DG Flugzeugbau DG-800S Operating instructions

DG Flugzeugbau GmbH
Otto-Lilienthal-Weg 2 / Am Flugplatz •
••
•D-76646 Bruchsal •
••
•Germany
Postbox 1480, D-76604 Bruchsal •
••
•Germany
Tel. [phone] •
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•Telefax 07251 3020-200 •
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•eMail: [e-mail]
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•lag[email protected]
www.dg-flugzeugbau.de
REPAIR MANUAL
FOR THE
SAILPLANE
DG-800S
Model: DG-800S
German Data Sheet No.: 384
Issued: April 1997
Approval of translation has been done by best knowledge and
judgement.
In any case the original text in German language is authoritative
0

Repair manual DG-800S
Record of revisions
No. Page Description Date Signature
Issued: April 1997 1

Repair manual DG-800S
content page issued
1. Preface 3 April 97
2. Definition of minor damage 4 April 97
3. Tools and facilities required 5 April 97
4. Material list for F R P repairs 6 April 97
" " " " 7 April 97
" " " " 8 April 97
5. Instructions for F R P repairs 9 April 97
" " " " 10 April 97
" " " " 11 April 97
6. Types of fabric and overlap
dimensions 12 April 97
" " " " " 13 April 97
Issued: April 1997 2

Repair manual DG-800S
1. Preface
The purpose of this repair manual is to provide basic repair instructions
for minor damage to GFRP and CFRP gliders. (Glass and Carbon fibre
reinforced plastics). Detailed information regarding all the processing of
GFRP and CFRP is not given in this manual assuming that all repairwork
will only be carried out by people with practical knowledge in the use of
these materials.
The repair of gliders should not be used to learn FRP laminating
techniques.
Before beginning any repairwork carefully determine what materials,
tools, jigs and repair methods are to be used. The required information can
be found in this manual. To insure that the aircrafts performance is
maintained, the surface finish of the repair work should be of the same
quality as the original finish.
When doubts arise as to the repairability of damage, the DG factory
should be contacted for further information.
The information in this manual refers only to repairs of minor damage like
holes in the underside of the fuselage resulting from a wheel up landing,
or damage from hangar accidents etc..
Major damage which is outside the scope of this manual should only be
repaired by a certified repair station rated for composite aircraft structure
work.
Note: For repair- and servicing work on parts of the equipment and for
motorgliders on the power plant, the instructions in the maintenance
manual of the aircraft and the manuals belonging to the equipment parts
are to be followed.
Issued: April 1997 3

Repair manual DG-800S
2. Definition of minor damage
Only the damage listed below can be considered as minor damage
repairable by oneself.
1. Any damage limited to gelcoat or filler.
2. Holes in the fuselage underside where the average diameter does
not exceed:
Forward fuselage 80 mm (3 in.)
Rear fuselage 40 mm (1.5 in.)
Cracks in fuselage underside max.
Forward fuselage 120 mm (5 in.)
Rear fuselage 80 mm (3 in.)
The fuselage glued joint (rear fuselage) should not be damaged.
3. Holes, cracks and tears, bubbles etc. in the wings, horizontal
stabilizer and control surfaces skins where the damage does not
exceed:
average diameter cracklength
Wings 100 mm (4 in.) 150 mm (6 in.)
Horiz. stabiliser 50 mm (2 in.) 80 mm (3 in.)
Rudder 50 mm (2 in.) 80 mm (3 in.)
Flaperon, Elevator30 mm (1.2 in.) 50 mm (2 in.)
The above parts should not be damaged in the spar area.
When repairing control surface refer to sect. 5.6 page 13.
4. Replacement of bent fittings: Part numbers, see diagrams in the
maintenance manual. Damaged fittings should not be repaired but
replaced.
Issued: April 1997 4

Repair manual DG-800S
3. Tools and facilities required
Tools
- Accurate scale for the correct mixing of resin and hardener
- Containers and wood mixing sticks
- Brushes (short hair) to apply the resin
- Metal roller to press down the glass cloth and to force the air out to
reduce the formation of bubbles
- Scissors to cut the fabric
- Adhesive tape
- Plastic film for a tempering tent
- Hot air blower
- Abrasive paper - various grades
- Knife
- Saw to cut tough plastic
- Rubber hand gloves
- Accurate thermometer up to 60°C (140° F)
Facilities
To insure proper curing, the room temperature during repairwork and at
least 12 hours afterwards should be maintened at 21°C (70° F). After that
the repaired parts are to be tempered. Therefore you may construct
a tempering tent, using plastic film or styrofoam plates.
Issued: April 1997 5

Repair manual DG-800S
4. Material list for FRP repairs
Resinsystems for repairs
Resin - Bakelite Rütapox L 20 with
Hardener - Bakelite Rütapox SL 50
- mixing ratio 100:30 by weight
or resin - MGS L 160 with
hardener - H 163
mixing ratio 100:28 by weight
or resin - MGS L 285 with
hardener - H 286
- mixing ratio 100:38 by weight
The repaired areas must be tempered for 20 hours at a min. of 54°C
(129°F) before the next take-off.
Fibre glass fabric
Interglas No. US-No. Weave Weight (g/m²)
90 070 1610 Linen 80
92 110 -.- Twill 163
92 125 -.- Twill 280
92 130 -.- Linen 390
92 140 -.- Twill 390
92 145 180-150 unidirectional 220
All fabrics - finish I 550 or FK 144
Fibre Glass Rovings
Gevetex EC-10-2400 K 92 with Silan finish
Carbonfibre fabric
Weight Weave Manufacturer/Type
appr. 285g/m² Atlas Interglas 98160, C.Cramer C 475
appr. 245g/m² Linen Sigri 8049, Interglas 98150
C. Cramer C 460
appr.245g/m² Twill Sigri KDK 8043, Interglas 98151
C. Cramer C 462
appr.205g/m² Linen Sigri 8003, Interglas 98140
C. Cramer C 450
appr.205g/m² Twill Sigri KDK 8042, Interglas 98141
C. Cramer C 452
appr.120g/m² unidi- Interglas 04387
rectional Linnen
Issued: April 1997 6

Repair manual DG-800S
Carbonfibre tape Sigri KDU 1009 7.5 cm (3 in) wide
Carbonfibre rovings TOHO or TENAX HTA 24000
Diolenfabric (as core in the flaperons)
C. Cramer style 14 K (158 g/m²)
Foam
Diab Divinycell H 60 colour green
Röhm GmbH Rohacell 51 colour white
Rohacell 71 colour white,
(only for the shear web of the wing spar).
Paint (Gelcoat)
Lesonal UP Schwabbellack 0369066
mixing ratio: 100:2
with 0720510 hardener.
Up to 10 % thinner 0630260 can be used.
or MGS T35
mixing ratio: 100:2-3 with hardener SF 2
Up to 10 % thinner SF can be used.
or PUR paint if such paint was optionally applied.
Issued: April 1997 7

Repair manual DG-800S
Glue for Plexiglas
To attach the canopy:
glue Casco Nobel 1805 Foss Than 2K
hardener Casco Nobel 1821 Curing Agent
mixing ratio 3 : 1 by weight
or 2 : 1 by volume
thickened with Aerosil.
To repair cracks in the canopy:
Röhm Acrifix 92 which hardens by exposure to light.
Filler
For gluing, the resin-hardener mix should be thickened with chopped
cotton fibres FL l f. (add enough so that the resin no longer flows). The
surfaces to be glued should be wetted with non-thickened resin +
hardener before.
To glue foam pieces into place when repairing sandwich sections and to
fill in irregularities and gaps etc. around the repair, Microballoons BJO -
0930 can be used mixed with the resin-hardener. Application and mixing
is the same as for the cotton flocks.
Sources for material
All materials can be obtained from the DG Factory.
Issued: April 1997 8

Repair manual DG-800S
5. Instructions for FRP repairs
5.1 Only materials listed in sect. 3 should be used.
5.2 Only damage defined in sect. 2 should be repaired.
5.3 Repair method for fibre reinforced plastics
see sect. 2 and 3
5.3.1 Cut out damaged area, roughen the surrounding area for the overlap
required see sect. 6.
5.3.2 Repairs should be made such that bonding is wet over dry. Specific
details concerning handling and using fibre reinforced plastics can be
obtained from various publications ie. "Petite Plane Patch Primer."
The use of Carbonfibre is the same as for glasfibre, except that the
Carbonfibres should not be kinked and only the specified resins are used
see sect. 4.
All repairs should be tempered for 20 hours at 54°C (129°F) before the
next take off.
5.3.3 Repairs of a FRP shell
Prepare the repair area as specified above. Scarf the shell so that the
individual layers of fabric can be seen like plywood layers. Remove the
gelcoat for at least 20 mm (.8 in.) around the damaged area.
New lay-up as shown on the sketch.
outside
Issued: April 1997 9

Repair manual DG-800S
5.3.4 Repairing the outer skin of a sandwich panel
Cut out the damaged area, remove the gelcoat over the overlap area +10
mm (0.4 in.) around the damaged area. Fill the damaged foam area with
resin thickened with microballoons (microballoons-resin), let harden.
Sand down. With a round headed hammer tap the outer skin around the
hole so that the foam is somewhat compressed, therefore heat this area to
ca. 60°C (140°F). Apply the new cloth.
5.3.5 Repair of outer and inner skin of a sandwich panel
See sect. 5.3.4. Additionally remove as much foam as is needed so that the
entire damage to the inner skin can be seen plus enough undamaged inner
skin as is required for overlapping. If the inner skin still holds together,
sand properly and lay up the new cloth over it. Insert a suitable cut piece
of foam, 1-2 mm (0.04 to 0.08 in.) thinner than the original, glued in with
microballoons-resin.
Should the inner skin be so damaged that the above process cannot be use,
the inner skin fabric should be applied to the foam first and left to harden
before inserting into the repair area. Microballoons-resin should once
again be used.
For lay up of the fabric to the foam, a layer of microballoons-resin should
be applied first to eliminate the formation of airbubbles.
Apply the outer layers as in sect. 5.3.4.
0.04 – 0.12 in.
Issued: April 1997 10
outer skin
foam
inner skin
resin thickened with
microballoons

Repair manual DG-800S
5.4 Repairing small dents in a sandwich panel skin (no cracks in the
gelcoat)
Small dents can usually be removed by heating up to 60° to 70° C (140° -
158°F). Use a hot air blower to heat the area of the dent. The crushed
foam will then spring back to its original form, so that the
dent will hardly be seen. Final sanding with wet sandpaper grade 600
should finish the job. In more severe cases, one coat of gelcoat will
remove all trace of the dent.
5.5 Outer skin finish
Repairs should be such that the area is exactly level or only slightly higher
than the surrounding skin surfaces. Sand the hardened repair surface with
dry grade 80 sandpaper. Fill with Polyesterfiller, let dry and sand with dry
sandpaper. When the surface is smooth, sand the repair area and at least
5 cm (2 in.) of the surrounding gelcoat with wet sandpaper grade 400.
Spray the repair area with 5 coats of gelcoat.
After the gelcoat has hardened, sand with grade 400, 600 and 800 wet
sandpaper until the surface is smooth. Polish with a power buffer (electric
drill or similar with cloth polishing wheel). Apply a block of wax onto the
rotating polishing wheel and then polish the repaired area. Do not polish
in only one direction, and do not polish one spot for too long so that
overheating occurs, see sect. "general maintenance" in the maintenance
manual.
5.6 After repairing control surfaces, the mass balance weights must be
checked again with the values given in the maintenance manual. Should
the maximum values be exceeded, then the parts have to be replaced.
Issued: April 1997 11

Repair manual DG-800S
6. Types of materials and overlap dimensions
The following overlap dimensions are to be maintained. Use the materials
given, see also pages 6 and 7.(Smaller reinforcements on high stressed
areas are not given in the table below).
Part overlap fabric type, etc.
(cm) (in.) d= + 45°
l= + 90°
_______________________________________________________________
Wing skin outside 3 1.2 1 x 90070 l outside
+1x245g/m² carbonfibre d
core / / H 60 - 6mm thick,
18m tip 3 mm thick
inside 3 1.2 1 x 285 g/m² carbonfibre d
from root up to y = 2000
1x245g/m² carbonfibre d
y = 2000 up to tip
+1x carbonfibre 120 g/m²
in flight direction in the
waterballast tank
compartment
_______________________________________________________________
Flaperons outside 3 1.2 1 x 90070 l outside
+1x245g/m² carbonfibre d
core / / 1xDiolenfabric 158 g/m²l
inside 2 .8 1x245g/m² carbonfibre d
_______________________________________________________________
Horizontal stabilizer
outside 2 .8 1x90070 d +1 x 92110 d
core / / H 60 - 5 mm thick
inside 1 .4 1 x 90070 d +1 x 90070 d in
the centre of the stabilizer
up to y = 300
______________________________________________________________
Elevator 2 .8 1x 92110 d outside
+ 2 x 9d2125 d
______________________________________________________________
Issued: April 1997 12

Repair manual DG-800S
Part overlap fabric type, etc.
(cm) (in.) d = + 45°
l = + 90°
_______________________________________________________________
Rudder outside 1 .4 1 x 90070 d .
core / / H 60 - 3 mm thick
Inside 1 .4 1 x 90070 d
_______________________________________________________________
Fuselage boom 7 2.8 1 x 92110 d outside
+ 2 x 92140 d
+ 2 x 92145 l unidirectional
+ 2 x 92140 d
Note: There are CFRP Rovings on the upper and lower side of the fuselage
boom which have to be repaired in case of
damage. 30 12. 32 rovings HTA 24000 in
each half of the fuselage
_______________________________________________________________
Forward fuselage belly up to wing suspension
6 2.4 1 x 92110 d
+ 4 x 92140 d
+ 2 x 92125 l
_______________________________________________________________
fin outside 2 .8 2 x 92110 d
core / / 2 x Jute-fabric impregnated
with microballoons-resin mixture
inside 2 .8 1 x 92145 perpendicular
to fuselage boom up to
400 mm above fuselage
centreline
1.5 .6 1 x 92 110 d
_______________________________________________________________
Issued: April 1997 13