Figure 2-14. Center of gravity expressed as percent mean
aerodynamic chord.
MAC MAC
30% MAC
15% MAC Datum
Quarter chord
Half
semi-span
Solution by Formula
The problem in Figure 2-11 can be solved by using variations
of this basic equation. First, rearrange the formula to
determine the distance weight B must be shifted:
Distance weight B is shifted = Total weight × Δ CG
Weight shifted
= 500 × –22
200
= –55 inches
The CG of the lever in Figure 2-11 was 72 inches from the
datum. This CG can be shifted to the center of the lever as in
Figure 2-13 by moving weight B. If the 200-pound weight B
is moved 55 inches to the left, the CG shifts from +72 inches
to +50 inches, a distance of 22 inches.
When the distance the weight is to be shifted is known,
the amount of weight to be shifted to move the CG to any
location can be determined by another arrangement of the
basic equation. Use the following arrangement of the formula
to determine the amount of weight that has to be shifted from
station 8 to station +25, to move the CG from station +72
to station +50.
Weight shifted = Total weight × Δ CG
Distance weight is shifted
= 500 × 22
55
= 200 inches
If the 200-pound weight B is shifted from station +80 to
station +25, the CG moves from station +72 to station +50.
A third arrangement of this basic equation is used to
determine the amount the CG is shifted when a given amount
of weight is moved for a specified distance (as it was done
in Figure 2-11). The following formula is used to determine
the amount the CG is shifted when 200-pound weight B is
moved from +80 to +25.
Δ CG = Weight shifted × Distance it is shifted
Total weight
= 200 × 55
500
= 22 inches
Moving weight B from +80 to +25 moves the CG 22 inches
from its original location at +72 to its new location at +50
as seen in Figure 2-13.
To complete the calculations, return to the original formula
and enter the appropriate numbers.
Weight to be shifted = Δ CG
Total weight Distance weight is shifted
200 = 22
500 55
.4 = .4
The equation is balanced.
Mean Aerodynamic Chord
The CG point affects the stability of the aircraft. To ensure
the aircraft is safe to fly, the CG must fall within specified
limits established by the manufacturer.
On some aircraft, the CG is expressed as a percentage of the
length of the mean aerodynamic chord (MAC) or “percent
MAC.” [Figure 2-14] In order to make such a calculation,
the position of the leading edge of the MAC must be known
ahead of time.
CG limits are specified forward and aft and/or lateral (left and
right) limits within which the aircraft’s CG must be located
during flight. The area between the limits is called the CG
range of the aircraft.
The position of the fore and aft CG limits is measured as a
percentage of MAC from the MAC leading edge. Usually for
a single or two-seat aircraft, the most forward position would
be forward of 30–35 percent MAC. Thus, the allowable CG
range in a light aircraft should not exceed 20 percent MAC.
Note: For a rectangular width of constant airfoil section
dimensions, MAC is just the chord. For a symmetrically-
tapered wing, it is the average of the root chord and the tip
chord.
FAA-Furnished Weight and Balance
Information
The information discussed to this point can be readily applied
to any aircraft weight and balance problem. To apply the
techniques, certain elements of information are required.
This information is obtained from both FAA documents and
manufacturer provided data.
Before an aircraft CG can be computed, certain information
must be known. This information, furnished by the FAA
for every certificated aircraft in the Type Certificate Data
Sheets (TCDS) or Aircraft Specifications, can be accessed
at www.faa.gov. When the design of an aircraft is approved
by the FAA, an Approved Type Certificate and TCDS are
issued. The TCDS includes all of the pertinent specification
for the aircraft; at each annual or 100-hour inspection, it is
the responsibility of the inspecting mechanic or repairman
to ensure that the aircraft adheres to them. A note about the
TCDS: aircraft certifi ated before January 1, 1958, were
issued Aircraft Specifica ions under the Civil Air Regulations
(CARs), but when the Civil Aeronautical Administration
(CAA) was replaced by the FAA, Aircraft Specification
were replaced by the TCDS.
The weight and balance information on a TCDS includes CG
range, empty weight CG range (EWCG), maximum weights,
number of seats, maximum baggage, fuel capacity, oil
capacity, and datum location. Data pertinent to an individual
model is located in its respective section of the TCDS. Use
the TCDS excerpts in Figure 2-15 to verify the following for
a Cirrus Design Corporation SR 20 normal category:
CG Range
S/N 1005 through 1147:
Forward Limits: 138.7 inches at 2,110 lb with a straight line
taper to 141.0 in at 2,694 lb and 143.0 in at 2,900 lb
Aft Limits: 144.6 in at 2,110 lb, with straight line taper to
147.4 in at 2,570 lb, and to 147.9 in at 2,745 lb, and 148.2
in at 2,900 lb
S/N 1148 through 1877, 1879 through 1885, and S/N 1005
through 1147 if Cirrus Service Bulletin SB 20-01-00 is
complied with:
Forward Limits: 138.7 in at 2,110 lb with a straight line taper
to 141.0 in at 2,694 lb and 144.1 in at 3,000 lb
Aft Limits: 144.6 in at 2,110 lb, with straight line taper to
147.4 in at 2,570 lb, and to 148.1 in at 2,900 lb, and 148.0
in at 3,000 lb
S/N 1878, 1886 and Subsequent:
Forward Limits: 137.8 in at 2,100 lb with a straight line taper
to 139.1 in at 2,700 lb, and to 140.7 in at 3,050 lb
Aft Limits: 148.1 in at 2,100 lb, with straight line to 148.1
in at 3,050 lb
Empty Weight CG Range (EWCG)
When all of the seats and baggage compartments are located
close together, it is not possible (as long as the EWCG is
located within the EWCG range) to legally load the aircraft
so that its operational CG falls outside this allowable range.
If the seats and baggage areas extend over a wide range, the
EWCG range is listed as “None.”
Maximum Weights
The maximum allowable takeoff and landing weights and
the maximum allowable ramp weight are given. This basic
information may be altered by a note. Notes are found in data
pertinent to all models. An example would be Note 6 at the
end of Figure 2-15.
Number of Seats
The number of seats and their arms are given in such terms
as: 4 (2 at 143.5 aft of datum, 2 at 180 aft of datum).
Maximum Baggage
Maximum baggage for this model is 130 pounds at 208
inches.
Fuel Capacity
This important information is given in such terms as: 60.5
gal at 153.75 in. Usable: 56 gal (See Note 1). Notes can be
found in data pertinent to all models.
Oil Capacity (Wet Sump)
The quantity of the full oil supply and its arm are given: 8
quarts at 76.2 in.
Figure 2-15. Sample excerpt from TCDS A00009CH.
Page No. 1 2 3 4 5 6 7
Rev. No. 11 12 12 14 14 16 16
DEPARTMENT OF TRANSPORTATION
FEDERAL AVIATION ADMINISTRATION
A00009CH
Revision 16
Cirrus Design Corporation
SR20
SR22
April 22, 2009
TYPE CERTIFICATE DATA SHEET NO. A00009CH
This data sheet, which is part of Type Certificate No. A00009CH, prescribes conditions and limitations under which the product
for the which type certificate was issued meets the airworthiness requirements of the Federal Aviation Regulations.
Type Certificate Holder: Cirrus Design Corporation
4515 Taylor Circle
Duluth, MN 55811
I - Model SR20, (Normal Category), Approved October 23, 1998
Engine Teledyne Continental IO-360-ES, Type Certificate Data Sheet (TCDS) E1CE
Fuel 100/100LL minimum grade aviation gasoline
Engine Limits Maximum Take-off 2700 RPM (200 hp)
Maximum Continuous Power 2700 RPM (200 hp)
Propeller and
Propeller limits 1. Hartzell Prope ller Inc. P/N BHC-J2YF-1BF/F7694
TCDS P37EA
Maximum Diameter: 76 inches
Minimum Diameter: 73 inches
Number of Blades: 2
Low Pitch: 14.6°+/-0.5°
High Pitch: 35.0°+/-1.0°
Not to be operated above 24 inches of manifold pressure between 1900 and 2200 RPM.
Spinner: Hartzell P/N A-2295(P) NOTE: Spinner may be painted or polished.
2. Hartzell Propeller Inc. P/N PHC-J3YF-1MF/F7392-1
TCDS P36EA
Maximum Diameter: 74 inches
Minimum Diameter: 72 inches
Number of Blades: 3
Low Pitch: 14.1°+/-0.5°
High Pitch: 35.0°+/-1.0°
No operating limitations to 2800 RPM
Spinner: Hartzell P/N A-2295-1P
3. Hartzell Propeller Inc. P/N PHC-J3YF-1RF/F7392-1
TCDS P36EA
Maximum Diameter: 74 inches
Minimum Diameter: 72 inches
Number of Blades: 3
Low Pitch: 13.9°+/-0.5°
High Pitch: 35.0°+/-1.0°
No operating limitations to 2800 RPM
Spinner: Hartzell P/N A-2295-1(P) NOTE: Spinner may be painted or polished.
Figure 2-15. Sample excerpt from TCDS A00009CH (continued).
A00009CH -2-
Airspeed Limits S/N 1005 thru 1147:
Vne Never Exceed Speed 200 KIAS
Vno Maximum Structural Cruising Speed 165 KIAS
Vo (2900 lbs) Operating Maneuvering Speed 135 KIAS
Vo (2600 lbs) Operating Maneuvering Speed 126 KIAS
Vo (2200 lbs) Operating Maneuvering Speed 116 KIAS
Vfe Maximum Flap Extension Speed 100 KIAS
Vpd Maximum Parachute Deployment Speed 135 KIAS
S/N 1148 thru 1877, 1879 thru 1885, and S/N 1005 thru 1147 if Cirrus Service Bulletin SB 20-01-
00 is complied with:
Vne Never Exceed Speed 200 KIAS
Vno Maximum Structural Cruising Speed 165 KIAS
Vo (3000 lbs) Operating Maneuvering Speed 131 KIAS
Vo (2600 lbs) Operating Maneuvering Speed 122 KIAS
Vo (2300 lbs) Operating Maneuvering Speed 114 KIAS
Vfe Maximum Flap Extension Speed 100 KIAS
Vpd Maximum Parachute Deployment Speed 135 KIAS
S/N 1878, 1886 and subsequent:
Vne Never Exceed Speed 200 KIAS
Vno Maximum Structural Cruising Speed 163 KIAS
Vo (3050 lbs) Operating Maneuvering Speed 130 KIAS
Vfe Maximum Flap Extension Speed 104 KIAS
Vpd Maximum Parachute Deployment Speed 133 KIAS
C.G. Range S/N 1005 thru 1147:
Forward Limits: 138.7 inches at 2110 lbs with a straight line taper to 141.0 inches at 2694 lbs, and
143.0 inches at 2900 lbs.
Aft Limits: 144.6 inches at 2110 lbs, with straight line taper to 147.4 inches at 2570 lbs, and to
147.9 inches at 2745 lbs, and 148.2 inches at 2900 lbs.
S/N 1148 thru 1877, 1879 thru 1885, and S/N 1005 thru 1147 if Cirrus Service Bulletin SB 20-01-
00 is complied with:
Forward Limits: 138.7 inches at 2110 lbs with a straight line taper to 141.0 inches at 2694 lbs, and
144.1 inches at 3000 lbs.
Aft Limits: 144.6 inches at 2110 lbs, with straight line taper to 147.4 inches at 2570 lbs, and to
148.1 inches at 2900 lbs, and 148.0 inches at 3000 lbs.
S/N 1878, 1886 and subsequent:
Forward Limits: 137.8 inches at 2100 lbs with a straight line taper to 139.1 inches at 2700 lbs, and
to 140.7 inches at 3050 lbs
Aft Limits: 148.1 inches at 2100 lbs, with straight line to 148.1 inches at 3050 lbs.
Empty Weight
C.G. Range None
Maximum Weight S/N 1005 thru 1147:
Takeoff and Landing: 2900 lbs.
S/N 1148 thru 1877, 1879 thru 1885, and S/N 1005 thru 1147 if Cirrus Service Bulletin SB 20-01-
00 is complied with:
Takeoff: 3000 lbs.
Landing: 2900 lbs.
Zero Fuel: 2900 lbs.
S/N 1878, 1886 and subsequent:
Takeoff and Landing: 3050 lbs.