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Component Maintenance Manual Revision (Aug 2013)

Bud McElroy

The King Air Component Maintenance Manual was recently revised. A more thorough  examination of the landing gear components is now mandatory . Not only has the inspection become more investigative, but more specialized. The King Air  90, 100 & 200   series fluorescent penetrant inspection requirements must meet the ASTM E1417 and or NAS410 requirements*. The requirements specify the qualifications, facilities and procedures. Here is a small excerpt from ASTM E1417.
Personnel Qualification—Personnel performing examinations to this practice shall be qualified and certified in accordance with ASNT Personnel Qualification SNT-TC-1A, ANSI/ASNT-CP-189 or NAS 410  
6.6 Equipment and Facilities—Processing equipment used in the penetrant examination process shall be constructed and arranged to permit a uniform and controlled operation. The equipment shall meet all applicable national and local safety requirements as well as the requirements specified herein.
 
6.6.1 Viewing Areas—Areas where parts are reviewed shall be kept clean at all times. For visible dye examination, Type II, the lighting system shall provide at least 100 fc (1076 lx) of visible light when measured at the examination surface. For stationary fluorescent dye examination, Type I, the ambient visible light background shall not exceed 2 fc (21.5 lx) at the examination surface. The black lights shall provide a minimum of 1000 μW/cm2 at the examination surface. Black lights shall meet the requirements of 7.8.4.1. Viewing areas for portable fluorescent dye examination shall utilize dark canvas, photographer's black cloth, or other methods to reduce the visible light background to the lowest possible level during examination and black light intensity shall meet the above requirements.
 

6.6.1.1 Where lamps are physically too large to directly illuminate the examination surface, special lighting, such as UV pencil lights, or UV light guides, or remote visual examination equipment shall be used. When using a borescope, the image viewed must have sufficient resolution to effectively evaluate the indication. Light intensity shall be measured at the expected working distance and shall be a minimum 1000 μW/cm2.

6.6.2 Drying Oven—When components are oven dried, the dryer must be a forced-air recirculating type. In automated systems, where parts are dried by radiant heat and forced air, the travel speed of the system shall be such as to preclude overdrying of parts. The forced air does not have to be recirculating but must preclude contamination of the parts. The temperature shall be controlled with a calibrated device capable of maintaining the oven temperature at 15F (9.44C) of the temperature for which it is set. The oven shall not exceed 160F (71C). The temperature indicator shall be accurate to 10F (12.22C) of the actual oven temperature.
 
6.7 Written Procedures—All liquid penetrant examination procedures are similar for many components, a master written procedure may be utilized that covers the details common to a variety of components. All written procedures, including technique sheets for specific parts shall be approved by an individual who is a qualified and certified Level III for penetrant examination in accordance with the requirements of 6.3. As a minimum, the following information is required either in individual procedures, specific technique sheets, or a master procedure, or a combination thereof:
 
6.7.1 Details of the precleaning and etching process, including the materials used and specification or other document controlling the examination process, the drying parameters and the processing times. If these operations are performed by other than examination personnel, details concerning the operations may be specified in other documents but must be referenced in the procedure(s). Reference Test Method E165 for detailed cleaning methods and instructions.
 
6.7.2 Classification of the penetrant examination materials required in accordance with Section 5 and AMS 2644.
 
6.7.3 Complete processing parameters for the penetrant examination materials including concentrations, application methods, dwell times, drying times, temperatures, and controls to prevent excessive drying of penetrant or overheating of component, as appropriate. Reference Practice E165 for additional details.
 
6.7.4 Complete examination/evaluation requirements including light intensities (both examination and ambient), the accept/reject criteria and the method and location of marking. Reference Practice E165for additional details.
 
6.7.4.1 When the examination is performed in accordance with this Standard Practice, engineering drawings, specifications, technique sheets, or other applicable documents shall indicate the accept/reject criteria by which the components are judged acceptable.
 
6.7.5 Identification of the components or areas within a component to be examined in accordance with the procedure.
 
6.7.6 Complete postcleaning procedures. If postcleaning is performed by other than examination personnel, details concerning this operation may be specified in other documents, but must be referenced in the procedure. Reference Test Method E165for additional details.
 
6.8 Examination Sequence—Final penetrant examination shall be performed after completion of all operations that could cause surface-connected discontinuities or operations that could expose discontinuities not previously open to the surface. Such operations include, but are not limited to, grinding, welding, straightening, machining, and heat treating.
 

6.8.1 Surface Treatment—Final penetrant examination may be performed prior to treatments that can smear the surface but not by themselves cause surface discontinuities. Such treatments include, but are not limited to, vapor blasting, deburring, sanding, buffing, sandblasting, lapping, or peening. Performance of final penetrant examination after such surface treatments requires that etching be included in the precleaning operation unless otherwise agreed on between the cognizant engineering organization and the NDT facility.

Note 2—Final penetrant examination should always precede peening.
 
6.8.2 Surface Coatings—All coatings and other surface conditions, such as, paint, plating, corrosion, etc. shall be removed from the area to be examined prior to penetrant examination. The penetrant examination shall precede any surface finish, such as anodize, except for inservice parts that may be examined without removing the anodize.
 
6.9 Material and Process Limitations—Not all penetrant sensitivity levels, materials, and process methods are applicable to all examination requirements. The sensitivity level shall be adequate for the intended purpose of the examination. Unless there is an approval for deviation given by the cognizant engineering organization, the following selections are mandatory or forbidden, as indicated:
 
6.9.1 Forms a and b (dry powder and water soluble) developers shall not be used with Type II (visible dye) penetrant systems. This is not intended to prohibit the use of a Form f developer that has been qualified with a particular Type II system in accordance with AMS 2644.
 
6.9.2 Type II penetrant examination shall not be used for final acceptance examination of aerospace products. In addition, Type II penetrant examination shall not be used prior to a Type I penetrant examination of the same surface. This is not intended to eliminate the use of in-process Type II examinations where subsequent fabrication/forming operations remove the surfaces inspected.
 
6.9.3 The maintenance or overhaul examination of turbine engine critical components shall be done only with Type I, Methods C or D (solvent removable or post emulsified, hydrophilic) processes and either sensitivity Levels 3 or 4 penetrant materials.
 
6.10 Records—Results of all final penetrant examinations shall be recorded. All recorded results shall be identified, filed, and made available to the cognizant engineering organization upon request. Records shall provide for traceability to the specific part or lot inspected. As a minimum, the records shall include: identification of the procedure used, disposition of the examination; identification of the inspector's examination stamp, electronic ID or signature; and the date of examination. Records shall be kept for a minimum of three years or as otherwise specified in the purchase order or contract.
 
 
The King Air Component Maintenance Manual was recently revised. A more thorough examination of the landing gear components is now mandatory . Not only has the inspection become more investigative, but more specialized. The King Air 90, 100 & 200 series magnatic particle inspection requirements must meet the ASTM E1444 and or NAS410 requirements*. The requirements specify the qualifications, facilities and procedures. Here is a small excerpt from ASTM E1444. 
  
5.1 Personnel Qualification—Personnel performing examinations in accordance with this practice shall be qualified and certified in accordance with ASNT Recommended Practice No. SNT-TC-1A, ANSI/ASNT Standard CP-189, NAS 410, or as specified in the contract or purchase order.
 
5.2 Agency Qualification—If specified in the contractual agreement, NDT agencies shall be qualified and evaluated as described in E543. The applicable edition of E543 shall be specified in the contractual agreement.
 
5.3 Written Procedure—Magnetic particle testing shall be performed in accordance with a written procedure applicable to the part or group of parts under examination. The procedure shall be in accordance with the requirements of this Practice. The process, when conducted in accordance with the written procedure, shall be capable of detecting discontinuities specified in the acceptance criteria. The written procedure may be general if it clearly applies to all of the specified parts being examined and meets the requirements of this practice. All written procedures, including technique sheets for specific parts, shall be approved by an individual qualified and certified at Level III for magnetic particle testing in accordance with the requirements of 5.1. Procedures shall be submitted to the Cognizant Engineering Organization for review, or approval, or both, when requested.
 
5.3.1 Elements of the Written Procedure—The written procedure shall include at least the following elements, either directly or by reference to the applicable documents:
 
5.3.1.1 Procedure identification number and the date it was written;
 
5.3.1.2 Identification of the part(s) to which the procedure applies; this shall include the material, or alloy, or both;
 
5.3.1.3 For new components, sequence of magnetic particle testing as related to manufacturing process operation (for example, post plating, after heat treat, etc.);
 
5.3.1.4 Identification of test parts used for system performance verification (see 7.1.1 and 7.1.2);
 
5.3.1.5 Process controls (see Table 1);
 
5.3.1.6 Areas of the part to be examined;
 
5.3.1.7 Part preparation required before examination;
 
5.3.1.8 Directions for positioning the item with respect to the magnetizing equipment;
 
5.3.1.9 The type of magnetizing current and the equipment to be used;
 
5.3.1.10 Method of establishing the magnetization (head, coil, prods, yoke, cable wrap, etc.);
 
5.3.1.11 Directions of magnetization to be used, the order in which they are applied, and any demagnetization procedures to be used between shots;
 
5.3.1.12 The current level, or the number of ampere turns, to be used and the duration of its application;
 
5.3.1.13 Type of magnetic particle material (dry or wet, visible or fluorescent, etc.) to be used and the method and equipment to be used for its application and, for the case of wet particles, the particle concentration limits;
 
5.3.1.14 Type of records and method of marking parts after examination;
 

5.3.1.15 Acceptance requirements, to be used for evaluating indications and disposition of parts after evaluation; and

5.3.1.16 Post-examination demagnetization and cleaning requirements.
 
5.4 Examination Sequence—Perform magnetic particle examination after all operations which might cause or reveal discontinuities. Such operations include, but are not limited to, forging, heat treating, electroplating, forming, welding, grinding, straightening, machining, and proof loading.
 

5.4.1 Perform magnetic particle examination prior to shot peening (to provide a beneficial compressive layer) and prior to applying protective finishes such as priming, painting, plating (see 5.4.3 through 5.4.3.5) or other coatings.

5.4.2 In-process examinations may not be substituted for final examination.
 
5.4.3 Plating and Coatings—Examine parts which will receive either a plating or coating as follows:
 
5.4.3.1 Examination is required prior to all non-electroplated coatings.
 
5.4.3.2 Electroplated surfaces with a final plating thickness of 0.0008 in. [0.02 mm] or less shall be examined either before or after electroplating, or grinding, or both, of electroplated surfaces.
 
5.4.3.3 Electroplated surfaces with a final plating thickness of between 0.0008 in. [0.02 mm] and 0.0050 in. [0.13 mm] shall be examined both before and after electroplating, or grinding, or both, of electroplated surfaces.
 

(1) Electroplated surfaces with a final plating thickness of 0.0050 in. [0.13 mm] or greater shall be examined before electroplating, or grinding, or both, of electroplated surfaces.

(2) Magnetic particle examination after electroplating is not required for steels with a tensile strength less than or equal to 160 ksi.
 
5.4.3.4 Use caution when examining parts with an electroplated nickel coating as indications may form from the resulting leakage fields within the nickel plating itself.
 
5.4.3.5 For in-service examination, plating or coatings do not require removal prior to examination unless they are damaged, or they interfere with the examination process.
 
5.5 Materials:
 
5.5.1 Dry Particle Requirements—Dryparticles shall meet the requirements of AMS 3040.
 
5.5.2 Wet Particle Requirements—Wet particles shall meet the requirements of AMS 3041, 3042, 3043, 3044, 3045, or 3046, as applicable.
 
5.5.3 Suspension Vehicles—The suspension vehicle for the wet method shall be a light petroleum distillate conforming to AMS 2641 (Type I) or A-A-59230, or a suitably conditioned water that conforms to the requirements of 5.5.4. When approved by the contracting agency, AMS 2641 (Type II) may be used. When specified, the oil suspension vehicle shall meet the salient characteristics specified in A-A-59230.
 
5.5.4 Conditioned Water Vehicle—When water is used as a suspension vehicle for magnetic particles, the conditioning agents used shall comply with AS 4792. Proper wetting shall be determined by a water break test (see 7.2.2). Smoother surfaces generally require a greater percent of wetting agent than rough surfaces. Foaming of the bath must be minimized to the point that it does not interfere with the examination process.
 
5.5.4.1 Water Vehicle Conditioning Agents—Any agents added to the water vehicle for any purpose shall conform to the requirements of the particle manufacturer.
 

5.5.5 Particle Concentration—The concentration of particles in the suspension bath shall be as specified in the written procedure. Particle concentrations outside of the range of 0.1 to 0.4 mL in a 100-mL bath sample for fluorescent particles and 1.2 to 2.4 mL in a 100 mL sample for nonfluorescent particles shall not be used. Fluorescent particles and nonfluorescent particles shall not be used together.

5.6 Safety—The safe handling of magnetic particles (wet or dry), oil vehicles, water baths, and water conditioner concentrates are governed by the suppliers' Material Safety Data Sheets (MSDS). Material Safety Data Sheets, conforming to 29 CFR 1910.1200, or equivalent, must be provided by the supplier to any user and shall be prepared in accordance with FEDSTD-313.
 
5.6.1 Flammability—Flash point of oil vehicles shall be in accordance with AMS 2641, Type I carriers. The suppliers MSDS shall certify the flash point.
 
5.6.2 Personnel Hazards—Precautions against inhalation, skin contact, and eye exposure are detailed in the suppliers MSDS. These precautions shall be observed.
 
5.6.3 Electrical Hazards—Magnetizing equipment shall be maintained properly to prevent personnel hazards from electrical short circuits. Care must be taken to reduce arcing and the possible ignition of oil baths.
 
5.6.4 Black Light—Replace cracked or broken ultraviolet filters immediately. Broken filters can allow harmful shortwave ultraviolet energy to be emitted and must be replaced immediately. Spectacles designed to absorb ultraviolet wavelength radiation are suggested for close, high-intensity black light examination.
 
TABLE 1 Required Verification Intervals

Item

Maximum Time
Between Verification
A

Lighting:B

 

Visible light intensity (7.3.1.1)

Weekly

Ambient light intensity (7.3.1.2)

Weekly

Black light intensity (7.3.2, 7.4.5)

Daily

Battery powered black
light intensity check (7.4.5.2)

Before and after each use

Black light integrity (7.3.2)

Weekly

System Performance:B (7.1, 7.1.1, 7.1.2)

Daily

Wet particle concentration (7.2.1.1)

8 hours, or every shift change

Wet particle contamination:B (7.2.1.2)

1 week

Water break test (7.2.2)

Daily

Equipment calibration check:B

 

Ammeter accuracy (7.4.1)

6 months

Timer control (7.4.2)

6 months

Quick break (7.4.3)

6 months

Yoke dead weight check (7.4.4)

6 months

Black and white light meters

6 months

Gaussmeter or Field Indicator accuracy

6 months

A When the inspection system is in operation.

B The maximum time between verifications may be reduced or extended when substantiated by actual technical/reliability data.

6. Specific Practice

Top

6.1 Preparation of Parts for Testing:
 
6.1.1 Pre-examination Demagnetization—The part shall be demagnetized before testing if prior operations have produced a residual magnetic field that may interfere with the examination.
 
6.1.2 Surface Cleanliness and Finish—The surface of the part to be examined shall be essentially smooth, clean, dry, and free of oil, scale, machining marks, or other contaminants or conditions that might interfere with the efficiency of the examination.
 
6.1.3 Plugging and Masking—Plugging and masking is required when specified by the Cognizant Engineering Organization.
 
6.1.4 All areas on the part where electrical contact is made shall be sufficiently clean to prevent electrical arcing.
 
6.1.5 Aircraft-Quality Steel Cleanliness—The inspection of aircraft-quality steel for cleanliness using magnetic particle testing shall be as appropriate to the type of steel being inspected. However, testing of parts fabricated from this material shall be in accordance with the requirements of this practice.
 
6.2 Magnetization Methods:
 
6.2.1 Types of Magnetizing Current—The types of currents used for magnetic particle testing are full-wave rectified current (1 or 3 phase), half-wave rectified current, and alternating current. The equipment used shall fulfill the magnetizing and demagnetizing requirements adequately, as outlined herein, without damage to the part under examination, and they shall include the necessary features required for safe operation.
 
6.2.2 Permanent Magnets—Permanent magnets are not to be used for magnetic particle testing unless specifically authorized by the Cognizant Engineering Organization. When permanent magnets are used, adequate magnetic field strength shall be established in accordance with 7.4.4.
 
6.2.3 Yokes—When using yokes (electromagnetic probes) for magnetic particle testing, they shall meet the requirements of 7.4.4.
 
6.2.4 Magnetizing Current Application—Alternating current is to be only used for the detection of discontinuities open to the surface. Full-wave direct current has the deepest possible penetration and must be used for examination of sub-surface discontinuities when using the wet magnetic particle method. Half-wave direct current can also be used for inspection of sub-surface discontinuities and due to the pulsating nature of the waveform; it has the advantage of increased particle mobility.
 
6.2.5 Magnetic Field Directions—Discontinuities are difficult to detect by the magnetic particle method when they make an angle less than 45 to the direction of magnetization. To ensure the detection of discontinuities in any direction, each part must be magnetized in a minimum of two directions at approximately right angles to each other. Depending on part geometry, this may consist of circular magnetization in two or more directions, multiple circular and longitudinal magnetization, or of longitudinal magnetization in two or more directions. The pie gauge as illustrated in Fig. X5.1, the flexible laminated strips as described in Annex A3, or a properly prepared master part using notched shims may only be used as a tool to demonstrate the direction of the external magnetic field. The pie gauge or flexible laminated strips shall not be used to determine adequate field strength. Exceptions necessitated by part geometry, size, or other factors require specific approval of the Cognizant Engineering Organization.
 
6.2.6 Multidirectional Magnetization— Multidirectional magnetization may be used to fulfill the requirement for magnetization in two or more directions if it is demonstrated that it is effective in all areas, which require inspection as practical. Test parts in accordance with 6.3.1.1 or shims manufactured to the requirements of AS 5371, or as otherwise approved by the Cognizant Engineering Organization, shall be used to verify field direction, strength, and balance in multidirectional magnetization. Balancing of the combined magnetic field is critical and an adequate balance must be visually demonstrated to be effective in all areas, which require inspection. The particle application must be timed so that the magnetization levels reach full value in all directions while the particles are mobile on the surface under examination. The residual method shall only be used with the approval of the Cognizant Engineering Organization.
 
6.2.7 Direct Magnetization—Direct magnetization is accomplished by passing current directly through the part under inspection. Electrical contact is made to the part using head and tail stock, prods, clamps, magnetic leeches, or by other means. Caution shall be taken to ensure that the electrical current is not flowing while contacts are being applied or removed and that excessive heating does not occur in any area of the part. Unless otherwise specified by the Cognizant Engineering Organization, prods shall not be used for the examination of aerospace components (flight hardware) or on finished surfaces.
 
6.2.8 Indirect Magnetization—Indirect part magnetization uses pre-formed coils, cable wraps, yokes, field (flux) flow fixtures, or a central conductor to induce a magnetic field in a part when no direct electrical contact is made.
 
6.2.9 Induced Current Magnetization—Induced current magnetization (toroidal or circumferential field) is accomplished by inductively coupling a part to an electrical coil in order to create a suitable current flow within the part as illustrated in Fig. X5.2. This method is often advantageous on ring-shaped parts with a central aperture and with an L/D ratio less than three, especially where the elimination of arcing or burning is of vital importance.
 
6.2.10 Parallel Current Induced Magnetization—This method of magnetization may occur when a ferromagnetic part is placed alongside and parallel to a current-carrying conductor. A magnetic field will be induced in the part that is more transverse than circular. This type of magnetization shall not be used for magnetic particle testing unless approved by the Cognizant Engineering Organization.
 
6.2.11 Magnetization of Aerospace Lifting Hardware—The use of permanent magnets, electromagnetic yokes, coil wraps or prods on aerospace lifting hardware must be approved by the Cognizant Engineering Organization.
 
6.3 Magnetic Field Strength:
 
6.3.1 Magnetic Field Strength—The applied magnetic field shall have sufficient strength to produce satisfactory indications, but it must not be so strong that it causes the masking of relevant indications by nonrelevant accumulations of magnetic particles. Adequate magnetic field strength may be determined by one or a combination of the following methods:
 
6.3.1.1 In unidirectional, or multidirectional magnetizing applications, by examining parts having known or artificial discontinuities of the type, size, and location specified in the acceptance requirements or by using the notched shims as defined in Annex A1;
  
6.3.1.2 In unidirectional magnetizing applications only, by using a Hall Effect probe gaussmeter capable of measuringthe peak values of the tangential field as described in Annex A5. Tangential-field strengths shall have a minimum value of 30 Gauss (30 10-4 Tesla [T]) when measured at the part surface using a Hall Effect probe gaussmeter as described in Annex A5. The maximum Gauss value derived is limited by the restrictions of 6.3.1.
 
6.3.1.3 Using the current levels specified by the formulas given in Appendix X3 and Appendix X4. These current levels and formulas provide only a rough guide and shall only be used in conjunction with either 6.3.1.1, or 6.3.1.2, or Cognizant Engineering Organization approval, or a combination thereof. In some cases the formulas in Appendix X3 and Appendix X4 may lead to over magnetization of the work piece and care should be exercised when using them.
 
6.3.2 Longitudinal Magnetization Using Coils—Longitudinal magnetization is often accomplished by passing current through a coil encircling the part, or section of the part, to be examined (that is, by using a coil shot). This produces a magnetic field parallel to the axis of the coil. The actual effective distance must be demonstrated based on the particular part to be examined. For parts longer than these effective distances, the entire length shall be examined by repositioning the part within the coil, allowing for approximately 10 % effective magnetic field overlap. See 6.3.1 for field strength methods that can be used in coil magnetization.
 
6.4 Particle Application:
 
6.4.1 Dry Magnetic Particle Application, Continuous Method—When using dry particles, the flow of magnetizing current shall be initiated prior to application of the magnetic particles to the surface under examination and terminated after powder application has been completed and any excess blown off. Precautions shall be taken to prevent any damage to the part due to overheating.
 
6.4.1.1 Apply dry powder so that a light, uniform, dust-like coating settles on the surface of the part under examination while the part is being magnetized. Specially designed powder blowers or shakers using compressed air or hand power shall be used. The applicators shall introduce the particles into the air in a manner such that they reach the part surface in a uniform cloud with a minimum of force.
 
6.4.1.2 After the powder is applied, and before the magnetizing force is removed, excess powder shall be removed, by means of a dry air current with sufficient force to remove the excess particles if it interferes with interpretation and evaluation, but not strong enough to disturb particles held by a leakage field that is indicative of discontinuities. In order to recognize the broad, fuzzy, lightly held powder patterns formed by near-surface discontinuities, the formation of indications must be observed carefully during both powder application and removal of the excess powder. The dry particle method shall not be used to examine aerospace components (flight hardware). Dry magnetic particles shall not be reused.
 
6.4.2 Wet Magnetic Particle Application, Continuous Method—Fluorescent or nonfluorescent particles suspended in a liquid vehicle at the required concentration shall be applied by gently spraying or flowing the suspension over the area to be examined or by immersion of the part in the suspension.
 
6.4.2.1 Proper sequencing and timing of part magnetization and application of particle suspension are required to obtain the proper formation and retention of indications. This requires that the stream of suspension be diverted from the part simultaneously with, or slightly before, energizing the magnetic circuit.
 
6.4.2.2 The magnetizing current shall be applied for a duration of at least 0.5 second for each application, with a minimum of two shots being used. The second shot shall follow the first while the particles are still mobile on the surface of the part.
 
6.4.2.3 Under special circumstances, such as the use of automated equipment or for critical parts, the 0.5second duration and the two-shot requirement may be waived provided it is demonstrated that the procedure can detect known discontinuities in reference parts.
 
6.4.2.4 Care shall be exercised to prevent any damage to the part due to overheating or other causes. Weakly held indications on highly finished parts are readily washed away, and care must be exercised to prevent high-velocity flow over critical surfaces.
 
6.4.3 Residual Magnetization Method—In the residual magnetization method, the magnetic particles are applied to the part under examination after the magnetizing force has been discontinued. The residual method is not as sensitive as the continuous method. It can be useful on materials with high retentivity. It is also useful for the examination of parts or areas of parts, which because of geometric constraints, cannot be examined with the continuous method. The residual method shall be used only when specifically approved by the Cognizant Engineering Organization or when it has been documented that it can detect discontinuities or artificial discontinuities in parts under examination. The test parts shall have the same material and processing steps, and similar geometry, to the actual parts being examined.
 
6.4.4 Magnetic Slurry/Paint Application—Magnetic paints or slurries are applied to the part with a brush, squeeze bottle, or aerosol can before or during the magnetization operation. This method is for special applications, such as overhead or underwater examination. This method may be used only when specifically approved by the Cognizant Engineering Organization.
 
6.4.5 Magnetic Polymer Application—Polymerizable material containing magnetic particles shall be held in contact with the part under examination during the period of its cure. Before curing takes place, and while the magnetic particles are still mobile, the part shall be magnetized to the specified level. This requires prolonged or repeated periods of magnetization. This method is for special applications, such as bolt holes which cannot be examined readily by the wet or dry method, and shall be used only when specifically approved by the Cognizant Engineering Organization. AMS-I-83387 establishes the examination process for magnetic rubber.
 
6.4.6 Particle Selection for Aerospace Lifting Hardware—The use of dry powder or non-fluorescent wet particles on aerospace lifting hardware must be approved by the Cognizant Engineering Organization.
 
6.5 Evaluation—Following magnetization and particle application, the parts shall be examined for indications. All indications will be identified as relevant or nonrelevant. Relevant indications will be compared to the proper accept/reject criteria and the parts accepted or rejected accordingly.
 
6.5.1 Eye Glasses—When using fluorescent materials, personnel shall not wear eye glasses that are photochromic or that have permanently darkened lenses. This is not intended to prohibit the use of eyeglasses with lenses treated to absorb ultraviolet light.
 
6.5.2 Dark Adaptation—Personnel must wait at least one minute after entering a darkened area for their eyes to adjust to the low-level lighting before performing fluorescent magnetic particle testing.
 
6.5.3 Acceptance Requirements—The acceptance requirements applicable to the part or group of parts shall be incorporated as part of the written procedure either specifically or by reference to other applicable documents containing the necessary information. When parts are zoned, the acceptance criteria for each zone shall be specified. Methods for establishing acceptance requirements for large crankshaft forgings are covered in Specification A456/A456M. Methods for establishing requirements for steel forgings are covered in Practice A275/A275M. Methods for classifying metal castings are given in AMS 2175 and AMS 5355.
 
6.6 Recording of Indications—When required by the written procedure, the location of all rejectable indications shall be marked on the part, and permanent records of the location, direction, and frequency of indications may be made by one or more of the following methods:
 
6.6.1 Written Description—By recording the location, length, direction, and number of indications in sketch or tabular form.
 
6.6.2 Transparent Tape—For dry particle indications, by applying transparent adhesive-backed tape to which the indications will adhere and placing it on an approved form along with information giving its location on the part.
 
6.6.3 Strippable Film—By covering the indication with a spray-on strippable film that fixes the indications in place and placing the resultant reproduction on an approved form along with information giving its location on the part.
 
6.6.4 Photography—By photographing or video recording the indications themselves, the tape, or the strippable film reproduction and placing the photograph in a tabular form along with information giving its location on the part.
 
6.7 Post Examination Demagnetization and Cleaning—All parts shall be demagnetized and cleaned after final examination. Apply corrosion protection as required.
 
6.7.1 Demagnetization:
 
6.7.1.1 When using AC demagnetization, the part shall be subjected to a field with a peak value greater than, and in nearly the same direction as, the field used during testing. This AC field is then decreased gradually to zero. When using an AC demagnetizing coil, the part is passed through the coil while the current is flowing. For effective demagnetization, parts having complex configurations may require rotating or tumbling while passing through the field of the coil prior to the current being shut off. Repeat this process as necessary.
 
6.7.1.2 When using DC demagnetization, the initial field shall be higher than, and in nearly the same direction as, the field reached during testing. The field shall then be reversed, decreased in magnitude, and the process repeated (cycled) until an acceptably low value of residual field is reached.
 
6.7.1.3 Whenever possible, parts that have been magnetized circularly shall be magnetized in the longitudinal direction before being demagnetized. After demagnetization, a calibrated field indicator shall not detect magnetic flux fields with an absolute value above 3 G (3 10-4 T) anywhere on the part.
 
6.7.2 Post-inspection Cleaning—Cleaning shall be done with a suitable solvent, air blower, or by other means.
 
6.7.2.1 Parts shall be examined to ensure that the cleaning procedure has removed magnetic particle residues from holes, crevices, passage ways, etc. Such residue could have an adverse effect on the intended use of the part.
 
6.7.2.2 Care shall be taken to remove all plugs, masking, or other processing aids that may affect the intended use of the part.
 
6.7.2.3 Parts shall be protected from corrosion or damage as required.
 
6.8 Record of Examination—The results of all magnetic particle examinations shall be recorded. Records shall provide for traceability to the specific part or lot examined, serial number if serialized, and they shall identify the NDE contractor or facility and the procedures used in the examination, the lot size, and the number of parts accepted. All recorded results shall be identified, filed, and made available for review by the contracting agency upon request.
 
6.9 Marking of Accepted Parts—Unless otherwise specified by the Cognizant Engineering Organization, parts that have been accepted using magnetic particle testing shall be marked in accordance with the applicable drawing, purchase order, contract, or as specified herein prior to leaving the testing facility.
 
6.9.1 Marking shall be applied in such a manner and location as to be harmless to the part. The identification shall not be obliterated or smeared by subsequent handling and, when practicable, placed in a location that will be visible after assembly.
 
6.9.1.1 When subsequent processing would remove the identification, the applicable marking shall be affixed to the record accompanying the finished parts or assembly.
 
6.9.1.2 Bolts and nuts and other fastener products may be identified as having met the requirements of magnetic particle testing by marking each package conspicuously.
 
6.9.2 Impression Stamping, Ink Stamping, Laser Marking, Dyeing, Vibro Engraving or Etching—Impression stamping, ink stamping, laser marking, dyeing, vibro engraving or etching may be used when permitted or required by the applicable written procedure, detail specification or drawing, or when the nature of the part is such as to provide for impression stamping of part numbers or other examination personnel markings. Impression stamping shall be located only in the area provided adjacent to the part number or examination personnel's stamp.
 
6.9.3 Other Identification—Other means of identification, such as tagging, may be used for parts that have a configuration or function precluding the use of stamping, vibro engraving, or etching, as in the case of completely ground or polished balls, rollers, pins, or bushings.
 
6.10 Identifying Symbols and Color Markings:
 
6.10.1 One-Hundred Percent Examination—When items are examined and accepted by 100 % examination, each item shall be marked as follows:
 
6.10.1.1 Dyeing—When dyeing is applicable, a dye of acceptable adherence which is predominantly blue (in accordance with FED-STD-595) shall be employed. However, if a color conflict is incurred with any other method, magnetic particle examination may be indicated by two adjacent blue dots or other suitable means.
 
6.10.1.2 Stamping, Laser Marking, Vibro Engraving, or Etching—When impression stamping or ink stamping, laser marking, vibro engraving, or etching is used to mark 100 % examined parts, the letter M with a circle around it shall be employed.
 
6.10.2 Marking Accepted Lots—When items are accepted by means of a sampling procedure, each item of an accepted lot shall be marked as follows:
 
6.10.2.1 Dyeing—When dyeing is applicable, a dye of acceptable adherence that is predominantly orange (in accordance with FED-STD-595) shall be employed.
 
6.10.2.2 Stamping, Laser Marking Vibro Engraving, or Etching —When impression stamping, vibro engraving or etching is used to mark lot examined parts, the letter M,without a circle around it shall be employed.
 

7. Quality Control

  
7.1 System Performance Verification— The overall performance of the magnetic particle testing system, including the equipment, materials, and the lighting environment being used, shall be verified initially and at regular intervals thereafter. The required verification intervals are stated in Table 1. Records of the verification results shall be maintained and retained for the time period specified in the contract. Establish a system in accordance with ANSI Z540-1 or ISO 10012-1 for calibration and certification of all current and voltage measuring devices, ammeter shunts, timers, lightmeters, gaussmeters, and field indicators used in verification.
 
7.1.1 Use of Test Parts with Discontinuities—A reliable method for system performance verification is the use of representative reference parts containing discontinuities of the type, location, and size specified in the acceptance requirements and examined in accordance with a written procedure. If correct magnetic particle indications can be produced and identified in these representative parts, the overall system performance is verified. Parts used for verification will be demagnetized, cleaned thoroughly following the examination, and checked under black or visible light, as appropriate to the examination process, to ensure that residual indications do not remain.
 
7.1.2 Fabricated Test Parts with Artificial Discontinuities—When actual production parts with known discontinuities of the type, location, and size needed for verification are not available or are impractical, fabricated test or production parts with artificial discontinuities or a ring specimen similar to the ring in Annex A4 may be used. Artificial discontinuities may be fabricated to meet a particular need or may be commercially available magnetic field indicators or shims as shown in Annex A2. All applicable conditions for the use of such reference parts, as described in 7.1.1, shall apply.
 
7.2 Suspension Vehicle Tests (Not required for aerosol can suspensions):
 
7.2.1 Concentration/Contamination Tests— Particle concentration and contamination shall be determined upon start up, at regular intervals thereafter, and whenever the bath is changed or adjusted. The required testing intervals are stated in Table 1.
 
7.2.1.1 Determination of Wet Particle Concentration—Agitate the particle suspension a minimum of 30 min to ensure uniform distribution of particles throughout the bath. Place a 100-mL sample of the agitated suspension in a pear-shaped centrifuge tube with a graduated stem in 0.05-mL increments for fluorescent baths and 0.1 mL for non-fluorescent baths. (Centrifuge tubes shall be as specified in Guide E709). Demagnetize the sample and allow the tube to stand undisturbed for a settling time of at least 60 min if using petroleum distillate or at least 30 min for conditioned water suspension. Read the volume of settled particles. If the concentration is out of the tolerance stated in the written procedure add particles or suspension vehicle, as required, and re-determine the particle concentration. If the settled particles appear to be loose agglomerates rather than a solid layer, repeat the process with a second sample. If the second sample also appears agglomerated, replace the entire bath suspension. Thirty-minute settling times (for oil suspensions), or other accelerated tests, may be used if they have been verified to give results equivalent to the procedure described in this clause.
 
7.2.1.2 Determination of Wet Particle Contamination—Perform the tests specified in 7.2.1.1. Examine the graduated portion of the tube, under both black light (for fluorescent baths only) and visible light (for both fluorescent and nonfluorescent baths), for striations or bands, different in color or appearance. Bands or striations may indicate contamination. If the total volume of the contaminants, including bands or striations, exceeds 30 % of the volume of magnetic particles the bath must be adjusted or replaced.
 
7.2.2 Water Break Test—In this test of water-based vehicles, a clean part with a surface finish the same as the parts to be examined or an actual production part is flooded with the conditioned water, and the appearance of the surface is noted after flooding is stopped. Sufficient wetting agent is present if a continuous even film forms over the entire part. If the film of suspension breaks, exposing bare surface, insufficient wetting agent is present or the part has not been cleaned adequately. For adequacy, this visual observation shall be performed individually under both white light and black light conditions as applicable.
 
7.2.3 Determination of Particle Sensitivity—Appendix X2 describes several devices that can demonstrate the sensitivity of either wet-method or dry-method particles. These devices contain permanent magnetization in some form and are independent of the magnetizing system. They should not be magnetized or demagnetized before or after use. Such devices can be useful whenever performance of the particles are subject to question or need to be verified.
 
7.3 Lighting:
 
7.3.1 Visible Light—Conduct visible light intensity measurements upon initial light installation, or when changes occur that would cause the light intensity to change and at the intervals specified in Table 1.
 
7.3.1.1 Visible light shall be used when examining with nonfluorescent magnetic particles and for interpretation of indications found with fluorescent magnetic particles. A minimum light intensity of 100 fc [1076 lx] shall be available at the surface of the part undergoing examination or evaluation.
 
7.3.1.2 Ambient Visible Light—Fluorescent magnetic particle examinations shall be performed in a darkened area with a maximum ambient visible light level of 2 fc [22 lx] measured at the part surface.
 
7.3.2 Black Lights—Black lights used for evaluation purposes shall meet the requirements of 7.4.5. The minimum acceptable intensity is 1000 μW/cm2 at the surface being examined. Black lights shall be checked daily for cleanliness and integrity and shall be cleaned, repaired or replaced as appropriate. These daily checks of cleanliness/integrity need not be recorded.
 
7.3.3 Restricted Area Examination—Where lamps are physically too large to directly illuminate the examination surface, special lighting, such as UV pencil lights, or UV light guides, or borescopes shall be used. The image viewed must have sufficient resolution to effectively evaluate the required discontinuities. Light intensity shall be measured at the expected working distance and shall meet the requirements of 7.3.2 as appropriate.
 
7.4 Equipment Calibration—Magnetic particle testing equipment shall be checked for performance and accuracy at the time of purchase and at intervals thereafter as indicated in Table 1; whenever malfunction is suspected, when specified by the Cognizant Engineering Organization, or whenever electrical maintenance that might affect equipment accuracy is performed.
 
7.4.1 Ammeter Accuracy—To check the equipment ammeter, a suitable calibrated shunt test kit shall be connected in series with the output circuit. Comparative readings shall be taken at three output levels encompassing the usable range of the equipment. The equipment meter reading shall not deviate by more than 10 % or 50 amperes, whichever is greater, from the current value shown by the calibrated ammeter. (When measuring half-wave rectified current, the current values shown by the calibrated FW-Rectified ammeter readings shall be doubled.) The frequency of the ammeter check is specified in Table 1. Machine output repeatability shall not vary more than 10 % or 50 amperes, whichever is greater, at any setpoint and the machine under test shall be marked with the value representing the lowest repeatable current level.
 
7.4.2 Timer Control Check—On equipment using a timer to control the current duration, the timer should be calibrated to within 0.1 s using a suitable electronic timer.
 
7.4.3 Magnetic Field Quick Break Check—On equipment that uses a quick break feature, proper functioning of this circuit shall be verified. The check may be performed using a suitable oscilloscope or other applicable method as specified by the equipment manufacturer.
 
7.4.4 Dead Weight Check—Yokes and permanent magnets (when allowed) shall be dead weight checked at intervals as stated in Table 1. Alternating current and permanent magnet yokes shall have a lifting force of at least 10 lb [4.5 kg], with a 2- to 6-in. [50- to 150-mm] spacing between legs. Direct current yokes shall have a lifting force of at least 30 lb [13.5 kg], with a 2- to 4-in. [50- to 100-mm] spacing between legs, or 50 lb [22.5 kg], with a 4- to 6-in. [100- to 150-mm] spacing.
 

7.4.5 Black Lights—Black lights, which are portable, hand-held, permanently mounted or fixed, and used to examine parts, shall be checked for output at the frequency specified in Table 1 and after bulb replacement. A longer period may be used if a plan justifying this extension is prepared by the NDT facility or its delegate. Minimum acceptable intensity is 1000μW/cm2 at 15 in. [38.1 cm] from the front of the filter to the face of the sensor. All black light filters shall be replaced or otherwise corrected as appropriate.

Note 2—Some UV-A sources other than mercury vapor, for example, micro-discharge, LED, etc., have been shown to have emission characteristics such as excessive visible light, and UV intensity that may result in fluorescent fade, veiling glare, etc., all of which can significantly degrade examination reliability.

7.4.5.1 Black lights that use an UV-A LED source shall produce a peak wavelength at 365 to 370 nanometers as measured with a spectroradiometer. When requested, the manufacturer shall provide a certification thereof.
 
7.4.5.2 Battery-powered black lights used to inspect parts shall have their intensity measured prior to use and after each use.
 
7.4.6 Gaussmeters—All field indicators shall be calibrated and reading taken at a minimum of three points in each dynamic range and each polarity, in addition to zero.
 
7.4.7 Black Light Meters—All meters shall be calibrated in accordance with manufacturers recommended procedures and shall be traceable to the National Institute of Standards and Technology (NIST) or other recognized national standards, where applicable.
 

7.4.8 White Light Meters—All meters shall be calibrated in accordance with manufacturers recommended procedures and shall be traceable to the National Institute of Standards and Technology (NIST) or other recognized national standards, where applicable.

Note 3—More information on UV-A visible lights and meters can be found in Guide E2297.

   *The 300 series aircraft had one notable difference. The personnel qualification specification changed from  ASNT Personnel Qualification SNT-TC-1A, ANSI/ASNT-CP-189 or NAS 410 to NAS410 only.
11/14/2013

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