CAUTION: DO NOT MOVE THE AIRPLANE IN HIGH WINDS (ABOVE 35 MPH, 30 KNOTS OR 56 KM/ HOUR).
4.
It is necessary to know the ground strength properties to find the best equipment or materials for your operation. This can include the jacks, tow vehicles, winch vehicles, ground cable fasteners (anchors), supports (cribs), or cover materials for the ground.
5.
Use an available special person (Civil Engineer or Ground Analyst) to find the necessary ground properties. Do this only if you have sufficient time.
6.
If you cannot use a special person, you must make the decisions about the procedures. Can you tow (or winch) the airplane? Can you use jacks? Here are the most important items that you must know.
A. The full damage to the landing gears
B. The vertical depth of the change in the ground surface at the wheels (wheel rut depth)
7.
Wheel Rut Depths
A. You must measure the rut depth at approximately 12 inches (30 cm) behind the main landing gear.
B. The charts (Figure 2-4 and Figure 2-5) show the maximum permitted depth that you can have to tow or winch the airplane. This charts also give the approximate weight of the airplane.
8.
This is the procedure for the wheel rut depth chart:
A. The load that you use to tow or winch the airplane is an important item. It cannot be more than the maximum permitted load on the tow fitting of the main gear. See Figure 4-16 and Figure 4-17. Also see CHAPTER 4.
B. You must first find the load on each main gear. If the airplane has a level attitude, have the same approximate load on each main gear. If the airplane attitude is not level, you must make an estimate of the different loads on each gear. You can use the pressure gage on each gear strut to do this (see Item 9).
C. Use the largest gear load for the chart. The depth that you have at the airplane wheel cannot be more than the depth in the chart. If your depth is more than this, you must prepare the ground surface before you can tow the airplane. See CHAPTER 4, for the procedures to increase the load capacity of the ground.
9.
Use the F70200-1 tool, or equivalent, to find the approximate weight on each main gear. This tool measures the strut pressure (in PSIG). You can then use that value in the following formulas to calculate the total airplane weight:
2-10-2
EFFECT OF TERRAIN AND WEATHER
Page 2-9 Jul 01/2005 D623N004
ITEM MEASURED PRESSURE USING F70200 TOOL PSIG (KG/SQ CM) OUTER CYLINDER CROSS SECTIONAL AREA SQ IN (SQ CM)
LEFT MAIN LANDING GEAR P A 57.7
RIGHT MAIN LANDING GEAR P B 57.7
NOSE LANDING GEAR P C 23.7
NOTE: WEIGHT (W) = PRESSURE x AREA
APPROXIMATE TOTAL AIRPLANE WEIGHT (W) = P A (57.7) +P B (57.7) +P C (23.7)
NOTE: . THIS METHOD DOES NOT TAKE INTO CONSIDERATION WEIGHT OF THE COMPONENTS BELOW THE INNER CYLINDER PRESSURE HEAD SUCH AS WHEELS, TIRES, BRAKES AND INNER CYLINDER ASSEMBLY. THESE ITEMS AMOUNT TO APPROXIMATELY 4,213 LB (1911 KG).
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