Multi Flashcards
What is VMC
Minimum controllable airspeed with critical engine INOP
- slowest airspeed at which directional control can be maintained with critical engine INOP
- marked by a red line
How to determine VMC speed
CUSTOMFAM
What is CUSTOMFAM
How to determine VMC
- critical engine INOP and windmilling
- up t 5 degrees bank and 0 side slip
- standard day at SLP
- trimmed on takeoff
- out of ground effect
- max power in operation engine
- flaps set for takeoff & gear up
- AFT CG
- most unfavorable weight (lighter)
How would Critical engine INOP effect performance and VMC
- Aircraft performance would decrease because of less power
- VMC would increase because PAST factor and prop drag
How does up to 5 degrees bank and zero slide slip effect performance and VMC
- aircraft performance would increase because of less drag
- VMC would decrease because it decreases PAST
( raise the dead engine) ( we are gaining more horizontal component of lift )( we are aligning the longitudinal axis of there aircraft with the relative wind)
How does standard day at SLP effect performance and VMC
- aircraft performance increases because of more dense air
- VMC would increase because asymmetrical engine performance
( More power = More PAST )
How does trimmed for takeoff effect performance and VMC
- aircraft performance stays the same
- VMC stays the same
How does out of ground effect, effect performance and VMC
- aircraft performance decreases because of greater induced drag
- VMC increases because less control effectiveness
( your now battle in both induced drag and directional control )
How does max power on the operating engine effect performance and VMC
- aircraft performance would increase because of more power
- VMC would increase because of greater asymmetric engine performance
( more power = more PAST )
How does Flaps set for takeoff and gear up effect performance and VMC
Flaps down
- aircraft performance would increase because of less drag
- VMC would increase because its less stable
( adding flaps adds stability because its taking some of the PAST out )
Gear up
- aircraft performance would increase because of decreased drag
- VMC would decrease because of keel effect
( gear coming forward shifts the CG forward creating a greater moment arm from the rudder making it more stable)
How does Aft center of gravity effect performance and VMC
Aft CG
- aircraft performance would increase because of less elevator/ stabilator drag
- VMC would increase because less rudder authority so less stable
( opposite for forward CG) ( moment arm from rudder to CG either creates a shorter arm (less stable) or a greater arm (more stable))
How does most unfavorble weight effect performance and VMC
Lighter
- aircraft performance would increase because of less work the plane has to do
- VMC would increase because less contribution from horizontal component of lift
(being lighter is easier to make unstable)
(Being heaver you have to have more momentum to make unstable so it’s harder to make unstable)
What is critical density altitude
Where VMC and VS are equal, so the airplane will reach VMC and VS at the same time which can be dangerous
Accelerated STOP distance
Start— engine failed at Vr — abort takeoff — full stop
- calculated from POH performance charts
Why do we need to know single engine performance
We need to know for making the right decisions in an emergency, must know your airplanes single engine performance available for each phase of flight
Why do we zero slide slip
- During flight with one engine INOP we do a very slight bank up to 5 degrees to create HCL on the dead engine (raise the dead)
- splitting the rudder into their operating engine creates alignment with the longitudinal axis with the relative wind
- zero side slip conditions align wind to minimize drag for best performance
What is a service ceiling
Both engines working and is able to climb at a 100 FPM
Absolute ceiling
Climb is no longer possible
Single engine service ceiling
No longer able to maintain a climb of 50 FPM
What is the unavoidable decent called when you are above the single engine service ceiling and you lose an engine
Drift down
Climb to cruise flow
- when advancing power, check all engine instruments and RPM has been reached
- tap breaks to stop from spinning to retract gear up
- climb out at blue line + 10kts ( Vyse + 10kts )( this creates a safe margin of airspeed in the instance that you lose an engine)
- when 500’ above airport elevation reduce throttles to 25 and prop to 2500 RPM
Before landing checklist
GUMPS
( do in each leg of the pattern)
- Gas on, for both tanks, fuel pumps on
- Undercarriage (gear) down below Vle
- mixture rich
- Propeller full on final
- Seatbelts secure and lights on
Why might your gear horn be going off while doing normal maneuvers and proper configuration
Check your POH
- below 14” of manifold pressure and gears is still up
- flaps extended past 25 and gear is still up
- gear selector is in the up position when aircraft is on the ground
- stall warning does not sound on the ground
Why do we fly Multiengine aircraft
Redundancy
What happened to our performance when we lose one engine
With one engine INOP we lose 50% of our power and 80% loss of climb performance
What is the critical engine
The engine failed it would have the most negative effect on performance and directional control
What are the two types of rotating twin engines
Conventional, and non conventional
What is a conventional engines
2 clockwise spinning props
- left engine is the critical engine
What is non-conventional engines
Counter rotating props
- no critical engine because the yawing, amid rolling caused from losing either engine is identical
What does P-factor cause
YAW
- with one engine INOP
- The greater the moment arm is, the tendency to turn left is greater
What does accelerated slipstream cause
What is our single engine best angle if climb
Vxse - 82
What os single engine best rate of climb (blue line)
Vyse - 88
What is the safe intentional OEI (one engine inop) speed
Vsse - 82
What is our minimum control airspeed (red line)
VMC - 56
What is our landing gear extension/ operation speed
Vle/lo - 140
What is our maximum landing gear retraction speed
Vlr - 109
What is our rotation speed
Vr - 75
What is our best angle of climb speed
Vx - 82
What is our minimum stall speed in landing configuration ( dirty )
Vs0 - 55
What is our minimum stall speed in clean configuration
Vs1 - 57
What is our maneuvering speed
Va - 112-135
What is our maximum structural cruising speed (smooth air)
Vno - 169
What is our never extend speed
Vne - 202
Departure brief with 4 outcomes if engine fails
- Has rotation occurred? No, then pull both throttles back and come to a stop
- We rotated with gear still down, pull both throttle and land straight ahead
- Rotation occurred gears up and below 2000agl,
- engine our flow
- feather inop engine
- declare
- return to land - Rotation occurred, gear is up, and above 2000agl
- engine out flow
- trouble shoot try and restart
- come back to land
Accelerate — go distance
Start — engine fails at Vr — continue takeoff — climb 50ft
( part 23.2120 — why we don’t have accelerate go distance )
What is a scimitar blade
Scimitar blade has swept tips, behaves similar to seat wings to minimize sonic shock wave formation at blade tip at high RPM
- performs better at cruise
- slows down the air flowing over it
What’s a good lean to
1325 degrees F — EGT
Tell my about our landing gear
It’s hydraulically operated, fully retractable, tricycle landing gear
- two way selector switch that activates am electric pump, which the pump then manages the hydraulic pressure to move the gear
- 6-10 seconds transit time
- gear selector switch should not be moved while gear is I transit
- gear retraction speed is VLR - 109
- gear extended/operating speed is VLE/LO - 140
What keeps the gear up and down
- hydraulic pressure keeps it up
- gravity keeps it down and the lack of hydraulic pressure
- also we have down lock hooks that keep it down
What type of engines do we have
Left - Lycoming IO-360-B1G6
Right- Lycoming LIO-360-B1G6
Rated at 180 horse power
Rated RPM 2700
What does Lycoming IO-360-B1G6 and LIO mean
I- fuel injected, O- horizontally opposed, 360- 361 cubic inches of displacement ( the amount of volume inside the cylinders)
The L before the LIO - means counter rotating
What is rate of climb
Is the altitude gain per unit of time
What is the time gradient
Is their actually measure of altitude gained per 100ft of horizontal travel, expressed as a percentage
What s induced flow
The propellers on the wing mounted engine creates an accelerated flow or accelerated slipstream of air over the wings
- happens in single engine as well but not as much because of the location of the prop in relation to the wings
What happens to p-factor and torque in a counter rotating props
They cancel each other out, so less rudder4 is needed to oppose these factors
What are the two motions that happen when an engine fails
YAW and ROLL
What causes YAW
Asymmetrical thrust will causer a yawing moment around the C.G. Towards the inop engine
What causes ROLL
Theyawingmomentfrom asymmetrical thrust will cause thewingwiththeoperatingenginetomovefasterthroughtheairastheairplaneyaws.Thiscausesafastervelocityofairoverthewingwiththeoperativeenginemeaningmoreliftonthatwingandresultsinarolltowardstheinoperativeengine.
Inducedflow(acceleratedslipstream)overthewingfromtheoperatingengineandlackofinducedflow(acceleratedslipstream)overtheinoperativeenginecausesasymmetricalliftonthewings,resultinginarollingmomentaround
theC.G.towardstheinoperativeengine.
What is the critical engine
The critical engine is the engine that, if it were to fail, would most adversely affect the performance or handling characteristics of the airplane
What is the critical engine on a conventional twin
The left engine
What is the critical engine in a counter rotating prop twin
thereisnot a critical enginesincetheyawingandrollingeffectsoflosingoneenginewillbeidenticalnomatter
whichenginefails.
What are the factors to determine them critical engine
PAST
P-factor (yaw)
Accelerated slipstream (roll)
Spiraling slipstream (yaw)
Torgue (roll)
What is P-factor
YAW
Pfactoriswherethedescendingpropellerbladecreatesmorethrustthanthe
ascendingblade.Thiscausesasymmetricalthrustoneachsideofthepropeller.Tofigure
outtheeffectontheairplane,theformulaTHRUSTxArm=Momentcanbeused.This
meansthatthelongerthearmfromtheC.G.tothethrust,thelargertheyawingmoment
willbe
What is accelerated slipstream
ROLL
Basically with one engine INOP the is no extra air from the prop flowing over that wing so there is less lift on one wing and vise Versa on the other wings so most air and more lift top it creates that asymmetrical thrust
P-factor - so because of pfactor there is greater airflow on the right side of the engines so changes the center of lift rightward. JustlikeP‐factor,thearmtotherightengineislongerthanthearmtotheleftengine.Thismeansthatiftheleftenginefails,therollmomentwillbegreatertotheleftthaniftherightenginefails.Therefore the left engine is the critical engine.
How does spiraling slipstream work
YAW
- Left engine prop-wash interacts with the vertical stabilizer and rudder which helps counter the asymmetrical thrust
- right prop-wash trails off
How does torque work
ROLL
- Rolls into dead engine
- Inthecounter rotatingtwin,thetorquewillopposetheyawingandrollingmomentcaused
byaninoperativeengine.Theresultingyawwillbethesamenomatterwhichenginefails.
Therefore,thereisnocriticalengine.
Astheengineandpropellerrotateinonedirection,they,inturn,trytorotate
theairplaneintheotherdirection.ThisisduetoNewton’sthirdlawwhichstates,“For
everyactionthereisanequalandoppositereaction.”Thisforcealsoactswhenanengine
failsbecausethereisstillasecondoperatingengine.
What must VMC not exceed
1.2 X Vs1 at maximum takeoff weight
VMC must be determined with
- Mostunfavorableweight(notnecessarilymaximumgrossweight)
- Mostunfavorablecenterofgravityposition
3.Theairplaneairborneandthegroundeffectnegligible
4.Maximumavailabletakeoffpowerinitiallyoneachengine
5.Theairplanetrimmedfortakeoff - Flapsinthetakeoffposition
- Landinggearretracted
8.Allpropellercontrolsintherecommendedtakeoffposition.
When recovering from VMC
1.Therudderpedalforcerequiredtomaintaincontrolmustnotexceed150pounds.
2.Itmustnotbenecessarytoreducepoweroftheoperativeengine(s).
3.Theairplanemustnotassumeanydangerousattitude.
4.Itmustbepossibletopreventaheadingchangeofmorethan20degrees.
What does VMC deal with
Directional control not performance
Warning signs to recognize that VMC is occurring
- Loss of directional control-therudderpedalisdepressedtoitsfullesttravelandtheairplaneisstillturningtowardstheinoperativeengine.
- Stall warning horn–asingle‐enginestallcouldbejustasdangerousasrunningoutofrudderauthorityandcouldevenresultinaspin.
- Buffeting before the stall–samereasonasthestallwarninghorn.
- A rapid decay of control effectiveness–anylossofcontroleffectivenesscould
resultinlossifcontroloftheairplane.
How to recover from VMC
Reduce power on the operating engine–thiswillreducetheasymmetricalthrust
causingtheVMCinthefirstplace.ReducingthepowerallthewaytoidlemayhelpstoptheVMC,butthelossofpowerandresultinglossofairspeedcouldleadtoastall.
- Pitch down–Loweringthenoseoftheairplanewillincreasetheforwardairspeedmakingtheruddermoreeffectiveinregainingandmaintainingdirectionalcontrol.
As density altitude increases what happens to VMC
VMCspeeddecreasesduetothefactthatasdensityaltitudeincreasesenginepowerwilldecrease.Thedecreaseinenginepowerresultsinlessasymmetricalthrust,meaningtheyawingfromafailedenginewillbelessatahighdensityaltitudethanalowerdensityaltitude
More power equals what
Most PAST
So more power or thrust in the operating engine, the more rudder is needed to stop the resulting yaw
What happens to your stall speed as your altitude increases and decreases
You stall speed is an indicated airspeed that will remain constant
As your density altitude increases what happens to VMC and why
Your VMC decreases because your engine output decreases, so less power = less PAST so easier to control the airplane and not as much rudder needed
How does forward CG effect VMC
the longer the arm, the more
effective the rudder; the more effective the rudder, the lower VMC. As the C.G. moves
forward, VMC decreases; as the C.G. moves aft, VMC increases.
What does your landing gear extended do to VMC and why
In the extended (down) position,
the landing gear can also act like the keel of a boat (increasing in longitudinal stability) , giving the airplane a stabilizing effect.
This stabilizing effect helps prevent a turn, thereby lowering VMC (very small effect on VMC)
Thelandinggearextended(down)alwaysdecreasesperformanceduetoparasitedrag.
What does a windmilling prop vs feathered prop do to your VMC
A windmilling propeller creates more drag than a feathered propeller. This extra drag adds
to the yawing from a failed engine to make the total effect worse. This situation will require more rudder deflection to maintain directional control, which means that less rudder is available to the pilot, thereby increasing VMC.
Once the propeller is feathered the drag is reduced, thereby reducing VMC.
A windmilling propeller decreases performance due to the parasite drag created by the
propeller blades.
How does your flaps down effect your VMC
When the flaps are down the wings create more liftthan if the flaps were up. However,
when lift is created, drag is also created (as lift increase, drag increases)
The side with the operating engine is creating even more lift because of the accelerated air
flowing over the wing.When the flaps are extended, the drag caused by the accelerated
flow opposes the yaw caused by the inoperative engine allowing the pilot to use less rudder to maintain heading. Having more rudder available to the pilot lowers VMC.
It should be noted more lift on the right wing will cause a roll to the left. If ailerons are
used to counteract the rolling of the airplane ,the drag from the adverse aileron yaw will
actually increase the yaw towards the inoperative engine.
How does weight effect VMC
- The horizontal component of lift(the force that causes the airplane to turn)will help
oppose the yaw due to an inoperative engine.The more weight, the more horizontal lift is
available to oppose the turn from the inoperative engine. - This means that horizontal lift can be used along with rudder to stop the turn. When more
horizontal lift is available, less rudder is needed, which means more rudder is available to the pilot and VMC decreases. So, as weight increases, VMC speed decreases. As weight
decreases, VMC increases.
How does the direction of the relative wind affect drag
Anytime the relative wind is not parallel to the longitudinal axis of the airplane more drag is created
What happens if the critical engine fails
If the critical engine fails the resulting yaw and roll would be worse that if the non-critical engine had failed. The greater yaw and roll will require more rudder and control surface input to maintain directional control.
The result is less rudder is available to the pilot which increases VMC.
Performance will be worse because the greater control inputs the control surface deflection will cause a greater amount of drag to be created
