Working instruction No. 1 for TN 348/12 (843/12)

Stiffening of the stand for the elevator control pushrod guide in the vertical fin
Details see drawing 5L36

1.	remove the rudder.
2.	a) gliders with fin battery installed: In the centre of the fin trailing edge shear web you will find the end of the battery box drain line. Make a mark 15mm below the centre of the drain line on the centre line of the shear web. 
b) Powered sailplanes: Measure from the lower edge of the upper rudder stand 555 mm (21.9 in.) downwards to make the mark. 
3.	Cover and tape the Mylar seals on both sides each with a piece of cardboard or similar in the working area to protect the seals and to secure your hands from being injured by the sharp ends of the seals. 
4.	Use a dia. 10mm drill. Wrap some layers of tape around the drill 16mm away from its tip.
5.	Carefully drill a hole into the shear web at the marking until  the tape touches the shear web.
6.	Prepare a dia. 2mm pianowire according to the sketch on drawing 5L36.
7.	Scratch out the foam 6mm (.24in.) around the hole, from both the shear web and the stand. Enlarge this hole up to the aluminium tube of the push rod guide. No foam shall remain at the tube in the area of the hole.
8.	Roughen the shear web over its whole width 30mm above and below the hole.
9.	Apply mixture of resin and hardener to the roughened surface and the inside of the  hole including the aluminium tube.
10.	Mix cottonflocks to the resin and fill the prepared hole completely.
11.	Cover the hole with a piece of glassfibre fabric style 92125 laid up diagonally 70mm (2.8 in.) wide and 50mm (2 in.) high.
gliders with fin battery installed: cut off the edge of this fabric at the drain hole so as not  close the hole.
12.	Allow to cure at room temperature. Then postcure for min. 18 hours with 54°C. Use a hot air gun, direct the hot air from behind onto the repaired area. Take care to give sufficient distance between the gun and the surface and check the temperature at the repaired surface. 
We recommend to protect the inside of the fin trailing edge with a heat resistant insulating fabric (e.g. as used for soldering or welding) to prevent deformation of the material.
13.	Execute a control check of the elevator control.
14.	Reinstall the rudder using new split pins.

September 28. 1999 

Dipl. Ing. Wilhelm Dirks
DG Flugzeugbau GmbH

Material:
Glasfibre fabric Style 92125 50x70mm
Epoxy resin with hardener: allowable types listed in the repair manual
Cottonflocks
2 split pins 1.5x12 DIM94 zn (zinc plated)
1 split pin 2x20 DIN94 zn
Drawing 5L36