EXTERML 3198
- STA.
58.159 FIGURE 1-3. MULTIPLE-SITE DAMAGE SURFACE FATIGUE CRACKS FIGURE 1-4. EXAMPLE OF SKIN-CRACKING AT FASTENERS
(2) Corrosion. Figure 1-5 illustrates areas most susceptible to corrosion. The various manifestations of corrosion such as missing rivet heads are shown in Figure 1-6.
Chap 1 Page 4 Par 5
Passenger Floor Supports Cargo and and Flooring Crew Doors Galley Areas Under De-Icer Boots Areas in Path of Battery Exhaust Gasses Areas Lavatory Areas Undercarriage Bays Integral Fuel Tanks FIGURE 1-5. AREAS MOST SUSCEPTIBLE TO CORROSION FIGURE 1-6. EXAMPLE OF MISSING RIVET HEADS RESULTING
FROM CORROSION PRODUCTS An example of blistering of paint in a fuel cell caused by corrosion is illustrated in Figure 1-7. Chipped and loose paint on a Chap 1 Par 5 Page 5
wing skin is shown in Figure 1-8. Figure 1-9 shows internal corrosion of a tubular engine mount.
FIGURE 1-7. EXAMPLE OF BLISTERING OF SEALANT IN A FUEL CELL
CAUSED BY CORROSION FIGURE 1-8. EXAMPLE OF CHIPPED AND LOOSE PAINT ON A WING
SKIN CAUSED BY CORROSION Chap 1 Page 6 Par 5
8/14/97 AC 43-204 FIGURE 1-9. INTERNAL CORROSION OF THE TUBULAR ENGINE MOUNT OF A 1946 VINTAGE CESSNA (Courtesy of Shoreline Aviation, Marshfield Municipal Airport, MA) chap 1 Par 5 Page 7
corrosion of a rudder control cable and elevator rib are shown in Figures 1-10 and 1-11, respectively. Figure 1-12 shows an example of skin-bulging from corrosion of the faying surface between skin and internal structure around a cargo doorway. Figure 1-13 shows two examples of a nut which cracked from corrosion fatigue.
Figure 1-14 illustrates landing gear and wheel corrosion points.
FIGURE 1-10. CORROSION OF THE RUDDER CONTROL CABLE OF A 1969 CESSNA 172, FOUND VISUALLY (Courtesy of Shoreline Aviation, Marshfield Municipal Airport, MA) Chap 1 Page 8 Par 5
FIGURE 1-11. CORROSION OF THE ELEVATOR RIB OF A 1969 CESSNA 172, FOUND VISUALLY (Courtesy of Shoreline Aviation, Marshfield Municipal Airport, MA) FIGURE 1-12. EXAMPLE OF SKIN-BULGING DUE TO CORROSION Chap 1 Par 5 Page 9
FIGURE 1- 13. EXAMPLE OF CRACKED NUT DUE TO CORROSION (Courtesy of McDonnell Douglas) Chap 1 Page 10 Par 5
• TYPICAL DEBRIS TRAPS WADSY WELLS
SWITCHES
- STRUTS
TIE DOWN POINTS
UNPLATED HIGH
INSIDE AXLES STRENGTH STEEL
SPRINGS
• WATER TRAPS
DISSIMILAR METAL
CONTACTS
UNDER FERRULES AND IDENTIFIÇATION TAPES
WHEEL BEARING RACES FIGURE 1-14. LANDING GEAR AND WHEEL CORROSION POINTS (Courtesy of the U.S. Navy)
(3) It is very difficult to detect disbonding by visual means, since it is usually an internal condition and not likely to show up on the surface of an aircraft.
Figure 1-15 illustrates areas most susceptible to disbonding.
Wherever a bonded surface becomes disbonded, corrosion is likely to occur and may be detected visually.
Chap 1 Par 5 Page 11
Composite Surfaces Multiple Element Wing Spar Assemblies
• Doublers Around Doors Skin Doublers FIGURE 1-15. AREAS MOST SUSCEPTIBLE TO DISBONDING during inspantion of ensire components. Fratientiv it is neces- Engine Defects. Figure 1-16 shows typical defects found sary to use visual aids to detect defects. Figure 1-17 illustrates typical defects seen through borescopes and other aids.
Chap 1 Page 12 Par 5
7-94223 7 24263 0:96930
NICK PICK-UP PILE-UF
PITTING SCORING SPALLING FIGURE 1-16. COMMON PHYSICAL CHARACTERISTICS OF ENGINE DEFECTS (Sheet 1 of 3) (Courtesy of Pratt & Whitney) Chap 1 Par 5 Page 13
• 63109
BLISTEP ING BRINELLING BURNING ₽ 61036 0 9420
BURNING CHIPPING CORROSION 9 85652 9-20%
CRACK CRACK AROSION FIGURE 1-16. COMMON PHYSICAL CHARACTERISTICS OF ENGINE DEFECTS (£ 70 2 7ЭЭЦ) Chap 1 Page 14 Par 5
FATIGUE PAILURE FLAKING FLOWING 9 94270 • 90262
FRACTURE FREETING CORROSION GARRITO 794205 9.94260 D7-4201
GOUGING GROOVEBIO GUTTERINO FIGURE 1-16. COMMON PHYSICAL CHARACTERISTICS OF ENGINE DEFECTS (Sheet 3 of 3) Page 15