NDT and inspection

This category covers non-destructive testing and inspection services: penetrant, magnetic particle, eddy current, ultrasonic, radiographic and borescope work, on parts and on aircraft. The laboratory that calibrates the equipment is under calibration and metrology, and the shop that repairs what the inspection finds is under MRO. What a buyer purchases here is evidence, and evidence is only worth what its procedure, its inspector and its equipment can support.

The procedure comes from the design approval holder

Inspections do not come from an inspector's judgement. Maintenance must be performed using the methods, techniques and practices in the manufacturer's maintenance manual or the instructions for continued airworthiness, or others acceptable to the Administrator, using the tools and test apparatus necessary, including the special apparatus the manufacturer recommends or its acceptable equivalent.¹ The airworthiness limitations that mandate many recurring inspections live in those instructions, which design approval holders must furnish, and where a rotorcraft maintenance manual carries an airworthiness limitations section, approved changes to replacement times, intervals and related procedures must be made available on request to any operator of the same type.⁴ Ask which revision of which procedure the supplier will inspect to, and check it against the one your programme calls out. A supplier working to a superseded procedure produces a report that fails an audit.

The person and the equipment

Ask what the inspector's qualification is, in which method, at what level, and when it was last renewed. Ask who wrote and approved the written procedure the inspection follows, and ask to see a redacted example report. Ask what equipment is used and how it is calibrated, because a repair station must ensure test and inspection equipment used to make airworthiness determinations is calibrated to a standard acceptable to the FAA, and equipment must be on the premises and under the station's control when the work is done.² For work released under a repair station certificate, ask which rating covers it, and remember that a certificate names what a station may work on and a capability list names the articles.³ Some NDT is performed by a service supplier rather than a certificated station, which is normal, and in that case ask under whose certificate and quality system the result is accepted.

Setting up the job properly

Ask what the detectable flaw size is for the method, the material and the geometry in front of you, and ask how that was established. Ask what surface preparation the method needs and who does it, since preparation is the usual reason for a rejected inspection. Ask what happens when an indication is found: who dispositions it, how fast, and what the escalation path is at two in the morning. Ask what the turn time is on a full report and whether the report includes the raw data.

Questions that sort suppliers

Ask for the procedure number and revision, and check it against your maintenance data. Ask for the inspector qualification records for the people who will do your job. Ask what the equipment calibration status is and where it is calibrated. Ask for an example report from a comparable part, redacted.