+- RIM --+ 400.0 MPa (58 (ksi)
434.4 MPa (63 ksi)
468.9 MPa (68 ksi)
503.4 MPa (73 ksi)
537.9 MPa (78 ksi) +- BORE --+ 572.4 MPa (83 ksi) Component·Stress ·:Model ➔ Str,ess · Volnm eDefinition1 r l rum in(05 ~ amoo Sdn l ;2 ➔ 10 f ~ I.S ~ ~ ,.....,..,- -.........
/ u ~ 12 Ill l2J 4 ➔ - Further break ,up of I the high stress/I.ow ;-t ll. 113 +- 21 llife z:ones performed I L_ b/ to reach ~j conve rgenoe 6 ➔ U.l 1 J " I~:'. I ii, ~,., ..,, ➔ 1-..-.,., S ➔ +- 24 '"' l6 4/17/23 AC 33.70-3 Appendix A Figure A-5. Component Stress Model and Component Principal Stress Contour Plot Figure A-6. Component Stress Model/Stress Volume Definition A-11
Appendix A T able A-2. Zone Volume Data Zone Number Volume, cm3 Volume, in3 1 0.69 0.042 2 18.8 1.15 3 34.9 2.13 4 29.2 1.78 5 24.2 1.48 6 20.1 1.23 7 16.1 0.98 8 0.49 0.030 9 134.37 8.20 10 3675.5 224.29 11 6809.8 415.56
12.1 144.48 8.81
12.2 5403.46 329.68
12.3 144.48 8.81
13.1 119.95 7.32
13.2 4488.2 273.84
13.3 119.95 7.32
14.1 99.58 6.08
14.2 3724.1 227.22
14.3 99.58 6.08
15.1 79.82 4.87
15.2a 1958.8 119.51
15.2b 324.02 19.77
15.2c 459.58 28.04
15.2d 182.75 11.15
15.2e 91.13 5.56
15.3 79.82 4.87 16 94.90 5.79 17 0.69 0.042 18 18.8 1.15 19 34.9 2.13 20 29.2 1.78 21 24.2 1.48 22 20.1 1.23 23 16.1 0.98 24 0.49 0.030 A-12
Appendix A WIDTH = 0.1 M (3.94 IN.)
1 ZONE 17 ZONE 10• ZONE 22 WIDTH = 0.0376 M (1.48 IN.) OFFSET = 0.1125 M (4.43 IN.)
THICKNESS = 0.1 M (3.94 IN.) WIDTH = 0.1 M (3.94 IN.)
Figure A-7. Zone Crack Location A-13
._.....n...,._...._...,.no .. ..,...111,.,._ ....
-· -· I l - ■ -G I i I " , .•
REMAINING LIFE DATA ~voLUMENO .
CYCLES 80 70 60 cil 50 ~ en 40 en 30 w er t;; 20 10 2 TIME 4/17/23 AC 33.70-3 Appendix A Figure A-8. Crack Growth Calculation A-14
Appendix A Anomaly Distribution Remaining Life Data Volume Data REMAINING LIFE DATA Volume Data VOLUME NO.
CYCLES Service Life CALCULATOR RISK Events/Cycle = 1.9E-9 Figure A-9. Overall Probabilistic Assessment Process - No In-Service Inspection A-15
r I Anomaly Distribution I r· I IY• I I ••• -- -
- - -. - ~~-. -- ~-- i "--::- - _ ,_ _, _ ''-
- II - Service Life I Ultrasonic lnsp. POD I "' T T TTTTT
• r + +++H- ,.
~ .. I ., I I I 1111' 1 I , 1 1 I ) .. ..
• '" , .... ANOMMYAAEACmlll"'2) .....
I Remaining Life Data I
REMAINING LIFE DATA ''" cYC<.£S RISK CULA' l- I JI I Volume Data Vo,11,1me o.t, I I I Events/Cyc le = 1.4E-9 4/17/23 AC 33.70-3 Appendix A Figure A-10. Overall Probabilistic Assessment Process – With In-Service Inspection A-16
1.0E+Ol ~ ,Q .2 ~ ·O ,O.
.z l.OE+OO ·O :i :i '" UII ,O.
-lu.l ·U :~ ,Q lu.l lu.l -0 l5 l .OE-01 "-..
1.0E-02
1.E+02 ' ..... .....
" '- ' I" Figure A-11. Hard Alpha, Ano maly Distribution for Test Case i\ ~ ' I'\.
'I.
\.
\ \ \ .
~
l.
'\ \.
' I'\. "r-,... r-,... ...
......
... ~
1.E+03 1.E+04 1.E+05 !LE+06 DEFECT AREA (SQ 1M IILS) 4/17/23 AC 33.70-3 Appendix A Figure A-11. Hard Alpha Anomaly Distribution for Test Case A-17
Appendix A Table A-3. Tabular Data – Anom aly Distribution Curves for Test Case (Figure A-11) Area Sq.
mils Anomaly Distribution For Test Case Exceedance /Million lbs.
Area Sq.
mils Anomaly Distribution For Test Case Exceedance /Million lbs.
Area Sq.
mils Anomaly Distribution For Test Case Exceedance /Million lbs.
3.9 5.91E+01 26.7 1.63E+01 181 3.72E+00
4.2 5.70E+01 28.3 1.56E+01 192 3.54E+00
4.4 5.49E+01 29.9 1.50E+01 203 3.37E+00
4.7 5.29E+01 31.7 1.44E+01 215 3.20E+00
4.9 5.10E+01 33.5 1.39E+01 227 3.04E+00
5.2 4.91E+01 35.4 1.33E+01 240 2.88E+00
5.5 4.73E+01 37.5 1.28E+01 254 2.73E+00
5.8 4.56E+01 39.7 1.23E+01 269 2.58E+00
6.2 4.39E+01 42.0 1.18E+01 284 2.44E+00
6.5 4.23E+01 44.4 1.13E+01 301 2.31E+00
6.9 4.07E+01 46.9 1.09E+01 318 2.18E+00
7.3 3.92E+01 49.7 1.04E+01 337 2.06E+00
7.7 3.78E+01 52.5 1.00E+01 356 1.94E+00
8.2 3.64E+01 55.6 9.60E+00 377 1.83E+00
8.7 3.51E+01 58.8 9.21E+00 399 1.72E+00
9.2 3.38E+01 62.2 8.83E+00 422 1.61E+00
9.7 3.25E+01 65.8 8.46E+00 446 1.51E+00
10.3 3.13E+01 69.6 8.11E+00 472 1.41E+00
10.9 3.01E+01 73.7 7.77E+00 499 1.32E+00
11.5 2.90E+01 77.9 7.44E+00 528 1.23E+00
12.2 2.79E+01 82.4 7.13E+00 559 1.15E+00
12.9 2.69E+01 87.2 6.82E+00 591 1.07E+00
13.6
2.59E+01 92.3 6.53E+00 626 9.91E-01
14.4 2.49E+01 97.6 6.24E+00 662 9.18E-01
15.2 2.40E+01 103 5.97E+00 700 8.48E-01
16.1 2.31E+01 109 5.71E+00 741 7.82E-01
17.0 2.22E+01 116 5.45E+00 784 7.19E-01
18.0 2.14E+01 122 5.21E+00 829 6.60E-01
19.1 2.06E+01 129 4.97E+00 877 6.03E-01
20.2 1.98E+01 137 4.74E+00 928 5.50E-01
21.3 1.90E+01 145 4.52E+00 981 5.00E-01
22.6 1.83E+01 153 4.31E+00 1038 4.54E-01
23.9 1.76E+01 162 4.11E+00 1098 4.10E-01
25.3 1.69E+01 171 3.91E+00 1162 3.69E-01 A-18
Appendix A Area Sq.
mils Anomaly Distribution For Test Case Exceedance /Million lbs.
Area Sq.
mils Anomaly Distribution For Test Case Exceedance /Million lbs.
Area Sq.
mils Anomaly Distribution For Test Case Exceedance /Million lbs.
1229 3.31E-01 5621 2.29E-02 25698 8.57E-03 1300 2.95E-01 5946 2.21E-02 27186 8.27E-03 1376 2.63E-01 6290 2.13E-02 28760 7.97E-03 1455 2.33E-01 6655 2.06E-02 30426 7.68E-03 1540 2.05E-01 7040 1.98E-02 32188 7.40E-03 1629 1.80E-01 7448 1.91E-02 34052 7.14E-03 1723 1.58E-01 7879 1.84E-02 36024 6.88E-03 1823 1.38E-01 8335 1.78E-02 38110 6.63E-03 1929 1.20E-01 8818 1.72E-02 40317 6.39E-03 2040 1.04E-01 9329 1.65E-02 42652 6.16E-03 2158 9.00E-02 9869 1.60E-02 45121 5.94E-03 2283 7.80E-02 10440 1.54E-02 47734 5.72E-03 2416 6.77E-02 11045 1.48E-02 50499 5.51E-03 2556 5.89E-02 11685 1.43E-02 53423 5.31E-03 2704 5.16E-02 12361 1.38E-02 56517 5.12E-03 2860 4.56E-02 13077 1.33E-02 59790 4.93E-03 3026 4.07E-02 13834 1.28E-02 63252 4.75E-03 3201 3.68E-02 14636 1.24E-02 66915 4.58E-03 3386 3.38E-02 15483 1.19E-02 70790 4.41E-03 3583 3.15E-02 16380 1.15E-02 74890 4.25E-03 3790 2.98E-02 17328 1.11E-02 79227 4.10E-03 4009 2.85E-02 18332 1.07E-02 83815 3.95E-03 4242 2.75E-02 19393 1.03E-02 88668 3.80E-03 4487 2.65E-02 20516 9.93E-03 93803 3.66E-03 4747 2.56E-02 21704 9.57E-03 99235 3.53E-03 5022 2.47E-02 22961 9.23E-03 ---- ---- 5313 2.38E-02 24291 8.89E-03 ---- ---- A-19
z ~ 0 z ::, ..
<II <II ::,
TOTAL FAILURE RISK WITHOUT INSPECTION MEAN VALUE m=1.57E-09 ~ m -1.65 s = 1.27E-09 m + 1.65 s = 1.93E-09
1.0E..10 1.0E..09 . 1.0E..08
FAILURE RISK PER CYCLE
TOTAL FAILURE RISK WITH IN-SERVICE INSPECTION MEAN VALUE m=1.13E-09 m -1.65 s = 8.36E-10 m + 1.65 s = 1.53E-09
1.oe.10 1.0E-09 1.0E-08
FAILURE RISK PER CYCLE 4/17/23 AC 33.70-3 Appendix A Figure A-12. Results A-20
Appendix B A PPENDIX B. SOFT-TIME INSPECTION EXAMPLE B.1 Overview of Soft-time Inspection Example.
This appendix provides an example of an acceptable process to set the opportunity inspection requirements that will be specified in the airworthiness limitations (AL) section of the instructions for continued airworthiness (ICA). As discussed in chapter 5, the application of the opportunity inspection is one of several options available to reduce the predicted probability of failure (POF) in the event that a component design does not meet the DTR criteria.
Chapter 5 introduced the following three scenarios for opportunity inspections to clarify the actions that technicians could take at a maintenance opportunity. The scenarios are as follows:
1. Hardware available for opportunity inspection.
2. Module below soft-time interval.
3. Module above soft-time interval.
B.2 Note: The FAA presents examples of the first and third scenarios in this appendix. The second scenario could be analyz ed in a similar manner to the third scenario.
The key elements to determine opportunity inspection requirements, given any scenario, are as follows:
• Type of inspection method and associated level of sensitivity.
• Maintenance interval at which time the hardware will be exposed for inspection.
• Cyclic threshold or soft-time interval for module exposure at which time the inspections wi ll be invoked.
Given each scenario, details of an inspection plan can take many forms. Figure B-1 shows the decision process to select the appropriate inspection requirements. The FAA will reference this flowchart throughout this section to guide the discussion.
Examples of Scenario 1: Hardware Available for Opportunity Inspection.
1. Figure B-1 shows that the predicted POF for the simple ring disk, without the benefit of in-service inspection, is 1.9 E-09 events/cycle. Therefore, the ring disk design does not meet the 1.0 E-09 event/cycle DTR (a “No” answer at block 3). If the ring disk POF were less than the DTR, the design would be considered acceptable (block 4), and no in-service inspection would be required.
2. Assuming a design change is not possible (for example, stress reduction, material change, or manufacturing inspection enhancement), then the decision is made (block 5) to explore the opportunity inspection option to reduce the component risk below the DTR.
3. With the decision made to pursue the inspection route, the level of maintenance opportunity is selected for the study. The options available are piece part, module, B-1
Appendix B eng ine, or some combination of these opportunities. The desire is to select an exposure level or combination of levels that minimize the impact on the operator, yet has a high potential to reduce the component risk level. It is anticipated that the applicant will use trial and error to arrive at the best solution. Working with these damage tolerance criteria will give the applicant experience to make good initial selections, which will reduce the amount of analytical effort in future analyses. For the initial pass, a one-time ultrasonic inspection at first piece part exposure (block
6) and an inspection threshold of zero cycles (block 7) will be evaluated. Figure B-2 shows the piece part, maintenance exposure distribution for the ring disk.
4. An ultrasonic inspection that rejects indications equal to or greater than a #3 FBH is selected. The solid line in figure E-4 is the POD for this inspection (block 8).
5. The POF calculations (block 9) are performed in the same manner as in paragraph A.4.7; except, instead of a fixed inspection at 10,000 cycles, inspections are assumed to occur as the piece parts are exposed. The piece part, exposure distribution is treated as a random variable in the probabilistic analysis.
6. The calculated probability of failure is 1.3E-9 events/cycle, which is still greater than the DTR (a “No” answer at block 10). On a second pass, a more sensitive ultrasonic inspection is assumed, which rejects indications equal to or greater than one-half the response from a #3 FBH. The dotted line in figure E-5 represents the associated POD for this inspection. The resulting POF is 9.9E-10 events/cycle, meeting the DTR (a “Yes” answer at block 10).
7. 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.
•
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.
B.3 Example of Scenario 3:
Module above Soft-Time Interval.
1. For this example, piece part exposure of the ring disk is expected to occur at a lower rate than in the previous scenario. Figure B-3 depicts this change.
2. The predicted POF is 1.2E-09 events/cycle, assuming this new exposure distribution and the same UT inspection and sensitivity as in scenario 1. Since the predicted POF exceeds the DTR, additional action is necessary.
3. Assuming that it is not reasonable to use a more sensitive field ultrasonic inspection (for example, calibration to a smaller flat bottom hole), then the module exposure distribution is evaluated (figure B-4).
B-2