Figure 9-46. Weight and balance diagram.
17,000
16,000
15,000
14,000
13,000
12,000
11,000
10,000
9,000
272 276 280 284 288 292 296 300 304
CG (inches aft of datum)
Weight (lb)
Maximum zero fuel weight
Maximum takeoff weight 16,600
Maximum landing weight 16,000
Maximum zero fuel weight 14,000
Maximum takeoff weight
Determining the Changes in CG When
Passengers Are Shifted
Using the loaded weight and CG of the Beech 1900, calculate
the change in CG when the passengers in rows 1 and 2 are
moved to rows 8 and 9. [Figure 9-47] Note that there is no
weight change, but the moment index has been increased by
1,155 pound-inches/100 to 44,294. The new CG is at fuselage
station 300.7. [Figure 9-48]
This type of problem is usually solved by using the following
two formulas. The total amount of weight shifted is 550
pounds (300 + 250) and both rows of passengers have moved
aft by 210 inches (410 – 200 and 440 – 230). The CG has
been shifted aft by 7.8 inches, and the new CG is at station
300.7. [Figure 9-49]
Figure 9-47. Changes in CG caused by shifting passenger seats.
Item Weight Arm Moment/100 CG
(−) 600
(−) 575
(+) 1,230
(+) 1,100
43,139
(+) 1,155
44,294 300.7
Row 1
Row 2
Row 8
Row 9
Original conditions
Changes
New conditions
(−) 300
(−) 250
(+) 300
(+) 250
14,729
0
14,729
200
230
410
440
Figure 9-48. Determining the new CG at fuselage station.
( )CG = × 10043,139 + 1,155
14,729
= 300.7
Figure 9-49. Determining the new CG at station after CG has
shifted aft.
CG = Weight shifted × Distance shifted
Total weight
= 550 × 210
14,729
= 7.8 inches
= 292.9 + 7.8
CG = Original CG + CG
= 300.7 inches aft of datum
Figure 9-50. One passenger configuration of a B737-800.
Mixed class:
12 first class seats at 36-inch pitch
148 economy class seats at 32-inch pitch
G
C
C
G
A
A
G
L
G
A
A
L
A
In a large cabin aircraft with high-density seating such as
the B737-800, the operator must account for the seating of
passengers in the cabin [Figure 9-50]. If assigned seating
is used to determine passenger location, the operator
must implement procedures to ensure the assignment of
passenger seating is incorporated into the loading procedure.
It is recommended that the operator take into account the
possibility that some passengers may not sit in their assigned
seats.
If the actual seating location of each passenger is not known,
the operator may assume that all passengers are seated
uniformly throughout the cabin or a specified subsection of
the cabin. Reasonable assumptions can be made about the
manner in which people distribute themselves throughout
the cabin. For example, window seats are occupied first
followed by aisle seats, followed by the remaining seats
(window-aisle-remaining seating). Both forward and rear
loading conditions should be considered. The passengers may
fill up the window, aisle, and remaining seats from the front
of the aircraft to the back, or the back to the front.
If necessary, the operator may divide the passenger cabin
into subsections or zones and manage the loading of each
zone individually. It can be assumed that passengers will be
sitting uniformly throughout each zone.
Another consideration is the inflight movement of passengers,
crew, and equipment. It is assumed that all passengers, crew,
and equipment are secured when the aircraft is in the takeoff
or landing configuration. Standard operating procedures
Figure 9-51. Loading data for cargo configuration.
Section A
Section B
Section C
Section D
Section E
Section F
Section G
Section H
Section I
Section K
Sec
J
F.S. 210
F.S. 240
F.S. 270
F.S. 300
F.S. 330
F.S. 360
F.S. 390
F.S. 420
F.S. 480
F.S. 513.5
F.S. 450
A 600 F.S. 225.0
B 600 F.S. 255.0
C 600 F.S. 285.0
D 600 F.S. 315.0
E 600 F.S. 345.0
F 600 F.S. 375.0
G 600 F.S. 405.0
H 600 F.S. 435.0
I 600 F.S. 465.0
J 250 F.S. 499.5
K 565 F.S. 533.0
Section
Notes:
1. All cargo in sections A
through J must be
supported on the seat
tracks and secured to the
seat tracks and side seat
rails by an FAA-approved
system.
2. Concentrated cargo loads
in sections A through L
must not exceed 100 lb
per square foot.
3. Cargo in sections K and L
must be retained by
baggage webs and
partitions provided as part
of standard airplane.
4. Any exception to the
above procedures
requires approval by a local
FAA office.
Centroid
arm
Maximum
structural
capacity
Loading cargo configuration
should be taken into account. Examples of items that can
move during flight are:
• Flight deck crew members moving to the lavatory.
• Flight attendants moving throughout the cabin.
• Service carts moving throughout the cabin.
• Passengers moving throughout the cabin.
• Passengers moving to the lavatory.
Determining Changes in Weight and CG
When the Aircraft Is Operated in Its Cargo
Configuratio
To determine changes in weight and CG when the aircraft
is operated in its cargo configuration, the Beech 1900 is
used as an example. Figure 9-51 illustrates the airplane
configuration. Notice that the arm of each cargo section is
the centroid of that section.
The flight manifest of the Beech 1900 in the cargo
confi uration is illustrated in Figure 9-52. The BOW includes
the pilots and their baggage and there is no separate item
for them.
At the standard temperature of 15 °C, the fuel weighs 6.8
pounds per gallon. Refer to Figure 9-45 to determine the
weight and moment index of 370 gallons of Jet A fuel. The
CG under these loading conditions is located at station 296.2.
Determining the CG Shift When Cargo Is Moved
From One Section to Another
To calculate the CG when cargo is shifted from one section
to another, use the formula found in Figure 9-53. If the cargo
is moved forward, the CG is subtracted from the original CG.
If the cargo is shifted aft, add the CG to the original.
Determining the CG Shift When Cargo Is Added
or Removed
To calculate the CG when cargo is added or removed, add or
subtract the weight and moment index of the affected cargo to
the original loading chart. Determine the new CG by dividing
the new moment index by the new total weight, and multiply
this by the reduction factor. [Figure 9-54]
Determining Which Limits Are Exceeded
When preparing an aircraft for flight, consider all parameters
and check to determine that no limits have been exceeded.
Consider the parameters below, and determine which limit,
if any, has been exceeded.
• The aircraft in this example has a basic empty weight
of 9,005 pounds and a moment index of 25,934 pound
inches/100.
• The crew weight is 340 pounds and its moment/100
is 439.
• The passengers and baggage have a weight of 3,950
pounds and a moment/100 of 13,221.
• The fuel is computed at 6.8 lb/gal. The ramp load is
340 gallons or 2,312 pounds. Fuel used for start and
taxi is 20 gallons, or 136 pounds. Fuel remaining at
landing is 100 gallons, or 680 pounds.
• Maximum takeoff weight is 16,600 pounds.
• Maximum zero fuel weight is 14,000 pounds.
• Maximum landing weight is 16,000 pounds.
Figure 9-53. Shifting cargo from one section to another.
CG = Weight shifted x Distance shifted
Total weight
Figure 9-52. Flight manifest of a Beech 1900 in the cargo configuration.
Item Weight Arm Moment/100 CG
25,934
675
1,020
1,283
1,890
2,070
2,250
810
7,520
43,452 296.2
BOW
Cargo section A
Cargo section B
Cargo section C
Cargo section D
Cargo section E
Cargo section F
Cargo section G
Cargo section H
Cargo section I
Cargo section J
Cargo section K
Fuel jet A at +15 °C
gallons 370
9,005
300
400
450
600
600
600
200
2,516
14,671
225.0
255.0
285.0
315.0
345.0
375.0
405.0
435.0
465.0
499.5
533.0
Figure 9-54. Determining the new CG by dividing the new moment
index by the new total weight, multiplied by the reduction factor.
CG = x Reduction factorTotal moment index
Total weight
Figure 9-55. Determining the zero fuel weight.
Item Weight (lb) Moment CG
Basic empty weight
Crew
Passengers & baggage
Zero fuel weight
9,005
340
3,950
13,295
25,934
439
13,221
39,594
Figure 9-56. Determining the takeoff weight and CG.
Item Weight (lb) Moment CG
Zero fuel weight
Takeoff fuel 320 gal
Ramp load−fuel for
start & taxi
340 − 20 = 320 gal
Takeoff weight
13,295
2,176
15,471
39,594
6,512
46,106 298.0
Figure 9-57. Determining the landing weight and CG.
Item Weight (lb) Moment CG
Zero fuel weight
Fuel at landing 100 gal
Landing weight
13,295
680
13,975
39,594
1,977
41,571 297.5
Take these steps to determine which limit, if any, is exceeded:
1. Determine the zero fuel weight, which is the weight
of the aircraft with all of the useful load except the
fuel onboard. [Figure 9-55]
The zero fuel weight of 13,295 pounds is less than
the maximum of 14,000 pounds, so this parameter is
acceptable.
2. Determine the takeoff weight and CG. The takeoff
weight is the zero fuel weight plus the weight of the
ramp load of fuel, minus the weight of the fuel used
for start and taxi. The takeoff CG is the moment/100
divided by the weight, and then the result multiplied
by 100. The takeoff weight of 15,471 pounds is below
the maximum takeoff weight of 16,600 pounds, and a
check of the weight and balance diagram shows that the
CG at station 298.0 is also within limits. [Figure 9-56]
3. Determine the landing weight and CG. This is the zero fuel
weight plus the weight of fuel at landing. [Figure 9-57]
The landing weight of 13,975 pounds is less than the
maximum landing weight of 14,000 to 16,000 pounds.
According to the weight and balance diagram, the
landing CG at station 297.5 is also within limits.