Appendix B
4. The resulting predicted POF is 8.3E-10 events/cycle, clearing the DTR with margin.
However, specifying an ultrasonic inspection of the ring disk upon module exposure requires removal of the disk from the module, increasing the burden on the operator. Since there is margin between the predicted POF and the DTR, consider another inspection plan to alleviate some of the burdens of forcing modules to piece part level. This approach implements the soft- time, inspection interval scenario. Instead of going to the module exposure, the inspections would be performed at piece part exposure, at a specified cyclic interval, and then change to inspections at module exposure. The cyclic interval, before imposing an inspection based on module exposure, is the soft-time inspection interval.
5. Thi s strategy essentially accelerates the piece part exposure rate, as shown in figure B-5. By iterating on the length of the soft-time interval, a 12,300 cycle value is found to yield a POF of 1.0E-09 events for each cycle, satisfying the DTR criteria.
The design would be considered acceptable, relative to the damage tolerance criteria, and the following inspection requirements would be placed in step 12 of the AL section of the ICA.
•
Inspect at first piece part exposure.
• For parts not previously inspected before 12,300 cycles, inspect at first module exposure above 12,300 cycles, soft-time inspection interval.
•
Ultrasonic inspection calibrated to a #3 FBH.
• Reject indications equal to or greater than one-half the response from a #3 FBH calibration.
•
Include reference to detailed ultrasonic inspection procedures.
6. The information contained in this section is provided for ex ample purposes only.
Each individual component design and engine maintenance practice may require different solutions than those presented here. The AL section of the ICA requirements should reflect actions consistent with the analytical assumptions made to meet the DTR criteria.
B-3
Appendix B CANDIDATE DESIGN 1 ASSESS POF 2 MEET DTR? YES → ACCEPTABLE DESIGN 4 NO 5 APPLY
NO OPPORTUNITY
INSPEC- TION?
YES 6 7 8
SELECT SELECT SELECT COMPONENT EXPOSURE -PIECE PART LEVEL THRESHOLD INSPECTION THRESHOLD INSPECTION SENSITIVITY -UT, #3 FBH, 1:1 ASSESS POF 9 -MODULE -3000 CYCLES -UT, #3 FBH, 2:1 -2000 CYCLES -ENGINE -FPI. FULL FIELD -COMBINATION - 1000 CYCLES -EC, 1:1 NO (SELECT 6, 7, OR 8) 10 MEET DTR?
YES 12
INCORPORATE ACCEPTABLE DESIGN 11 • REQUREMENTS IN CHAPTER 5 OF INSPECTION
ENGINE MANUAL AC33.70-3_15.TIF Figure B-1. In-Service Inspection Decision Process B-4
Q LU 120 z a: 100 ~ BO LU a:
~ a:
60 ~ 40 ~ 20 z LU 0 u a: 0 5000 LU
0..
100 80 0 w V'I 0 60 0..
X w V'I li: 40 ~ t-z w 20 u a: w
0..
0 0 / I / / 10000 CYCLES MEAN = 9000 CYCLES 15000 STANDARD DEVIATION = 1500 CYCLES / / V ~ / 5000 10000 15000 20000 20000 25000 CYCLES MEAN = 19,000 CYCLES 25000 STANDARD DEVIATION= 7000 CYCLES 4/17/23 AC 33.70-3 Appendix B Figure B-2. Ring Disk Overhaul First Piece Part Exposure Distribution Figure B-3. New Ring Disk First Exposure Distribution B-5
0 w V'I 0 c..
~ ~ ~ !z: w u a: w c..
Cl w V'I 0 c.. X w ~ ~ !z w u CZ:
w c..
0 5000 10000 15000 20000 25000 CYCLES
PIECE PART EXPOSURE MEAN= 19,000 CYCLES STANDARD DEVIATION = 7000 CYCLES 120 100 80 60 40 20 0 0 5000 10000
MODULE EXPOSURE MEAN= 13,000 CYCLES STANDARD DEVIATION = 3000 CYCLES -MOD-UL 15000 20000 25000 CYCLES 4/17/23 AC 33.70-3 Appendix B Figure B-4. New Ring Disk First Exposure Distributions Figure B-5. Combination of First Piece Part and Module Exposure Distributions B-6
Appendix C AP PENDIX C. DEFAULT ANOMALY DISTRIBUTION CURVES C.1 Use of Anomaly Distribution Curves.
The anomaly distribution curves associated with hard alpha inclusions in titanium engine rotors are shown in figures C-1 through C-6. The following text provides additional information associated with using these distributions.
1. The distributions apply only to hard alpha inclusions in rotor grade (premium) titanium, melted using triple VAR or CHM plus VAR processes.
2. It is crucial to use the appropriate distribution curve that accurately reflects the inspection sensitivities performed at the billet and forging stages of the manufacturing process. The distributions in this appendix are applicable to components that were inspected at the billet stage using a zoned, ultrasonic inspection performed in accordance with the ultrasonic titanium billet inspection policy found in the FAA’s Policy Memo ANE 2002-33.15-R0.
3. For example, the material must be inspected using ultrasonic inspection to at least a #3 FBH with the reject level set at one-half that of the calibration level (for additional instructions, see appendix E). Technicians must perform inspections at both the billet and sonic shape stages.
4. The distribution accounts for all steps required to manufacture a finished part, including the in-process billet and sonic shape, forging ultrasonic inspections.
Therefore, the distribution used should reflect the inspection sensitivities used in the billet and forging inspections and should not be altered.
C.2 Critical Elements of Anomaly Distribution Curves.
Applicants and technicians should consider the following elements when referring to figures C-1 through C-6:
1. The vertical axis represents the expected number of hard alpha inclusions for each million-pounds of titanium. This information should be treated as the probability of having an inclusion of a given size or larger (exceedance probability).
2. The horizontal axis is the inclusion cross-sectional area, including the hard alpha core and the surrounding diffusion zone. Technicians should assume a circular inclusion cross-section with the corresponding diameter used as the initial size in the crack growth analysis.
3. Default curves, listed in Table C-1, are available to demonstrate compliance with § 33.70.
C- 1
Appendix C T able C-1. Default Curves Billet Inspection Forging Inspection Figure AMS2628 Class A Zoned >10 in. Billet Diameter (#3 FBH) #3 FBH Conventional Figure C-1 AMS2628 Class A Zoned >10 in. Billet Diameter (#3 FBH) #2 FBH Conventional Figure C-2 AMS2628 Class A Zoned >10 in. Billet Diameter (#3 FBH) #1 FBH Conventional Figure C-3 AMS2628 Class A Zoned 5-10 in.
Billet Diameter (#2 FBH) #3 FBH Conventional Figure C-4 AMS2628 Class A Zoned 5-10 in.
Billet Diameter (#2 FBH) #2 FBH Conventional Figure C-5 AMS2628 Class A Zoned 5-10 in.
Billet Diameter (#2 FBH) #1 FBH Conventional Figure C-6 Note: For convenience, tabular data defining each curve is shown after the plots.
Manufacturers using forging input material < 5 inches in diameter should provide data to substantiate use of the default anomaly distribution selected.
C- 2
1.E+0l vi 0 z 1.E+OO :::> 0
0..
z 0 :::i _, ~ a:
LI.I e:_ 1.E-01 w u z ~ w w u X LI.I
1.E-02
1.E-03 >- 1 Figure C-1. Hard Alpha Exceedance Curves - Billet Zoned AMS2628 Class A (>10 In. Billet) Calibrated to #3 FBH / Forging Conventional #3 FBH
- --- ...... -- :-,.I"',._ 10 ............... ........
100 - '" 1000
DEFECT AREA (SQ MILS) " I\ \.
' i\ ' .- 1~~1" ' -- - 10000
- >- -- 100000 4/17/23 AC 33.70-3 Appendix C Figure C-1. Hard Alpha Exceedance Curves - Billet Zoned AMS2628 Class A (>10 In. Billet) Calibrated to #3 FBH / Forging Conventional #3 FBH C-3
1.E+01 vi 0 Z 1.E+00 :::)
~ z 0 3 ~ a: w .!=, 1.E-01 w u z ~ w w u X w
1.E-02
1.E-03 1 Figure C-2. Hard Alpha Exceedance Curves - Billet Zoned AMS2628 Class A (>10 In. Billet) Calibrated to #3 FBH / Forging Conventional #2 FBH
- --- ---_
- :- 10 '-" ~ 1 ............... , 100 " 1000 DEFECT AREA {SQ MILS) ' l\ :-,- ' ' ' ' r~, - ~ ---~ 10000 - ,..._ 100000 4/17/23 AC 33.70-3 Appendix C Figure C-2. Hard Alpha Exceedance Curves – Billet Zoned AMS2628 Class A (>10 In. Billet) Calibrated to #3 FBH / Forging Conventional #2 FBH C-4
1.E+01 iii' 0 Z 1.E+00 :::, ~ z 0 ::i ..., :iE a: w ~ 1.E-01 w u z ct 0 w w u X w
1.E-02
1.E-03 1 Figure C-3. Hard Alpha Exceedance Curves - Billet Zoned AMS2628 Class A (>10 In. Billet) Calibrated to #3 FBH / Forging Conventional #1 FBH --- r--,,....
i"', ........
,...
10 Ill',~ 100
- ...
~ \ ..
\ 1000
DEFECT AREA (SQ MILS) ' " ' ' \.
1' 1\, ~ 10000 ... _ 100000 4/17/23 AC 33.70-3 Appendix C Figure C-3. Hard Alpha Exceedance Curves – Billet Zoned AMS2628 Class A (>10 In. Billet) Calibrated to #3 FBH / Forging Conventional #1 FBH C-5
1 .E+0 l ~ Z 1 .E+00 ::::> 2 z 0 :::; _.
~ er:
LU ~ 1.E-0 1 LU u z c3 LU LU u X LU
1.E-02
1.E-03 1 Figure C-4. Hard Alpha Exceedance Curves· Billet Zoned AMS2628 Class A (5-10 In. Billet) Calibrated to #2 FBH / Forging Conventional #3 FBH ---- -..........
r-,, .......
10 I I ~~ 100 .....
- I""- r'\.
"\ 1000
DEFECT AREA (SQ MILS) ' ' "' ' l'-,,.r-.
~I' I ~ -- ~ 10000 I I - 100000 4/17/23 AC 33.70-3 Appendix C Figure C-4. Hard Alpha Exceedance Curves - Billet Zoned AMS2628 Class A (5-10 In. Billet) Calibrated to #2 FBH / Forging Conventional #3 FBH C-6
1.E+01 vi 0 Z 1.E+00 :::> 0
0..
z 0 ::::;
...J ~ er::
UJ ~ 1.E-01 UJ u z ~ UJ UJ u ~
1.E-02
1.E-03 1 Figure C-5. Hard Alpha Exceedance Curves - Billet ZonedAMS2628 Class A (5-10 In. Billet) Calibrated to #2 FBH / Forging Conventional #2 FBH ---- r-..
r-,,, .......
10 T',~ -- 100 ~ ....
I\ ~ I\.
'\ 1000
DEFECT AREA (SQ MILS) ' ' " '\,,.
l"'I\ 1',, - 10000 ....
I" 100000 4/17/23 AC 33.70-3 Appendix C Figure C-5. Hard Alpha Exceedance Curves - Billet Zoned AMS2628 Class A (5-10 In. Billet) Calibrated to #2 FBH / Forging Conventional #2 FBH C-7
1.E+0l iii 0 Z 1.E+00 ::::> ~ z 0 :::; ..., ~ ex: w ~ 1.E-01 w u z c3 w w ~
1.E-02
1.E-03 1 Figure C-6. Hard Alpha Exceedan ce Curves - Billet Zoned AMS2628 Class A (5-10 In. Billet) Calibrated to #2 FBH / Forging Conventional #1 FBH
--- ,___
~i-,,.., 10 ~r .............
100 , ....
..., i\ , ;'I\ L 1000
DEFECT AREA (SQ MILS) . .
'\ ' \ \ ' ....... l"'o,, ...
- - 10000
- i"' 100000 4/17/23 AC 33.70-3 Appendix C Figure C-6. Hard Alpha Exceedance Curves - Billet Zoned AMS2628 Class A (5-10 In. Billet) Calibrated to #2 FBH / Forging Conventional #1 FBH C-8