DOC AIRBUS | AMM A320FAircraft Stability
TASK 05-57-00-200-001-C
Aircraft Stability
1. Reason for the Job
Use the method that follows to do graphical checks of the aircraft stability.
A. Referenced Information
3. Job Set-up
Subtask 05-57-00-860-052-A ** ON A/C NOT FOR ALL
Subtask 05-57-00-210-054-A ** ON A/C NOT FOR ALL
[Rev.10 from 2021]
2026.03.31 22:52:16 UTC
Aircraft Stability
1. Reason for the Job
Use the method that follows to do graphical checks of the aircraft stability.
NOTE: The stability graphs for aircraft on wheels (on dry or wet ground) given in this procedure are applicable to a parked or towed aircraft.
NOTE: With the stability graphs (A/C on wheels) given in this procedure, you can do a check of shifting or tipping stability limits. Do this if it is necessary to know only one such limit (towing, for example).
You can also calculate the ballast necessary for aircraft stability in unfavorable conditions in the configurations that follow: - aircraft with 2 engines
- 1 or 2 engines removed
- engine re-installation.
A. Referenced Information
| REFERENCE | DESIGNATION |
|---|---|
Subtask 05-57-00-860-052-A ** ON A/C NOT FOR ALL
A. Aircraft Maintenance Configuration
(1) Make sure that the flaps, the slats, the spoilers, the speed brakes and the thrust reverser are retracted.
(2) Make sure that the THS is set to neutral.
4. Procedure(1) Make sure that the flaps, the slats, the spoilers, the speed brakes and the thrust reverser are retracted.
(2) Make sure that the THS is set to neutral.
Subtask 05-57-00-210-054-A ** ON A/C NOT FOR ALL
A. Stability of the Aircraft
Subtask 05-57-00-210-055-A ** ON A/C NOT FOR ALL CAUTION:
MAKE SURE THAT THE AIRCRAFT WEIGHT ON THE JACKS IS NOT MORE THAN 57 000 KG (125 663.45 LB) IN NO-WIND CONDITIONS. IF YOU DO NOT OBEY THIS LIMIT, DAMAGE TO THE AIRCRAFT STRUCTURE AND/OR THE JACKS CAN OCCUR.
CAUTION:
WHEN YOU LIFT THE AIRCRAFT ON JACKS OUTDOORS, OBEY THE JACK OVERLOAD LIMIT IN WIND CONDITIONS. IF YOU DO NOT OBEY THIS LIMIT, DAMAGE TO THE AIRCRAFT STRUCTURE AND/OR THE JACKS CAN OCCUR.
(1) If necessary, install the ballast: - In the forward compartment
- At pax/crew door No. 1.
NOTE: Before you put ballasts on the aircraft, make sure that you obey the limits below:
(3) This procedure is applicable to these aircraft configurations for each of which a diagram is given:- For the maximum weight of section 11, refer to Weight and Balance Manual (WBM) CTL-LIM-FWD
- For the maximum load on the cabin floor, refer to WBM CTL-LIM-CAB
- For the maximum load on the jacking points, refer to WBM CTL-LIM-JACK.
- Diagram for the aircraft on its wheels, on a dry ground
Aircraft on its Wheels (on Dry Ground) (Applicable to a parked or towed aircraft) ** ON A/C NOT FOR ALL - Diagram for the aircraft on its wheels, on a wet ground Aircraft on its Wheels (on Wet Ground) (applicable to a parked or towed aircraft) ** ON A/C NOT FOR ALL
- Diagram for the aircraft on its wheels, on an ice ground
- Diagram for the aircraft on the jacks
- Diagram for the aircraft on the forward jack or on the nose wheel jack
- Diagram for the aircraft on one MLG wheel jack
- Diagram for the aircraft jacked at the MLG and NLG for wheel change.
B. Check of the Aircraft Stability
Aircraft on its Wheels (on Dry Ground) (Applicable to a parked or towed aircraft) ** ON A/C NOT FOR ALL
(1) Do a check of the aircraft stability, aircraft with two engines installed:
(a) From point A, make a horizontal line: this goes across the weight axis at point B.
(b) From this point B, subtract the weight of the two removed engines 7000 kg (15432.35 lb) approx. to get the point B'.
(c) From point A, make a vertical line: this goes across one division of the "removed engine" scale at point C.
(d) Make a line across the two divisions on this scale (1 division for each engine) to get the point C'.
(e) From point C', make a vertical line and from point B', make a horizontal line: the intersection of these two lines is at point D. For this point, the diagram gives these values:
For this example, we calculate that the hydraulic lift puts a 800 kg (1763.70 lb) contact force on the pylon.
(a) Continue vertical line DC' until it goes across the "contact force" scale to get the point E.
(b) From this point, make a line across one division (0.8 ton/division) to get the point E'.
(c) From this point E', make a vertical line until it goes across the horizontal line DB' to get the point F.
The diagram shows that in these conditions, the engine installation is possible in the open air in winds of less than 23 kts (43 km/h).
(4) Calculation of the weight of the ballast which is necessary for the removal of the engine(s):
If necessary, install the ballast in the forward cargo compartment in position 11 or at the cabin door No. 1.
(a) Continue line B'F until it goes across the 30 kts (56 km/h) maximum windspeed line at point H.
(b) Continue vertical line FE' until it goes across the "ballast on section 11" scale at point G.
(c) From point G, make a horizontal line which goes across the vertical line from point H at point J.
(d) Count the number of divisions on the scale between point G and point J:
1 For the forward cargo compartment position 11: 1.9 divisions
The weight of ballast necessary is thus:
1.9 x 500 kg (1102.31 lb) = 950 kg (2094.39 lb).
2 Or for the cabin door No. 1: 1.2 divisions.
The weight of ballast necessary is thus:
1.2 x 500 kg (1102.31 lb) = 600 kg (1322.77 lb).
NOTE: The same procedure is applicable in all the above configurations. The diagram related to the aircraft on its wheels on the dry ground is used as an example.
Aircraft on its Wheels (on Dry Ground) (Applicable to a parked or towed aircraft) ** ON A/C NOT FOR ALL - Without the crew
- Without the galleys
- Without the pallets and the containers.
- Weight: 40000 kg (88184.88 lb)
- CG: 21%.
NOTE: In these conditions, the aircraft will be safe in the winds less than or equal to 52kts (96 km/h).
(2) Do a check of the aircraft stability after the removal of two engines.(a) From point A, make a horizontal line: this goes across the weight axis at point B.
(b) From this point B, subtract the weight of the two removed engines 7000 kg (15432.35 lb) approx. to get the point B'.
(c) From point A, make a vertical line: this goes across one division of the "removed engine" scale at point C.
(d) Make a line across the two divisions on this scale (1 division for each engine) to get the point C'.
(e) From point C', make a vertical line and from point B', make a horizontal line: the intersection of these two lines is at point D. For this point, the diagram gives these values:
- Aircraft weight: 33000 kg (72752.53 lb)
- CG: 34.2%
- Permitted wind: 26 kts (48 km/h).
For this example, we calculate that the hydraulic lift puts a 800 kg (1763.70 lb) contact force on the pylon.
(a) Continue vertical line DC' until it goes across the "contact force" scale to get the point E.
(b) From this point, make a line across one division (0.8 ton/division) to get the point E'.
(c) From this point E', make a vertical line until it goes across the horizontal line DB' to get the point F.
The diagram shows that in these conditions, the engine installation is possible in the open air in winds of less than 23 kts (43 km/h).
(4) Calculation of the weight of the ballast which is necessary for the removal of the engine(s):
NOTE: The graph gives two possible ballast locations.
The conditions are with the engine(s) removed in the open air with a maximum wind speed of 30 kts (56 km/h).If necessary, install the ballast in the forward cargo compartment in position 11 or at the cabin door No. 1.
(a) Continue line B'F until it goes across the 30 kts (56 km/h) maximum windspeed line at point H.
(b) Continue vertical line FE' until it goes across the "ballast on section 11" scale at point G.
(c) From point G, make a horizontal line which goes across the vertical line from point H at point J.
(d) Count the number of divisions on the scale between point G and point J:
1 For the forward cargo compartment position 11: 1.9 divisions
The weight of ballast necessary is thus:
1.9 x 500 kg (1102.31 lb) = 950 kg (2094.39 lb).
2 Or for the cabin door No. 1: 1.2 divisions.
The weight of ballast necessary is thus:
1.2 x 500 kg (1102.31 lb) = 600 kg (1322.77 lb).
NOTE: Before you put the ballasts on the aircraft, make sure that the limits below are not more than:
- For the maximum weight of section 11, refer to WBM CTL-LIM-FWD
- For the maximum loads on the cabin floor, refer to WBM CTL-LIM-CAB.