PUBLIC CONCERNED:

All Non destructive testing Agents concerned with a level 1 certification.
During the certification exam of Level 1 Eddy currents, the questionnaires relating to the specific part relate more particularly to procedures used in the aircraft industry.

OPERATING TECHNIQUES :

Principle: frequency ranges, limitations, setting, parameters to be respected, calibration, probes usable for the headings below:

- Conductivity measurement
- Surface cracks detection by high frequencies
- Crack detection in borings by revolving probes
- Under the surface defects detection by low frequencies
- Versatile Equipments
- Special Equipments (pulsated Eddy current, multi-frequency and multi-channel)

METALLURGY :

- Concepts of metallurgy
- Heat treatment (conductivity, hardness)
- Surface treatment (painting, oxidation, etc..)
- Development defects met
- Manufacturing defects met
- In service defects met

CALIBRATION :

a) Calibration block:

- Universal block (conductivity, thickness coating, HF)
- Borings block (various materials)
- Specific Block (LF)

b) Implementation of the calibration:

- Type of artificial defects
- Calibration execution
- Representativeness of calibration defects
- Concept of detection threshold

PROBES :

a) Theoretical principle:

- absolutes
- differentials
- separate emission/reception
- multifunction

b) Applications:

- conductivity (absolutes)
- pencil probes HF (absolute or differential)
- revolving probes (differential)

* for borings,
* for plane surfaces

- probes LF (absolute differentials or separate E/R)

* slippery and static
* multi elements sensors

- absolute probes for coating thickness measurement (painting)
- profile probes

* annular: LF
* special profile : HF

c) Shielding and focusing:

- role of the shielding and focusing
- applications examples

ADEQUACY OF TECHNIQUES TO MATERIALS:

With examples by problem

a) Nonferrous alloys:

- corrosion: absolute LF
- emerging cracks

* absolute or differential standard HF “pencil”

- not emerging cracks

* absolute - differential, E/R separate

- holes inspection

* differential HF

- conductivity

* absolute intermediate frequency

- coating thickness

* absolute intermediate frequency

b) Ferromagnetic alloys:

- differentials HF

SIGNAL & RESULTS TREATMENT :

types of signal & results

- equipment signal : report

- signal & results recordings

HEALTH AND SAFETY :

w/o

QUALITY :

- Operators qualification
- Procedures, maintenance manuals, job card, service bulletins, etc…
- Periodic calibration of the Eddy Current equipment
- Establishment of a inspection statement or a inspection report
- Specifications
- Read a procedure or a inspection instruction
- Doubtful case

PUBLIC CONCERNED:

All Non destructive testing Agents concerned with a level 2 certification.
During the certification exam of Level 2 Eddy currents, the questionnaires relating to the specific part relate more particularly to procedures used in the aircraft industry.

OPERATING PROCEDURES:

Principle: frequency ranges, limitations, adjustments, parameters to be respected, calibration, sensors usable for the headings below:

- Conductivity measurement
- Surface cracks detection by high frequencies
- Crack detection in borings by revolving probes
- Under the surface defects detection by low frequencies
- Versatile Equipments
- Special Equipments (pulsated Eddy current, multi frequency and multi channel)

METALLURGY :

- Concepts of metallurgy
- Heat treatment (conductivity, hardness)
- Surface treatment (painting, oxidation, etc..)
- Development defects met
- Manufacturing defects met
- In service defects met

CALIBRATION :

a) Calibration block:

- Universal block (conductivity, thickness coating, HF)
- Borings block (various materials)
- Specific Block (LF)

b) Implementation of the calibration:

- Type of artificial defects
- Calibration execution
- Representativeness of calibration defects
- Concept of detection threshold

PROBES :

a) Theoretical principle:

- absolutes
- differentials
- separate emission/reception
- multifunction

b) Applications:

- conductivity (absolutes)
- probes pencil HF (absolute or differential)
- revolving probes (differential)

* for borings,
* for plane surfaces

- probes LF (absolute differentials or separate E/R)

* slipping and static
* multi elements sensors

- absolute probes of coating thickness measurement (painting)
- profile probes

* annular: LF
* special forms: HF

c) Shielding and focusing:

- role of the shielding and focusing
- applications examples

d) Probes balancing :

- integrated into the probe

- dedicated to equipment

ADEQUACY OF TECHNIQUES TO MATERIALS:

With examples by problem

a) Nonferrous alloys:

- corrosion: absolute LF
- emerging cracks

* absolute or differential standard HF “pencil”

- not emerging cracks

* absolute - differential, E/R separate

- holes inspection

* differential HF

- conductivity

* absolute intermediate frequency

- coating thickness

* absolute intermediate frequency

b) Ferromagnetic alloys:

- differentials HF

 

c) Composites (conducting):

(example: encircling coils)

SIGNAL TREATMENT:

- imagery, etc…

INSPECTION INSTRUCTION DRAFT :

- plan of the instruction,

- specification & documentation requirements,

- equipment specification

- preparation before inspection

* visual inspection

* aspect of the parts

- calibration

- inspection procedure

- acceptance criteria and sanctions

- treatment of doubtful cases

RESULTS TREATMENT :

types of results

- equipment indications : report
- recordings

HEALTH AND SAFETY :

w/o

QUALITY :

- Operators qualification
- Procedures, maintenance manuals, job card, service bulletins, etc…
- Periodic calibration of the Eddy Current Equipment
- Establishment of a inspection statement or a inspection report
- Specifications

PUBLIC CONCERNED:

All Non destructive testing Agents concerned with a level 3 certification.
During the certification exam of Level 3 Eddy currents, the questionnaires relating to the specific part relate more particularly to procedures used in the aircraft industry.

OPERATORS:

Visual and colour perception.
Training and industrial experience.

SCOPE OF THE APPLICATION:

In the aircraft industry, control by EDDY CURRENTS applies in production and maintenance of :

- Semi-finished products and gross products (industry upstream),

- End products (material quality control),

- Airframes,

- Engines,

- The landing gears,

- The equipments and accessories.

EQUIPMENT:

- Installations and equipment:

* fixed installations for specific use (production inspection),

* testing device by EDDY CURRENTS for specific task :

- Conductivity check,

- coating thickness check.

* testing device by EDDY CURRENTS multi uses:

- high frequency generators,

- low frequency generators,

- pulsated current generators.

* inspection mode: manual, semi automatic, automatic.

- Inspection systems:

- generator architecture (circuits, components, etc…),

- fixed or adjustable frequency,

- single frequency or multi-frequency,

- sensor-probes standard:

encircling probes,

pencil probes,

hole or bore probes,

profile probes,

characteristics: focusing-shielding

probes function : absolute

: differential

- electronic filtration.

- Result Analysis

. sensors metrology :

- physical characteristics checking,

- spectral analyzes of signal,

. signals views (galvanometers, fluorescent screens, graphic recording…)

. signals exploitation (modes X-Y, Y_(T) ),

. computer helped diagnosis (software),

. image processing,

. data storage.

- Standards and reference blocks

APPLICATIONS OF THE PHYSICAL PRINCIPLES:

- disturbance of the signal when there is presence of a defect,

- impedance/Inductance of a coil,

- effect of the gap,

- penetration depth of the EDDY CURRENTS,

- magnetic field created by the ET coil,

- electric conductivity of materials. Measuring units, correspondence between SI system & IACS system,

- characteristic frequency of a product (bars, tube),

- ferromagnetism (permeability, saturation, hysteresis loop).

PROCEDURE:

- parts preparation before inspection,

- inspection parameters :

. phase adjustments, gain, filters and windows of analysis, threshold,

. working frequency.

- impedance plan,

- results viewing,

- interpretation

- geometrical & dimensional evaluation of the defects,

- sanctions.

QUALITY CONTROL - MEASUREMENTS OF DEFECTS INDICATIONS

For remembrance, upstream inspection on semi-finished products (thin and thick sheets, plated sheets, pipes, wire, forged parts, casting).

- quality control: heat treatments and surface treatments and, measures of electric conductivity check in relations with:

* heat treatment,

* metallurgical properties,

* stress corrosion behaviour,

* the test temperature,

* material sorting.

- thickness check of:

* metal coatings,

* paintings and varnish,

* anodic oxidation,

* relationships with the nature of the coatings and substrate (metal or not).

- quality control on finished parts:

* rolling track of bearings (metallurgical alteration),

* wall thickness check,

* assembly check (welding, riveting, etc…).

- Repair - Maintenance Inspection :

* In service cracks detection (airframes, engines, wheels of aircraft),

corrosion detection, wear check, local overheating on airframe elements.

- raise of doubt: in complement or replacement of other NDT methods.

PERIODIC CONTROL OF THE EQUIPMENTS AND INSTALLATIONS

- periodic monitoring of equipments,

- periodic monitoring of probes and sensors,

- maintenance and renewal of the standard and calibration blocks.

STANDARDS:

Required standards ASTM, EN