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
TYPICAL SURFACE FINISHES
MACHINE FINISHES MANUFRCTURING BLEMISHES hing Done ou the Cutting Shor Mocks That Mop Our Dunc
TYPICAL CORROSION IMAGES
SAMPLE ENDOSCOPE IMAGES FIGURE 1-17. TYPICAL DEFECTS AS SEEN THROUGH BORESCOPE AND
OTHER AIDS (Courtesy of McDonnell Douglas) Chap 1 Page 16 Par 5
6. FACTORS AFFECTING VISUAL INSPECTION. Any factor that aids visual effectiveness increases the probability of detecting the potential cause of a failure and subsequent corrective action.
Inspection Personnel Qualifications and Training. Inspection personnel should posses experience and knowledge of the origins and causes of defects in raw material manufacturing processes, the reshaping and redistribution of these defects in subsequent part manufacturing processes, and defects that develop after the part is put in service. Inspection personnel should also have a working knowledge of the part, component, or aircraft being inspected. It is essential that inspection personnel be knowledgeable concerning the structural detail being evaluated to enable them to properly locate, identify, and evaluate aircraft defects. Persons who inspect, approve, and return to service an aircraft appliance or part, must be certified in accordance with the appropriate FARS or perform the work under a certificate holder who is directly in charge of that person.
Inspection Area Access. Ease of access to the inspection area is important in obtaining reliable visual inspection results. Access consists of the act of getting into an inspection position (primary access) and performing the visual inspection (secondary access). Unusual positions (i.e., crouching, lying on back, and overhead reaching) constitute examples of difficult ac- Impact on Inspection. The necessity to get both hands into the aircraft structure while holding a flashlight or mirror or reaching into awkward openings can affect the inspector's motivation, attitude, decision-making, and ability to interpret what is seen.
(2) Access and Safety. Staging equipment (e.g., forms, ladders, stools) used to permit access to the airframe and engines should be used safely, i.e., secured manually or brake engaged to prevent slips and falls. Protection should be provided to prevent potential injury from sharp edges and shifts in heavy weights. Adequate protection from falls should be provided wherever possible, such as railings and harnesses and lanyards on high working platforms.
c. Lighting. Adequate quality and intensity of illuminance and elimination of direct glare, reflected glare, and harsh shadows all enhance the identification of defects. Conversely, cessive visual fatigue and the delayed eye adaptation experienced when moving from bright surroundings into dark ones and vice versa could reduce effective detection of defects.
(1) Localized Illumination. Illumination should be provided during occupancy of spaces that possess limited access. In Chap 1 Par 6 Page 17