Document ID: chunk:federal_register_of_legislation:F2011C00880:body:0:p2
Version: federal_register_of_legislation:F2011C00880
Segment Type: other
Provision Reference: 
Character Range: 3330–6349

the requirements of paragraph 7.1.

4 Materials

       4.1The magnetic indication particles used must have high permeability and low retentivity and must be a suitable blend of sizes and shapes to readily produce magnetic particle indications.

Note   Magnetic flaw detection inks and powders complying with British Standard Specification BS.4069 are acceptable.

       4.2If colour contrast particles are used they must provide a good colour contrast with the part being inspected. If black particles are unsuitable, this requirement can be achieved by the use of coloured particles or by modifying the surface condition of the part to maximise the contrast.

       4.3Where maximum sensitivity of inspection is required for cracks resulting from service conditions, such as fatigue cracks, wet fluorescent magnetic particles in conjunction with the continuous ac method should be used.

5 Procedures

       5.1The inspection procedures used for a given inspection must be in accordance with those specified in the relevant Civil Aviation Order or approved maintenance document. When no inspection procedures are specified in these documents, Appendix I to this Order constitutes approved procedures.

Note   A relevant approved maintenance document in this context would normally be a process manual or process specification issued by the manufacturer of the part being inspected.

       5.2The magnetising current or flux density used for a given inspection must be that specified in the Civil Aviation Order or approved maintenance document relevant to the part being inspected or to another part of similar size and shape.

Note   A relevant approved maintenance document in this context would normally be an overhaul manual or service bulletin issued by the manufacturer of the part or similar part.

       5.3For parts of essentially simple shape, magnetising current values may be computed using the methods specified in Appendix II to this Order.

6 Control of equipment and materials

       6.1A magnetic particle inspection must not be made unless the magnetic particle materials and equipment have been checked within the time and according to the procedures specified in Appendix III to this Order.

7 Demagnetisation after inspection

       7.1After inspection, parts must be so demagnetised that they do not cause a compass deflection of more than 3 degrees when placed at right angles to and 150 mm from an aircraft compass.

Note   Large ferromagnetic parts may, even though demagnetised, cause a deflection of the compass needle to this extent or greater. In such cases, all surfaces of the part should be explored for evidence of free poles causing the direction of needle deflection to be reversed.
Appendix I

This Appendix specifies procedures for the performance of magnetic particle inspections.

1 Preparation of parts for inspection

      1.1 Wherever possible parts must be disassembled before inspection.

      1.2 The surface of all parts must be free from grease, oil, swarf,