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sexta-feira, 18 de novembro de 2011


LOAD FACTOR PROTECTION

On commercial aircraft, high load factors can be
encountered during evasive maneuvers due to potential collisions,
or CFIT …

Pulling "g" is efficient, if the resulting maneuver
is really flown with this "g" number.
If the aircraft is not able to fly this trajectory,
or to perform this maneuver, pulling "g" will be detrimental.

On commercial aircraft, the maximum load that is structurally allowed is:

• 2.5 g in clean configuration,
• 2.0 g with the flaps extended.

AIRBUS LOAD FACTOR PROTECTION and safety


On most commercial aircraft, the potential
for an efficient 2.5 g maneuver is very remote.

Furthermore, as G Load information is not continuously
provided in the cockpit, airline pilots are
not used to controlling this parameter.

This is further evidenced by inflight experience, which
reveals that: In emergency situations, initial PF reaction
on a yoke or sidestick is hesitant, then aggressive.

With load factor protection, the PF may immediately and
instinctively pull the sidestick full aft:
The aircraft will initially fly a 2.5 g maneuver without losing time.

Then, if the PF still needs to maintain the sidestick full aft stick,
because the danger still exists, then the high AOA protection will take over.

Load factor protection enhances this high AOA protection.

Load factor protection enables immediate PF reaction,
without any risk of overstressing the aircraft.

Flight experience has also revealed that an immediate 2.5 g reaction
provides larger obstacle clearance, than a hesitant
and delayed high G Load maneuver (two-second delay).

HIGH PITCH ATTITUDE PROTECTION

Excessive pitch attitudes, caused by upsets or
inappropriate maneuvers, lead to hazardous situations:

• Too high a nose-up ▸ Very rapid energy loss

• Too low a nose-down ▸ Very rapid energy gain

Furthermore, there is no emergency situation that
requires flying at excessive attitudes.
For these reasons, pitch attitude protection
limits pitch attitude to plus 30 °/minus 15 °.

Pitch attitude protection enhances high speed protection,
high load factor protection, and high AOA protection.

HIGH ANGLE-OF-ATTACK (AOA) PROTECTION

High AOA protection enables the PF to pull the sidestick full aft
in dangerous situations, and thus consistently achieve
the best possible aircraft lift.

This action on the sidestick is instinctive, and the
high AOA protection minimizes the risk of stalls or control loss.

High AOA protection is an aerodynamic protection:

• The PF will notice if the normal flight envelope is exceeded
for any reason, because the autopitch trim will stop,
the aircraft will sink to maintain its current AOA (alpha PROT, strong
static stability), and a significant change
in aircraft behavior will occur.

• If the PF then pulls the sidestick full aft,
a maximum AOA (approximately corresponding to CL Max) is commanded.
In addition, the speedbrakes will automatically retract, if extended.

airbus AOA PROTECTION

In addition to this aerodynamic protection, there are
three more energy features:

• If ATHR is in SPEED mode, the speed cannot drop below VLS,
even if the target speed is below VLS

• If the angle-of-attack still increases and reaches
ALPHA Floor threshold, the A/THR triggers TOGA thrust and
engages (unless in some cases of one engine-out).

In case of an emergency situation, such as Windshear or CFIT,
the PF is assisted in order to optimize aircraft performance via the:

• A/THR: Adds thrust to maintain the speed above VLS

• ALPHA FLOOR: Provides TOGA thrust

• HIGH AOA protection: Provides maximum aerodynamic lift

• Automatic speedbrake retraction: Minimizes drag.

OPERATIONAL RECOMMENDATIONS:

When flying at alpha max, the PF can make gentle turns, if necessary.

The PF must not deliberately fly the aircraft in alpha protection,
except for brief periods, when maximum maneuvering speed is required.

If alpha protection is inadvertently entered, the PF must exit
it as quickly as possible, by easing the sidestick forward
to reduce the angle-of-attack, while simultaneously adding power
(if alpha floor has not yet been activated, or has been cancelled).
If alpha floor has been triggered, it must be cancelled with
the instinctive disconnect pushbutton (on either thrust lever),
as soon as a safe speed is resumed.

In case of GPWS/SHEAR:

• Set the thrust levers to TOGA

• Pull the sidestick to full aft
(For shear, fly the SRS, until full aft sidestick).

• Initially maintain the wings level

This immediately provides maximum lift/maximum thrust/minimum drag.

Therefore, CFIT escape maneuvers will be much more efficient.

PROTECTED A/C VERSUS NON PROTECTED A/C GO-AROUND TRAJECTORY



The above-illustrated are typical trajectories flown
by all protected or not protected aircraft, when the PF applies
the escape procedure after an aural “ GPWS PULL UP” alert.

The graph demonstrates the efficiency of the protection,
to ensure a duck-under that is 50 % lower, a bucket-distance
that is 50 % shorter, a safety margin that more than doubles
(due to a quicker reaction time),
and a significant altitude gain (± 250 ft).

These characteristics are common to all protected aircraft,
because the escape procedure is easy to achieve, and enables
the PF to fly the aircraft at a constant AOA, close to the max AOA.

It is much more difficult to fly
the stick shaker AOA on an aircraft that is not protected.

PROTECTIONS


OBJECTIVES

One of the PF's primary tasks is to maintain the aircraft
within the limits of the normal flight envelope.
However, some circumstances, due to extreme situations
or aircraft mishandling, may provoke the violation of these limits.

Despite system protections, the PF must
not deliberately exceed the normal flight envelope.

In addition, these protections are not designed to be structural
limit protections (e.g. opposite rudder pedal inputs).
Rather, they are designed to assist the PF in
emergency and stressful situations, where only instinctive
and rapid reactions will be effective.

Protections are intended to:

• Provide full authority to the PF to consistently achieve
the best possible aircraft performance in extreme conditions

• Reduce the risks of overcontrolling, or overstressing the aircraft

• Provide PF with an instinctive and immediate procedure
to ensure that the PF achieves the best possible result.

BANK ANGLE PROTECTION

Bank angle protection prevents that any major upset,
or PF mishandling, causes the aircraft to be in a high-bank situation
(wherein aircraft recovery is complex, due to the difficulty to properly
assess such a situation and readily react).

Bank angle protection provides the PF with full authority
to efficiently achieve any required roll maneuver.

The maximum achievable bank angle is plus or minus:

• 67 °, within the Normal Flight envelope (2.5 g level flight)
• 40 °, in high Speed protection (to prevent spiral dive)
• 45 °, in high Angle-Of-Attack protection

HIGH SPEED PROTECTION

When flying beyond maximum design speeds VD/MD (which are greater that VMO/MMO),
there is an increased potential for aircraft control difficulties
and structural concerns, due to high air loads.

Therefore, the margin between VMO/MMO and VD/MD must
be such that any possible overshoot of the normal flight envelope
should not cause any major difficulty.

High speed protection adds a positive nose-up G demand to a sidestick order,
in order to protect the aircraft, in the event of a dive or vertical upset.
As a result, this enables a reduction in the margin betwen VMO/MMO and VD/MD.

Therefore, in a dive situation:

• If there is no sidestick input on the sidestick, the aircraft
will slightly overshoot VMO/MMO and fly back towards the envelope.

• If the sidestick is maintained full forward, the aircraft will
significantly overshoot VMO/MMO without reaching VD/MD.

At approximately VMO +16 / MMO +0.04, the pitch nose-down
authority smoothly reduces to zero (which does not mean that
the aircraft stabilizes at that speed).

airbus HIGH SPEED PROTECTION



The PF, therefore, has full authority to perform a high speed/steep
dive escape maneuver, when required, via a reflex action on the sidestick.

Note:

1. An OVERSPEED warning is provided.

2. At high altitude, this may result in activation of
the angle of attack protection.

Depending on the ELAC standard, the crew may have to
push on the stick to get out of this protection law.




DIRECT LAW

In most triple failure cases, direct law triggers.

When this occurs:

• Elevator deflection is proportional to stick deflection.
Maximum deflection depends on the configuration and on the CG

• Aileron and spoiler deflections are proportional
to stick deflection, but vary with the aircraft configuration

• Pitch trim is commanded manually

Handling characteristics are natural, of high-quality aircraft,
almost independent of the configuration and of the CG.
Therefore, the aircraft obviously has no protections,
no automatic pitch trim, but overspeed or stall warnings.

OPERATIONAL RECOMMENDATION:

The PF must avoid performing large thrust changes,
or sudden speedbrake movements, particularly if the center of gravity is aft.

If the speedbrakes are out, and the aircraft has been re-trimmed,
the PF must gently retract the speedbrakes,
to give time to retrim, and thereby avoid a
large, nose-down trim change.

INDICATIONS


The ECAM and PFD indicate any control law degradation.

ON THE ECAM

 In ALTN Law:

FLT CTL ALTN LAW (PROT LOST)
MAX SPEED 320 kt(320 kt/M 0.77 on A318)

 In Direct Law:
FLT CTL DIRECT LAW (PROT LOST)
MAX SPEED 320 kt/M 0.77

MAN PITCH TRIM USE ON THE PFD

The PFD enhances the PF’s awarness of the status of flight controls.

Specific symbols (= in green), and specific formatting
of low speed information on the speed scale
in normal law, indicate which protections are available.

When protections are lost, amber crosses (X) appear,
instead of the green protection symbols (=).

When automatic pitch trim is no longer available,
the PFD indicates this with an amber “USE MAN PITCH TRIM”
message below the FMA.

Fly-by-Wire Status Awareness via the PFD


Therefore, by simply looking at this main instrument (PFD),
the flight crew is immediately aware of
the status of flight controls, and the operational consequences.

OPERATIONAL PHILOSOPHY

FLIGHT CONTROLS


ENGINE FAILURE

In flight, if an engine failure occurs,
and no input is applied on the sidestick,
lateral normal law controls the natural tendency
of the aircraft to roll and yaw.

If no input is applied on the sidestick,
the aircraft will reach an approximate 5 °
constant bank angle, a constant sideslip,
and a slowly-diverging heading rate.

The lateral behavior of aircraft is safe.

However, the PF is best suited to adapt the
lateral trimming technique, when necessary.

From a performance standpoint, the most effective
flying technique, in the event of an engine failure
at takeoff, is to fly a constant heading
with roll surfaces retracted.

This technique dictates the amount of rudder
that is required, and the resulting residual sideslip.

As a result, to indicate the amount of rudder that is
required to correctly fly with an engine-out
at takeoff, the measured sideslip index is shifted on the
PFD by the computed, residual-sideslip value.
This index appears in blue, instead of in yellow,
and is referred to as the beta target.

If the rudder pedal is pressed to center the beta target index,
the PF will fly with the residual slip, as required by
the engine-out condition.
Therefore, the aircraft will fly at a constant heading with
ailerons and spoilers close to neutral position.

BETA TARGET ON PFD




Operational Recommendation:

In the case of an engine failure at takeoff, the PF must:

• Smoothly adjust pitch to maintain a safe speed
(as per SRS guidance)

• Center the Beta target
(there is no hurry, because the aircraft is laterally safe)

• When appropriate, trim the aircraft laterally
using the rudder trim

• Apply small lateral sidestick inputs,
so that the aircraft flies the appropriate heading.

AVAILABLE PROTECTIONS

Normal Law provides five different protections :

• High angle-of-attack protection

• Load factor protection

• High pitch attitude protection

• Bank angle protection

• High speed protection.

OPERATIONAL PHILOSOPHY

FLIGHT CONTROLS

AlTERNATE LAW


In some double failure cases, the integrity and redundancy
of the computers and of the peripherals are not sufficient
to achieve normal law and associated protections.

System degradation is progressive, and will evolve according
to the availability of remaining peripherals or computers.

Alternate law characteristics (usually triggered in case of a dual failure):

‐ In pitch: same as in normal law with FLARE in DIRECT

‐ In roll: Roll DIRECT

‐ Most protections are lost, except Load factor protection.

At the flight envelope limit, the aircraft is not protected, i.e.:

‐ In high speed, natural aircraft static stability
is restored with an overspeed warning

‐ In low speed (at a speed threshold that is below VLS),
the automatic pitch trim stops and natural
longitudinal static stability is restored, with a stall warning at 1.03 VS1G.

In certain failure cases, such as the loss of VS1G
computation or the loss of two ADRs, the longitudinal static stability
cannot be restored at low speed. In the case of a loss of three ADRs,
it cannot be restored at high speed.

In alternate law, VMO setting is reduced to 320 kt,
and α FLOOR is inhibited. (On A318, MMO setting is also reduced to M 0.77.)

OPERATIONAL RECOMMENDATION:

The handling characteristics within the normal flight envelope,
are identical in pitch with normal law.

Outside the normal flight envelope, the PF must take
appropriate preventive actions to avoid losing control,
and/or avoid high speed excursions.
These actions are the same as those that would be
applied in any case where non protected aircraft
(e.g. in case of stall warning: add thrust, reduce
pitch, check speedbrakes retracted).

OPERATIONAL PHILOSOPHY

FLIGHT CONTROLS

The relationship between the Pilot Flying’s (PF’s)
input on the sidestick, and the aircraft’s response,
is referred to as control law.

This relationship determines the handling
characteristics of the aircraft.

There are three sets of control laws,
and they are provided according to the
status of the: Computers,
peripherals, and hydraulic generation.

The three sets of control laws are:

• Normal law
• Alternate law
• Direct law.

OBJECTIVES

The aim of normal law is to provide the
following handling characteristics within the
normal flight envelope
(regardless of aircraft speed,
altitude, gross weight and CG):

• Aircraft must be stable and maneuverable

• The same response must be consistently obtained from the acft

• The Actions on the sidestick must be balanced in pitch and in roll.


The normal law handling characteristics,
at the flight envelope limit are:

• The PF has full authority to achieve Maximum aircraft Performance

• The PF can have instinctive/immediate reaction,
in the event of an emergency

• There is a reduced possibility of overcontrolling or
overstressing the aircraft.

Normal Law is the law that is most commonly available,
and it handles single failures.


CHARACTERISTICS IN PITCH

IN FLIGHT

When the PF performs sidestick inputs, a constant
G-load maneuver is ordered, and the aircraft
responds with a G-Load/Pitch rate.

Therefore, the PF’s order is consistent with the response
that is "naturally" expected from the aircraft:

Pitch rate at low speed; Flight Path Rate or G, at
high speed.

So, if there is no input on the stick:

• The aircraft maintains the flight path, even in case of speed changes

• In case of configuration changes or thrust variations,
the aircraft compensates for the pitching moment effects

• In turbulence, small deviations occur on the flight path.
However, the aircraft tends to regain a steady condition.

AIRBUS PITCH CHARACTERISTIC


Operational Recommendation:

From the moment the aircraft is stable and auto-trimmed,
the PF needs to perform minor corrections on the sidestick,
if the aircraft deviates from its intended flight path.

The PF should not force the sidestick, or overcontrol it.
If the PF suspects an overcontrol,they should release the sidestick.

AT TAKEOFF AND LANDING

The above-mentioned pitch law is not the most appropriate
for takeoff and flare, because the stable flight path is
not what the PF naturally expects.

Therefore, the computers automatically adapt
the control laws to the flight phases:

• GROUND LAW: The control law is direct law
• FLARE LAW: The control law is a pitch demand law.

Operational Recommendation:

Takeoff and landing maneuvers are naturally achieved.
For example, a flare requires the PF to apply permanent aft pressure on
the sidestick, in order to achieve a progressive flare.

Whereas, derotation consists of smoothly flying the nose gear down,
by applying slight aft pressure on the sidestick.


LATERAL CHARACTERISTICS

NORMAL CONDITIONS

When the PF performs a lateral input on the sidestick,
a roll rate is ordered and naturally obtained.

Therefore, at a bank angle of less than 33 °,
with no input on the sidestick, a zero roll rate is ordered,
and the current bank angle is maintained.

Consequently, the aircraft is laterally stable,
and no aileron trim is required.

However, lateral law is also a mixture of roll and yaw demand with:

‐ Automatic turn coordination

‐ Automatic yaw damping

‐ Initial yaw damper response to a major aircraft assymetry.

In addition, if the bank angle is less than 33 °,
pitch compensation is provided.

If the bank angle is greater than 33 °,
spiral stability is reintroduced and pitch
compensation is no longer available.

This is because, in normal situations,
there is no operational reason to fly
with such high bank angles for a long period of time.

AIRBUS LATERAL CHARACTERISTIC



Operational Recommendation:

During a normal turn (bank angle less than 33 °), in level flight:

• The PF moves the sidestick laterally
(the more the sidestick is moved laterally, the greater
the resulting roll rate - e.g. 15 °/s at max deflection)

• It is not necessary to make a pitch correction

• It is not necessary to use the rudder.

In the case of steep turns (bank angle greater than 33 °), the PF must apply:

• Lateral pressure on the sidestick to maintain bank

• Aft pressure on the sidestick to maintain level flight.
Relembrando os MEMORY ITEMS:

01 - CREW INCAPACITATION
02 - EGPWS ALERTS
03 - EMERGENCY DESCENT
04 - UNRELIABLE SPEED INDICATION
05 - LOSS OF BRAKING
06 - STALL RECOVERY
07 - STALL WARNING AT LIFT-OFF
08 - TCAS WARNING
09 - WINDSHEAR
10 - WINDSHEAR AHEAD



CONFORME CITADO ANTERIORMENTE PARA O CASO DE:

CREW INCAPACITATION:

- CHAMAR A COMISSARIA VIA PA
- A CMRA DEVE APERTAR E TRAVAR OS CINTOS PILOTO INCAPACITADO
- AFASTAR O ASSENTO TOTALMENTE PARA TRAS
- RECLINAR O ENCOSTO
> SÃO NECESSÁRIOS DUAS PESSOAS PARA REMOVER UM CORPO DA
CABINE SEM QUE HAJA INTERFERÊNCIA NOS COMANDOS
> SE NÃO FOR POSSÍVEL REMOVER O CORPO, A CMRA DEVE PERMANECER
NA CABINE PARA CUIDAR DO PILOTO INCAPACITADO
> COM A AJUDA DE UMA CMRA, VERIFICAR SE HÁ A BORDO ALGUM
PASSAGEIRO MÉDICO.
> VERIFICAR SE HÁ A BORDO ALGUM PILOTO DA CIA HABILITADO
PARA SUBSTITUIR O PILOTO INCAPACITADO.



CASO OCORRA EGPWS ALERT:

> AUTO PILOT:.....OFF
> PITCH:..........PULL UP
> THR LVRS:.......TOGA
> SPD BRK:........CHECK RETRACT
> WINGS:..........LEVEL



EM HAVENDO A NECESSIDADE DE EFETUAR UMA DESCIDA DE EMERGENCIA
OS PILOTOS DEVEM:

PRIMEIRAMENTE COLOCAR AS MASCARAS DE OXIGÊNIO E ESTABELECER
COMUNICAÇÕES: "VC ME OUVE - ESTÁ ME OUVINDO ? AFIRMO TE ESCUTO"

EM SEGUIDA O PILOT FLYING VAI INSTINTIVAMENTE:

- GIRAR E PUXAR O SELETOR DE ALTITUDE NO FCU
- GIRAR E PUXAR O SELETOR DE HDG NO FCU
- APENAS PUXAR O SELETOR DE VELOCIDADE QUE TB ESTÁ NO FCU
E LER O FMA PARA CONFIRMAR QUE A AERONAVE INICIOU
UMA DESCIDA EM CURVA COM A VELOCIDADE SELECIONADA.
- E COMANDAR O SPEED BRAKE, VERIFICANDO A VELOCIDADE

SIMULTANEAMENTE, O PILOT NOT FLYING DEVE:

- LIGAR O AVISO DE PRENDER OS CINTOS (SIGNS : ON)
- COLOCAR O ENG MODE SEL EM IGN
- SELECIONAR 7700 NO TRANSPONDER
- E AVISAR O CONTROLE: "centro/controle_____aqui é o ____/____
em descida de emergência para o FL____, na proa____.
- O PNF DEVE AINDA MONITORAR A ALTITUDE DE CABINE E CASO
ESTA ULTRAPASSE OS 14000 FT DEVERÁ ACIONAR AS MÁSCARAS DE
OXIGÊNIO PARA PASSAGEIROS (PAX OXY MASK: MAN ON)

O PF DEVE EFETUAR UM SEGUNDO LOOP PARA REFINAMENTOS DAS SELEÇÕES
DE ALTITUDE, HDG E VELOCIDADE.



PARA O CASO DE OCORRER UM "UNRELIABLE SPEED INDICATION" OS ITENS DE
MEMÓRIA SÃO OS SEGUINTES:

- AP....OFF / FD....OFF / AUTO THRUST....OFF

- PITCH AND THRUST:

> ABAIXO DA THRUST REDUCTION.........................15/TOGA.
> ACIMA DA THRUST REDUCTION, ABAIXO DO FL 100........10/CLB.
> ACIMA DA THRUST REDUCTION, ACIMA DO FL 100..........5/CLB.

- MANTER A PRESENTE CONFIGURAÇÃO DE FLAPS E
- CHECAR SPEED BRAKES RETRAIDOS.


SE OCORRER UMA SITUAÇÃO DE "LOSS OF BRAKE", OS ITENS DE MEMÓRIA A
SEREM EXECUTADOS, SÃO:

- REVERSORES EM MÁXIMO
- PEDAIS DO FREIO: SOLTAR
- SWITCH DO NOSE WHEEL ANTI SKID COLOCAR EM OFF
- PRESSIONAR OS PEDAIS DO FREIO
- MONITORAR A PRESSAO (MAXIMO 1000 PSI)

> SE MESMO ASSIM CONTINUAR SEM FREIOS:

- EFETUAR APLICAÇÕES CURTAS E SUCESSIVAS NO PARKING BRAKE HANDLE.



PARA O CASO DE UM ALERTA DE "STALL":

- NOSE PITCH DOWN APPLY
- BANK: WINGS LEVELLED.



PARA O CASO DE UM ALERTA DE "STALL" NA DECOLAGEM (NO "LIFT-OFF")

- THRUST........TOGA
- PITCH.........15
- BANK..........WINGS LEVELLED


PARA O CASO DE "TCAS WARNINGS":

- callout: "TCAS I HAVE CONTROL"

- AP......OFF / FD......OFF
- FOLLOW THE GREEN ON VERTICAL SPEED SCALE.


PARA O CASO DE "WINDSHEAR":

- THR LVRS.......TOGA
- VR.............ROTATE
- SRS............FOLLOW
- IF AIRBORNE: MAINTAIN PRESENT CONFIG


PARA O CASO DE "WINDSHEAR A HEAD":

- THR LVRS.......TOGA
- SRS............FOLLOW
- GO AROUND PERFORM IF IN APPROACH OR LANDING PHASE
- IF FD IS NOT AVAILABLE: PITCH UP TO 17,5 DEGREES


ESSES SÃO TODOS OS ITENS DE MEMÓRIA DO AIRBUS 320F.