Multi Engine Considerations Flashcards
How is the Critical Engine defined?
The engine whose failure would most adversely affect the performance or handling qualities of an aircraft.
P.A.S.T.
FAR 1.1
What are the criteria for certifying & establishing Vmc?
COMBATS
C - Critical Engine inop
O - Operating engine full power
M - Most unfavorable weight
B - Bank 5 degrees into operative
A - Aft most allowable CG
T - Takeoff configuration: Flaps & Gear up, fine pitch on the prop
S - Standard Atmospheric conditioins
AND
1. Be able to stop the turn within 20 degrees of original HDG
Found in FAR part 23.149
Define Vmc
- The calibrated airspeed at which..
- When the Critical Engine suddenly becomes inoporative..
- It is possible to maintain control of the airplane with that engine still inoporative..
- And thereafter maintain straight flight..
- At the same speed with….
- An angle of bank of not more than 5 degrees
FAR 23.149 (airworthiness standards)
What is it called when you fly at VYse above the aircrafts Absolute Ceiling?
VYse will deliver your Minimum Sink rate
What is Minimum Sink rate?
Minimum sink rate is the lowest rate of descent for an aircraft, or the speed at which an aircraft loses altitude the slowest
- It occurs at VYse when above the aircrafts absolute ceiling
What is Absolute ceiling?
The altitude at which the Aircraft will no longer climb
What is Service Ceiling?
The alitutde at which an aircraft can maintain a 100 FPM climb
Source: AFH Glossary
What is OEI Service Ceiling?
The altitude that a twin engine airplane can no longer climb at a rate greater than 50 FPM with one engine inoperative AT max takeoff weight
Source: AFH Glossary
Which FAR governs the certification of Vmc speed in light twins prior to 2011?
FAR 23.149
- The DA42 was certified in 2010, so its Vmc falls under this defintion
The new Vmc definition can be found in FAR 23.2135
The in depth details are laid out in AC 22-8C
Which FAR governs certification of Vmc after 2011?
FAR 23.2135
If no Vr speed is published for the aircraft, what speed should be used?
Vmc + 5 kts
Because an twin engine aircraft should not be airborn prior to Vmc. Its unsafe
When should the landing gear be retracted on take off?
The landing gear should be retracted as soon as a positive rate is acheived AND a safe landing can no longer be made
Source: Flying Twins Safely
What are the 6 main elements of the Vmc definition in FAR 23.149
- Calibrated airspeed
- Critical engine suddenly made inop
- Maintain aircraft control
- Straight flight
- Same airspeed
- Bank of not more than 5 degrees
Explain why we need rudder and aileron when our engine dies
- Rudder to counteract the YAW created by the Asymmetrical Thrust
- Aileron to counteract the Roll created by Accelerated Slip Stream due to propeller blast being eliminated on the dead engines wing
What is meant by Zero Sideslip when flying the airplane with one engine inoporative?
Side slip is the angle where the relative wind meets the longituinal axis of the airplane
Achieving Zero Side Slip occurs when the longitudinal axis of the airplane is lined up with the direction of travel through the use of Aileron & Rudder
What is important to remember about how Vmc changes with bank angle?
Vmc may increase by as much as 3 kts for every degree of bank below 5 degrees
Source: Flying Twins Safely
Is VXse higher or lower than VYse? Why dont we use it?
- Slower than VYse, & may be just a few kts above Vmc
- We dont use it because your climb rate will be too low, less than Vy
What is the Blue line on the Airspeed indicator
VYSe - Best rate of climb single engine
85 kts
What is the Red line on the airpseed indicator?
Vmc - Minimum Control speed