CR-MM-1-0-00
PS-28 Cruiser
PS-28N Cruiser
CHAPTER 15 – AIRPLANE REPAIRS
Date of issue: 2011-03-08
Revision No.: -
15 - 13
Stiffener preparation
For this kind of repairs we recommend the stiffener G (glass) with plain weave 150 g/m
2
(
0.037 lb/ft
2
), with surface protection for epoxy resins. Number of needed stiffener layers
depends on depth of damage. It is possible to say that each layer of the mentioned fabric
represents at proper saturation by matrix resin thickness of 0.5 mm (
0.020 in
).
Stiffener layers must be prepared (cut out) gradually from the smallest (the lowest) up to
the bigger (upper), each with overrun of 19 mm (
0.75 in
).
Putting layers
After preparing lamination mixture (for recommendation of material see the Tab. 15-4), it is
applied to the place of repair by means of rigid brush. The first stiffener is laid into the
deposit and it is again saturated by brush. Another layer of stiffener is laid and saturated.
When putting the last layer it is necessary to pay attention to a proper saturation and
compression of stiffeners so that they cannot „come up" to the surface and subsequent
useless damage at final grinding. For better saturation of the surface by resin and securing
against curtaining it is possible to put PE or PP transparent foil across the surface. When
applied properly, the layer is without bubbles. Repair thickness should exceed surrounding
surface in this phase by about 0.5 to 1 mm (
0.02 in to 0.04 in
) for finishing.
Sanding
Carry out sanding and eventually apply mastic on the surface after setting, eventually
tearing of the foil (see small damage). It is suitable to begin sanding by abrasive with grain
size of 160 and finish by grain size of at least 400. Dry sanding equipment is used with
suction from the sanding area. Al
2
O
3
or equivalent can be used as sanding material. It is
important not to diminish basic material of the part at sanding.
NOTE:
Especially in case of c/k stiffener in the basic part there must not be any
sanding through up to the stiffener (complication - see the note about
preparatory sanding).
Finishing
See Section 15.6 - Paint repairs
15.5.3.3
Major damage
At such damage we recommend to change the part or to do this repair in a professional
facility. Use instructions in chapter about medium damage as recommendation for used
materials.
