DG Flugzeugbau GmbH 

76646 Bruchsal 

Subject 

Effectivity 

Accomplishment 

Reason 

[nstructions 

Material 

Weight and balance 

Remarks 

nruchsal, date: 

30.08.2011 

Author: 

W. Dirks 

Technical note 

No~ 500/04 

Bulkheads of the C.G. tow hook 

page I from 1 

Instructions 1 and 2: DG-500 all variants (sailplanes and motorglidcrs), all ser. 

No.'s. 

Instruction 3: Ser. No.'s 5EI up to 5E23 

In~1ruction 1 : Prior to next winch launch 

Instructions 2 and 3: Mandatory latest March 31.2012 

Damage of the bulkheads of the C.G. tow hook and their glued joints to the 

fuselage shell has been reported. 

This damage may be due to a wheel up landing. If this damage is not detected, the 

glued joint may later fai I completely during a winch launch. 

To overcome this potential loss of safety the bulkheads must be reinforced to 

minimize the risk of damage after a wheel up landing. 

I. Check the bulkheads of the C. G. tow hook according to working instruction 

No. 1 tor TN500/04. In case of damage instruction 2 must be performed 

immediately. 

2. Reinforce the bulkheads of the C.G. tow hook according to working instruction 

No. 1 for TN500/04. 

3. Ser. No. 's 5El up to 5E23: exchange the C. G. tow hook access cover. 

Working instruction No. 1 for TN500/04 

2 GFRP-reinforcement plates 5R308 

Scr. No.'s 5El up to 5.£23: tow hook access cover 5RU32/7 

Epoxy resin/hardener Momcntive EPIKOTE TM Resin MGS LR 285 with 

EPIKURE TM Curing /\gent MGS LH 286 

Cotton flocks 

Glasfibre fabric Interglas 92140 FK144 

influence negligible 

Instruction No. I may be executed by the pilot/owner himself and is to be inspected 

and entered in the aircraft logs by a licensed inspector at the latest with the next 

annual inspection. 

Instructions No.2 and 3: 

I. EASA countries: The actions have to be performed in a Part -145 approved 

organisation, or in a Part M, Subpart F approved organisation according to the 

regulations of the Part M and released according to M.A.80 I. 

2. Non EASA countries: The actions have to be performed in a licensed 

workshop. All instructions are to be inspected and entered in the aircraft logs 

by a licensed inspector. 

Modifications approved by EASA Date 22.09.20 II 

under Approval No. 10036611 
DG Flugzeugbau Working instruction No. l for 1N500/04 Seite 1 von2 

Reinforcement of the bulkheads of the C. G. tow hook 

1) Remove the height adjustable rear seat shell. 

2) Remove the tow hook access cover . . 

3) Check ifthe bulkheads of the C.G. tow hook (5RU44/45) or their glued joints to the 

fuselage shell are damaged. Ifthis is the case repair (glassfibre fabric 3 x 92140) or 

exchange the bulkheads. 

4) The bulkheads of the C.G. tow hook shall be reinforced with GFRP-rei.nforcement 

plates 5R308, 8 mm thick. To accomplish this roughen the areas D at the bulkheads and 

the fuselage shell area E between the bulkheads with abrasive paper 60 grit, areas se~ 

sketc~ I. Don't damage the tow hook! Remove any excess glue resin at the glue '!) 

of the bulkheads to the fuselage as far as possible. ~ 

! ~ 

~ 

E 

0 

Sketch 1 

~ D~' 

5) Roughen all surfaces~~ ~~''U GFRP-reinforcement plates F and scarf the contact 

surface of the pia~~ step-up of the bulkheads according to sketch 2. If the excess 

glue resin (see it~ •. ~ouldn't be removed sufficiently, scarf the GFRP plates 

accordingly. ~\0tlre plates at the lower i·ear end to match the recess of the fuselage 

shell in fr~1t (011e tow hook. 

6) Ser.. ~~~~up to 5E23: If the GFRP-reinforcement plates F interfere with the 

rec:_~~~ main bulkhead for the tow hook access cover, grind matchjng cut outs into 

~ss. · 

~ I 

F Schaftungl 

scarf --------------- · 

Sketch 2 

Issued: 30.08.2011 
DG Flugzeugbau Working instruction No. 1 for TN500/04 Seite 2 von 2 

Reinforcement of the bulkheads of the C.G. tow hook 

F---__ 

I Sketch 3 only tow-hook 

Bulkhead with GFRP-plate F 

shown (_ --··----------··"'"'" ·-· ................ ~--- -- ----·- ·------ ~ ::.::--:.:~---·"" --- ---

7) Preparing the reinforcement glasfibre fabric G: 

Mix Epoxy-resin/hardener Momentive EPlKOTE TM Resin MGS LR 285 with 

EPIKURE TM Curing Agent MGS LH 286 (mixing ratio 100:40 by weight). Laminate 

3 layers of Interglas 92140, ±45° on a plastic foil. Cut exactly according to sketch 4. 

64 

Sketch 4 202 

~ FlugrichtunW, 

dlrectlon of fl1ght 

8) Apply the resin/hardener mix (see item 7) to all gluing surfaces. 

9) Thicken the resin/hardener mix with cotton-flocks and apply this mix to the gluing 

smfaces of the GFRP-plates. 

1 0) Place the GFRP-plates to the bulkheads and 

press. 

Apply the pre-laminated reinforcement 

glasfibre fabric G according to sketch 5. 

11) Let cure at room temperature 

12) Post cure this fuselage section at min. 54°C 

for 18 hours. 

13) Sand off excess glasfibre.fabric. 

14)From ser. no. 5E24 on: reinstall the tow hook 

access cover 

Ser. no. 5El + 5E23: Trim the new tow hook 

access cover 5RU32/7, drill the holes and 

install. 

15) Reinstall the height adjustable rear seat shell. 

Issued: 30.08.2011