nondestructive inspection (ndi)

7/28/2019 Nondestructive Inspection (Ndi)

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NONDESTRUCTIVE INSPECTION

(NDI)


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INTRODUCTION

The effectiveness of any particular method of NDI

depends upon the skill, experience, and training of

the person(s) performing the inspection process.

The product manufacturer or the Federal Aviation

Administration (FAA) generally especifies the

particular NDI method and procedure to be used in

inspection.


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TRAINING, QUALIFICATION, AND

CERTIFICATION.

The success of any NDI method and procedure

depends upon the knowledge, skill, and experience

of the NDI personnel involved.

The person should be familiar with the test method,

know the potential types of discontinuities peculiarto the material, and be familiar with their effect on

the structural integrity of the part.


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NDT LEVELS.

Level I Special (Optional). Level I Special is the

lowest qualification level and is task specific.

Personnel may be qualified to this level to perform

a specific task on a particular component.

An example of this level is the Eddy Current

Inspection of aircraft wheels.


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LEVEL I. LEVEL I SHOULDBEFORASPECIFIC

METHOD.

To be qualified for Level I, an individual should have

the skills and knowledge to perform specific tests,

specific calibrations, and specific interpretations

and evaluations for acceptance or rejection.

1) be knowledgeable of any necessary preparation

of parts before or after inspection,

2) be able to follow procedures pertinent to the

techniques for which he/she is qualified,


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3) receive the necessary guidance or supervision

from a qualified Level H, Level M, or other

designated individual, and

4) meet the training and experience guidelines in

Table 1.


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LEVEL II.

Should have the skills and knowledge to set up and

calibrate equipment, conduct tests, and to interpret,

evaluate, and document results in accordance with

procedures in all techniques in the methods used

by his or her organization.


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He or she should be able to organize and document NDIresults and should be familiar with the codes, standards,and other regulatory documents which control themethod used by the organization.

(1) AIA-NAS410, Aerospace Industries Association,National Aerospace Standard, NAS Certification &Qualification of Nondestructive Test Personnel

(2) ATA Specification 105, Air Transport Association,Guidelines for Training and Qualifying Personnel inNondestructive Testing Methods

(3) PCN/GEN/92, General Requirements for the Certificationof Personnel Engaged in Nondestructive Testing at Levels 1,2, and 3. (PCN Certification Services, British Institute of NDI, 1Spencer Parade, Northampton NN1 5AA, UK)


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LEVEL III.

(a) Have graduated from a minimum four-year

college or university curriculum degree in

engineering or a related science, plus one year

minimum experience in NDI testing assignment

comparable to that of an NDI Level II in the applicableNDI method(s);

(b) Have completed two years of engineering or

related science study at a university, college, or

technical school, plus two years experience in

assignments at least comparable to that for NDI Level II

in the applicable NDI method(s);


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(c) Have four years experience in an

assignment at least comparable to that of an

NDI Level II in the applicable NDI method(s).


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EXAMINATION.

(1) Physical Examination.

(a) Vision. the individual can read Snellen equivalent

of 20/20 (Jaeger #1).

(b) Color Perception. Distinguish anddifferentiate

between colors necessary for the inspection

method

(c) Physical Requirements. The physical

requirements established by the organization as a

condition of employment will normally suffice.


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(2) General Skills Examination.

(a) The general examination for all skill levelsshould be a closed-book examination consisting

of questions that cover the basic inspection/test

principles

(b)A minimum of 40 questions should be used for the

general examination and

(c) The examination should also cover thespecifications and/or standards used by the

organization in its nondestructive inspection

procedures.


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(3) Practical Examination (Classroom). should

satisfactorily demonstrate that he/she is familiar

with and canoperate the necessary test equipment

and interpret the resultant information to the degree

required by the Level III instructor.

(4) Practical Examination (OJT Shop). The hours

of OJT training are defined inthe experience section

of Table 1.


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(5) FAA Certification. Upon satisfactory

completion of the required physical and general

skills examinations; the classroom and OJT shop

practical examinations,

REQUALIFICATION/RECURRENT TRAINING.

Requalification examinations should consist of

a demonstration of proficiency in the procedure for

which the applicant is being examined.

Requalification should occur, at a minimum, every

three years.


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SELECTING THE NDI METHOD.

The NDI method and procedure to be used forany

specific part or component will generally bespecified in the aircraft or component

manufacturers maintenance or overhaul manuals,

SSIDs, SBs, or in ADs.


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b. Other Factors. Other factors affecting the

inspection are:

(1) The critical nature of the component;

(2) The material, size, shape, and weight of the part;

(3) The type of defect sought;

(4) Maximum acceptable defect limits in size anddistribution;

(5) Possible locations and orientations of defects

(6) Part accessibility or portability; and

(7) The number of parts to be inspected.


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c. Material Safety Data Sheets (MSDS). The

various materials used in NDI may contain

chemicals, that if improperly used, can be

hazardous to the health and safety of operators and

the safety of the environment, aircraft, and engines.


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e. Advantages and Disadvantages. Table

provides a list of the advantages and

disadvantages of common NDI methods.


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VISUAL INSPECTION

Visual inspection is the oldest and most common

form of NDI for aircraft. Approximately 80 percent of

all NDI procedures are accomplished by the direct

visual methods.

Visual inspection provides a means of detecting

and examining a wide variety of component and

material surface discontinuities, such as cracks,

corrosion, contamination, surface finish, weld joints,solder connections, and adhesive disbonds.


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SIMPLE VISUAL INSPECTION

Visual inspection aids such as a powerful flashlight,

a mirror with a ball joint, and a 2 to 10 power

magnifying glass are essential in the inspection

process.

a. Flashlights. Flashlights used for aircraft

inspection should be suitable for industrial use.


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b. Inspection Mirrors.

An inspection mirror is

used to view an area

that is not in the normalline of sight.

c. Simple Magnifiers. A

single converging lens,

the simplest form of a

microscope, is often

referred to as a simple

magnifier.


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BORESCOPES.

These instruments are long, tubular, precision

optical instruments with built-in illumination,

designed to allow remote visual inspection of

internal surfaces or otherwise inaccessible areas.

The tube, which can be rigid or flexible with a wide

variety of lengths and diameters, provides the

necessary optical connection between the viewing

end and an objective lens at the distant, or distal tipof the borescope.


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VISUAL INSPECTION PROCEDURES.

Preliminary Inspection.

Corrosion Treatment.

Lighting.

Personal Comfort. Noise.

Inspection Area Access.

Precleaning.

Inspection.

Recordkeeping.


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nondestructive inspection (ndi)

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