DOC AIRBUS | AMM A320FAircraft Stability
TASK 05-57-00-200-001-A
Aircraft Stability
1. Reason for the Job
Use the procedure that follows to do graphical checks of the aircraft stability.
A. Referenced Information
3. Job Set-up
Subtask 05-57-00-582-050-A ** ON A/C NOT FOR ALL
Subtask 05-57-00-210-050-A ** ON A/C NOT FOR ALL
[Rev.10 from 2021]
2026.03.31 22:52:14 UTC
Aircraft Stability
1. Reason for the Job
Use the procedure 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 (aircraft on wheels) given in this procedure, you can do a check of the shifting and tipping stability limits.
2. Job Set-up InformationA. Referenced Information
| REFERENCE | DESIGNATION |
|---|---|
 Aircraft on its Wheels (on Dry Ground) (Applicable to a parked or towed aircraft) ** ON A/C NOT FOR ALL | |
| Aircraft on its Wheels (on Wet Ground) (applicable to a parked or towed aircraft) ** ON A/C NOT FOR ALL | |
| Aircraft on its Wheels (on a Dry Ground) (Applicable to a Parked or Towed Aircraft) ** ON A/C NOT FOR ALL | |
| Aircraft on its Wheels (on a Wet Ground) (Applicable to a Parked or Towed Aircraft) ** ON A/C NOT FOR ALL | |
Subtask 05-57-00-582-050-A ** ON A/C NOT FOR ALL
A. Stability and Engine Configuration
You can also calculate the ballast necessary for the aircraft stability in unsatisfactory conditions in the configurations that follow:
Subtask 05-57-00-582-050-B ** ON A/C NOT FOR ALL You can also calculate the ballast necessary for the aircraft stability in unsatisfactory conditions in the configurations that follow:
- Aircraft with 2 engines
- 1 or 2 engines removed
- Engine installation after removal.
A. Stability Configuration after Item Removals
It is necessary to calculate again the aircraft CG and weight to know the aircraft stability after removal of items (engines, pylons, galleys, seats, etc.).
Subtask 05-57-00-860-050-A ** ON A/C NOT FOR ALL It is necessary to calculate again the aircraft CG and weight to know the aircraft stability after removal of items (engines, pylons, galleys, seats, etc.).
NOTE: The Weight and Balance Manual (WBM) CTL-GRD-EQP gives the weight and H-arm of some removable items.
B. Aircraft Maintenance Configuration
(1) Make sure that the flaps, the slats, the spoilers, the speed brakes and the thrust reversers 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 reversers are retracted.
(2) Make sure that the THS is set to neutral.
Subtask 05-57-00-210-050-A ** ON A/C NOT FOR ALL
A. Stability of the Aircraft
Subtask 05-57-00-210-052-A ** ON A/C NOT FOR ALL CAUTION:
MAKE SURE THAT THE AIRCRAFT WEIGHT ON THE JACKS IS NOT MORE THAN 59 000 KG (130 073 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 the pax/crew door No 1.
NOTE: Before ballasts are put on the aircraft, make sure that the limits below are not exceeded:
(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
(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 16 kts (29 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: 2.8 divisions
The weight of the ballast necessary is thus:
2.8 x 500 kg (1102.31 lb) = 1400 kg (3086.47 lb).
2 Or for the cabin door No. 1: 2 divisions
The weight of the ballast necessary is thus:
2 x 500 kg (1102.31 lb) = 1000 kg (2204.62 lb).
Subtask 05-57-00-210-050-B ** ON A/C NOT FOR ALL 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
(1) Do a check of the aircraft stability, aircraft with two engines installed: 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 47kts (87 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: 19 kts (35 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 16 kts (29 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: 2.8 divisions
The weight of the ballast necessary is thus:
2.8 x 500 kg (1102.31 lb) = 1400 kg (3086.47 lb).
2 Or for the cabin door No. 1: 2 divisions
The weight of the ballast necessary is thus:
2 x 500 kg (1102.31 lb) = 1000 kg (2204.62 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 load on the cabin floor, refer to WBM CTL-LIM-CAB.
C. Stability of the Aircraft
(2) This procedure is applicable to these aircraft configurations for each of which a diagram is given:
Subtask 05-57-00-210-052-B ** ON A/C NOT FOR ALL CAUTION:
MAKE SURE THAT THE AIRCRAFT WEIGHT ON THE JACKS IS NOT MORE THAN 59 000 KG (130 073 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) To put the aircraft back into balance, you can also do a refueling procedure of the wing tanks. When you do this, you must add the weight of the fuel to the aircraft weight. (2) This procedure is applicable to these aircraft configurations for each of which a diagram is given:
- Diagram for the aircraft on its wheels, on a dry ground Aircraft on its Wheels (on a 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 a 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.
D. Check of the Aircraft Stability
(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 8000 kg (17636.98 lb) approx. to get 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 two divisions on this scale (1 division for each engine) to get 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 point E.
(b) From this point, make a line across one division (0.8 ton/division) to get point E'.
(c) From this point E', make a vertical line until it goes across the horizontal line DB' to get point F.
The diagram shows that in these conditions, engine installation is possible in the open air in winds of less than 10 kt (19 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: 2.8 divisions
The weight of ballast necessary is thus:
2.8 x 500 kg (1102.31 lb) = 1400 kg (3086.47 lb).
2 Or for the cabin door No. 1: 2 divisions
The weight of ballast necessary is thus:
2 x 500 kg (1102.31 lb) = 1000 kg (2204.62 lb).
NOTE: The same procedure is applicable in all the above configurations. The diagram related to aircraft on wheels on dry ground is used as an example.
Aircraft on its Wheels (on a 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: Aircraft on its Wheels (on a Dry Ground) (Applicable to a Parked or Towed Aircraft) ** ON A/C NOT FOR ALL - Without crew
- Without galleys
- Without pallets and containers.
- Weight: 40000 kg (88184.88 lb)
- CG: 21%.
NOTE: In these conditions, the aircraft will be safe in winds less than or equal to 49 kts (91 km/h).
(2) Do a check of the aircraft stability after 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 8000 kg (17636.98 lb) approx. to get 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 two divisions on this scale (1 division for each engine) to get 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: 32000 kg (70547.90 lb)
- CG: 38%
- Permitted wind: 14 kt (26 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 point E.
(b) From this point, make a line across one division (0.8 ton/division) to get point E'.
(c) From this point E', make a vertical line until it goes across the horizontal line DB' to get point F.
The diagram shows that in these conditions, engine installation is possible in the open air in winds of less than 10 kt (19 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: 2.8 divisions
The weight of ballast necessary is thus:
2.8 x 500 kg (1102.31 lb) = 1400 kg (3086.47 lb).
2 Or for the cabin door No. 1: 2 divisions
The weight of ballast necessary is thus:
2 x 500 kg (1102.31 lb) = 1000 kg (2204.62 lb).
NOTE: Before you put ballasts on the aircraft, make sure that the limits below are not exceeded:
- For the maximum weight of section 11, refer to WBM CTL-LIM-FWD
- For the maximum load on the cabin floor, refer to WBM CTL-LIM-CAB.