amcr Flashcards
three classification of damage
negligible, repairable, non-repairable
is damaged that may be corrected by a simple procedure with no restrictions on flight operations
negligible
is damaged to the skin, bond, or core that places restrictions on the aircraft or part
repairable
is damaged beyond established repair limits
non-repairable
defect on the outer surface that does not involve damage to the structural reinforcing fibers
cosmetic defects
often caused by chipping or scratching during handling
cosmetic defects
occurs when foreign object strike the part
impact damage
is a defect on the outer surface that does not involve damage to the structural reinforcing fibers
impact damage
most common cause of impact damage
careless handling during transportation or storage, or standing parts on their edge without adequate protection
is a separation of fabric layers of a material in a laminate
delamination
delamination occurs as a result of several causes like?
impact, moisture in the fabric, lightning strikes
another type of delamination
unbond or disbond
occurs when the skin of the sandwich structure becomes separated from the core
disbond / unbond
can occur in advanced composite structures just as in metallic ones
cracks
may occur from impact damage, over-torquing fasteners, or as a result of fastener pull-through. holes filled in the wrong location, wrong size, wrong number of holes can also be classified as this.
hole damage
are not easily detected however, they could lead to extensive damage
tiny holes
types of damage
cosmetic defects, impact damage, delamination, cracks, hole damage
used to detect cracks, surface irregularities, and surface defects such as delamination and blistering
visual inspections
one of the most important tools used to detect internal flaws or delamination
coin tap test
uses a high frequency sound wave as a means of detecting flaws in a part by beaming a high frequency wave response, delamination, flaws, or other condition are detected
ultrasonic inspections
is time versus amplitude display read from left to right
a-scan
takes a cross-sectional view of the material being tested and used as an oscilloscope screen to compare the sample
b-scan
imaging shows the shape, size, and location of the damage, but does not show the depth
c-scan
locates flaws by temperature variations at the surface of a damaged part. heat is applied to the part then the temperature gradients are measured using an infrared camera or film
thermography
it calls for the suspected part to be heated and then photographed using a laser light source and a special infrared camera film system
laser holography
used to detect disbands or water in honeycomb and impact damage
laser holography
used to detect cracks that cannot be visually detected, both internally and externally
radiography
useful in detecting the extent of the damage that cannot be visually detected
radiography
used to determine whether the resins have reached their proper strength such as the barcol tester
hardness testing
used successfully for detecting cracks in metallic surfaces, however, it should not be used with advance composite because if it is allowed to sit on the surface, the wicking action of the fibers may take the dye penetrant and would no longer bond the new material
dye-penetrant
types of inspections
visual inspection, coin tap test, ultrasonic inspection, thermography, laser holography, radiography, hardness testing, dye-penetrant
a superficial, non-structural filler is used to restore a surface to keep fluids out until a more permanent repair is made
cosmetic repair
this type of repair will not regain any strength and is used only where strength is unimportant.
cosmetic repair
this type of repair can be effective in limited instances, where the delamination is restricted to one ply.
resin injection
quick and cheap repair
resin injection
this type of repair can hope to slow the spread of delamination and is generally considered a temporary measure
resin injection
this type of repair can gain some strength
semi-structural plug/patch
mechanically-fastened plug and patch repair can be especially effective where thick solid laminated are used, since they take the bolt loads well
semi-structural plug/patch
Full structural repairs using bolted doublers can be used in heavily loaded solid laminates. This is often the only practical means of repairing such structures.
structural mechanically-fastened doubler
often used to perform repairs to lightly loaded thin laminate structures
structural bonded external doubler
this type of repair is especially common using wet lay-up materials
structural bonded external doubler
This repair restores full structural properties by forming a joint between the prepared repair area and the repair patch
structural flush repair
made by replacing each ply of the composite laminate that has been removed from the damage area
structural flush repair
types of repair
cosmetic repair, resin injection, semi-structural plug/patch, structural mechanically-fastened doubler, structural bonded external doubler, structural flush repair
