Diamond Aircraft DV 20 E 2022, Airplane Maintenance Manual

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AIRCRAFT
DV 20 E AMM
Standard Practices and
Structures
Doc # 4.02.25
Rev. 2
51-20-00
Page 201
15 Mar 2022
Maintenance Practices
1. General
These Maintenance Practices tell you about composite repair processes and how to repair Class 2,
3 and 4 damage to the composite structure. Refer to Section 51-10 for data about damage
classification. Class 1 damage may only be repaired in accordance with a repair scheme approved by
the manufacturer. All repairs must be carried out by approved persons.
You must only use the materials approved by the manufacturer when repairing the airplane. Refer to
Section 51-30 for data about approved materials.
Inspect the damaged area. Look specially at the adjacent structure. Damage can go a long way under
the surface. Use the techniques given in Section 51-10.
You must take care to do the repair correctly. The outer shell of a composite structure is stressed.
Failure of the structure can cause an accident.
2. Resin
You must use the correct quantity of mixed resin for the repair. Weigh all the cut cloth patches that you
will use for the repair. The ratio for glass cloth to mixed resin is 100 : 70. For example, 100 grams of
dry glass cloth require 70 grams of mixed resin. The ratio for carbon cloth to mixed resin is 100 : 100.
For example, 100 grams of dry carbon cloth require 100 grams of mixed resin.
Measure the quantities of resin and hardener accurately (± 2% by weight). Mix the resin and hardener
thoroughly before laminating, or adding fillers or other additives.
Always use clean containers for mixing resin and only mix as much resin as you can use within its pot
life.
When using a large quantity of resin put it into a shallow container. This will increase the ratio of
surface area to volume which will reduce the risk of an exothermic reaction and can improve pot life.
For parts made from self extinguishing resin use the same resin system for repair (refer to
Section 51-30).