Technical data

13773-001
51-00
Page 1
STANDARD PRACTICES: STRUCTURES
1. GENERAL
This chapter contains information and procedures applicable to all composite repairs as well as information
and procedures for aircraft painting and priming. The basic elements of successful repair are; preparation
of the laminate and repair material, proper mixing of resin, technique, and a complete cure cycle. If any
element is not properly executed the repair will be substandard. The procedures are not difficult, but the
location of the repair might be difficult to access.
A. Repairs Areas
The majority of the airplane structure is made of composite materials, except for the console, engine
mount, and flight control surfaces. Skins, bulkheads, floors, longerons, and ribs are made from fiber-
glass/epoxy composite and closed-cell foam core. Some areas of the structure are considered not field
repairable. The non-repairable areas are indicated by shaded areas on the figures in this chapter.
Although most areas of the airplane structure are field repairable, some areas are difficult to repair or
require special procedures to be followed to assure the structural integrity of a repair. If the area of
damage is inside the fuselage or in a figures shaded area, Cirrus Design must be contacted prior to
beginning a repair. (See Figure 51-001)
B. Lightning Protection (EMM)
Expanded metal mesh (EMM) is used in many areas on the airplane for lightning protection. When
repairing an area that contains EMM, the EMM must overlap the existing EMM by 0.200-inch (5 mm).
Shaded areas which contain EMM are not field repairable. EMM shall be laid over the final repair ply.
(See Figure 51-002)
CAUTION: Replacement EMM must overlap the existing EMM by 0.200-inch (5 mm). Contact Cir-
rus Design before repairing any composite surface within the figures shaded area.
C. Composite Repair Requirements and Materials
(1) Only approved composite materials may be used to complete repairs to the airplane structure.
(2) Some figures in this chapter contain shaded areas. The shaded areas indicate portions of the
airplane which must not be repaired without first contacting Cirrus Design. Flight control surfaces
are not repairable.
(3) All external areas which are not shaded (excluding flight control surfaces) can be repaired with-
out contacting Cirrus Design.
(4) Repairs must be completed by competent technicians that are trained in composite repair. Tech-
nicians should use materials and procedures outlined in this Chapter. (Refer to 51-20)
(5) Repairs should be made in a clean, temperature controlled environment. Optimal repair temper-
ature ranges from 60°- 80°F (16°- 27°C) with 50% relative humidity or less.
D. Exterior Finish Requirements and Materials
(1) To ensure that the temperature of the composite structure is kept below 150° F (66°C), the max-
imum allowable paint on the wing will have an absorptivity not greater than 0.4, with an emissiv-
ity no less than 0.9. The maximum allowable paint on the fuselage will have an absorptivity not
greater than 0.6 with no less than 0.7 emissivity.
(2) Use of approved paints and primers for the base color will satisfy the above absorptivity and
emissivity requirements.
(3) Special precautions and guidelines regarding the use of contrasting colors for identification and
styling apply. Adherence to the painting procedures given in this chapter are required. (Refer to
51-30)
30 Nov 2000