A320/321 AP bank angle limits

[The Hedge]

Hi,

Cant find this in FCOM or FCTM.

What are the bank angle limits with the AP engaged and can someone pls provide a reference.

Cheers

[Vc10Tail]

I stand to be corrected but from the first time i learnt about this type in 1989 it was 33 degrees??

[OPEN DES]

No!

It's more complicated than that! Will post once I find a reference. (not in FCOM/FCTM anyway).

The OEI-case is described in FCOM though......................

[kijangnim]

Greetings
Bank limit is modulated with speed and ALTITUDE ,19000 ft is the crossover beyond which it is limited from 15 deg to 20 deg max.

[Oxidant]

It is more complicated than that.
However, the absolute limit is 45 degrees....(FCOM 1.27.20.P6)

[kijangnim]

Greetings,
45 deg seems a bit high, considering that the law is based on passebger comfort :}

[Dualinput]

The FMGS will apply ROLL LIMIT 1 or 2 as appropriate...
Generally Roll Limit 2 is applied. It is based on TAS (varies between 15 to 25 degress)

Roll Limit 1 is applied when the roll limit 2 turn does not capture the engaged leg (intercepting LOC, etc). The max bank angle for Roll Limit 1 is 30 degress.

During an engine out condition, both these limits are set to max 15...

--> Covered well in Honeywell FMGS manual...You will not find this info in FCOMs

cheers,
google

[OPEN DES]

This is an excerpt from the Honeywell FMGS manual:

BANK ANGLE LIMITS
The bank angle limits, roll limit 1, and roll limit 2 are defined by the roll
limit graph shown in Figure 5-3 and are based on true airspeed. During
an engine out condition, both limits are set at 15°.
Control Roll Limit
During selected headingmode, the flight guidance part of the computer
imposes the roll limits.
During managed heading mode, the flight management part of the
computer imposes the roll limits based on true airspeed and the active
segment of the active leg, depending on the need for simple turn control
(the path over the ground is not fixed) or fixed path control (a defined
path over the ground).
D For simple turn control (while turning to a heading target) roll limit 2
is imposed.
D For fixed path control (in legs to capture a path) the FMS uses either
roll limit 1 or roll limit 2 as required below:
— Roll limit 1 - When the turn does not result in a captured and
engaged leg.
— Roll limit 2
D When flying an arc to capture and engage a leg
D When flying an arc to a fix unless:
- The active leg is a holding pattern or procedure turn when
roll limit 2 is imposed.
- The aircraft is within lateral overshoot navigation limits,
(then the en route roll limit is 15°), except in the terminal
area where roll limit 2 is imposed.
The roll limit for lateral path construction is always the bank limit, roll
limit 1, or roll limit 2 for a specific true airspeed.
FMS Roll Limit
Figure 5-3
NOTE: Below 700 ft radio altitude, when in LAND track and LOC
track, bank angle is further limited to 10° by the flight
guidance function.
ROLL LIMIT SUMMARY
Roll limit 1 is used for most straight line segments of a flight leg, and by
the FMS when the heading is managed.
Roll limit 2 is used by the FMS on most managed transitions in the
terminal area, and for specific procedures such as holding patterns,
procedure turns, and arcs.





FCOM 3.2.10 p5 (eng fail after V1) however has the following:

IN TURN FOLLOW FD OR AP* ORDER. WITH NO AP/FD LIMIT BANK ANGLE TO 15deg UP TO F, S, GREEN DOT.

*BANK ANGLE IS LIMITED TO:
-15deg UP TO (MANEUVERING SPEEDS - 10 KTS)
-THEN, LINEAR INCREASE TO 25deg UP TO (MANEUVERING SPEEDS - 3 KTS)
-25deg ABOVE (MANEUVERING SPEEDS - 3 KTS)

The FCOM contradicts the Honeywell manual in stating that bank limit can be above 15 deg with OEI.

Your thoughts??

[FlightDetent]

Honeywell Pegasus FMGS Guide:
The FMS steering command is limited to an optimum maximum bank
angle that gives a stall speedmargin and an initial bank angle limit.Bank
angle limits are described later in this section.
http://img37.imageshack.us/img37/9413/bank1.th.gif (http://img37.imageshack.us/my.php?image=bank1.gif)
http://img40.imageshack.us/img40/9206/bank2.th.gif (http://img40.imageshack.us/my.php?image=bank2.gif)

Note: The FCOM definition of EO bank guidance limits (which I cannot find right now, book 4 ?) are different from those I copied.

Yours,
FD (the un-real)

EDIT: OP DES, you beat me to it, by 7 hours. Shall learn to manage my browser better :ok:

[OPEN DES]

EDIT: OP DES, you beat me to it, by 7 hours. Shall learn to manage my browser better

But you win, you have pictures....... :ok:


EOI bank-limits can be found in:
FCOM 3.2.10 p5 (eng fail after V1: notes in T/O profile)
FCOM 4.4.30 p10 (engine out)


I am sure I have seen bank-angles exceeding 15deg with OEI as ordered by the FD, as per the FCOM. So is the Honeywell manual wrong?

[The Hedge]

Thanks for all the replies.

Was just wondering how you could guarantee a certain AoB during a SID with min a min bank angle of 20/25 degrees etc.

Cheers

[Vc10Tail]

Bank angle is basically limited to 67deg, with the flight control system returning it to 33deg when you release the stick. In normal control mode, that's always the same..

Now, with autopilot on, the system will recognise an EF situation and fly the procedures with 15deg bank angle until "green dot" speed is reached, green dot being a function of VS. As long as the autopilot is on, sideslip is also controlled, but I don't remember what the limit is...

With autopilot off, no limit is made on sideslip, except of course the traditional rudder throw limiter as a function of speed...

[OPEN DES]

Now, with autopilot on, the system will recognise an EF situation and fly the procedures with 15deg bank angle until "green dot" speed is reached, green dot being a function of VS. As long as the autopilot is on, sideslip is also controlled, but I don't remember what the limit is...

With One Engine Inoperative (OEI) the actual bank-limit as commanded by the FDs will be 15deg up to characteristic speed (for the config either: F, S or green dot) minus 10 kt and then linearly increasing to 25deg up to characteristic speed minus 3 kt.


The 33 and 67 deg you describe are features of the FBW (Normal Law) and are not related to AP/FD commanded roll rates nor with manual flying bank limits.

Also the rudder thraw limiter? I suspect you mean the rudder travel limiter is not related at all with maximum sideslip! There is no maximum sideslip defined, the sideslip is whatever it is, and you better keep it optimum as per the BETA target when flying manually. Or keep the sideslip zero on the sideslip indicator whenever the BETA target is not available (config 0 and N1 less than 80%).


Was just wondering how you could guarantee a certain AoB during a SID with min a min bank angle of 20/25 degre

You can't. NAV mode will try to fly the green line up to 30 deg bank basically (a lot will depend on how the SID is constructed by the database programmers). If necessary you can intervene with heading-mode which will give you 25 deg bank with all-engines-operative at most speeds (see the graph).

Cheers

[OPEN DES]

It is more complicated than that.
However, the absolute limit is 45 degrees....(FCOM 1.27.20.P6)


45 deg is the point where the FDs will dissappear when flying manually. (they're assuming you're attempting some type of extreme escape maneuver)

[ECAM_Actions]

What is the roll rate applied to achieve these bank angles with AP engaged? Anyone know?

ECAM Actions.