航空 发表于 2011-6-13 17:13:49

LIFTING AND SHORING

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航空 发表于 2011-6-13 17:16:24

<P>LIFTING<BR>1. General<BR>A. Two general types of airplane lifting will be covered in this chapter, airplane jacking for normal<BR>maintenance, and lifting damaged airplanes.<BR>B. When the airplane is jacked for normal maintenance, the main and auxiliary jacking points are<BR>used. The airplane is usually jacked for weighing, leveling, alignment checks, and gear<BR>retraction.<BR>C. Procedures for lifting and recovery of damaged aircraft are contained in the Boeing Document<BR>D6-40146, 707, 727, 737 AIRPLANE RECOVERY.<BR>D. When necessary to obtain additional tail clearance for positioning an airplane in a hangar or<BR>storage area, a nose lift dolly may be used to tilt the airplane. The nose lift dolly raises the<BR>airplane nose section, causing the airplane to rotate about the main gear.</P>
<P>LIFTING AIRPLANE FOR MAINTENANCE<BR>1. General<BR>A. Lifting the airplane for maintenance is accomplished by using conventional airplane jacks at<BR>jacking points provided on the wing, forward and aft body or at the nose and main landing gear.<BR>The jacking points on the wing and body are provided with receptacles for the attachment of<BR>removable ball-type jack adapters. The nose and main landing gear jacking points are integral<BR>with the landing gear.</P>
<P>JACK AIRPLANE<BR>1. General<BR>A. The airplane is provided with three main jacking points and four auxiliary jacking points. The<BR>main jacking points are wing jacking point D and aft body jacking point G. The four auxiliary<BR>jacking points consist of one stabilizing and three landing gear jacking points. The stabilizing<BR>jacking point is forward body jacking point C. The three landing gear jacking points are points<BR>E-F at each main gear axle and points A-B under the nose gear axle. See Fig. 201 and 202 for<BR>jacking point locations, jacking point maximum loads, wing and body jack adapters and<BR>applicable jacks.<BR>B. The airplane may be jacked at any gross weight provided the maximum load of any jacking<BR>point is not exceeded. However, if the airplane is supported entirely by the three main jacks and<BR>the stabilizing jack, the maximum jacking weight of the airplane must not be exceeded<BR>(Fig. 202). At any weight, the airplane center of gravity must be within the forward and aft limits<BR>prior to jacking.<BR>C. The axle jacking points are designed to permit the changing of two flat tires on the same<BR>landing gear while the airplane is at maximum taxi weight. The maximum load on an axle<BR>jacking point must not be exceeded.<BR>2. Equipment and Materials<BR>A. Main Landing Gear Oleo Lock Assembly - F80016 or F80234-1<BR>B. Nose Landing Gear Shock Strut Restrainer - 6ME65-73762 or F70263-1<BR>C. Wing and Fuselage Jacks, Axle Jacks and Jack Pad Adapters (Fig. 202)<BR>(1) Wing Jacks - Regent Model 986CT (or equivalent)<BR>(2) Body Jacks - Regent Model 8156 (or equivalent)<BR>(3) Axle Jacks - Regent Model 5923 (or equivalent)<BR>D. Nose and Main Landing Gear Ground Lockpins - F72735 (flyaway)<BR>3. Raise Airplane<BR>CAUTION: DO NOT EXCEED 1 INCH CLEARANCE FROM JACK RAM LOCKNUT TO COLLAR<BR>AS JACK IS BEING RAISED OR LOWERED. EXCESSIVE CLEARANCE CAN<BR>RESULT IN DAMAGE TO AIRPLANE STRUCTURE IF JACK FAILS.<BR>DO NOT OPERATE THE MAIN DECK CARGO DOOR WHILE JACK FORCE IS<BR>BEING APPLIED TO THE JACK POINT AT THE FORWARD BODY. OPERATION OF<BR>THE DOOR CAN RESULT IN DAMAGE TO BOTH THE DOOR AND THE FUSELAGE.<BR>A. Ensure that the maximum allowable jacking gross weight will not be exceeded and that C.G.<BR>conditions are such that airplane jack points allowable loads are not exceeded, and that all<BR>landing gear downlocks are in place.</P>
<P>B. Set stabilizer, aileron and rudder trim controls to O.<BR>C. Trip flight recorder circuit breakers before jacking so that recorded data is not lost while airplane<BR>is on jacks.<BR>D. Head airplane into the wind if in an exposed area.<BR>CAUTION: DO NOT JACK AIRPLANE AT JACK POINTS D, G, AND C IF WINDS EXCEED<BR>35 MILES PER HOUR.<BR>E. When airplane is being jacked for weighing, leveling, or for general requirements, the landing<BR>gear shock struts may be deflated and locked in the compressed position using oleo lock<BR>assemblies at the main gear and nose gear. The airplane does not have to be jacked as high<BR>with the shock struts locked in the compressed position.<BR>CAUTION: DO NOT PERFORM THIS STEP IF AIRPLANE IS BEING RAISED TO PERMIT A<BR>GEAR RETRACTION TEST. SUCH A TEST REQUIRES THAT GEAR BE FULLY<BR>EXTENDED.<BR>IF SHOCK STRUT IS NOT COMPLETELY DEFLATED PRIOR TO OLEO LOCK<BR>ASSEMBLY INSTALLATION, OLEO LOCK ASSEMBLY MAY BE DAMAGED<BR>DURING JACKING OPERATION.<BR>TO AVOID SERIOUS DAMAGE TO SHOCK STRUT, DO NOT JACK AIRPLANE<BR>WEIGHT OFF WHEELS WITH SHOCK STRUTS INFLATED ABOVE NORMAL<BR>PRESSURE.<BR>F. When airplane is being jacked for gear retraction test or when airplane is jacked and shock<BR>struts are not deflated and locked, it should be noted that the main gear shock strut is canted to<BR>trail 1.85 degrees aft of the vertical axis. When jacking the airplane, normal oleo extension on<BR>the 88.15-degree angle causes aft wheel movement on the ground up to a maximum of 0.55<BR>inch. If wheels are chocked or parking brakes are set during the jacking or lowering operation,<BR>wheel movement will result in sliding of the chocks or scuffing of tires on the pavement.<BR>CAUTION: HORIZONTAL REACTION LOADS DUE TO SCUFFING OR SLIDING WILL BE<BR>TRANSMITTED THROUGH STRUCTURE TO THE JACK PADS, RESULTING IN<BR>A TENDENCY TO TIP THE JACKS OVER.<BR>G. Jacking the airplane for weighing, leveling, gear retraction test, or for general requirements<BR>open the following circuit breakers.<BR>(1) Drain, Mast. Air.<BR>H. Remove jack pad adapter recess fillers and fasteners at position D.<BR>NOTE: Aft body jacking adapter F80000-7 is a threaded rod with a machined semiball on one<BR>end. The F80000-7 is inserted into a jack pad fitting that is an integral part of the<BR>airplane structure.</P>
<P>I. Install jack pad adapters and position jacks per Fig. 201 making sure that one leg of jack at<BR>position D points straight forward.<BR>CAUTION: WHEN INSTALLING JACK PAD ADAPTERS, USE ATTACH BOLTS AS<BR>SPECIFIED IN FIG. 202 OR STRUCTURAL DAMAGE MAY RESULT.<BR>STABILIZING JACK MUST BE USED DURING WINDY CONDITIONS.<BR>STABILIZER JACK MUST BE PRELOADED TO A MAXIMUM OF 5000 POUNDS<BR>AT WINDS OF 35 MPH.<BR>NOTE: Jacks must be equipped with pressure gages and a conversion table to give pounds<BR>of load at each jack point.<BR>J. After jacks have been positioned and jacking is ready to proceed, ensure that wheel chocks are<BR>removed and that parking brakes have been released.<BR>K. Use plumb bob and leveling scale in right wheel well to establish lateral level and longitudinal<BR>attitude while raising airplane.<BR>NOTE: The plumb bob method is accurate enough for general jacking requirements,<BR>weighing, and gear retraction only. If more accurate leveling is required, refer to<BR>Chapter 8, Leveling.<BR>L. Station one man at each jack to operate the jack and to ensure that the jack loads are not<BR>exceeded. Raise airplane in a level attitude, using jacks at wing jacking pad D and at aft<BR>fuselage jacking pad G, until landing gear clears the ground.<BR>CAUTION: JACKS AT PAD D MUST BE RAISED PRIOR TO OR SIMULTANEOUSLY WITH<BR>JACK AT JACK PAD G. RAISING TAIL JACK AHEAD OF WING JACKS MAY<BR>OVERLOAD TAIL JACK POINT BY FORCING NOSE OF AIRPLANE DOWN ON<BR>NOSE GEAR, OR IT MAY OVERLOAD TAIL JACK POINT AND NOSE<BR>STABILIZING JACK POINT WHEN LATTER IS USED.<BR>JACK AIRPLANE IN A LEVEL ATTITUDE TO PREVENT INTRODUCING SIDE<BR>LOADS INTO THE JACK POINTS THAT COULD CAUSE JACKS TO SLIP OFF<BR>THE PADS OR OVERLOAD THE JACK POINTS AND DAMAGE STRUCTURE.<BR>NOTE: When airplane is being jacked for gear retraction test, include 3 inches for tire arc<BR>sweep clearance plus 1 inch additional clearance.</P>

bocome 发表于 2011-7-30 19:49:17

LIFTING AND SHORING
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