There are many restrictions to jacking for each type aircraft If you violate any of these restrictions, there is a good chance that you will have an accident, damage the aircraft, or injure someone. The restrictions gen-eral] y concern aircraft gross weight and configuration. Some of the considerations are fuel dispersion in fuselage and wing tanks, engines in or out, and tail hook up or down.

Details on restrictions and procedures are in the MIMs, and you must know them and follow them exactly. If you dont, you will be in trouble. Dont forget that many squadrons will have their own local standing instructions for jacking aircraft, which contain additional safety precautions and restrictions. You must know them also.

The jacking procedures vary for each aircraft type and its configuration. The procedures that follow are examples of what you could encounter. Fairly exacting steps are given to provide clarity. Remember these steps are from representative type aircraft, and are not necessarily accurate for all. When actually jacking aircraft, you must follow the exact procedures described in your MIMs.

The location of your aircratt will determine what you need for equipment. Jacking procedures on a ship require tiedown procedures to prevent aircraft from shifting on jacks. When tiedown chains are to be used, position them in accordance with the MIM, so as not to interfere with the landing gear during the drop check of the gear. Jacking procedures on land do not require tiedowns, except in high-wind conditions. Aboard ship, squadron maintenance controls will request, through the carrier air group (CAG), permission to place an aircraft on jacks. Check your MIM for jacking restrictions, warnings, and cautions. Obtain the support equipment required by the MIM, ensuring all preoperational inspections have been completed. Make sure that all protective covers and ground safety devices are installed, as required by the MIM. The surrounding area around the aircraft must be roped off during the entire aircraft jacking operation, and signs posted stating "DANGER: AIRCRAFT ON JACKS? The area below and around the aircraft must be cleared of all equipment not required for the jacking operation. Install jack adapters, aircraft mooring adapters, and tiedown chains as required by the MIM. Figure 3-29 shows an

example of carrier tiedown for aircraft jacking. Position and extend wing and nose jacks until seated on wing jack and tiedown adapters.

NOTE: Some aircraft require the extension of the center screw to provide for clearance of the gear doors.

Apply jack pressure on each jack without lifting the aircraft, and check to see that the base of each jack is evenly seated. Correct base position of jack, as required, for firm base seating. For shipboard operations, all jacks must be tied down before jacking aircraft with a minimum of three tiedown chains per jack. The jack must be tied down at the spring-loaded wheel caster mounts, thus allowing the jacks to make small move-ments with the aircraft jack points. Release the aircraft parking brake. Remove main landing gear chocks. Jack aircraft evenly and extend tiedown chains while jacking. Extension of tiedown chains must be coordinated in a way that preload on each tiedown chain is partially removed before jacking. Partial preload is maintained with jacking of aircraft by rotation of the chain tensioning grip.

Figure 3-30.Aircraft leveling.

CAUTION Use extreme care to raise wing jacks in coordinated, small, equal amounts. Reload on the tiedown chain is too high when tensioning grip cannot be rotated manually.

Screw the leek collar down as each jack is being extended. Jack the aircraft until its wheels clear the deck, and set the lock collar handtight. Set each tiedown chain to preload by manually rotating and tightening tensioning grip.

An aircraft leveling technique is shown in figure 3-30. Jack aircraft at wing and nose jack point as described earlier. Attach plumb bob and string to eye bolt at FS 259 (fuselage station). Position the plumb bob directly over the leveling plate on floor of aircraft. Level aircraft laterally (left to right) by adjusting wing jacks until plumb bob tip is directly above the center line in the leveling plate. Level the aircraft longitudinaly (forward and aft) by adjusting the nose jack until plumb bob tip is directly above FS 259 line on the leveling plate. This procedure varies greatly with different types of aircraft. You must use the applicable MIM to perform a leveling procedure.