JACK POINT LOCATIONS
Page 3-63 Jul 01/2005 D623N004
THIS PAGE INTENTIONALLY LEFT BLANK
3-30-5 Important Data About the Jacks
1. General
A. The usual jacks (axle, wing and body) are all applicable to some special phases of each airplane recovery. See Figure 3-38 for some frequently used jacks. The axle jacks are used the most when the clearances are at a minimum. You can use the usual tripod jacks when sufficient clearance is available.
B. There are two different types of recovery jacks available to lift the airplane. Each of the two types are hydraulic (low-profile, multi-stage) jacks. Their load capacity and their height ranges are equivalent. You can operate each of the two types by hand. You can also operate them with power from a different point (use a remote console).
(1)
The first jack type (tripod-type) is shown in Figure 3-39. It is almost equivalent to the usual maintenance jack. There are two differences. The top part of the jack (the ram) becomes a solid head and each of the three legs have hydraulic cylinders (multi-stage). This permits horizontal movement of the jack head (within limits). This movement is the possible arc that the airplane moves through until it has a level attitude. It is possible with this jack to get only small horizontal loads on the jack head. Be careful. It is best if you know this jack from other incidents. The best performance (small horizontal loads) occurs when you use the jack frequently.
(2)
The second jack type (strut-type) (shown in Figure 3-40) is a hydraulic jack (multi-stage, hydraulic ram) on a bottom plate. The bottom plate has a spring that aligns the jack automatically. This jack is easy to operate and it can align with the airplane through an arc of 8 degrees. A lock ring (vertical, mechanical) makes the jack more stable. This jack, with the lock ring removed, permits the head to move with the airplane (within limits).
NOTE: BOTH THE TRIPOD-TYPE AND STRUT-TYPE RECOVERY JACKS MAY ENCOUNTER CLEARANCE DIFFICULTIES WHEN BEING USED AT THE WING TO BODY PRIMARY JACK POINTS (A&B).
C. Using jacks at the primary jack points (see Figure 3-30), provides for a safe procedure to correct the airplane attitude. Use jacks at the auxiliary points (see Figure 3-30) only to make the airplane stable. Do not use loads that are more than the jack point loads shown in Figure 3-34 through Figure 3-37. Monitor load gages on the jacks to make sure that you do not use loads that are too large. Use the body nose jack only to make the airplane stable. When the airplane nose is down, lift the nose jack point first until you have a level airplane. Do not exceed the jacking loads specified for this area. You should lower the tail jack to the level position before the tail of the airplane moves down.
中國航空網(wǎng) m.k6050.com
航空翻譯 www.aviation.cn
本文鏈接地址：757 Airplane Recovery Document 飛機恢復(fù)文件(77)
