AC 43.13-1A 1972
DATUM - DATUM D *-D Cic
NOSE WHEEL TYPE AIRCRAFT
DATUM LOCATED FORWARD OF THE
MAIN WHEELS C.O. - D - (4X4)
TAIL WHEEL TYPE AIRCRAFT
DATUM LOCATED FORWARD OF THE
MAIN WHEELS C.G. = D +(RX L.)
-DATUM • DATUM *D~ G.S
NOSE WHEEL TYPE AIRCRAFT
DATUM LOCATED AFT OF THE MAIN WHEELS C.O.. - (D+ (D+ L)
TAIL WHEEL TYPE AIRCRAFT
DATUM LOCATED AFT OF THE MAIN WHEELS C.O.= -D (REL) CG • Distance from datum to center of gravity of the aircraft.
W - The weight of the aircraft at the time of weighing.
D = The horizontal distance measured from the datum to the main wheel weighing point, I • The horizontal distance measured from the main wheel weighing point to the nose or tall weighing point.
F = The weight at the nose weighing point.
R = The weight at the tall weighing point.
FIGURE 18.4.-Empty weight center-of-gravity formulas.
Par 657 Chap 13
Page 248 AC 43.13-1A 1972
DATUM (LEADING EDGE OF
WING ROOT SECTION)
COMPUTED C.G.
TARE 27 LBS.
LEFT SCALE 565 LBS. • SCALE READING WEIGHING POINT RIGHT SCALE 564 LES. 67LBS.
(@ MAIN WHEEL)
D, MEASURED - L, MEASURED -WEIGHING POINT (E TAIL WHEEL) TO FIND: EMPTY WEIGHT AND EMPTY WEIGHT CENTER OF GRAVITY Datum is the leading edge of the wing (from aircraft specification) (D) Actual measured horizontal distance from the main wheel weighing point f main wheel) to the Datum-- (L) Actual measured horizontal distance from the rear wheel weighing point (G rear wheel) to the main wheel weighing point-- --22211 SOLVING: EMPTY WEIGHT Weighing Scale Net Point Reading * Tare # Weight # Right 564 564 Left 565 565 Rear 67 27 40 Empty Weight (W) 1169 SOLVING: EMPTY WEIGHT CENTER OF GRAVITY Formula: C.G. = D + B x L = 9" + 40 × 222 = 3" + 7.6" = 10.6" 1169 Reference for formula, Figure 13,4 This case is shown properly entered on a sample weight and balance report form, Figure 13.17 FIGURE 18.5.-Empty weight and empty weight center of gravity-tail-wheel type aircraft.
Par 657 Chap 13
AC 43.13-1A Pago 249 1972
DATUM (LEADING EDGE OF
WING ROOT SECTION) COMPUTED •
NOSE SCALE 464 LBS. LEFT SCALE 620LB8., TARE 5LBS.
TARE IO LBS. RIGHT SOALE 609 L8S., TARE 5 LBS.
WEIGHING POINT - D, MEASURED (E NOSE WHEEL)
WEIGHING POINT L, MEASURED (2 MAIN WHEEL) TO FIND: EMPTY WEIGHT AND EMPTY WEIGHT CENTER OF GRAVITY Datum is the leading edge of the wing (from aircraft specification) (D) Actual measured horizontal distance from the main wheel weight point (Qmain wheel) to the Datum---- ---- 34.011 (L) Actual measured horizontal distance from the front wheel weighing point (C front wheel) to the main wheel weighing point--- -- 67.8"1 SOLVING: EMPTY WEIGHT Weighing Scale Tare # Net Point Reading * Weight Right 609 604 Leit 820 5 615 From 464 10 454 Empty Weight (W) 1678 SOLVING: EMPTY WEIGHT CENTER OF GRAVITY Formula: C.O. = D - 2&1 - 3411 - 456 2 87.8 - 3411 - 18.811 = 15.711 Reference for formula, Figure 13,4.
FioURE 18.8.-Empty welght and empty weight center-of-gravity-nose-wheel type aircraft.
Chap 13 Par 687
Page 250 AC 43.12-1A 1972 C.G. RANGE, THE LOADED C.G. MUST BE
WITHIN THE LIMITS SHOWN ON THE AIR-
CRAFT SPECIFICATION FOR ALL FLIGHT OPERATIONS, DATUM FORWARD LIMIT •- REARWARD LIMIT
- C.G.
FIGURE 18.7.-Operating center-of-gravity range.
ance report when used in lieu of the landing gear. Typical locations of the weighing points are shown in figure 18.8.
n. Zero fuel weight is the maximum permissible weight of a loaded aircraft (passengers, crew, cargo, etc.) less its fuel. All weights in excess of maximum zero fuel weight must consist of useable fuel.
o. Minimum Fuel. Minimum fuel for balance purposes is no more than the quantity of fuel necessary for one-half hour of operation at rated maximum continuous power, and is the maximum amount of fuel used in weight and balance computation when low fuel may adversely affect the most critical balance condition.
p. Full Oll. Full oil is the quantity of oil shown in the aircraft specifications as oil capacity.
Use full oil as the quantity of oil when making the loaded weight and balance computations.
q. Tare. Tare is the weight of chocks, blocks, stands, etc., used when weighing aircraft, and Par 657 is included in the scale readings. Tare is deducted from the scale reading at each respective weighing point where tare is involved to obtain the actual aircraft weight.
658. WEIGHING PROCEDURE. Accepted procedures when weighing an aircraft are:
a. Remove excessive dirt, grease, moisture, etc., from the aircraft before weighing.
b. Weigh the aircraft inside a closed building to prevent error in scale reading due to wind.
c. To determine the center of gravity, place the aircraft in a level flight attitude.
d. Have all items of equipment included in the certificated empty weight installed in the aircraft when weighing. These items of equipment are a part of the current weight and balance report. (See paragraph 662.)
•. Properly calibrate, zero, and use the scales in accordance with the scale manufacturer's instructions. The scales and suitable support for the aircraft, if necessary, are usually placed Chap 13
AC 43.13-1А 1972 I. Note tare when the aircraft is removed from the scales.
659. WEIGHT AND BALANCE COMPUTATIONS.
It is often necessary, after completing an extensive alteration, to establish by computation that the authorized weight or c.g. limits as shown on the FAA Aircraft Specifications are not exceeded. Paragraph b. explains the significance of algebraic signs used in balance computations.
The Aircraft Specifications contain the following information relating to the subject:
1. Center of gravity range.
2. Empty weight c.g. range when applicable.
8. Leveling means.
4. Datum.
5. Maximum weights.
6. Number of seats and arm.
7. Maximum baggage and arm.
8. Fuel capacity and arm.
9. Oil capacity and arm.
10. Equipment items and arm.
FAA Type Certificate Data Sheets do not list the basic required equipment prescribed by the applicable airworthiness regulations for certification. Refer to the manufacturer's equipment list for such information.
a. Unit Weight for Weight and Balance Purposes.
Gasoline - 6 pounds per U.S. gal.
Turbine fuel 6.7 pounds per U.S. gal.
Lubricating oil.... 7.5 pounds per U.S. gal.
Crew and passengers .... 170 pounds per person.
b. Algebralc Signs. It is important to retain the proper algebraic sign (+ or -) through all balance computations. For the sake of uniformity in these computations, visualize the aircraft with the nose to the left. In this position any arm to the left (forward) of the datum is "minus" and any arm to the right (rearward) of the datum is "plus." Any item of weight added to the aircraft either side of the datum is plus weight. Any weight item removed is a minus weight. When multiplying weights by arms, the answer is plus if the signs are alike, and minus if the signs are unlike.
Chap 13 Page 253 The following combinations are possible:
Items added forward of the datum- (+) weight × (-) arm = (-) moment.
Items added to the rear of the datum- (+) weight × (+) arm = (+) moment.
Items removed forward of the datum- (-) weight × (-) arm = (+) moment.
Items removed rear of the datum- (-) weight × (+) arm = (-) moment.
The total weight of the airplane is equal to the weight of the empty aircraft plus the weight of the items added, minus the weight of the items removed.
The total moment of the aircraft is the algebraic sum of the empty weight moment of the aircraft and all of the individual moments of the items added and/or removed.
660. WEIGHT AND BALANCE EXTREME CONDI- TIONS. The weight and balance extreme conditions represent the maximum forward and rearward c.g. position for the aircraft. Include in the weight and balance data information showing that the c.g. of the aircraft (usually in the fully loaded condition) falls between the extreme conditions.
a. Forward Weight and Balance Check, When a forward weight and balance check is made, establish that neither the maximum weight nor the forward c.g. limit listed in the Aircraft Specifications is exceeded. To make this check, the following information is needed:
(1) The weights, arms, and moment of the empty aircraft.
(2) The maximum weights, arms, and moments of the items of useful load which are located ahead of the forward c.g. limit; and
(3) The minimum weights, arms, and moments of the items of useful load which are located aft of the forward c.g. limit.
A typical example of the computation necessary to make this check, using the above data, is shown in figure 18.10.
b. Rearward Weight and Balance Check.
When a rearward weight and balance check is made, establish that neither the maximum weight nor the rearward c.g. limit listed in the Par 658
Pago 234 AC 43.13-14 1972
- DATUM
- NO BAGGAGE
NO PASSENGERS
FULL OIL- - MINIMUM FUEL
- PILOT ONLY FORWARD C.G. LIMIT.
TO CHECK: MOST FORWARD WEIGHT AND BALANCE EXTREME.
GIVEN: Actual empty weight of the airplane - 1169# Empty weight center of gravity - +10.6'' *Maximum weight 2100# *Forward C,G. limit + 8,5" "Oil, capacity 8 qts. 17# at - 49 *Pilot in farthest forward seat equipped with controls (unless otherwise placarded) -- 170# at + 16" *Since the fuel tank is located to the rear of the forward C.G. limit, minimum fuel should be Included. 12 12 13,75 gal. × 64 83# at + 22" *Information should be obtained from the aircraft specification.
Note: Any items or passengers must be used if they are located ahead of the forward C.G. limit.
Full fuel must be used If the tank is located ahead of the forward C.G. limit.
CHECK OF FORWARD WEIGHT AND BALANCE EXTREME Weight (*) x Arm ("") Moment (P+) Aircraft Empty + 1169 + 10.6 + 12391 OIL + 17 - 49 B33 Pilot + 170 + 16 + 2720 Fuel 83 + 22 + 1828 Total + 1439 (TW) + 16104 (TM) Divide the TM (Total Moment) by the TW (Total Weight) to obtain the forward weight and balance extreme.
TM - 16190 = + 11.21 Since the forward C.G. limit and the maximum weight are not exceeded, the forward weight and balance extreme condition is satisfactory.
FIGURE 18.10.-Example of check of most forward weight and balance extreme.
Par 660 Chap 13
AC 49.13-1А Page 251 1972
WEIGHING POINT (C MAIN WHEEL) SCALE
WEIGHING POINT SCALE -→ (@ TAIL WHEEL)
WEIGHING POINT (& NOSE WHEEL) SCALE
- SCALE
WEIGHING POINT (JACKPAD) SCALE FOURE 19.8.-Weighing point centerline.
under the wheels of a iandplane, the keel of a seaplane float, or the skis of a skiplane. Other structural locations capable of supporting the aircraft, such as jack pads, may be used.
Clearly indicate these points in the weight and balance report.
f. Unless otherwise noted in the aircraft specification, drain the fuel system until the quantity indicator reads "zero" or empty with the Chap 13 aircraft in level flight attitude. The amount of fuel remaining in the tank, lines, and engine is termed "residual fuel" and it is to be included in the empty weight. In special cases, the aircraft may be weighed with full fuel in tanks provided a definite means of determining the exact weight of the fuel is available.
g. Unless otherwise noted in the aircraft specification, the oil system should be completely Par 658
AC 43.13-1A 1972
- DATUM
• EMPTY WEIGHT C.G.
OIL TANK 9QTS AT - 49" C.G. AS WEIGHED WITH OIL IS +9.7" WEIGHT OF AIRCRAFT WITH OIL IS 1186 LES.
EMPTY WEIGHT AND EMPTY WEIGHT CENTER OF GRAVITY (when aircraft is weighed with oil) GIVEN:
Aircraft as weighed with full oll-. 1186 lbs.
Center of gravity---- 9.718 Full oil capacity 9 qts. 17 ibs.
SOLVING:
Weight # × Arm" = Moment "# Aircrait as weighed + 1186 + 9.7 + 11504 Less oil 17 - 49.0 833 Total + 1169(A)| + 12337(B) Empty Weight (A) = 1169 pounds.
Empty Weight Center of Gravity B = 12337 = +10.6"1 1169 FIGURE 18.9 -Empty weight and empty weight center-of-gravity when aircraft is weighed with oil.
drained with all drain cocks open. Under these conditions, the amount of oil remaining in the oll tank, lines and engine is termed "residual oil," and it will be included in the empty weight. When weighed with full oil, actual empty weight equals the actual recorded weight less the weight of the oil in the oil tank (oil weight = oil capacity in gallons × 7.5 pounds). Indicate in all weight and balance reports whether weights include full oil or oil drained (see figure 18.9).
h. Do not set brakes while taking scale reading.
Par 65B Chap 13
Pago 237 AC 43.13-1A 1972 FIGURE 12.8.-Blade leading edge and trim tab.
Par 644 Chap 13
Page 238 AC 43.13-14 1972 FIGURE 12.9.-Blade bonding and crack location.
E A FIGURE 12.10.-Blade damage location.
Par 644 Chap 12
AC 43.13-1A Page 255 1972
• DATUM
• MAXIMUM BAGGAGE -MAXIMUM PASSENGERS FULL OIL → MAXIMUM FUEL PILOT ONLY - - REARWARD C.G. LIMIT TO CHECK: MOST REARWARD WEIGHT AND BALANCE EXTREME.
GIVEN: Actual empty weight of the airplane 1169# Empty weight center of gravity 10.6" *Maximum weight - 2100# *Rearward C.O. limit 21.9" *Oll capacity 9 ots. 17# at - 49" *Baggage, placarded do not exceed 100 ibs. 100# at + 75.5" *Two passengers in rear seats, 170 x 2 - 340# at + 48" *Pilot in most rearward seat equipped with controls (unless otherwise placarded) 170# at + 16" *Since the fuel tank is located aft of the rearward C.G. limit full fuel must be used --- 240# at + 22"
• Information should be obtained from the aircraft specification.
Note: If fuel tanks are located ahead of the rearward C.G. limit minimum fuel should be used.
CHECK OF REARWARD WEIGHT AND BALANCE EXTREME Weight (P) x Arm ("'). = Moment ("*) Aircraft empty + 1169 + 10,6 + 12391 17 49 833 Pilot (1) 170 + 18 2720 Passengers (2) + 340 + 48 + 16920 Fuel (40 gals.) + 240 + 22 + 5280 Baggage + 100 + 75.5 7650 Total + 2038 (TW) + 43428 (TM) Divide the TM (Total Moment) by the TW (Total Weight) to obtain the rearward weight and balance extreme. TH - 19428 2038 - + 31,9" Since the rearward C.G. limit and the maximum weight are not exceeded, the rearward woight and balance extreme condition is satisfactory.
FIGURE 18.11. -Example of check of most rearward weight and balance extreme.
Chap 13 Par 660
Lage 356 AC 43.13-14 1972
EXAMPLE OF THE DETERMINATION OF THE NUMBER OF
PASSENGERS AND BAGGAGE PERMISSIBLE WITH FULL FUEL GIVEN:
Actual empty weight of the aircraft 1168+ Empty weight center of gravity ---. 10.6" Maximum weight ------ 2100# Datum is leading edge of the wing Forward center of gravity limit -- Rearward center of gravity limit - 21.9" Oil capacity, 9 qts.; show full capacity 17# at -49" Baggage, maximum -- 100# at +75.5" Two passengers in rear seat, 170# x 2 - 340# at +48" Pilot in most rearward seat equipped with controls (unless otherwise placarded) 170# at + 16" Full fuel, 40 gals. × 6# -- 240# at + 22" Weight(*) × Arm (") = Moment("") Aircrait empty + 1168 + 10,6 + 12391 oil 17 - 49 833 Full fuel + 240 + 22 + 5280 Passengers, 2 rear + 340* + 48 + 16320 Pilot + 170 + 26 + 2720 Baggage + 100 + 75.5 + 7550 Total + 2036 (TW) + 43428(TM) Divide the TM (total moment) by the TW (total weight) to obtain the loaded center of gravity.
TM = 43428 = +21.3" TW 2036 The above computations show that with full fuel, 100 pounds of baggage and two passengers in the rear seat may be carried in this aircraft without exceeding either the maximum weight or the approved C.G. range.
This condition may be entered in the loading schedule as follows:
GALLONS NUMBER OF POUNDS OF
OF FUEL PASSENGERS BAGGAGE Full 2 Rear 100 * Only two passengers are listed to prevent the maximum weight of 2100 Ibs. from being exceeded.
Fiours 18.12. -Loading conditions: determinatlon of the number of passengers and baggage permissible with full fuel.
Par 660 Chap 13