....................................................................... | B |All dents are permitted. |Pushed out areas are | | |Pushed out areas on the |caused by dents on the | | |opposite side of the airfoil |opposite side of the | | |are permitted if there are |airfoil surface. | | |no cracks. | | ....................................................................... | C |Damage that is not more than |Nicks in the leading and | | |0.031 inch (0.794 mm) in |trailing edges change the | | |depth is permitted if the |performance of the engine | | |damage is radially apart by |more when they are closer | | |a minimum of 0.25 inch (6.35 |to the blade root. Damage| | |mm). Signs of too much heat |with small radii or sharp | | |(blue colors) are permitted |edges change it the most. | | |on the tip, but not on the | | | |concave or convex surfaces. | | ....................................................................... | D | Small surface erosion is |The small surface erosion | | | permitted. No other damage |will look larger because | | | is permitted. |of borescope magnification| 2............….............................…..........................1
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////////////////////////A / PW4000 SERIES /747-400 / ENGINES/MAINTENANCE MANUAL ////////////////////////
No. 15 - HPC Vane and Blade (5th- through 15th-Stage) Inspection
________________________________________________________________
CAUTION:_______ USE CAUTION WHEN YOU USE THESE LIMITS TO MAKE A DECISION
ABOUT THE CONDITION OF THE ENGINE. THE BORESCOPE
INSPECTION LIMITS ARE A RESULT OF TESTS AND STRUCTURAL
ANALYSIS. THE PART LIFE AND THE PERFORMANCE OF THE ENGINE
CAN DECREASE QUICKLY WHILE THE DAMAGE OF THE PARTS BECOMES
NEAR TO THE MAXIMUM CONTINUE-IN-SERVICE LIMITS.
(g) Examine the HPC IGV and the HPC 5th- thru 15th-stage vanes for nicks (Fig. 613). 1) If you find damage that is more than the limits, examine it
to find if the area is a defect or a blend repair.
NOTE: Repaired areas have a 4 to 1 length to depth ratio
____ and have smooth round corners. This is important because a repaired area can possibly be more than the continue-in-service limits that follow. The limits apply only to defects and not to repaired areas.
2) The conditions that follow are for nicks that are at the maximum depth on opposite edges: a) The distance between the nicks must be more than the
vane width average. b) The nick on one edge must not be directly opposite the nick on the other edge.
3) The condition that follows is for nicks that are not at the maximum depth and are on opposite edges: a) Nicks can be directly opposite if the sum of the depths
is less than the depth limit for one nick. 4) No more than two nicks that are at the maximum depth are permitted on each vane. 5) The total nick length on a vane edge cannot be more than 1/8 of the total edge length. 6) No cracks are permitted.
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