TASK 72-50-32-200-007-B00 LPT Stage 4 Blade - Examine For Overtemperature, Inspection-007

DMC:V2500-A0-72-50-3204-01B-300A-C|Issue No:001.00|Issue Date:2013-11-01

Export Control

EAR Export Classification: Not subject to the EAR per 15 C.F.R. Chapter 1, Part 734.3(b)(3), except for the following Service Bulletins which are currently published as EAR Export Classification 9E991: SBE70-0992, SBE72-0483, SBE72-0580, SBE72-0588, SBE72-0640, SBE73-0209, SBE80-0024 and SBE80-0025.

Copyright

© IAE International Aero Engines AG (2001, 2014 - 2021) The information contained in this document is the property of © IAE International Aero Engines AG and may not be copied or used for any purpose other than that for which it is supplied without the express written authority of © IAE International Aero Engines AG. (This does not preclude use by engine and aircraft operators for normal instructional, maintenance or overhaul purposes.).

Applicability

All

Common Information

TASK 72-50-32-200-007-B00 LPT Stage 4 Blade - Examine For Overtemperature, Inspection-007

Effectivity

FIG/ITEM

PART NO.

01-150

3A0884

General

This TASK gives the procedure for the inspection of the stage 4 turbine blades.

Fig/Item numbers in parentheses in the procedure agree with those used in the EIPC.

The policy that is necessary for inspection is given in the SPM TASK 70-20-00-200-501.

All parts must be cleaned before any part is examined. Refer to TASK 72-50-32-100-000 (CLEANING-000).

All parts must be visually examined for damage, corrosion and wear. Any defects that are not identified in the procedure must be referred to IAE.

The practices and processes referred to in the procedure by the TASK number are in the SPM.

References

Refer to the SPM for data on these items:

Definition of Damage, SPM TASK 70-02-02-350-501.

Inspection of Parts, SPM TASK 70-20-00-200-501.

Some data on these items are contained in this TASK. For more data on these items refer to the SPM.

Chemical Processes

Surface Protection

Preliminary Requirements

Pre-Conditions

NONE

Support Equipment

NONE

Consumables, Materials and Expendables

NONE

Spares

NONE

Safety Requirements

NONE

Procedure

    1. SUBTASK 72-50-32-220-234 Examine the Stage 4 Turbine Blades for Overtemperature

      NOTE

      1. Do this inspection if the stage 3 LP turbine blades are rejected for an overtemperature condition.

      2. Before examination of the blade do the hardness test of the stage 4 turbine disk. Refer to TASK 72-50-31-200-004 (INSPECTION/CHECK-004).

      3. Blades that were at temperatures more than the limit of 2000 deg F (1093 deg C) for a short time will cause a change in the alloy microstructure of the blade.

      4. Overtemperature condition, also for a short time, changes the structure of the gamma particles, together with a decrease of size and volume percentage. Signs of overtemperature are decrease in volume percentage of the gamma phase and compare the microstructure against a referenced standard.

      1. Examine one blade for overtemperature by metallurgical analysis.

        Use the blade with the strongest discoloration.

        NOTE

        Do this inspection only if the hardness test of the stage 4 turbine disk shows no decrease of hardness. Refer to TASK 72-50-31-200-004 (INSPECTION/CHECK-004).

      1. If the stage 4 turbine disk shows hardness loss, reject complete set of stage 4 turbine blades and vanes and examine the stage 5 turbine blades, refer to TASK 72-50-32-200-008 (INSPECTION/CHECK-008).

    2. SUBTASK 72-50-32-320-069 Prepare the Stage 4 Turbine Blade for Metallurgical Analysis

    1. Refer to Figure.

    2. Cut the blade at locations 1.1, 1.2 and 1.3 to get the blade airfoil samples to be analyzed. Refer to the SPM TASK 70-02-03-220-501.

      NOTE

      When a discoloration on the airfoil indicates a position of max. overtemperature deviating from the specified locations, make an additional cut at the position where the max. overtemperature is expected.

    3. Cut a small vee shaped groove on each blade airfoil sample on the cut surface at location 2.

      NOTE

      The groove identifies the blade airfoil sample surface to be analyzed.

    4. Cut outer shroud from blade airfoil sample at location 3.

    5. Cut out the blade root sample at location 7.

    6. Discard the remaining blade pieces.

      7. Attach and polish the blade samples as follows, refer to the SPM TASK 70-02-03-220-501:

      1. The blade airfoil samples where small vee groove is, shows the surfaces to be polished.

      2. The blade root sample where the longest cut is, shows the surface to be polished.

    3. SUBTASK 72-50-32-220-235 Metallurgical Analysis of the Stage 4 Turbine Blade

      1. Examine the microstructure of the blade samples. Refer to the SPM TASK 70-02-09-220-501.

      1. Examine the blade airfoil samples for metal temperature at locations 4, 5 and 6.

        2. Examine the blade root sample for metal temperature at location 8. This location must be nearest to the inner diameter of the blade. The correct points to be examined under magnification must be 0.010 to 0.015 in. (0.25 to 0.38 mm) from the edge of the root sample.

        1. This location is to be used to compare the hot areas of the airfoil.

    4. SUBTASK 72-50-32-220-236 Reject the Stage 4 Turbine Blades

    1. Reject all stage 4 turbine blades in the engine if the analysis indicates temperatures higher than 2000 deg F (1093 deg C) at one location.

    5. SUBTASK 72-50-32-220-237 Reject the Stage 4 Turbine Vanes

    1. If blade metal temperature exceeded specified limit 2000 deg F (1093 deg C), but not more than 2050 deg F (1121 deg C), the 4th stage vanes with the following part numbers must be inspected for cracks as follows:

      PN 3A0637CL45

      PN 3A2131, 3A2274

      PN 3A2244, 3A2284

      PN 3A2417, 3A2898

      refer to TASK 72-50-22-200-004-D00

      4th stage vanes with unacceptable cracks have to be rejected.

    2. If blade metal temperature exceeded 2050 deg F (1121 deg C), reject all 4th stage vanes.

    6. SUBTASK 72-50-32-220-238 Examine the Stage 5 Turbine Blades for Overtemperature

    1. If the stage 4 turbine blades were rejected because of overtemperature, examine the stage 5 turbine blades, refer to TASK 72-50-32-200-008 (INSPECTION/CHECK-008) for overtemperature.

    7. Figure: LP Stage 4 Turbine Blade - Inspection Locations

    LP Stage 4 Turbine Blade - Inspection Locations

Requirements After Job Completion

Follow-On Conditions

NONE