Cessna 172 Skyhawk SERIES User manual

Maintenance Manual
SINGLE ENGINE
MODELS 172, 182,
T182, 206 AND T206
1996 And On
.
Member of GAMA
COPYRIGHT © 1996
CESSNA AIRCRAFT COMPANY
WICHITA, KANSAS, USA 2 DECEMBER 1996
SESR04REVISION41JUNE2005

CESSNA AIRCRAFT COMPANY
SINGLE ENGINE
STRUCTURAL REPAIR MANUAL
LIST OF EFFECTIVE PAGES
CHAPTER-SECTION-SUBJECT PAGE DATE
00-Title
00-List of Effective Pages
00-Record of Revisions
00-Record of Temporary Revisions
00-Table of Contents
INTRODUCTION Pages 1-3 Jun 1/2005
LIST OF REVISIONS Page 1 Jun 1/2005
LIST OF CHAPTER Page 1 Jun 1/2005
00 - LIST OF EFFECTIVE PAGES Page 1 of 1
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Revision
Number Date Inserted Date Removed Page Number Revision Number Date Inserted Date Removed Page Number
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STRUCTURAL REPAIR MANUAL
CONTENTS
INTRODUCTION ................................................................ INTRODUCTION
Page 1
General.................................................................... INTRODUCTION
Page 1
Coverage .................................................................. INTRODUCTION
Page 1
Airplane Identification ....................................................... INTRODUCTION
Page 1
Aerofiche (microfiche)....................................................... INTRODUCTION
Page 1
Using the Structural Repair Manual or Aerofiche............................... INTRODUCTION
Page 2
Revision(Manual)........................................................... INTRODUCTION
Page 2
IdentifyingRevisedMaterial.................................................. INTRODUCTION
Page 3
LISTOFREVISIONS............................................................. LISTOFREVISIONS
Page 1
General.................................................................... LISTOFREVISIONS
Page 1
LISTOFCHAPTERS............................................................. LISTOFCHAPTERS
Page 1
CONTENTS Page 1 of 1
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CESSNA AIRCRAFT COMPANY
SINGLE ENGINE
STRUCTURAL REPAIR MANUAL
INTRODUCTION
1. General
A. The information in this publication is based on data available at the time of publication and is
updated, supplemented, and automatically amended by all information issued in Service News
Letters, Service Bulletins, Supplier Service Notices, Publication Changes, Revisions, Reissues and
Temporary Revisions. All such amendments become part of and are specifically incorporated within
this publication. Users are urged to keep abreast of the latest amendments to this publication through
information available at Cessna Authorized Service Stations or through the Cessna Product Support
subscription services. Cessna Service Stations have also been supplied with a group of supplier
publications which provide disassembly, overhaul, and parts breakdowns for some of the various
supplier issued revisions and service information which may be reissued by Cessna’s Authorized
Service Stations and/or through Cessna’s subscription services.
WARNING: All inspection intervals, replacement time limits, overhaul time
limits, the method of inspection, life limits, cycle limits, etc.,
recommended by Cessna are solely based on the use of new,
remanufactured, or overhauled Cessna approved parts. If parts are
designed, manufactured, remanufactured, overhauled, purchased,
and/or approved by entities other than Cessna, then the data in
Cessna’s maintenance/service manuals and parts catalogs are no
longer applicable and the purchaser is warned not to rely on such
data for non-Cessna parts. All inspection intervals, replacement
time limits, overhaul time limits, the method of inspection, life
limits, cycle limits, etc., for such non-Cessna parts must be
obtained from the manufacturer and/or seller of such non-Cessna
parts.
2. Coverage
A. The Cessna Single Engine Structural Repair Manual is prepared in accordance with the Air Transport
Association Specification 2200 for Manufacturers’ Technical Data.
B. ThisStructuralRepairManualcontainsmaterialidentificationforstructuresubjecttofield repair; typical
repairs applicable to structural components; information relative to material substitution and fastener
installation; and a description of procedures that must be performed with structural repair, such as
protective treatment of the repair and sealing.
C. This manual will serve as a medium through which all single engine operators will be advised of actual
repairs. As service records indicate a requirement, this manual will be revised to include additional
specificrepairs.
3. Airplane Identification
A. To identify structural differences to associated airplanes, the specific airplane identity may appear in
the figure and the text. Items not identified for a specific airplane or group of airplanes are suitable
for all airplanes.
4. Aerofiche (microfiche)
A. The Structural Repair Manual is prepared for Aerofiche presentation in addition to 8 ½by 11 inch loose
leaf manual format. To facilitate the use of the aerofiche, a list of chapters with an aerofiche frame
reference has bee tabulated and incorporated into the Introduction of the Structural Repair Manual.
B. Aerofiche isa microformreproductionof thecontents ofthe 8½by11 inchmanual ina formconvenient
for service areas. An aerofiche reader is required to view the 4-inch by 6-inch aerofiche card. Each
aerofiche card contains 12 horizontal rows of 24 images each. An image displays information equal
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to an 8 ½ by 11 inch loose leaf page and represents a frame. Horizontal rows are lettered from A
at the top to L at the bottom. Vertical columns are numbered 1 to 24. The combination of a letter
and a number identifies a frame (image) in the aerofiche card. The List of Chapters provides a quick
reference to information contained in the aerofiche.
5. Using the Structural Repair Manual or Aerofiche
A. Division of Subject Matter.
(1) Structural repair information is divided into chapters in accordance with Air Transport Association
Specification 100. Each Chapter is further subdivided to provide individual or related structural
member presentation.
(2) Chapter 51 provides general structural information required to perform a repair. Also included
in Chapter 51 are general repair procedures that may be accomplished in noncritical areas.
B. Effectivity Page.
(1) Alistof effectivepages isprovidedwith eachchapter. Allpages listed areactiveand shallappear
in sequence as recorded in the Effectivity Page.
(2) The Effectivity Page contains tabular listing of ATA number, page and date of each page in that
chapter. A change in the chapter requires a revision to the chapter’s Effectivity Page. The date
corresponds to the date that appears on the individual page which defines when that page was
issued.
C. Page Numbering System.
(1) The Structural Repair Manual or corresponding aerofiche page numbering system consists of
the Air Transport Association Specification 100 three element numbers separated by dashes.
The page number and date are printed immediately to the right of the three element number. The
three element number is assigned to a component, with the first set of numbers corresponding
to the ATA-100 assigned chapter number.
(2) The page number complies with Air Transport Association Specification 100 for subdividing a
Structural Repair Manual. Blocks of sequential page numbers are used to identify:
Pages 1 Through 100 - Structural Identification
Pages 101 Through 199 - Allowable Damage
Pages 201 through 999 - Repair Procedures
(3) The date which appears below the page number signifies when the page was issued. If no
revisions to that page have occurred, the date signifies original date.
(4) Illustrationsusethesame figurenumberingasthepage blockinwhich theyappear. Forexample:
Figure 202 would be the second figure in a repair procedure.
6. Revision (Manual)
A. Regular Revision.
(1) Pages to be removed or inserted in the Structural Repair Manual are controlled by the Effectivity
Page. Pages are listed in sequence by the three element number and then by page number.
When two pages display the same three element number and page number, the page displaying
the most recent Date of Page Issue shall be inserted into the Structural Repair Manual. Thedate
column on the corresponding chapter Effectivity Page shall verify the active page.
B. Temporary Revision.
(1) For paper publications:
(a) Temporary revision pages are filed in the Structural Repair Manual by replacing existing
pages in the manual. File the temporary revision cover page according to the filing
instructions on the Temporary Revision Cover Page.
(2) For aerofiche publications:
(a) Draw a line through any aerofiche frame (page) affected by the Temporary Revision with a
permanent red ink marker. This will be a visual identifier that the information on the frame
(page) is no longer valid and the Temporary Revision should be referenced. for "added"
pages in a temporary Revision, draw a vertical line between the applicable frames which is
wide enough to show on the edges of the pages. Temporary Revisions should be collected
and maintained in a notebook or binder near the aerofiche library for quick reference.
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7. Identifying Revised Material
A. Additions or revisions to text in an existing section will be identified by a revision bar in the left margin
of the page and adjacent to the change.
B. When additions or revisions are made to text in an existing section, all pages displaying the same
three element number shall also display the same Date of Page Issue. The date column on the
corresponding chapter Effectivity Page shall verify the active page. These pages will display the
current revision date in the Date of Page Issue location.
C. When extensive technical changes are made to text in an existing section that requires extensive
revision, revision bars will appear the full length of text.
D. When art is revised or added, a change bar will appear on the full length of the page.
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STRUCTURAL REPAIR MANUAL
LIST OF REVISIONS
1. General
A. This Structural Repair Manual includes the original issue and the following listed revisions. To make
sure that information in this manual is current and the latest maintenance and inspections procedures
are available, revisions must be incorporated in the manual as they are issued.
Table 1. Original Issue--2 December 1996
Revision Number Date Writer Revision Number Date Writer
1 16 May 1997 2 16 July 1999
3 15 January 2001 4 1 June 2005 jmk
LIST OF REVISIONS Page 1
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LIST OF CHAPTERS
CHAPTER Jun 1/2005 FICHE/FRAME
51 Standard Practices - Structures Jun 1/2005 1 A10
52 Doors Jun 1/2005 1 D2
53 Fuselage Jun 1/2005 1 D8
55 Stabilizers Jun 1/2005 1 E7
56 Windows Jun 1/2005 1 E16
57 Wings Jun 1/2005 1 F2
71 Powerplant Jun 1/2005 1 H2
NOTE 1: *Represents date of page one of each chapter's List of Effective Pages which is applicable to Manual
revision date.
LIST OF CHAPTERS Page 1
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CHAPTER
STANDARD
PRACTICES -
STRUCTURES

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LIST OF EFFECTIVE PAGES
CHAPTER-SECTION-SUBJECT PAGE DATE
51-Title
51-List of Effective Pages
51-Record of Temporary Revisions
51-Table of Contents
51-00-00 Page 1 Jun 1/2005
51-10-00 Pages 1-2 Jun 1/2005
51-11-00 Pages 1-8 Jun 1/2005
51-30-00 Pages 1-5 Jun 1/2005
51-40-00 Pages 1-12 Jun 1/2005
51-60-00 Pages 1-8 Jun 1/2005
51-70-00 Page 801 Jun 1/2005
51-71-00 Page 801 Jun 1/2005
51-73-00 Pages 801-802 Jun 1/2005
51-73-01 Page 801 Jun 1/2005
51-75-00 Pages 801-808 Jun 1/2005
51-76-00 Pages 801-803 Jun 1/2005
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CONTENTS
STANDARD PRACTICES AND STRUCTURES - GENERAL. ... .. .... .. .. .. .. ...... . 51-00-00 Page 1
General.................................................................... 51-00-00Page1
Description................................................................. 51-00-00Page1
DAMAGE INVESTIGATION AND CLASSIFICATION .... .. .. .. .. .. .... .. ... ...... .. . 51-10-00 Page 1
General.................................................................... 51-10-00Page1
DamageInvestigation....................................................... 51-10-00Page1
Damage Classification....................................................... 51-10-00Page2
Refinishing Damaged Areas Following Repairs ... .. .. ......... .. .... .. .. .. .. .. 51-10-00 Page 2
CORROSION AND CORROSION CONTROL - GENERAL .. .. .. .. .... .. ......... .. . 51-11-00 Page 1
General.................................................................... 51-11-00Page1
TypesofCorrosion.......................................................... 51-11-00Page1
TypicalCorrosionAreas..................................................... 51-11-00Page3
CorrosionDetection......................................................... 51-11-00Page4
Corrosion Damage Limits. .. ...... ... .. .. .. .. .. .. .. .. ...... ... .. .. .. .. .... .. . 51-11-00 Page 4
CorrosionRemoval.......................................................... 51-11-00Page5
Control of Corrosion on Landing Gear Springs. .. ... ...... .. .. .. .. ...... ... .. .. 51-11-00 Page 7
REPAIRMATERIALS............................................................. 51-30-00Page1
General.................................................................... 51-30-00Page1
RepairMaterials............................................................ 51-30-00Page1
Extrusions and Formed Sections . .. .. .. .. ......... .. .. .. .. .... .. ... .. .... .. .. 51-30-00 Page 1
FASTENERS.................................................................... 51-40-00Page1
General.................................................................... 51-40-00Page1
Rivets...................................................................... 51-40-00Page1
Replacement Of Hi-Shear Rivets . .. .. .. .. .... .. ... .. .... .. .. .. .. ......... .. .. 51-40-00 Page 1
Substitution Of Rivets .. .. .. ......... .. .. .. .. .. .... .. ......... .. .. .. .. ...... . 51-40-00 Page 1
RivetDiameters............................................................. 51-40-00Page2
RivetLengths............................................................... 51-40-00Page2
SolidShankRivets.......................................................... 51-40-00Page2
BlindRivets ................................................................ 51-40-00Page7
SpacingOfRivets........................................................... 51-40-00Page10
Threaded Fasteners Bolt Torques .... .. .. .. .. .. .... .. ... ...... .. .. .. .. ...... . 51-40-00 Page 10
Rivets for Plastic or Composite Parts .. .. .. .. .. ......... .. .... .. .. .. .. .. ...... 51-40-00 Page 10
FLIGHT CONTROL SURFACE BALANCING .. .. .. .. ...... ... .. .... .. .. .. .. .. ...... 51-60-00 Page 1
General.................................................................... 51-60-00Page1
ToolsandEquipment........................................................ 51-60-00Page1
Procedures for Balancing Control Surfaces... .. ... .. .... .. .. .. .. .. ...... ... .. . 51-60-00 Page 1
Balancing Definitions........................................................ 51-60-00Page1
Control Surface Balance Requirements ... ... .. .... .. .... .. ... ...... .. .. .. .. .. 51-60-00 Page 7
REPAIRS-GENERAL............................................................ 51-70-00Page801
Introduction................................................................. 51-70-00Page801
Usage ..................................................................... 51-70-00Page801
Preparation for Repair ... ...... .. .. .. .. .. ...... ... .. .... .. .. .. .. ......... .. .. 51-70-00 Page 801
RIVETED ALUMINUM STRUCTURE REPAIR . ... .. ... .. .. ... .. .. ... .. ... ....... ... 51-71-00 Page 801
Preparing Riveted Aluminum Structure For Repair . ...... .. .. .. .. .. .... .. ... .. . 51-71-00 Page 801
GLASSFABRICREPAIR......................................................... 51-73-00Page801
General.................................................................... 51-73-00Page801
ToolsandMaterials ......................................................... 51-73-00Page801
Repair Of Glass Fabric Parts. .. .. .. .... .. ... ...... .. .. .. .. ...... ... .. .... .. .. 51-73-00 Page 801
REPAIR OF THERMO-FORMED THERMO PLASTIC COMPONENTS .. .... .. .. .. .. . 51-73-01 Page 801
Thermo-formed Thermo Plastic Repair.. .. .. .. .. .... .. ... ...... .. .. .. .. ...... . 51-73-01 Page 801
TemporaryRepairs.......................................................... 51-73-01Page801
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TYPICAL SKIN REPAIRS.. .. .. .... .. ... .. .... .. .. .. .. .. .... .. ... .. .... .. .. .. .. ... 51-75-00 Page 801
General.................................................................... 51-75-00Page801
Guidelines for Corrugated Skin Crack Repairs ... .. .. .. .. .. ...... ... .. .... .. .. . 51-75-00 Page 801
CONTROL SURFACE REPAIR. ... .. .... .. .. .. .. .. ...... ... .. .... .. .. .. .. ... ...... 51-76-00 Page 801
General.................................................................... 51-76-00Page801
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STRUCTURAL REPAIR MANUAL
STANDARD PRACTICES AND STRUCTURES - GENERAL
1. General
A. Chapter 51 describes general repair practices, materials and procedures which are applicable
throughout the subsequent chapters. This chapter also provides general information for performing
any structural repairs.
B. Unless otherwise specified, all dimensions are in inches; forces are in pounds and torques are in
inch-pounds.
C. The airplanes are of an all metal, semimonocoque construction, with the skin carrying a portion of all
structural loads.
D. To obtain information covering dimensions, areas and stations diagrams, refer to current appropriate
Model 172, Model 182 or Model 206 Maintenance Manual, Chapter 6, Dimensions and Areas.
E. For information covering leveling and weighing, refer to current appropriate Model 172, Model 182 or
Model 206 Maintenance Manual, Chapter 8, Leveling and Weighing.
2. Description
A. The fuselage is of conventional semimonocoque construction. Construction consists of formed
bulkheads, longitudinal stringers, reinforcing channels, and skin panels.
B. The wings are of an all metal, strut-braced, semimonocoque construction, utilizing two spars. Each
wing consists of a wing panel with an integral fuel bay, an aileron and a flap.
C. The empennage group is of a fully cantilevered design and consists of a conventional rudder and
elevator configuration. The horizontal stabilizer is of one-piece construction, consisting of spars, ribs,
and skins. Elevators are constructed of spars, ribs, and skin panels. The skin panels are riveted to
the ribs and spars. A balance weight is located in the outboard end of each elevator, forward of the
hinge line. An elevator trim tab is attached to the right hand elevator and is constructed of a spar,
ribs, and skin, riveted together. The vertical stabilizer is constructed of a forward and aft spar, ribs,
and skin. The rudder is constructed of spars, ribs, and skin panels.
D. The main landing gear consists of 6150M alloy spring-steel, cantilevered with attaching parts of high-
strength 7075-T73 aluminum alloy forgings. Nose gear components are 4130 alloy steel and 7075-
T73 aluminum alloy forgings.
E. The engine mount is constructed of welded 4130 steel tubing on the 172 and 182. The 206 has a
built-up aluminum sheet metal engine mount.
F. The removable engine cowling is made of 2024 Alclad secured with quarter turn fasteners.
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DAMAGE INVESTIGATION AND CLASSIFICATION
1. General
A. For the purposes of this manual, damage is considered to be a deviation from the original
configuration of a structural part that compromises its structural integrity by significantly reducing its
strength, significantly decreasing its resistance to fatigue, significantly increasing its susceptibility to
corrosion, significantly altering its flutter characteristics, or adversely affecting the flight characteristics
of the airplane. This can include - but is not limited to - scratches, dents, dings, gouges, cracks,
drill starts, double drilled holes, plastic deformation, reduction in cross-sectional areas, changes in
component center-of-gravity, missing or inadequate fasteners, corrosion, dissimilar metal contact,
work hardening, temper change due to excessive heat, and so forth.
B. Use good judgment in determining the type of significant change to flat stock structural material. The
terms, dent, crease, abrasion, gouge, nick, scratch, crack and corrosion, referred to elsewhere in the
manual, are defined below as a guide for this determination, particularly with respect to the external
skin of the airplane:
(1) Dent - A dent is normally a damaged area which is depressed with respect to its normal contour.
There is no cross sectional area change in the material. Area boundaries are smooth. Its form
is generally the result of contact with a relatively smoothly contoured object.
NOTE: A dent-like form of damage to skin may be the result of the peening action of a
smoothly contoured object contacting it. If the inner surface of skin shows no contour
change, consider that such damage results in a local cross sectional area change.
(2) Crease - A damaged area which is depressed or folded back upon itself in such a manner that its
boundaries are sharp or well defined lines or ridges. Consider it to be the equivalent of a crack.
(3) Abrasion - An abrasion is a damaged area of any size which results in a cross sectional area
change due to scuffing, rubbing, scraping or other surface erosion. It is usually rough and
irregular.
(4) Gouge - A gouge is a damaged area of any size, which results in a cross sectional area change.
It is usually caused by contact with a relatively sharp object which produces a continuous, sharp
or smooth channel-like groove in the material.
(5) Nick - A nick is a local gouge with sharp edges. Consider a series of nicks, in a line pattern to
be the equivalent of a gouge.
(6) Scratch -A scratchis alineofdamageof anydepthin thematerialand resultsinacrosssectional
area change. It is usually caused by contact with a very sharp object.
(7) Crack - A crack is a partial fracture or complete break in the material with the most significant
cross sectional area change. In appearance, it is usually an irregular line and is normally the
result of fatigue failure.
(8) Corrosion - Corrosion, due to a complex electrochemical action, is a damaged area of any size
and depth which results in a cross sectional area change. Depth of such pitting damage must
be determined by a cleanup operation. Damage of this type may occur on surfaces of structural
elements. Refer to Corrosion and Corrosion Control, Section 51-11-00.
C. Use good sense and proper visual measurement in the determination of significant cross sectional
area changes of both depth and length of any type (or combinations) of damage mentioned above.
2. Damage Investigation
A. After a thorough cleaning of the damaged area, all structural parts should be carefully examined
to determine the extent of damage. Frequently, the force causing the initial damage is transmitted
from one member to the next, causing strains and distortions. Abnormal stresses incurred by shock
or impact forces on a rib, bulkhead, or similar structure, may be transmitted to the extremity of the
structural member, resulting in secondary damage, such as sheared or stretched rivets, elongated bolt
holes, or canned skins or bulkheads. Points of attachment should be examined carefully for distortion
and security of fastenings in the primary and secondary damaged areas at locations beyond the local
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damage. This is particularly true with wing tip, horizontal stabilizer tip, or vertical fin tip damage. If
the damage is due to an aft load, the rear spars should be checked for indications of compression
damage for the full length, including the fuselage components.
3. Damage Classification
A. Damage to the airplane can be divided into three major categories: negligible damage, repairable
damage, and major replacement damage. These categories are intended to provide the mechanic
with some general guidelines to use in determining the extent and criticalness of any damage.
Obviously, there will be some overlapping between categories, and common sense should be used
in determining the final action to be taken with regard to any damage.
(1) For damage criteria of specific structure (wings, fuselage, and so forth), refer to applicable
chapters within this repair manual.
4. Refinishing Damaged Areas Following Repairs
A. Areas of structure which are damaged and then repaired in the field, must be refinished to restore the
original paint and corrosion protectant properties to factory standards. Refer to applicable airplane
Maintenance Manual, Chapter 20, Exterior Finish - Cleaning/Painting, for refinishing procedures and
required materials.
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CORROSION AND CORROSION CONTROL - GENERAL
1. General
A. Corrosion is a natural phenomenon which destroys metal by chemical or electrochemical action and
converts it to a metallic compound such as an oxide, hydroxide, or sulfate. All metals used in airplane
construction are subject to corrosion. If exposed, attack may take place over an entire metal surface.
It may penetrate a surface atrandom forming deep pits or may follow grain boundaries. Corrosion may
be accentuated by stresses from external loads or from lack of homogeneity in the metallic structure
or from improper heat treatment. It is promoted by contact between dissimilar metals or with materials
which absorb moisture such as wool, rubber, felt, dirt, and so forth.
NOTE: For additional information oncorrosion control foraircraft, refer to theFAAAdvisory Circular
No. 43-4.
(1) Refer toFigure 1 for a simplified illustration of the conditions which must exist for electrochemical
corrosion to occur.
(a) There must be a metal that corrodes and acts as the anode.
(b) There must be a less corrodible metal that acts as the cathode
(c) There must be a continuous liquid path between the two metals which acts as the
electrolyte, usually condensation and salt or other contamination.
(d) There must be a conductor to carry the flow of electrons from the cathode to the anode.
This conductor is usually in the form of a metal-to-metal contact (rivets, bolts, welds, etc.)
(2) The elimination of any one of the four conditions described above will stop the corrosion reaction
process as shown in Figure 1.
(3) One of the best ways to eliminate one of the four described conditions is to apply an organic film
(such as paint, grease, plastic, etc.) to the surface of the metal affected. This will prevent the
electrolyte from connecting the cathode to the anode, and since current cannot flow, it prevents
corrosive reaction.
(4) At normal atmospheric temperatures, metals do not corrode appreciably without moisture, but
the moisture in the air is usually enough to start corrosive action.
(5) When components and systems constructed of many different types of metals must perform
under various climatic conditions, corrosion becomes a complex problem. The presence of salts
on metal surfaces (from sea coast operation) greatly increases the electrical conductivity of any
moisture present and accelerates corrosion.
(6) Other environmental conditions which contribute to corrosion are:
(a) Moisture collecting on dirt particles.
(b) Moisture collecting in crevices between lap joints, around rivets, bolt, and screws.
2. Types of Corrosion
A. Direct Surface Attack.
(1) The most common type of general surface corrosion results from direct reaction of a metal
surface with oxygen in the atmosphere. Unless properly protected, steel will rust and aluminum
and magnesium will form oxides. The attack may be accelerated by salt spray or salt bearing
air, by industrial gasses, or by engine exhaust gasses.
B. Pitting.
(1) While pitting can occur in any metal, it is particularly characteristic of passive materials such
as alloys of aluminum, nickel, and chromium. It is first noticeable as a white or gray powdery
deposit similar to dust, which blotches the surface. When the deposits are cleaned away, tiny
pits can be seen in the surface.
C. Dissimilar Metal Corrosion.
(1) When two dissimilar metals are in contact and are connected by an electrolyte (continuous liquid
or gas path), accelerated corrosion ofone of the metals occurs. The most easily oxidized surface
becomes the anode and corrodes. The less active member of the couple becomes the cathode
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Corrosion Identification
Figure 1 (Sheet 1)
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