TECHNICAL BULLETIN May 2013 Revision A, 11 July 2013 SUBJECT: TAIL ROTOR GEARBOX 3 PIECE FAIRING, MODIFICATION OF

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1 TECHNICAL BULLETIN May 2013 Revision A, 11 July 2013 MODEL AFFECTED: 206A/B SUBJECT: TAIL ROTOR GEARBOX 3 PIECE FAIRING, MODIFICATION OF HELICOPTERS AFFECTED: Serial number 004 through COMPLIANCE: At customer s option DESCRIPTION: This bulletin gives instructions how to install the 3 piece tail rotor gearbox fairings when tailboom is installed or when a support fitting A is fitted to tailboom assemblies , -067, -071, -097, and Revision A of this Bulletin makes a correction to the MATERIAL section, change to figure 1 in sheet 1 for addition of view J, dimensional review from sheet 4, and Part Number corrections to sheet 6. APPROVAL: The engineering design aspects of this bulletin are Transport Canada Civil Aviation (TCCA) approved. CONTACT INFO: For any questions regarding this bulletin, please contact: Bell Helicopter Product Support Engineering - Light Helicopters Tel: / / pselight@bellhelicopter.textron.com MANPOWER: Approximately 10 man-hours are required to complete this bulletin. This estimate is based on hands-on time, and may vary with personnel and facilities available. Page 1 of 13

2 WARRANTY: There is no warranty credit applicable for parts or labor associated with this bulletin. MATERIAL: Required Material: The following material is required for the accomplishment of this bulletin and may be obtained through your Bell Helicopter Textron Supply Center. Part Number Nomenclature Qty Washer Fwd doubler Aft doubler Fwd seal Aft seal Fwd shim Aft shim Fwd doubler shim Aft doubler shim Shim Aft edge shim Angle Angle 1 MS20426AD3-2 Rivet 14 (note 1) MS20426AD3-3 Rivet 4 (note 1) MS21075L3N Nutplate 9 MS Screw 2 MS Screw 7 MS Screw 2 NAS1097AD4-3 Rivet 11 (note 1) NAS1097AD4-4 Rivet 13 (note 1) NAS Nutplate 2 NAS1149D0332J Washer 13 Note: 1. Length of rivets may vary from one aircraft to another. The correct length of rivets must be determined at installation. Page 2 of 13

3 Consumable Material: The following material is required to accomplish this bulletin, but may not require ordering, depending on the operator s consumable material stock levels. This material may be obtained through your Bell Helicopter Textron Supply Center. Part Number Nomenclature Qty Reference * Wet layup adhesive 1 C Adhesive 1 C Cheesecloth 1 C Adhesive 1 C Isopropyl alcohol 1 C-385 (note 2) Fiberglass 1 C-404 (note 1) Abrasive paper 1 C-423 Notes: 1. Order by pound. 1 Lb = sheet of 36 inches wide X 72 inches long 2. As an alternate, use ethyl alcohol (C-339) or toluene (C-306). * C-XXX numbers refer to the consumables list in BHT-ALL-SPM Standard Practices Manual SPECIAL TOOLS: None required WEIGHT AND BALANCE: Not affected ELECTRICAL LOAD DATA: Not affected REFERENCES: BHT-206A/B-SERIES-MM Maintenance Manual BHT-206A/B-SERIES-IPB Illustrated Parts Breakdown BHT-ALL-SPM Standard Practice Manual BHT-ALL-SRM Structural Repair Manual BHT-ELEC-SPM Standard Practice Manual PUBLICATIONS AFFECTED: BHT-206A/B-SERIES-IPB Illustrated Parts Breakdown Page 3 of 13

4 ACCOMPLISHMENT INSTRUCTIONS: Modification of the 3 piece tail rotor gearbox fairing 1. If not already done, clean the forward fairing (1, Figure 1), aft fairing (2) and lower fairing (3), (BHT-ALL-SPM, Chapter 5). 2. Fill the 9 screw holes (4) of forward fairing (1), aft fairing (2) and lower fairing (3) with epoxy resin at locations shown in Figure 1, views B, I, and J. (BHT-ALL-SRM, section ). Finish with one fiberglass ply on the both side surface of the holes (4) and fair the contours (BHT-ALL-SRM, section 4-4-3, application B). 3. Cut the shaded section of the frame (5) as shown in Figure 1 view F to prevent fouling with support fitting (24). 4. Temporarily install the forward fairing (1), aft fairing (2) lower fairing (3), and frame (5) on tailboom using screw holes available (BHT-206A/B-SERIES-MM-5, Chapter 53) and applicable hardware). Ensure all parts are stable. 5. Place the fwd doubler (6) on the forward fairing (1) and aft doubler (7) on the aft fairing (2) at location shown in Figure 1, detail A and view B. CAUTION It is recommended to install a piece of wood or Masonite against the opposite face of the fairings (1 and 2) to prevent damage to the tail rotor gearbox support fitting (24) during drilling process. 6. Drill holes for eight rivets (8) in the forward doubler (6), forward fairing (1), aft doubler (7) and aft fairing (2) using inch diameter drill. 7. Countersink each hole of rivet (8) on the external surface of doublers (6 and 7). 8. Temporarily install the forward doubler (6) to the fwd fairing (1) and aft doubler (7) to the aft fairing (2) with clecos. 9. Remove fairings (1, 2, and 3) from the tailboom. 10. Place shim (9) inboard of fwd fairing (1) at location shown in Figure 1, detail A and view B. 11. Drill holes for three rivets (10) in the forward doubler (6), fwd fairing (1), and the shim (9) using inch diameter drill. 12. Countersink holes of rivets (10) on forward doubler (6) and shim (9) as shown in Figure 1 section E-E. Page 4 of 13

5 13. Place the shim (11) and two doubler shims (12) on the fairing (1) at location shown in Figure 1, detail A, view B, section C-C. 14. Place the shim (13) and the two doubler shims (14) on the fairing (2) at location shown in Figure 1, detail A, view B and section D-D. CAUTION It is recommended to install a piece of wood or Masonite against the opposite face of the fairings (1 and 2) to prevent damage separation of the glass layers during drilling process. 15. Drill thirteen holes for rivets (15) in shims (11, 12, 13 and 14) and doublers (6 and 7) using inch diameter drill. 16. Remove doublers (6 and 7) and shims (11, 12, 13, 14, and 9), deburr all holes. Countersink holes of rivet (15) on the external surface of doublers (6 and 7) and external surface of shims (11, 12, 13, and 14) for installation of rivets (15) flush both sides. -NOTE- Use a rivet squeezer to install the solid rivets in the glass fiber laminates to prevent cracking of the matrix. 17. Coat the faying surface of fairings (1 and 2) doublers (6 and 7), shims (11, 12, 13, 14 and 9) with adhesive (C-317). 18. Use rivets (8) and washer (16) to secure the forward doubler (6) on the forward fairing (1) and aft doubler (7) on the aft fairing (2) as shown in Figure 1, view B, section C-C and section D-D. 19. Secure shim (9) on the forward fairing (1) with rivets (10) flush both sides as shown in Figure 1 section E-E. Secure shims (11 and 12) on the forward doubler (6) and forward fairing (1) and shims (13 and 14) on the aft doubler (7) and aft fairing (2) with rivets (15) flush both side as shown in Figure 1, view B, section C-C and section D-D. 20. Clean excessive adhesive (C-317) squeeze out. Ensure no voids exist around the edges of doublers (6 and 7) and shim (11, 12, 13, 14 and 9) after final installation. Page 5 of 13

6 21. Install the fwd seal (17) and aft seal (18) as follow: a. Coat the faying surface between seals (17 and 18), shims (11 and 13) and fairings (1 and 2) with adhesive (C-324). b. Place the seal (17) on the shim (11) and fwd fairing (1) at location shown in Figure 1, detail A, view B and section C-C. c. Place the seal (18) on the shim (13) and aft fairing (2) at location shown in Figure 1, detail A, view B and section D-D. 22. Install all nutplates associated with the 3 pieces fairings as follow: a. Position shim (23) and angles (20 and 21) above the existing 7 and 8 o clock holes of tail rotor support fitting (24) at location shown in Figure 1, view F. b. Transfer holes from the fitting (24) to the shim (23) and angles (20 and 21). Deburr drilled holes. c. Install shim (23) and angles (20 and 21) with screw (25), washers (26), and nut (27). d. Position nutplates (19) on angles (20 and 21) and drill rivet holes, see Figure 1 view G and H. Deburr holes and install nutplates (19) on angles (20 and 21) with rivets (22). e. Drill two holes for nutplates (28) on the tail rotor gearbox support fitting (24) as shown in Figure 1, view F and view I. Deburr holes and install nutplates (28) with rivets (29). f. Temporarily install fairings (2 and 3) on tailboom using screw holes available (BHT-206A/B-SERIES-MM-5, Chapter 53) and applicable hardware. Ensure all parts are stable. g. Mark position of the two holes for nutplates (28) to the fairings (2 and 3). h. Mark position of the two holes for nutplates (19) to the fairing (2). i. Remove fairings (2 and 3). j. Transfer the holes for nutplates (28) to fairings (2 and 3) and nutplates (19) to the fairing (2) as shown in figure 1, view H. k. Temporarily install fairings (1, 2, and 3) on tailboom using screw holes available (BHT-206A/B-SERIES-MM-5, Chapter 53). l. Transfer the five holes for nutplate (32) to the closure skin (36) Figure 1 view B, section C-C, and section D-D. Page 6 of 13

7 m. Transfer the two screw holes (37) to the closure skin (36) at location shown in Figure 1, view I. n. Remove fairings (1, 2, and 3) from the tailboom. o. Deburr drilled holes and install the two nutplates (38) with rivets (39) and the five nutplates (32) with rivets (33) on far side of closure skin (36). 23. Make an entry in helicopter logbook and historical service records indicating compliance with of this bulletin. Page 7 of 13

8 Figure 1. Modification of the tail rotor gearbox fairings (sheet 1 of 6) Page 8 of 13

9 Figure 1. Modification of the tail rotor gearbox fairings (sheet 2) Page 9 of 13

10 Figure 1. Modification of the tail rotor gearbox fairings (sheet 3) Page 10 of 13

11 Figure 1. Modification of the tail rotor gearbox fairings (sheet 4) Page 11 of 13

12 Figure 1. Modification of the tail rotor gearbox fairings (sheet 5) Page 12 of 13

13 Figure 1. Modification of the tail rotor gearbox fairings (sheet 6) Page 13 of 13