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---:::::::: C-H-' .. I I I 100 1000 10000 ANOMALY AREA (mils"2) BILLET: DATA TAKEN WITH 05 x 1 IN. CYLINDRICALLY FOCUSED TRANSDUCER FINISH-MACHINED PART: DATA TAKEN WITH 0.75 IN. DIAMETER SPHERICALLY FOCUSEDlRANSDUCER REJECT INDICATIONS EQUAL TO OR GREATER THAN THOSE FROM A 1/64 IN. DIA FBH REJECT IN DI CATIONS EQUAL TO OR GREATER THAN ONE HALF THOSE FROM A 1 /64 IN. DIA FBH APPLICABILITY:
HARD-ALPHA ASSOCIATED INCLUSIONS/ CRACKS/VOIDS (INCLUDES DIFFUSION ZONES).
BILLET: S Mhz LONGITUDINAL [COMPRESSIONAL)WAVE INSPECTION GRCULAR-CYUNDRICAL BILLET.
100000 FINISH-MACHINED: S Mhz SHEAR (lRANSVERSE) WAVE INSPECTION APPLICABLE ONLY IF THE INDICATED SENSITIVITY IS ATTAINABLE.
4/17/23 AC 33.70-3 Appendix E Figure E-2. Mean (50 Percent Confidence) POD for Ultrasonic Inspection of Field Components, #1 FBH (1/64 In. Diameter) Calibration E-3
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Appendix E 100
PERCENT POD 30 20 10 100 1000 10000 100000 ANOMALY AREA (mils^2) BILLET: DATA TAKEN WITH 0.5 × 1 IN. CYLINDRICALLY FOCUSED TRANSDUCER FINISH-MACHINED PART: DATA TAKEN WITH 0.75 IN. DIAMETER SPHERICALLY FOCUSED TRANSDUCER REJECT INDICATIONS EQUAL TO OR GREATER THAN THOSE FROM A 3/64 IN. DIA FBH REJECT INDICATIONS EQUAL TO OR GREATER THAN ONE HALF THOSE FROM A 3/64 IN. DIA FBH APPLICABILITY:
HARD-ALPHA ASSOCIATED INCLUSIONS / CRACKS / VOIDS (INCLUDES DIFFUSION ZONES).
BILLET: 5 Mhz LONGITUDINAL (COMPRESSIONAL) WAVE INSPECTION CIRCULAR-CYLINDRICAL BILLET.
FINISH-MACHINED: 5 MhZ SHEAR (TRANSVERSE) WAVE INSPECTION APPLICABLE ONLY IF THE INDICATED SENSITIVITY IS ATTAINABLE.
Figure E-4. Mean (50 Percent Confidence) POD for Ultrasonic Inspection of Field Components, #3 FBH (3/64 In. Diameter) Calibration E-5
Appendix E 100 PERCENT POD 50 10 10
• 100 ANOMALY LENGTH (mils)
REJECT AT THE CALIBRATION NOTCH THRESHOLD RESPONSE AND ABOVE
REJECT AT ONE HALF THE CALBRATION NOTCH THRESHOLD RESPONSE AND ABOVE APPLICABILITY:
ABSOLUTE COLLS, 2-6 MH INSPECTION FREQUENCY.
CALIBRATION ON 0,030 IN X 0.015 IN, NOTCH, ONLY IF THE INDICATED SENSITVITY IS ATTAINABLE, Figure E-5. Mean (50 Percent Confidence) POD for Eddy Current Inspection of Finish Machined Components E-6
Appendix F APPENDIX F. DEFINITIONS These definitions are for the purpose of this AC only.
• Component Event Rate. The number of events for a given titanium rotor component stage for each flight cycle, calculated over the projected life of the component.
• Damage Tolerance. An element of the life management process that recognizes the potential existence of component imperfections. The potential existence of component imperfections is the result of inherent material str ucture, material processing, component design, manufacturing, or usage. Damage tolerance addresses this situation through the incorporation of fracture resistant design, fracture-mechanics, process control, or nondestructive inspection.
• Default Probability of Detection (POD) Values. Values representing mean probabilities of detecting anomalies of various types and sizes under specified inspection conditions consistent with good industry practice.
• Design Target Risk (DTR) Value. The standard against which probabilistic assessment results, stated in terms of component event rates and engine-level event rates, as defined above, are compared.
• Di rected Inspection. Inspections where specialized processing instructions have been provided and the inspector has been instructed to pay attention to specific critical features.
• Event A rotor structural part separation, failure, or burst with no regard to the consequence.
• Full-Field Inspection. The general inspection of a component without special attention to any specific features.
• Hard Alpha. An interstitially stabilized alpha phase region of substantially higher hardness than the surrounding material. This comes from very high local nitrogen, oxygen, or carbon concentrations that increase the beta transus and produce the high hardness, often brittle, alpha phase. A high interstitial defect is also commonly called a Type I defect, low-density inclusion (LDI), or a hard alpha often associated with voids and cracks.
• Inspected Material. The portion of the total volume of a component that is actually inspected under the described conditions. Inspected material does not guarantee anomaly free material.
• Inspection Opportunity. An occasion when an engine is disassembled to at least the modular level and the hardware in question is accessible for inspection, whether or not the hardware has been reduced to the piece part level.
F-1
Appendix F
• Maintenance Exposure Interval. Distribution of shop visits (in-flight cycles), new or last overhaul, since an engine, module, or component is exposed to as a function of normal maintenance activity.
• Mean POD. The 50 percent confidence level POD versus anomaly size curve.
• Module. A combination of assemblies, subassemblies, and parts contained in one package, or arranged to be installed in one maintenance action.
• Probabilistic (Relative Risk) Assessment. A fracture-mechanics based simulation procedure that uses statistical techniques to mathematically model and quantitatively combine the influence of two or more variables to estimate a most likely outcome or range of outcomes for a product. Since not all variables may be considered or may not be capable of being accurately quantified, the numerical predictions are used on a comparative basis to evaluate various options having the same level of inputs. Results from these analyses are typically used for design optimization to meet a predefined target, or to conduct parametric studies. This type of procedure is distinctly different from an absolute risk analysis, which attempts to consider all significant variables and is used to quantify, on an absolute basis, the predicted number of future events having safety and reliability ramifications.
• Probability of Detection (POD). A quantitative statistical measure of detecting a particular type of anomaly over a range of sizes using a specific nondestructive inspection technique under specific conditions. Typically, the mean POD curve is used.
• Safe-Life. An LCF-based process where components are designed and substantiated to have a specified service life, stated in operating cycles, operating hours, or both. Continued safe operation up to the stated life-limit is not contingent on each unit of a given design receiving interim inspections. When a component reaches its published life-limit, it is retired from service.
• Soft-Time Inspection Interval. The number of flight cycles since new, or the most recent inspection, after which a rotor or engine part in an available module must receive the inspection specified in the AL section of the ICA.
• Stage. The rotor structure that supports and is attached to a single aerodynamic blade row.
F-2
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