SERVICE BULLETIN No. SB-NG-1-23

12. Carefully measure the depth of all four holes. Adapt the bushings in length accordingly by grinding or cutting as appropriate. They must be inserted completely flush with the fuselage later in the process. IMPORTANT Do not use the bushing for measuring! Once the bushing is inserted into the fuselage, it is difficult to remove again without potential damage to the bushing and/or surrounding structure! 13. When cut to length, clean them with acetone, then apply pressure sensitive tape to both ends. EXTRA Aerobatic Service Bulletin Aircraft GmbH EXTRA NG EASA.21J.593 Main Gear Attachment Issue: A SB-NG-1-23 Date: 31.01.2023 Page: 9 of 15 NOTE Only handle bushings with gloves from here on. Fig. 15 – Prepared bushings (sandblasted) 14. Apply release agent or grease to the contact surface of the fuselage mounting bracket as well as to the shaft of the MS20006-38 bolts. Do not apply grease to the thread of the bolts. Use release agent on the threads. Also apply release agent or grease to the 4 Phillips head screw heads adjacent to the drilled holes, see Fig. 17 and Fig. 18 below. Fig. 16 – Fuselage mounting bracket prepared with release agent / grease 15. Prepare epoxy resin “Epikote Resin L20” with hardener “Epikure Curing Agent 111” (weight ratio 100:27). Alternatively, resin L285 with hardener H285, H286 or H287 is also acceptable (weight ratio 100:38-40). However, additional post-curing of 10h at 60°C is required in this case. Combine resin and hardener in the correct ratio and mix thoroughly. NOTE Once prepared, pot life is approx. 15 minutes! Prepare only small amount as necessary for one side to prevent dangerous heat build-up causing uncontrolled decomposition of mixed adhesive. 16. Apply epoxy-resin to the bushings’ cylindrical surface. Also thoroughly apply epoxy-resin to the surface of the enlarged holes in the fuselage until the wooden insert and laminate are entirely soaked and properly sealed. Pressure sensitive tape on both ends Pressure sensitive tape on both ends Covered with grease or release agent Release agent on threads EXTRA Aerobatic Service Bulletin Aircraft GmbH EXTRA NG EASA.21J.593 Main Gear Attachment Issue: A SB-NG-1-23 Date: 31.01.2023 Page: 10 of 15 Fig. 17 – Application of epoxy-resin inside the aft hole Fig. 18 – Application of epoxy-resin inside the front hole Fig. 19 – Application of epoxy-resin to the cylindrical surface of the bushing 17. Prepare epoxy-resin compound by mixing cotton flocks with the previously prepared resin-hardener mixture. The weight ratio should be 100% resin- hardener mixture and 20% cotton flocks, so called “HB20”. 18. Generously cover the entire cylindrical surface of the bushings with HB20. Apply release agent or grease to head of screw Apply release agent or grease to head of screw Wooden insert EXTRA Aerobatic Service Bulletin Aircraft GmbH EXTRA NG EASA.21J.593 Main Gear Attachment Issue: A SB-NG-1-23 Date: 31.01.2023 Page: 11 of 15 Fig. 20 – Applying HB20 to cylindrical surface of the bushing 19. Also apply small amount of HB20 into the holes, then use handle of the brush (or similar tool) to distribute the HB20 on the surface. Take care not to push it into the nutplates on the top end of the holes. Remove any residue. Fig. 21 – Applying HB20 into holes 20. Insert bushings flush into the drilled holes and remove excess HB20. Fig. 22 – Insert bushing 21. Immediately reinstall fuselage mounting brackets using the prepared MS20006-38 bolts (referenced in step 14.) to verify installation of bushings is flush and threads within the fuselage are free from HB20; use rubber mallet as necessary. EXTRA Aerobatic Service Bulletin Aircraft GmbH EXTRA NG EASA.21J.593 Main Gear Attachment Issue: A SB-NG-1-23 Date: 31.01.2023 Page: 12 of 15 Fig. 23 – Reinstallation of fuselage mounting bracket 22. Loosely insert AN5-52A bolts with AN960-516 washers connecting the main landing gear bracket through the spar bridge to the fuselage for alignment. Fig. 24 – Spar bridge alignment 23. Torque landing gear bracket bolts (MS20006-38) as per chapter 20-10-03 of the AMM to 22,5 – 28 Nm / 200 – 250 lb inch. Fig. 25 – Torque 24. Fully install and tighten the AN5-52A bolts with AN960-516 washers and AN365-524 stop nuts and torque to 16 Nm / 140 lb inch. Refer to Figures 10 and 11 in chapter 57-00-01 (item 1) and to chapter 20-10-04 of the AMM (Figures 5 & 6). AN5-52A bolts still loose! EXTRA Aerobatic Service Bulletin Aircraft GmbH EXTRA NG EASA.21J.593 Main Gear Attachment Issue: A SB-NG-1-23 Date: 31.01.2023 Page: 13 of 15 Fig. 26 – Bracket completely reinstalled and all bolts torqued 25. Let cure for 24h at room temperature. In case the alternative L285/H28x resin-hardener mixture was used, additional post-curing of 10h at 60°C is necessary before returning the aircraft to service. 26. Reinstall main landing gear by connecting the mounting clamps to the mounting bracket at the fuselage with the AN6-15A and AN6H24A bolts. Torque bolts to specific values as given in chapter 20-10-04 of the AMM. Secure rear bolts (AN6H24A) with safety wire. 27. Apply locking varnish to all other bolt connections. 28. Release aircraft from crane (ref. step 3 and chapter 07-10-02 of the AMM). 29. Reinstall side panels in front cockpit as per AMM chapter 25-10-30, belly fairing as per chapter 53-30-01, wheel pants as per chapter 32-40-02 and upper engine cowling as per chapter 71-10. 30. Make appropriate Service Bulletin entry in the aircraft logbook. Please also report the completion of this Service Bulletin to EXTRA by returning the completed Form in Appendix A. MATERIAL The required parts are listed in Table 1 below. They can to be ordered from: EXTRA Flugzeugproduktions- und Vertriebs GmbH Flugplatz Dinslaken Schwarze Heide 21 46569 Hünxe / Germany parts@extraaircraft.com EXTRA Aerobatic Service Bulletin Aircraft GmbH EXTRA NG EASA.21J.593 Main Gear Attachment Issue: A SB-NG-1-23 Date: 31.01.2023 Page: 14 of 15 Table 1: Parts/Material required EXTRA P/N QTY Description Additional part: EX-21113.02 4 Bushing (sandblasted) SB Material kits: SB-NG-1-23- TK 1 Special Tool Kit: includes Ø 17 mm piloted counterbore, Ø 17 mm non-piloted counterbore, and brass guiding sleeve (MS58, Ø 17 x 2,25 mm, l = 15 mm) SB-NG-1-23- HK 1 Hardware Kit: includes all standard hardware as listed below Hardware – as necessary: 35204 4 MS20006-38 Bolt, socket head cap 35400 4 AN5-52A Bolt NA4220 2 AN6-15A Bolt 35101 2 AN6H24A Bolt 700014 8 AN960-516 Washer 31248 10 AN960-616 Washer 35134 4 AN365-524 / MS21045 – 5/16-24 Locknut – Nylon NA3000 2 AN365-624A / MS21045 – 3/8-24 Locknut – Nylon Tools and other material required: 36459(*) 1 Ø 17 mm Counterbore (piloted Ø 3/8”) / Flachsenker mit Führung (Ø 9,52 mm) 36460(*) 1 Ø 17 mm Counterbore (non-piloted) / Flachsenker ohne Führung 36462(*) 1 Brass guiding sleeve (MS58, Ø 17 x 2,25 mm, l = 15 mm) --- 1 Drill bit extension (Øinner 12,5 mm / ½”, l = 125 mm / 5”) Torque wrench with Phillips, Allen and hex nuts, rubber mallet, scissors Pressure sensitive tape (e.g. Flashbreaker tape or equivalent) Acetone, release agent and/or grease (AeroShell Grease 22 or equivalent) Gloves, brush, mixing cups, spatula, plastic bag, safety wire, locking varnish Epoxy resin (Epikote Resin L20 or L285), hardener (Epikure Curing Agent 111 or H285/286/287), cotton flocks Vacuum cleaner, power drill (low rpm & high torque) Crane, support jacks (*) included in Special Tool Kit SB-NG-1-23-TK EXTRA Aerobatic Service Bulletin Aircraft GmbH EXTRA NG EASA.21J.593 Main Gear Attachment Issue: A SB-NG-1-23 Date: 31.01.2023 Page: 15 of 15 Appendix A: Aircraft Type and model: EXTRA NG Serial Number: NG0 Owner: Registration: Total Time: Total landings (if known): _______________________________________________________________________________ The aircraft mentioned above has been modified according to this Service Bulletin. Any abnormality at the main landing gear brackets or the carbon fibre support structure was detected: Yes No If yes, description of damage found (please include pictures): Comments: Company: ________________ Aircraft inspector: ________________ Date: __________________ Please return a copy of this page to: EXTRA Aerobatic Aircraft GmbH Engineering Department / Office of Airworthiness / Quality Assurance Schwarze Heide 21 46569 Hünxe (Germany) Fax. N°: (+49)-2858-9137-42 or email: engineering@ExtraAircraft.com