(a)  
All quantities of spalling are permitted.
 (b)  
Ceramic spalling causes the conditions that follow: 1) Increase tip clearance of the HPT 1st stage blade. 2) Increase EGT. 3) Increase fuel consumption. 4) Possible damage to the tip of the HPT 1st stage blades. 5) Possible damage to the HPT 2nd stage blades.
 (c)  
If the HPT 1st stage duct segments are spalled, do the inspection of the HPT 1st and 2nd stage blades for damage.
 S 216-315-N00
 (8)  
Examine the HPT 2nd stage duct segments for spalling (ceramic coating which is missing).
 (a)  
All quantities of spalling are permitted.
 (b)  
Ceramic spalling causes the conditions that follow: 1) Increase tip clearance of the HPT 2nd stage blade. 2) Increase EGT. 3) Increase fuel consumption. 4) Possible damage to the tip of the HPT 2nd stage blades.
 (c)  
If the HPT 2nd stage duct segments are spalled, do the inspection of the HPT 1st and 2nd stage blades for damage.
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COMBUSTION CHAMBER 
SEE  C  
SEE  A  
1ST-STAGE  
HPT BLADE  
ACCESS PORT  
AP-9 (93`)  INNER BURNER  
LINER  
BORESCOPE  TRAILING EDGE  
LEADING  
1ST-STAGE  EDGE COOLING  
HPT BLADE  AIR HOLES  
SEE  B 
TIP
0.10 INCH 0.25 INCH 
(2.540 mm) (6.350 mm) 
AREA B 
1.00 INCH 1
(25.400 mm) TRAILING 1ST-STAGE HPT VANE OUTER BURNER EDGE LINER 
FRONT ROW OF 
COOLING  L-A0597VERTICAL COOLING AREA A AIR SLOTS
HOLES ON THE A CONCAVE SIDE 1 
2.80 INCHES LEADING (71.120 mm) EDGE 
COOLING 
PLATFORM 
HOLES
TO AIRFOIL 
AREA C FILLET 
ALL OF THE TOP RADIUS 
SURFACE OF THE PLATFORM 
L-A9423 (0994) 1ST-STAGE HPT BLADE 1 AREAS A AND B ARE ON THE CONVEX AND CONCAVE SIDE
(SHOWN TURNED 180`) 
OF THE BLADE B 
1st-Stage HPT Blade Continue-In-Service Limits Figure 622 (Sheet 1) 
E24504
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details. 
////////////////////////A / PW4000 SERIES /747-400 / ENGINES /MAINTENANCE MANUAL ////////////////////////
L-A7731 (0000) 
 
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