TOWING AND TAXIING
**** Hidden Message ***** <P>TOWING<BR>1. General<BR>A. The airplane is normally towed or pushed by a tow bar attached to the nose gear. Maximum<BR>normal towing turning limits are indicated by painted stripes on the nose gear doors.<BR>B. The airplane is capable of being towed on firm and level terrain by the nose gear with one tire<BR>flat on each landing gear if starting loads are held to the minimum. For other abnormal towing<BR>loads, such as towing with two flat tires on one main gear, towing on soft terrain, towing up<BR>inclines greater than 5 degrees, the towing should be done from the main gears as the<BR>structural limitations of the nose gear may be exceeded.<BR>NOTE: With two flat tires on one main gear, effort should be made to replace one of the flat<BR>tires with a serviceable tire before towing to prevent excessive damage to the tires<BR>and wheels.<BR>C. Towing airplane with either or both engines removed presents no problem as long as the center<BR>of gravity remains forward of the aft center of gravity limits. Refer to par. 7 for center of gravity<BR>data.<BR>D. When it is necessary to tilt the airplane for tail clearance in hangars and storage areas, refer to<BR>7-13-0, Tilt Airplane for Tail Clearance.<BR>2. Equipment and Materials<BR>A. Standard tow tractor<BR>B. Tow Bar –C09002 (-1,-2,-5,-10,12 and –13) –9 is replaced by –58 and F72951-51.<BR>C. Eyebolt Assembly, Main Landing Gear Towing - F72719<BR>D. Wire cable (3/4 inch) with end fittings to match F72719 and tow tractor (local fabrication)<BR>E. Steering depressurization valve lockout pin - F72735-13<BR>3. Prepare for Towing Airplane<BR>A. Check airplane is within center of gravity towing limitations and for fuel imbalance. Refer to par.<BR>7 for center of gravity data.<BR>B. Check that all landing gear ground lock pins are installed (Ref 32-00-01).<BR>NOTE: Towing or pushing with landing gear ground lock pins removed is optional.<BR>C. Tires and shock struts properly inflated (Ref Chapter 12).<BR>CAUTION: DO NOT TOW AIRPLANE WITH NOSE GEAR FULLY COLLAPSED OR<BR>EXTENDED MORE THAN 22 INCHES FROM BOTTOM OF INNER CYLINDER<BR>TO BOTTOM OF STEERING PLATE AS NOSE GEAR STRUT MAY BE<BR>DAMAGED INTERNALLY.<BR>D. Apply external electrical power or start and operate APU (Ref 24-41-0 or 49-11-0).<BR>NOTE: With external power applied or APU providing electrical power, parking brakes in<BR>parked position, and hydraulic system ground interconnect valve on (open), system B<BR>pump will pressurize both inboard and outboard brake accumulators A and B. If<BR>parking brakes are off, only outboard brake accumulator B will be charged and<BR>outboard brakes continuously pressurized.</P><P>E. Check that brake hydraulic pressure is normal, approximately 3000 psi.<BR>F. Check that antiskid switch is off.<BR>G. On airplanes without nose gear steering depressurization valve or if Lockout Pin is not installed.<BR>(1) Check that hydraulic system A is depressurized.<BR>NOTE: If hydraulic system A is pressurized, system pressure prevents steering actuator<BR>bypass valve from opening, preventing nose gear from being turned by the tow<BR>bar. (Do not confuse system A pressure with brake accumulator A which<BR>pressurizes only the inboard brakes.)<BR>(2) Remove external electrical power (Ref 24-22-0). The APU may be operated if the engines<BR>are not operating, or the engines are operating but no electrical power changes are made<BR>while towing.<BR>WARNING: ENSURE HYDRAULIC SYSTEM A IS COMPLETELY DEPRESSURIZED<BR>AND DO NOT MAKE ANY ELECTRICAL POWER CHANGES WITH TOW<BR>BAR CONNECTED. AN INTERRUPTION OF ELECTRICAL POWER<BR>COULD CAUSE MOMENTARY PRESSURIZATION OF ENGINE DRIVEN<BR>HYDRAULIC PUMPS WHICH COULD PRESSURIZE SYSTEM A AND<BR>CAUSE NOSE GEAR TO ALIGN WITH STEERING WHEEL POSITION.<BR>DAMAGE TO EQUIPMENT AND INJURY TO PERSONNEL COULD<BR>OCCUR.<BR>H. On airplanes with nose gear steering depressurization valve, depress button and install nose<BR>gear steering lockout pin in steering depressurization valve (Ref 32-00-01).<BR>CAUTION: TO AVOID DAMAGE TO STEERING COMPONENTS OR TOWING<BR>EQUIPMENT, THE DEPRESSURIZATION VALVE BUTTON MUST BE<BR>DEPRESSED AND HELD WHEN LOCKOUT PIN IS INSERTED.<BR>NOTE: Nose gear steering depressurizing lockout pin can be installed and removed without<BR>entering wheel well from aft of right nose wheel well door.<BR>I. Connect interphone system between control cabin, tow tractor operator and towing ground<BR>crew.<BR>J. Check that ramp area is cleared of all stands and equipment in the towing path.<BR>K. Connect tow bar to tow tractor and to airplane.<BR>L. Remove airplane static ground wires.<BR>M. Close the fan cowl panels, thrust reverser (Ref Chapter 71).<BR>CAUTION: MAKE SURE ALL ENGINE COWLS ARE CLOSED AND LATCHED BEFORE<BR>THE AIRPLANE IS TOWED. DAMAGE TO EQUIPMENT CAN OCCUR.<BR>N. To tow the airplane with the entry or lower cargo door open is optional.</P>
<P>4. Tow Airplane from Nose Gear<BR>A. Position wing, tail, tow tractor operator and ground crew so that all are in visual contact.<BR>B. Check that cockpit man, ground crew, and tow tractor operator are in intercom communication.<BR>C. Check that wheel chocks are removed.<BR>D. Check that hydraulic brakes are released.<BR>E. Tow airplane. Begin towing slowly and straight ahead before attempting to turn.<BR>CAUTION: MOVE AIRPLANE FORWARD BEFORE STARTING SHARP TURNS.<BR>AVOID SUDDEN STARTS AND STOPS.<BR>IF TOWING IS BEING DONE UNDER HIGH LOAD CONDITIONS, SUCH<BR>AS TOWING WITH BOTH TIRES FLAT ON ONE MAIN GEAR, TOWING<BR>ON SOFT TERRAIN, TOWING UP INCLINES GREATER THAN 5<BR>DEGREES, OR SIMILAR CONDITIONS, REFER TO MAIN GEAR<BR>TOWING, PAR. 5, AS NOSE GEAR TOWING STRUCTURAL<BR>LIMITATIONS MAY BE EXCEEDED.<BR>F. Limit brake applications to minimum use within safety limitations. Fully charged accumulators<BR>are capable of approximately three brake applications.<BR>CAUTION: IF YOU USE A TOW BAR, YOU CAN CAUSE THE SHEAR PINS TO SHEAR IF<BR>YOU USE THE AIRPLANE BRAKES WHILE YOU TOW THE AIRPLANE.<BR>MOST TOWBARLESS TOW VEHICLES DO NOT HAVE A SHEAR PIN TO LIMIT<BR>THE LOADS IF AIRPLANE BRAKES ARE USED DURING TOWING. IF<BR>AIRPLANE BRAKES ARE USED WHILE TOWING WITH A TOWBARLESS TOW<BR>VEHICLE ATTACHED TO THE NOSE LANDING GEAR, PERFORM THE “HARD<BR>LANDING OR HIGH DRAG/SLIDE LOAD LANDING” INSPECTION FOR THE<BR>NOSE LANDING GEAR AREAS (REF 5-51-51).</P>
<P>G. Maximum normal turning angle is 78 degrees as indicated by red stripes on nose gear doors. If<BR>a greater turning angle is required, disconnect torsion links on nose gear. If an angle in excess<BR>of 90 degrees is required, disconnect nose gear taxi light wire. When disconnected, support<BR>lower torsion link against dragging to prevent damage to lubrication fittings. See Fig. 202 for<BR>turning dimensions. See Fig. 203 for wingtip turning radius for various turning angles. See Fig.<BR>204 for ground turning techniques.<BR>H. Finish towing in a straight path for a minimum of 10 feet to relieve turning stresses remaining in<BR>tires and shock struts.<BR>I. At end of towing, position wheel chocks fore and aft of a main gear wheel on each main gear.<BR>J. Disconnect tow bar and remove nose gear steering nulling pin.<BR>5. Tow Airplane under Abnormal Loads (Main Gear Towing)<BR>A. Preparation for towing and towing the airplane under abnormal loads is the same as towing<BR>airplane from the nose gear except for the following:<BR>(1) Eyebolt assemblies are installed in place of the jacking cone on each main gear and<BR>locally fabricated cables attach the gears to the tow tractors. The nose gear tow bar is not<BR>used.<BR>(2) Hydraulic system A is pressurized and airplane is steered during towing by the nose wheel<BR>steering system by directions from the ground crew.<BR>(3) The airplane motion is interrupted by application of airplane brakes. The number of<BR>applications is not limited as the hydraulic systems are operational.<BR>6. Return Airplane to Normal<BR>A. Attach static ground wires.<BR>B. Disconnect and stow intercommunication set.<BR>C. If operating, shut down APU.<BR>D. If landing gear downlock pins were installed, remove them prior to taxi and takeoff.<BR>7. Center of Gravity Calculations for Towing<BR>A. During all phases of ground handling and maintenance, the center of gravity (CG) of the<BR>airplane must be forward of the aft CG limit (Fig. 201). This CG limit provides a margin of safety<BR>to allow for grade, winds, and acceleration forces as noted. The configuration to be towed<BR>should be carefully checked to ensure that the CG is forward of the towing limit. If the aft towing<BR>limit is exceeded, the recommended procedure is to move the CG forward by adding ballast or<BR>fuel. The table in Fig. 201 gives the incremental CG shift for some of the items to be<BR>considered. A forward CG shift is (-) and an aft CG shift is (+). All data is for a level airplane.</P>
<P>8. Tow Airplane in High Wind<BR>A. The airplane may be towed in high winds provided conditions are observed per Fig. 205.</P> TOWING AND TAXIING
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