2.
You must use supports (shoring) for jacks that can not lift the airplane to the correct height. This condition usually occurs when the jack point on the airplane is higher than the lowest height of the jack. Use available wood (timbers) for the supports. Put covers on the supports made of steel plates or layers of other wood (3/4-inch or 19 mm thick plywood sheets). Make sure that the supports are level for a stable condition.
3-30-6
IMPORTANT DATA ABOUT THE SURFACES UNDER THE JACK Page 3-81 Jul 01/2005
D623N004
757
AIRPLANE RECOVERY DOCUMENT
Figure 3-46 JACK SUPPORT BASES FOR SOFT GROUND
3-30-6
IMPORTANT DATA ABOUT THE SURFACES UNDER THE JACK Page 3-82 Jul 01/2005
D623N004
3-30-7 General Precautions When You Use Jacks
1.
When you lift the airplane with jacks, different jacks usually have different procedures. Make sure that you use the correct procedures for your type of a jack.
2.
The persons who lift the airplane with jacks must include a person to monitor each jack. These persons must also include a person to monitor the movement tool (plumb bob) and a person to control the full operation. Adjust each jack only when the control person tells you to adjust it. Each jack person must monitor the jack gage continuously. Each jack person must immediately tell the control person of all problems in that jack area.
3.
If the airplane moves horizontally (in an arc) while you lift the plane, you must be careful with the jacks. Make sure that the jack points move no more than the travel limits of the jacks. Each jack person must tell the control person when a jack is near its travel limit. When a jack point moves to the travel limit of a jack, a new jack position can be necessary. It can also be necessary to put some new supports in the area while you move the jack.
3-30-7
GENERAL PRECAUTIONS WHEN YOU USE JACKS Page 3-83 Jul 01/2005
D623N004
THIS PAGE INTENTIONALLY LEFT BLANK
3-30-8 General Procedures When You Use Recovery Jacks
1.
Put the jack in a position below the airplane jack point.
2.
Make the jack level with a tool (carpenter’s level) on the head of the jack. Make sure the strength of the ground surface below the jack is sufficient for the usual jack loads. Use the higher heights (screw extensions) on the jack if it is necessary.
3.
Connect the jack to its console with the hydraulic lines. On tripod type jacks, make sure you use the color code correctly. Connect each color line to the correct color jack leg. Connect the air line to the console.
4.
Lift each jack point when the control person tells you to lift it. See the instructions from the manufacturer for correct jack procedures.
3-30-8
GENERAL PROCEDURES WHEN YOU USE RECOVERY JACKS Page 3-85 Jul 01/2005 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：757 Airplane Recovery Document 飞机恢复文件(83)
