Fatigue failure, Flaking, Flowing, Foreign material, Forging marks, Fusion line, Fusion zone, Galling, Glazing

Tabel 2.1 i

DEFFECT	DESCRIPTION
Fatigue failure	Progressive yielding of one or more local areas of weakness such as tool marks, sharp indentation, minute cracks, or inclusions, under repeated stress. As working stress on piece is repeated, cracks develope, at ends of which there are high concentrations of stress. Cracks spread, usually from the surface or near surface, of the area. After a time, there is so little sound metal left the normal stress is higher than strength of remaining material, and it snaps. Failure is not due to crystallization of metal, as many believe. Appearance of a typical fatigue failure is easily explained. As failure proceeds, severed surfaces rubs and batter each other, crushing grains of material and producing full or smooth appearance, remaining unfractured portion preserves normal grain structure up to moment of failure. The progressive nature of the failure is usually indicated by several more or less concentric lines, the center or focus, of which discloses original point or line of failure. • Usual causes are tool marks, sharp corners, nicks, cracks, inclusions, galling, corrosions, or insufficient tightening of studs or bolts to obtain proper stretch.
Flaking	Breaking away of pieces of flated or painted surface. • Usual causes are incomplete bonding, excessive loading, or blistering.
Flowing	Spreading of a plated or painted surface. Usually accompanied by flaking. • Usual causes are incomplete bonding, excessive loading or blistering.
Foreign material	Any solid or liquid material not integral to a part. Such material may or may not be adherent to a surface or passage.
Forging marks	Ridges or grooves on the external surface of a part caused by foreign unwanted material or irregularities on the forming die.
Fusion line	Interface of the weld bead and parent metal.
Fusion zone	The weld bead formed by the melting of filler metal and parent metal, or of parent metal only.
Galling	A transfer of metal from one surface to the other of closely fetted surfaces causing damage to both surfaces. • Usual cause is severe chafing or fretting action caused during engine operation by a slight relative movement on two surfaces under high contact pressure.
Glazing	Development of a hard glossy surface on bearing surfaces. An often beneficial condition except on inner and outer races. • Usual cause is a combination of pressure, oil and heat.

Discontinuity, Distortion, Draw mark, Dross, Electrolytic action, Erosion, Excess braze, Fatigue, Fatigue crack

Tabel 2.1 h

DEFFECT	DESCRIPTION
Discontinuity	Is an interruption in the normal physical structure or configuration of a part such as cracks, laps, folds, seams, porosity, etc. A discontinuity may or may not affects the quality of the part.
Distortion	Extensive deformation of the original contour of apart Usual cause is impact of an unwanted object, structural stresses, or excessive localized heating.
Draw mark	Linear, trough-like grooves which result from the action of die imperfections or foreign material on the drawn material
Dross	Linear imperfection or imperfections in the form of the branching or irregular patterns, caused by impurities or oxides in a cast material.
Electrolytic action	Breakdown of surfaces by electrical action between parts made of dissimilar metals. Usual cause is galvanic action between dissimilar metals.
Erosion	Carrying away of material by flow of hot gases, grit, or chemicals. Usual causes are flow of corroding liquids, hot gases, or dirt-laden oil.
Excess braze	Braze material beyond the joint fillet. Sometimes refered to as a run, streak or flash.
Fatigue	The progressive fracture of a material under circled stress loading.
Fatigue crack	Occurs only in parts that have been in service under repeated stress reversals or stress variations. The crack starts at a highly stress area and propagates through the section until failure occurs. A fatigue crack will start more readily where the design or surface condition provides a point of stress concentration, such as fillets, poor surface finish, seams, grinding cracks, and from fastener holes that have poor surface finish and sharp burrs.

Crack, Crater, Crazing, Creep, Deformation, Delimitation, Dent, Deviation, Depressed Imperfection

Tabel 2.1 g

DEFFECT	DESCRIPTION
Crack	A partial fracture. Linear imperfection in the form of a narrow break or fissure. Usual cause is excessive stress due to sudden overloading, extension of a nick or scratch, or overheating.
Crater	A depression at the termination of a weld bead.
Crazing	A network of minute cracks appearing in the coating of coated parts.
Creep	Gradual continuous distortion or plastic flow under constant stresses.
Deformation	Any alteration or change of shape, diminution, or configuration resulting from stress or damage.
Delimitation	A separation of the layers in a layered material.
Dent	Small smoothly rounded hollow in the surface. Usual causes are concentrated overloading resulting from peening, or presence of chips between loaded surfaces, or the striking of a part.
Deviation	Any condition that causes a part to differ from the manufacturer’s blueprint.
Depressed Imperfection	One that is below the general surface of the part, may have either smooth or irregular sharp edges or bottom

Chipping or chip, Corrosion, Surface Corrosion, Dissimilar metal corrosion, Stress corrosion, Fretting corrosion

Tabel 2.1 f

DEFFECT	DESCRIPTION
Chipping or chip	Breaking out of small pieces of metal which have been removed mechanically. Usual cause is a concentration of stress due to nick, scratches, inclusions, peening, or careless handling of parts. Do not confuse with flaking.
Corrosion	Metal corrosion is the deterioration of the metal by chemical or electrochemical attack, water of water vapor containing salt combined with oxygen in the atmosphere produce the main source of corrosion in engines. Engines operating near the sea or in areas where the atmosphere contains industrial fumes which are corrosive are susceptible to corrosion attack. Corrosion may change the smooth surface, weaken the interior or damage and lossen adjacent parts. In some cases treatment of parts especially ligh alloys take place by corrosion caused by fabrication. An electrochemical attach may be linked chemically to the electrolytic reaction which takes place in electroplating, anodizing, etc
Surface Corrosion	Appears as a general roughness, or pitting of the surface of the metal. Sometimes corrosion will spread under the surface coating and cannot be recognized either by roughening of the surface or the powder deposit (rust). In case like this, the paint or plating will be lifted off in surface in small blisters which results from the pressure of the underlying accumulation of corrosion products.
Dissimilar metal corrosion	Excessive pitting damage may result from contact between dissimilar metal parts in presence of a conductor. While suface corrosion may or may not take place, a galvanic action not unlike electroplating occurs at the point of areas of contact where the insulation has broken down or being omitted. This electrochemical attach can be serious because the action is, in many instances, taking place out of sight and the only way to detect it is by disassembly and inspection.
Stress corrosion	Stress corrosion occurs as a result of the combined effect of sustained tensile stresses and corrosive environment. Stress corrosion cracking is found in most metal systems especially of aluminum, copper, certain stainless steels and high srtength alloy steels. Aluminum alloy parts with pressed in bushings, clevis, pin, joints, shrink fits and overstressed nut are examples of parts which are suscestible to stress corrosion cracks.
Fretting corrosion	Is a form of corrosion attach which occurs when two matting surfaces, normally at rest with respect to one another are subject to a slightly relative motion. It is characterized by pitting on the surfaces and the generation of considerable quantities of finely devited debris. Since the restricted movements of the two surfaces prevent the debris from escaping, an localized abrasion is occurs. The presence of water vapor increases this type of deterioration.

Burst, Chain Porosity, Chafing, Chatter Marks, Clearly separated, Cluster, Cold Shut

Tabel 2.1 e

DEFFECT	DESCRIPTION
Burst	Crack caused by rupture extending out ward for a central point.
Chain Porosity	Porosity in linear alignment.
Chafing	A rubbing action between parts having limited relative motion. To be interpreted as an action which produces a surface condition rather than as a description of a damage. See also “gall” or “scratch”.
Chatter Marks	Waves or ripples on a machined surface, in the direction of the cut. Caused by a loose or dull cutting tool, or a tool that is not rigidly supported.
Clearly separated	Imperfections which are not touching when viewed with the unaided eye
Cluster	Two or more imperfections, clearly separated which can be contained within a circle of the maximum diameter allowed circle shall be counted as one imperfection
Cold Shut	Intermittent of continuous lines caused by unfused material.

Burn, Burn Out, Burning, Burnish, Burnishing, Burr

Tabel 2.1 d

DEFFECT	DESCRIPTION
Burn	A rapid, destructive, oxidizing action. Change in color appearance often indicates this condition. Usually caused by higher temperature than the parent material can withstand
Burn Out	Electrochemical machining erosion beyond the desired feature profile
burning	Damage to part by excessive heat. Evidenced by characteristic discoloration or in severe cases, by a loss or flow of material. Usual causes are excessive heat due to lack of lubrication, improper clearance, or abnormal flame pattern
Burnish	Shiny area resulting from rubbing against a hard smooth surfaces, may contain scratches of no apparent depth.
Burnishing	Mechanical smoothing of a metal surface by rubbing. Not accomplished by removal of material but sometimes by discoloration around outer edges of area. Operation burnishing is not detrimental if it covers approximately the area carrying the load, and if there is no evidence of pile-up or burning. Usual cause is normal operation of parts.
Burr	A sharp projection or rough edge Usual cause is excessive wear, peening, or machining operations.

Break, Brinelling, Brittle, Buckle, Bulge, and Burn Marks

Tabel 2.1 c

DEFFECT	DESCRIPTION
Break	Complete separation by force into two or more pieces. Usual causes are fatique or sudden overload
Brinelling	Indentations some times found on the surface of ball or roller bearing parts. Usual cause are improper assembly or dissasembly techniques by the aplication of force on the free race. Bearing which do not have full, constant rotation and are subject to sudden loading, have brinelling tendencies.
Brittle	A large scale deformation of the original contour of the part. Usually caused by aging, extreme cold, chemical action, or cold working
Buckle	A large scale deformation of the original contour of the part. Usually caused by pressure or impact from a foreign object, structural stresses, excessive localized heating, high pressure differentials, or any other combination of these
Bulge	An outward bending or swelling. Usual cause is excessive pressure or weekening due to excessive heat.
Burn marks	Localized indication of excessive heating (for example, blue to blue blackdiscoloration) due to excessive dwell time of a tool at that location, or electrical arcing due to improper contact between an electrode and the part.

Bottomed Impression, Braze Crack, Braze Fillet, Braze Porosity, Braze Ripping, Braze Void)

Tabel 2.1 b

DEFFECT	DESCRIPTION
Bottomed impression	Pit, cavity or hole in which the bottom can be seen.
Braze crack	Linear fracture of the braze surface
Braze fillet	Braze in a joint crating a smooth transition between the details being joint
Braze porosity	A group of closely spaces, small voids (internal pores) in the braze joint or fillet open to the braze surfaces
Braze ripping	A condition of the braze surface characterized by unevennes and irregular appearance with peaks and valleys that are gradual in nature
Braze void	Unfilled space in braze material in which a bottom is visible

Abrasion, Arc Burn, Back to back imperfection, Bend, Blending, Blistering

Tabel 2.1 a

DEFFECT	DESCRIPTION
Abrasion	A roughened area. Varying edges of abrasion can be describe as light or heavy, depending upon extent of reconditioning required to restore surface. Usual cause is resent of fine unwanted material between moving surfaces
Arc burn	Evidenced by a small circular or semi-circular heat affected area on the surface of a part that may contain shallow pitting, remold, or crack. Blades with arc burn are not acceptable for further service.
Back to back imperfection	Imperfections on the opposite faces of a specific wall (or weld) which normally are opposite each other. This condition is considered evidence of a single through-wall imperfection.
Bend	General distortion in stucture as distinguished for alocal damage in comformation. Usual causes are uneven aplication of heat, excessive heat or pressure, or forces defined under stresses
Blending	An operation which removes an irregularity from a surface and results in a shallow, smooth depression.
Blistering	Raised areas that indicate separation of surface from base. Usually found on plated or painted surfaces. Associated with flaking or peeling. Usual cause is imperfect bond with base, usually aggravated by presence of moisture, gas, heat, or pressure

Common Inspection Terms

In the aircraft engine and industrial, some useful terms that are used to describe inspection characteristics, criteria, and defect. It is very important the inspection personel to become familiar with these inspection terms in order to interpret the technical manuals properly. Without the knowledge of these terms, inspector will be unable to perform verification activities as required by the OEM technical manuals. Common Inspection Terms are shown in the table 2.1a(Abrasion, Arc burn, Back to back imperfection, Bend, Blending, Blistering), 2.1b(Bottomed impression, Braze crack, Braze fillet, Braze porosity, Braze ripping, Braze void), 2.1c(Break, Brinelling, Brittle, Buckle, Bulge, Burn marks), 2.1d(Burn, Burn Out, burning, Burnish, Burnishing, Burr), 2.1e(Burst, Chain Porosity, Chafing, Chatter Marks, Clearly separated, Cluster, Cold Shut) , 2.1f(Chipping or chip, Corrosion, Surface Corrosion, Dissimilar metal corrosion, Stress corrosion, Fretting corrosion) , 2.1g(Crack, Crater, Crazing, Creep, Deformation, Delimitation, Dent, Deviation, Depressed Imperfection) , 2.1h(Discontinuity, Distortion, Draw mark, Dross, Electrolytic action, Erosion, Excess braze, Fatigue, Fatigue crack) , 2.1i(Fatigue failure, Flaking, Flowing, Foreign material, Forging marks, Fusion line, Fusion zone, Galling, Glazing)

Radiographic X-Ray Inspection Method Advantage and Disadvantage

Tabel 1.6

Method	Advantage	Disadvantage
Radiographic X-Ray	Ability to inspect for both internal and surface defects Ability to inspect parts covered for hidden by other parts or structure Permanent test records obtained Minimum part preparation required	Most expensive Airplane have to be defueled Area must be cleared of other personel to avoid X-Ray exposure Test method is highly directional, depends on crack / X-Ray source orientation High degree of skill required for varied technique development and radiographic interpretation

Eddy Current Inspection Methode Advantage and Disadvantage

Tabel 1.5

Method	Advantage	Disadvantage
Eddy Current	Portable Moderate cost Immediate results Sensitive to small indications Little part preparation	Essentially a surface inspection Surface to be inspected must be accessible to contact by the eddy current probe Rough surfaces interface with test sensitivity Suitable for inspection of metals only No permanent test records Considerable skill and familiarity required in handling test equipment Time consuming to scan large areas

Ultrasonic Inspection Method Advantage and Disadvantage

Tabel 1.4

Method	Advantage	Disadvantage
Ultrasonic	Suitable for surface and subsurface defects Sensitive to small defects Immediate test results Little part preparation Wide range of material thickness can be inspected	Surface of part to be inspected must be accessible to sonic probe Rough surfaces interface with test results No permanent test records Test method is directional depending on sound beam defect orientation High degree of skill and experience required to set up and interpret results for varied test conditions

Magnetic Particle Inspection Method Advantage and Disadvantage

Tabel 1.3

Method	Advantage	Disadvantage
Magnetic Particle	Semi-portable Sensitive to small indications Defects surface and near surface defects Sensitive to inclusions as well as cracks Moderate skill is required	Only suitable for ferro magnetic material Part must be physically and visually accessible to perform test Removal of most surface coatings and sealant required Inspection is semi-direction requiring a general orientation of field to defect Not usable in area where strong magnetic field may damage instruments Part must be demagnetized after inspection

Dye Penetrant Inspection Method Advantage and Disadvantage

Tabel 1.2

Method	Advantage	Disadvantage
Dye Penetrant	Cheapness Portability High sensitivity Immediate result Minimum skill required	Can only inspect surface of parts accessible to penetrant application Defects must be open to surface Part preparation such as removal of finishes and sealant required No permanent test result Direct visual detection of result required Requires a high degree of cleanliness for satisfactory inspection

Visual Inspection Method Advantage and Disadvantage

Tabel 1.1

Method	Advantage	Disadvantage
Visual	Cheapness Portability Immediate result Minimum special skills Minimum part preparation	Suitable only for surface which can be viewed Generally detect only larger defects Misinterpretation of cracks and scratches

Inspection Techniques – Advantages and Disadvantages

The advantages and disadvantages of each type of inspection are described in table (1.1 Visual Inspection), (1.2 Dye Penetrant Inspection), (1.3 Magnetic Particle Inspection), (1.4 Ultrasonic Inspection), (1.5 Eddy Current Inspection), (1.6 Radiographic X-Ray Inspection). These should be studied by personnel who are about to make the inspection on an area that is not covered in a specific instruction (manufacturer’s manual, etc.). The information given in this table is for information only and not as a guide to be used on the daily inspection activities. Always the manufacturer technical manuals will be followed.

Inspection Illustrations

Usually inspection illustrations are given by the Original Equipment Manufacturer (OEM) in the engine manuals and other publications to cover each part of the engine that needs inspection. Areas of inspected parts or assemblies are indexed on the Illustrated Parts Catalog, or other illustrated manuals. Each illustration shown the location of the area to be inspected, type of inspection, the method of performing the inspection such as type of dye penetrant to be used, etc. The technical manuals also indicate the preparation of the part as cleaning, paint removal, etc., before the part is to be inspected. When a particular type of inspection has been completed, reference is made to the next step of inspection. For example, if an FPI has been performed, it may be necessary to confirm any suspected or visible defect by visual inspection.

Radiographic Inspection (X-RAY)

Is used to show internal and external structural details of all types of parts and materials. It is used for inspection of structures inaccessible or unsatisfactory for the application of other NDT methods. It is accomplished by passing the X-Ray or Gamma-Ray through the part being tested to expose a radiographic film. The processed film shows the structural details of the part. Interpretation of the radiographic film will indicate defects or damage.

Eddy Current Inspection

Is a method suitable for the inspection of surface or near surface defects of most metals and to separate metals and alloys and their heat treat condition. It can be applied to parts or assemblies where the suspected detected area is accessible to contact by the eddy current probe. The inspection is performed by inducting eddy currents into a part and electronically observing variations in the induced field. The character of observed field change is interpreted to determine the nature of defect condition.

Ultrasonic Inspection

Is a method suitable for the inspection of surface or subsurface defects of most metals, ceramics, and plastics. The inspection is accomplished by beaming high frequency sound wave through the part and viewing the response pattern on an oscilloscope (cathode ray) tube. By examine the variations of a given response pattern, discontinuities, flaws, or boundary conditions are detected.

Magnetic Particle Inspection – MPI

Is used to indicate surface or near surface defects in ferro magnetic parts. This inspection is performed by inducting a magnetic field into the part and applying a dry powder or liquid suspension of iron oxide particles. Local magnetic poles are formed by defects so that may be seen and evaluated by color contrast under a “black light”.

Dye Penetrant Inspection – FPI

Is used to detect cracks and discontinuities open to the surface which can not be seen by visual inspection. Dye penetrant inspection can be used on most engine parts accessible for this application. The inspection is performed by applying a liquid which penetrates into surface defects. Excessive penetrant liquid is removed and suitable developers applied to draw the penetrant from the surface defects so that visual indications are obtained by color contrast of the penetrant under the influence of a “black light”.

Visual Inspection

Is the most common form of inspection and consists of examining the area with the eyes, and with the help of magnifying glass, borescope, light source, etc.

Type of Inspection

The type of inspection can be classified into two major categories: 1. The non-destructive inspection, and 2. The destructive inspection The most common types of non-destructive inspection in aircraft engine and industrial are: 1. Visual Inspection 2. Dye Penetrat Inspection - FPI 3. Magnetic Particle Inspection - MPI 4. Ultrasonic Inspection 5. Eddy Current Inspection 6. Radiographic Inspection ( X – Ray )

Inspector Attitudes

The good inspector is not the inspector that accepts everything or the inspector that rejects everything. The good inspector is the inspector who considers himself a real working member of the team. The good inspector is the inspector who has the skills and knowledge and confidence to assure that a product is acceptable to specifications. The good inspector is the inspector who has gained the confidence of the people he works with and those people know that when he rejects a part, the part is not acceptable and when he accepts a part the part is not reject. He is able to apply his skills and knowledge to the specifications and make sound judgements.

Responsibility of Inspector

In study of inspection, the responsibility of inspection can be viewed from two directions: in one view, the inspector job includes a management function and responsibility. This is to assure that the products conform to the required standars and specification. In this way the inspector actually represents the “boss”. Another view of inspection is that the inspector should not try to make laws, originate, change, elaborate, or establish specification, but assure that the laws, specifications and standards are followed as established.

Scope of the Inspection

The mention of inspection may immediately signify to many an ability to measure. It calls up visions of micrometer, height gages, surface plates, indicators, and the host of measuring devices developed use for inspection. Measurement is an important part of inspection. But it is not only this. The term implies visual inspection, the act of looking at parts and pieces and classifying the work by eye as satisfactory or reject. Visual skill and good judgement, good interpretation of the specifications, in determine the quality of shop products are properly the successful inspector should develop.

Aircraft engine Inspection Description

Aircraft Engine Inspection is a critical examination of engine and components, and the inspector in industry is supposed by the very of his title to examine products very closely, perhaps even more closely that the mechanic, and other employees performing other tasks on the products. Other industrial sense, an aircraft engine inspection is a critical examination directed to some pre-determined purpose. This is comparing of determine the conformance of a product to its specifications. Before any meaningful aircraft engine inspection can be performed, the inspector must know and understand the aircraft engine inspection criteria (the spesifications) for the item being inspected. For example, suppose the inspector is inspecting a compressor blade. The spesification for the compressor blade calls for a smooth blending without nicks, and sharp corners, certain finish and no discoloration. Regarding to industrial requirements, aircraft engine inspection are visual examination and manual checks in order to determine the condition of aircraft engine and its components. An aircraft engine inspection involving complete disassembly and the use of complex inspection aids. An aircraft engine inspection system is designed to maintain the aircraft engine in the best possible condition. In order to achieve this, detailed and repeated aircraft engine inspections must be performed with a good maintenance program. Irregular and careless aircraft engine inspection will result in gradual and certain deterioration of the engine. It has been proven that regular scheduled aircraft engine inspection and preventive maintenance assure airworthiness. Operating failures and malfunction of equipment are reduced if excessive wear or minor defects are corrected early. The importance of aircraft engine inspections on aircraft engines is necessitates trained inspectors to perform the inspection of the engine and components.