S 016-033-N00

 (2)  
Open the fan cowl panels (AMM 71-11-04/201).

 S 016-035-N00

 (3)  
Open the core cowl panels (AMM 71-11-06/201).

 S 016-036-N00
 WARNING: OBEY THE INSTRUCTIONS IN AMM 78-31-00/201 WHEN YOU OPEN THE
_______ THRUST REVERSERS. IF YOU DO NOT OBEY THE INSTRUCTIONS, INJURIES TO PERSONS OR DAMAGE TO EQUIPMENT CAN OCCUR.
 (4)  
Open the thrust reversers (AMM 78-31-00/201).

 E.
Procedure

 S 226-003-N00
 (1)  
Visually examine the Turbine Case Cooling (TCC) system manifolds and tubes:

 (a)  
Refer to the table below for inspection limits.

 NOTE: This inspection procedure does not require tube
____ removal in order to inspect and verify acceptable tube condition. Air system tube dents are to be considered acceptable for continued service if, visually, the tube OD is seen to not be decreased be more than 20 percent at any particular location.
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---------------------------------------------------------------
INSPECT FOR  IN-SERVICE LIMITS
 ---------------------------------------------------------------
Cracks  Up to 180 degrees circumferentially or 6.0 inches (152.400 mm) axially if the crack is stop-drilled and does not permit air to blow on the case or flange. Up to 2 cracks per tube or collector. If tubes are found cracked, the TCC system must be inspected for loose and worn clamps. Loose clamps must be tightened and worn clamps must be replaced before the next flight. Cracked tubes must be replaced at the next A-check.
 Holes  Up to 0.150 inch (3.810 mm) diameter permitted if the air exiting the hole does not blow directly on the turbine case or flange. Up to 4 holes in all tubes connected to the collector and the collector. Up to 4 holes for each tube or collector is permitted if the total area is not more than
 0.071 square inch (46.0 square mm). Tubes with holes that are more than 0.150 inch
 (3.810 mm) must be replaced at the next A-check.
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////////////////////////A / PW4000 SERIES /747-400 / ENGINES/MAINTENANCE MANUAL ////////////////////////
Corrosion and Stains  Permitted if it can be removed.
 Loose Tube Nuts  None Permitted
 Loose or Broken Lockwire  None Permitted
 Nicks, Scratches, Chafing  Nicks, scratches, chafing and
 and Pitting  pitting is permitted with no limit until air leakage occurs. If there is leakage, treat it as a hole.
 Dents (without sharp edges  Permitted if the tubing outer
 or corners)  diameter is not decreased by more than 20 percent at each location. No dents permitted within 0.25 inch (6.35 mm) from the tube ferrule.
 Dents (with sharp edges  Dents with or without sharp
 or corners)  edges or corners are permitted with no limit as long as the tubing OD is not decreased by more than 20 percent at each location. Tubes dented more than 20 percent must be replaced at the next A-check.
 (b)  If above limits are more than permitted, replace the applicable tube that follows:
 HPT case cooling manifolds (AMM 75-24-07/401)
 LPT case cooling manifolds (AMM 75-24-09/401)
 HPT case cooling collector (AMM 75-24-06/401)
 LPT case cooling collector (AMM 75-24-08/401).

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