Multi Add-On: Engine Inop Flight Principles

Define Vmc

The minimum calibrated airspeed at which directional control can be maintained with the critical engine inoperative

What factors affect Vmc?

a. CG position
b. Weight
c. Density altitude
d. Landing gear position
e. Position of flaps
f. Propeller (windmilling or feathered)
g. Sideslip condition

What factors would cause Vmc to be higher?

a. Rearward CG location
b. Decrease in weight
c. Decrease in density altitude (increase in air
density)
d. Landing gear retracted
e. Flaps retracted
f. Propeller windmilling
g. Sideslip condition (lack of bank towards
operative engine)

Explain why the movement of the center of gravity affects Vmc (AC 61-21A)

VMC is greater when the CG is at the rearmost allowable position. Since the airplane rotates around the center of gravity, the moments are measured using that point as a reference. A rearward CG would not affect a thrust moment, but would shorten the arm

Why does a change in weight affect Vmc?

Vmc is unaffected by weight in straight and level flight. Vmc will be affected by the aircraft's weight in turning (banked) flight. When an aircraft is banked, a component of the aircraft weight acts along with the horizontal component of lift to create a

Why does a change in density altitude affect Vmc? (AC 61-21A)

For an airplane with non-tuber/supercharged engines, Vmc decreases as density altitude increases. Consequently, directional control can be maintained at a lower airspeed than at sea level. This is because since power decreases with altitude, the thrust mo

Explain why a change in landing gear position affects Vmc

Extension of the landing gear has a directionally stabilizing effect on the airplane (much like the keel of a boat). Vmc will be lower

Explain why extending the flaps changes Vmc?

It is generally accepted that Vmc will be slightly lower with flaps extended. Extended flaps will increase both drag and lift. The drag produced by the extended flap on the operating engine side will tend to oppose the yawing motion of that engine. The ov

How does a windmilling propeller affect Vmc? (AC 61-21A)

A windmilling propeller will generate significant drag, resulting in less directional control and a higher Vmc

How does a sideslip condition affect Vmc? (AC 61-21A)

During engine-out flight the large rudder deflection required to counteract the asymmetric thrust also results in a "lateral lift" force on the vertical fin. The lateral "lift" represents an unbalanced side force on the airplane which is counteracted by a

Define the term "critical engine

The "critical engine" is the engine that when failed, most adversely affects the performance and handling characteristics of the airplane

Do all multi-engine airplanes have a critical engine? (AC 61-21A)

Some aircraft are equipped with counter-rotating propellers which eliminate the critical engine factor. These aircraft are equipped with engines turning in opposite directions; that is, the left engine and propeller turn clockwise and the right engine and

On most multi-engine aircraft, which engine is considered the critical engine? (AC 61-21A)

The critical engine on most U.S. light twins is the left engine, as its failure requires the most rudder force to overcome yaw

Arrange the following in order of least amount of drag to most amount of drag contributed in an engine-out situation:
a. Flaps
b. Landing gear
c. Windmilling propeller

i. Windmilling prop: -200 FPM
ii. Flaps 25: -240 FPM
iii. Landing gear extended: -250 FPM
iv. Flaps 40: -275 FPM

What speed does the blue line on the airspeed indicator represent?

Best single-engine rate of climb speed (Vyse)

What speed does the red line on the airspeed indicator represent?

Minimum Control Speed (Vmc)

What three performance/control problems must a pilot deal with immediately after the loss of one engine on a multi-engine aircraft?

The loss of power on one engine affects both climb performance and controllability of any light twin. The following problems occur:
i. Loss of climb performance (at least 80%)
ii. A yawing moment towards the inoperative
engine (due to asymmetric thrust)
i

Why does a multi-engine airplane become directionally uncontrollable during flight at an airspeed less than Vmc? (AC 61-21A)

When one engine fails, the pilot must overcome the asymmetrical thrust (except on airplanes with centerline thrust) created by the operating engine by setting up a counteracting moment with the rudder. When the rudder is fully deflected, its yawing power

Why is flight below Vmc so dangerous? (AC 61-21A)

With full power applied to the operating engine, as the airspeed drops below Vmc, the airplane tends to roll as well as yaw into the inoperative engine. This tendency becomes greater as the airspeed is further reduced, and since this tendency must be coun

Why does a multi-engine airplane with one engine inoperative roll in the direction of the inoperative engine?

Loss of power on one engine reduces the induced airflow from the propeller slipstream over that wing. As a result, total lift for that wing is substantially reduced, causing the airplane to roll in the direction of the inoperative engine. Yaw also affects

What are the reasons for feathering the propeller of an inoperative engine as soon as possible? (AC 61-21A)

When an engine fails in flight, the movement of the airplane through the air tends to keep the propeller rotating, much like a windmill. Since the failed engine is no longer delivering power to the propeller to produce thrust, but instead may be absorbing

Why is it necessary to bank toward the operative engine in an engine-out emergency? (AC 61-21A)

If the wings are kept level and the ball in the turn coordinator centered, the airplane will be in a moderate sidesip toward the inoperative engine, resulting in a substantial increase in Vmc and a significant reductioni n climb and/or acceleration capabi

What is the correct amount of bank angle necessary in an engine-out emergency?

a. FAA research indicates that no one value for
an optimum performance bank angle can be
assigned to all aircraft. The particular aircraft's
characteristics, weight, the density altitude,
etc. area ll factors which will influence the
amount of bank necess

How much of an increase in Vmc will occur if a bank toward the operative engine is not established? (AC 61-21A)

Flight tests have shown that holding the ball of the turn coordinator in the center while maintaining heading with the wings level drastically increases Vmc as much as 20 kts in some airplanes.

Are most light twins required to demonstrate single-engine climb? (AC 61-21A)

No; many pilots erroneously believe that because a light twin has two engines, it will continue to perform at least half as well with only one of those engines operating. There is nothing in CFR Part 23, governing the certification of light twins, that re

What items on the single-engine emergency checklist should be committed to memory (at a minimum?

a. Maintain directional control and airspeed at
all times. This is cardinal rule number one.
b. Usually apply maximum power to the
operating engine. However, if the engine
failure occurs during cruise or in a steep turn,
you may elect to use only enough p

If the airspeed is allowed to fall below Vmc during single-engine operation, what procedure should be followed? (AC 61-21A)

If the airspeed should fall below Vmc, for whatever reason, power must be reduced on the operative engine and the airplane must be banked, as necessary, toward the operative engine if the airplane is to be safely controlled.

What immediate actions must be taken if loss of one engine occurs prior to reaching Vmc? (AC 61-21A)

If one engine fails prior to reaching Vmc, there is no choice but to close both throttles and bring the airplane to a stop. If the engine failure occurs after becoming airborne, the pilot must make an immediate decision to either continue flight or land.

Before feathering a suspected inoperative engine, what action should be taken first? (AC 61-21A)

Verify which engine has failed by closing the throttle on the suspected dead engine

Which direction would the rudder be applied, if the right engine failed? (AC 61-21A)

The aircraft would yaw to the right, requiring application of left rudder pressure immediately

In the event of an engine failure in IMC, what methods should be used to positively identify the inoperative engine?

a. Methods used for inoperative engine
identification in VMC also apply to light in
IMC. Give priority to scanning your flight
instruments, ensuring that heading and
airspeed are maintained. Control the ehading
primarily with rudder pressure. The airplane

If an engine failure occurs immediately after takeoff (gear down) but before reaching the single-engine best rate-of-climb speed (Vyse), what procedure is recommended? (AC 61-21A)

If an engine failure occurs immediately after takeoff, before obtaining single-engine best rate-of-climb speed (Vyse), it is advisable to either land on remaining runway or select a suitable area for landing. An immediate landing is usually inevitable bec

If an engine failure occurs immediately after takeoff (gear up) but before reaching safe single-engine climb speed, what procedure is recommended? (Assuming no more runway available.) (AC 61-21A)f an engine failure occurs immediately after takeoff (gear u

a. If the engine-out best angle of climb speed
(Vxse) has been obtained and the landing
gear is in the retract cycle, the pilot should
climb at Vxse to clear any obstacles, and then
stabilize the airspeed at Vyse while retracting
the landing gear and flap

Following an engine failure on takeoff (airborne) a climb cannot be established. What speed should be sued to establish the slowest descent rate? (AC 61-21A)

If it is apparent a climb cannot be established and an emergency landing is imminent, Vyse will produce the slowest rate of decent and provide the most amount of time for executing an emergency landing.

In the event of an engine failure immediately after takeoff, which is more important, more altitude or airspeed in excess of Vyse? (AC 61-21A)

Altitude is more essential to safety after takeoff than is excess airspeed. Excess airspeed cannot be converted readily to the altitude, or the distance necessary to reach a landing area safely in the event of an emergency. In contrast, however, an airpla

In the event of an engine failure during the approach and landing phases of flight, what procedures are recommended? (AC 61-21A)

a. The traffic pattern should be identical to a
normal traffic pattern
b. The flight path on base to final should be
normal; neither high nor low. Avoid long flat
approaches with high power output on the
operative engine
c. Maintain Vyse. Final approach s

Are single-engine go arounds recommended? Why? (AC 61-21A)

Single-engine go arounds are not recommended unless absolutely necessary. Unless more than sufficient altitude and airspeed exist, a single-engine go-around is, for the most part, impossible in light twins certified under Part 23. Accident statistics indi