Many fatigue cracks in aircraft structure are stop drilled
to slow the crack until repair or rework can be performed.
However, stop drilling only stops a crack from growing
for a very short time. Often, the tip of the crack is
not visible on the surface and is missed by the stop
drill hole therefore not slowing crack growth at all.
Fatigue Technology's StopCrack
System can be used to dramatically extend the fatigue
life of a stop drilled hole by slowing the growth of
the crack. The StopCrack System can also virtually eliminate
the danger of missing the crack tip. This ensures that
the crack will not re-initiate and the structure will
not fail before repair can be performed.
FTI's StopCrack System is based
on the Split Sleeve Cold Expansion System being used
by virtually every commercial and military aircraft
manufacturer worldwide to extend the fatigue life of
holes in metallic structures. The StopCrack System cold
expands a stop drilled hole, imparting residual compressive
stresses around it, protecting it from cyclic loads.
This large zone of residual compression around the hole
greatly reduces crack growth, even when the stop drill
hole misses the tip of the crack.
FTI's StopCrack System is designed as an enhanced stop
drill repair method. The system has been designed for
use by mechanics, maintenance personnel, or owners and
pilots of light aircraft. The process is easy to apply
and usually takes less than a minute to use. It is not
meant to be used as a permanent repair of the structure
and does not increase the residual strength of the structure.
Whenever a crack is discovered in a structure, an engineering
assessment should be performed and necessary repair
started as soon as possible.
• Retards growth of pre-existing fatigue cracks
• Enhances effectiveness of doubler crack repairs
• Can be used in all standard aerospace aluminum
alloys
• Can be used in varying material thicknesses
• Federally stock listed: #4920-01272-0989
 
Step 1.Drill and ream the stop drill hole.
Step 2.Use the blade
end of the combination gage to check the hole diameter.
Step 3. Slide the
sleeve over the mandrel.
Step 4. Place the
mandrel in the hole until the nosecap is flush against
the work piece.
Step 5. Pull the mandrel
through the sleeve and the hole. Remove and discard
the spent sleeve.
Step 6. Using the
round end of the combination gage check the cold expanded
diameter of the hole.
The Standard StopCrack Kit includes all the necessary
durable and expendable tooling and documentation to
cold expand stop drill holes of 3/16 inch, 1/4 inch
and 17/64 inch oversize.
The StopCrack tooling system
includes:
Cutting Tools
Reamers
Mandrel
Split Sleeves
Combination Gage
Mandrel Gage
Nosecap
Hand Puller Unit
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