full forward
- Mixtures full rich
- 3rd notch of flaps up
- Gear up
- Rest of the flaps up
- Fuel selectors ON
- Fuel pumps ON
- IDENTIFY – dead foot dead engine
- VERIFY – throttle to idle. There should be no extra yaw or power changes
- FEATHER – prop to feather
- Mixture to idle cut-off
- EVALUATE – can I climb? Do I need to land ahead or what are my options
- Checklist if time permits
- Fuel pumps back off
- Fuel selector off on dead engine
Be certain to be efficient as well as thorough when you have an engine failure. A windmilling propeller causes a huge amount of drag because of the interruption of the airflow over the wing. You want to reduce your drag as quickly as possible. Also, if you roil pressure is dropping and your RPM’s drop below 800 RPM, a pin moved by centrifugal force will drop into place, preventing feather. You will then be “stuck” with a windmilling propeller, causing a large amount of drag, and be unable to feather.
When your engine fails, the airplane will yaw and roll towards the dead engine. You will need to put in up to 5 degrees bank with your aileron to combat the rolling tendency, and ruder towards the operating engine to combat the rolling tendency. This will put you from a sideslip situation to a zero sideslip situation by “straightening” the airplane into the relative wind.
In the event of engine failure during:
Rollout prior to lift-off – close both throttles immediately and bring the airplane to a safe, complete stop.
Immediately after take-off, prior to safe single engine speed – lower your nose to gain airspeed, if can’t climb close both throttles and land straight ahead. If you CAN climb, reduce drag, follow all procedures, and come in for a safe landing.
It is always better to prepare for a safe, controlled emergency landing than to try to force a climb and lose control.
Try to avoid single-engine go-arounds. In most twins, a single-engine go-around is almost impossible. More fatal accidents come from attempts at these than at off-runway landings. However, if you must do one, plan ahead. You will want all the altitude you can muster. Full power first, then reduce your drag. MAINTAIN YOUR BEST CLIMB SPEED AT ALL TIMES!