NORMAL PARKING 1. General A. The airplane is normally parked for short periods with chocks in front of and behind at least one main gear wheel, and with parking brakes off. The parking brake is used to hold the airplane until chocks are in place. Openings in the airplane structure such as vents and scoops shall be covered or plugged to keep out weather and foreign matter. Should very high winds be expected, refer to 10-21-0, High Wind Conditions, Mooring. For special procedures to park the airplane for engine operation refer to 71-09-100/201. B. A static ground on the airplane is not necessary when the airplane is parked or is serviced during the turnaround operation. This does not include when the maintenance steps given below are done (Ref chapter 20-40-11). (1) A static ground on the airplane is not necessary when you pressure refuel the airplane. An electrical bond between the airplane and the refuel vehicle is recommended. (2) A static ground of the airplane when you fuel over the wing is recommended. (3) Do a static ground of the airplane when you do maintenance procedures. Do this when you use devices such as lights, power tools, and instruments powered from external cords that are attached to grounded electrical power sources. C. Pitot probe covers and static port covers are recommended when the airplane is parked for more than a standard turnaround. D. Failure to remove covers from pitot probes or coverings from static ports before flight may cause large errors in airspeed-sensing and altitude-sensing signals, which may lead to loss of safe flight. E. A minimum distance of 15 feet should be maintained between airplanes being towed or parked to give adequate turning clearances (Fig. 201). If engine operation is anticipated, refer to Fig. 202 to ensure airplanes, maintenance personnel and equipment, and buildings, adequate protection from jet blast and heat at breakaway from standstill. Various thrust settings that will be required for breakaway from standstill are governed by airplane position, type of area, and surface conditions. A high initial thrust setting is required to start airplane movement. The setting is then reduced to idle, or slightly above, to continue the maneuver. WARNING: DO NOT CROSS ENGINE EXHAUST AREA DURING ENGINE RUN-UP OR TAXIING. BE SURE AREAS IN FRONT OF ENGINES ARE CLEAR BEFORE ENGINE RUN-UP. F. The curves in Fig. 202 present the estimated jet wake characteristics for the 737 airplane at breakaway thrust. The results obtained are based on a gross weight of 70,000 pounds and a friction coefficient of 0.04. It should be realized that this is an average value and does not apply to an airplane that has been parked for a long time.
G. Review Fig. 202 for identification of engine hazard areas, entry and exit corridors, and personnel safety lanyard assembly (F80239) attach points. Awareness of hazard areas and proper entry/exit corridors is essential whenever maintenance tasks are performed around or near an operating engine. Use of personnel safety lanyard is recommended, but not mandatory. WARNING: DO NOT LATCH OR UNLATCH ENGINE SIDE COWLS WHILE ENGINE IS OPERATING. FORWARD SIDE COWL LATCHES ARE IN ENGINE INLET HAZARD AREA. IF ENGINE SIDE COWLS HAVE NOT BEEN REMOVED FOR PERFORMING ENGINE TRIM, LEAK CHECKS, OR OTHER MAINTENANCE TASKS REQUIRING ENGINE OPERATION, DO NOT ENTER OR EXIT FROM FORWARD END OF SIDE COWLS. ENTERING OR EXITING FROM FORWARD END OF SIDE COWL WILL PLACE PERSONNEL IN ENGINE INLET HAZARD AREA, AND MAY CAUSE POSSIBLE PERSONNEL INJURY. DO NOT CONNECT SAFETY LANYARD ASSEMBLY TO ANY TUBING, WIRE HARNESS, ETC. DAMAGE TO ENGINE OR INJURY TO PERSONNEL MAY OCCUR. 2. Equipment and Materials A. Nose and Main Landing Gear Ground Lock Assembly - F72735 B. Plug, Engine Exhaust - F80093 C. Plug, Side Engine Inlet - F72717 D. Plug, APU Exhaust - F80076 E. Mat or suitable material for placing between tires and parking area if airplane is to be parked on ice or packed snow F. Pitot Static Tube Cover – HTC 73-75 PPCW (Fwd Fuselage) G. Pitot Static Tube Cover – HT 73-75 PPC (Vert. Stabilizer) H. Wheel chocks I. Safety Lanyard Assembly - F80239 J. B00316 Solvent - Aliphatic Naphtha, TT-N-95, Type I K. G02443 Orange barricade tape, 3 inches wide, 4 mils thick, non-adhesive, with “REMOVE BEFORE FLIGHT” printed on it in black letters. L. G02219 3M Scotch Brand No. 471 vinyl adhesive tape (1.5 inches wide) bright yellow color. M. G02444 Red paper tag (3 inches wide, 6 inches long) with attaching wire that has “STATIC PORTS COVERED” printed on it in black letters - P/N 2000s. N. G02447 Red paper tag (3 inches long, 6 inches wide) with attaching wire that has “PITOT PROBES COVERED” printed on it in black letters - P.N 1000P.
3. Park Airplane A. Pitot probe covers and static port covers are recommended when the airplane is parked for more than a standard turnaround. WARNING: PITOT PROBE COVERS AND STATIC PORT COVERS ARE RECOMMENDED WHEN THE AIRPLANE IS PARKED FOR MORE THAN A STANDARD TURNAROUND OR WHEN CONDITIONS SUCH AS INSECT ACTIVITY, DUST STORMS OR VOLCANIC ASH MAY INCREASE THE THE RISK OF PITOT PROBE OR STATIC PORT CONTAMINATION. A PITOT PROBE OR STATIC PORT SYSTEM BLOCKED BY FOREIGN OBJECTS SUCH AS INSECTS MAY CAUSE LARGE ERRORS IN AIRSPEED-SENSING AND ALTITUDE-SENSING SIGNALS, WHICH MAY LEAD TO LOSS OF SAFE FLIGHT. B. Taxi or tow airplane into position designated for parking. If the airplane is towed into position, install main and nose gear ground lock assemblies before towing (Fig. 203 and 204). Terminate maneuver with airplane headed into the prevailing wind. NOTE: Installation of nose gear lockpin is optional when airplane is being towed with gear hydraulic system pressurized. C. Install nose gear downlock assembly when airplane stops after taxiing if the airplane is to be packed or maintenance accomplished. If the airplane is to be jacked, install main gear downlock assemblies jacked, install main gear downlock assemblies (Fig. 204). D. If high winds are expected, refer to 10-21-0, High Wind Conditions Mooring. E. Ground airplane (Ref. Chapter 20, Static Grounding). F. If parking area is covered by ice or packed snow, place a mat or suitable material under and around tires to prevent tires from becoming frozen to the ground. G. Turn on battery switch. H. Set parking brake by depressing brake pedals and pulling up the parking brake handle on the captain's control stand. Relieve pressure on brake pedals before releasing the parking brake handle. I. Place wheel chocks in front of and behind at least one set of main gear wheels per truck. J. To release parking brakes, the captain's or first officer's brake pedals need only to be fully applied and then released. A light on the control stand next to the parking brake lever, is provided to indicate when the parking brake is on. CAUTION: DO NOT LEAVE PARKING BRAKES ON ANY LONGER THAN NECESSARY WHEN BRAKES ARE HOT, FOLLOWING A HIGH ENERGY STOP, OR STOP OTHER THAN NORMAL. UNDER STATIC PRESSURE, HOT BRAKE SURFACES TEND TO FUSE TOGETHER. K. Turn off battery switch if no longer required. L. Set stabilizer, aileron and rudder trim control to ZERO. M. Raise flaps to the fully up position. CAUTION: DO NOT RESTRAIN THE CONTROL COLUMN OR RUDDER PEDALS. DOING SO COULD RESULT IN CONTROL SYSTEM DAMAGE.
N. Place aileron control wheel in neutral. O. Close all lavatory doors when airplane is parked to prevent the spreading of any possible fire. P. Ensure that electronic access door is closed. Q. Install plugs and covers as required. R. In cold weather, it is necessary to drain fuel tank sumps prior to fueling to remove water from fuel tanks if the airplane has been idle for more than 45 minutes prior to fueling. Drain fuel tank sumps again after refueling if the airplane has been idle for 2 hours or more after refueling. In cold weather, water can freeze and not let the drain valves open. S. Install the covers on the pitot probes. (1) Install the engine inlet and exhaust covers. WARNING: WHEN THE PITOT PROBES ARE COVERED, MAKE SURE THAT CONDITION IS VISIBLE FROM THE GROUND. IN ADDITION, ATTACH A TAG TO THE LEFT CONTROL WHEEL IN THE FLIGHT DECK AS A REMINDER THAT PITOT PROBES ARE COVERED, FAILURE TO OBSERVE AND REMOVE COVERINGS OVER PITOT PROBES BEFORE FLIGHT MAY CAUSE LARGE ERRORS IN AIRSPEED-SENSING AND ALTITUDE SENSING SIGNALS, WHICH MAY LEAD TO LOSS OF SAFE FLIGHT. CAUTION: WHENEVER AN OPENING IS COVERED, MAKE SURE THAT CONDITION IS VISIBLE FROM THE GROUND. ENGINES SHOULD NOT BE OPERATED WITH COVERS IN PLACE BECAUSE THE COVERS CAN COME OFF AND DAMAGE THE ENGINES. (2) Put the covers on the pitot probes (see Fig. 205 for locations of the pitot). CAUTION: MAKE SURE THE PITOT PROBE COVER IS IN GOOD WORKING CONDITION WITH NO EVIDENCE OF DAMAGE, ESPECIALLY FRAYING AROUND THE COVER OPENING. FRAYED FIBERS FROM THE COVER COMBINED WITH OTHER SUBSTANCES SUCH AS DIRT, GREASE OR FLUIDS CAN CAUSE OBSTRUCTION IN THE PROBE. (3) Attach a red paper tag that has “PITOT PROBES COVERED” printed on it in black letters, to the top of the left control wheel in the flight deck. WARNING: WHEN THE STATIC PORTS ARE COVERED, MAKE SURE THAT CONDITION IS VISIBLE FROM THE GROUND. IN ADDITION, ATTACH A TAG TO THE LEFT CONTROL WHEEL IN THE FLIGHT DECK AS A REMINDER THAT PITOT PROBES ARE COVERED, FAILURE TO OBSERVE AND REMOVE COVERINGS OVER PITOT PROBES BEFORE FLIGHT MAY CAUSE LARGE ERRORS IN AIRSPEED-SENSING AND ALTITUDE SENSING SIGNALS, WHICH MAY LEAD TO LOSS OF SAFE FLIGHT. CAUTION: WHENEVER AN OPENING IS COVERED, MAKE SURE THAT CONDITION IS VISIBLE FROM THE GROUND. ENGINES SHOULD NOT BE OPERATED WITH COVERS IN PLACE BECAUSE THE COVERS CAN COME OFF AND DAMAGE THE ENGINES. |