PYLON BOX - DESCRIPTION AND OPERATION
_____________________________________
 1. Description
___________
R **ON A/C 001-049, 051-099, 101-105, 151-199, 201-220, 229-230,
 (Ref. Fig. 001)
 A. Pylon Box Structure
 The pylon box is damage tolerant and comprises:

 -
1 lower spar made of corrosion resistant steel

 -
1 forward upper spar made of special carbon steel

 -
1 rearward upper spar made of special carbon steel

 -10 ribs, 4 of which introduce loads : At pylon-to-engine attach fittings : RIB1 is made of corrosion resistant steel and RIB3 is made of titanium At pylon-to-wing attach fittings : RIBs 4 to 10 made of titanium RIBs 2, 5, 6, 7, 8, 9, are made of titanium.

R **ON A/C 106-149, 221-228, 231-299, 301-399, 401-499,
 (Ref. Fig. 001A)
 A. Pylon Box Structure
 The pylon box structure has these components :

 -
1 lower spar made of corrosion resistant steel

 -
1 forward upper spar made of special carbon steel

 -
1 rearward upper spar made of special carbon steel

 -Ten ribs, as follows RIB1 (pyramid), made of corrosion resistant steel, and which includes the forward engine-to-pylon attach fitting. RIB2, made of titanium alloy. RIB3, made of titanium alloy, and which includes the aft engine-to-pylon attach fitting. RIB4, made of titanium alloy, to attach the pylon-to-wing aft attach fitting. RIB5 and RIB6, made of titanium alloy. RIB7 to RIB9, made of corrosion resistant steel. RIB10, made of titanium alloy, and which includes the pylon-to-wing aft attach fitting.

 Primary Structure - Materials and Protections Description
 Figure 001

R 1EFF : 001-049, 051-099, 101-105, 151-199, 1 54-51-00Page 2 1201-220, 229-230, 1Aug 01/05 1 1 1CES 1

 Primary Structure - Materials and Protections Description
 Figure 001A

R 1EFF : 106-149, 221-228, 231-299, 301-399, 1 54-51-00Page 3 1401-499, 1Aug 01/05 1 1 1CES 1R **ON A/C ALL

 B. Pylon-to-Wing Attach Fitting
 (Ref. Fig. 002)
 The engine is installed on the wing by means of:

 -at RIB4, four shackles made of high tensile stainless steel and four sleeve/threaded pin assemblies
 -a spigot fitting located in the aft upper spar between RIB4 and RIB5
 -at RIB10 , four aft shackles made of titanium alloy and three
 sleeve/threaded pin assemblies. Bushes are installed on each shackle. The sleeve/threaded pins are made of inconel 718. External surfaces are chrome-plated in the area in contact with the bushes.

 Pylon-to-Wing Attach Fittings Figure 002
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 C. Pylon-to-Engine Attach Fitting (Ref. Fig. 003) The pylon-to-engine junction is provided by the forward attach fitting located at the forward end of the pyramid at RIB1. The aft attach fitting is located at RIB3. The forward attach fitting reacts to engine thrust, vertical and side load. The aft attach fitting reacts to vertical and side loads, roll moments.
 D. Pylon Box Components The pylon box is fitted with :
 -Thrust reverser cowl hinge fittings.
 -
Attachment bracket for thrust reverser cowl opening jack.

 -
Attachment bracket for rearward secondary structure.

 -Provision to mount ground support equipment required for engine hoisting. All components of the pylon box structure are attached by means of close fit corrosion resistant steel bolts or lock bolts.
 E. Doors (Ref. Fig. 004) The pylon box is fitted with four doors giving access to the various systems:
 -
The forward access doors are located on each side of the pylon box between RIB2 and RIB3. They are made of light alloy and are attached by means of four screws.

 -
The aft access doors are located on each side of the pylon box between RIB5 and RIB6. They are made of carbon fiber reinforced plastic and honeycomb web sandwich type and are attached by means of four captive screws.

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 Pylon to Engine Attach Fittings
 Figure 003
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 Doors
 Figure 004
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 PYLON BOX - INSPECTION/CHECK
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 TASK 54-51-00-200-001
 Special Detailed Inspection of Engine Forward Mount Fitting and Spigot Fitting
　
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