SUBJECT: FUEL SYSTEM FLOW SWITCHES, P/N , , -003, -101 AND -103, REPLACEMENT OF

Transcription

1 ALERT SERVICE BULLETIN 206L June 1988 Revision A, 26 March 2013 MODEL AFFECTED: 206L and 206L-1 SUBJECT: FUEL SYSTEM FLOW SWITCHES, P/N , , -003, -101 AND -103, REPLACEMENT OF HELICOPTERS AFFECTED: Model 206L, serial number through and through Model 206L1, serial number through NOTE- Those helicopters that have previously had T.B. 206L Rev. A, accomplished on them are in compliance with this bulletin. COMPLIANCE: For those helicopters that have not previously complied with T.B. 206L Rev. A, accomplish at the next scheduled 100 hour or annual inspection after receipt of parts, but in no case later than 30 November DESCRIPTION: Revision A is issued to show the part number and location of replacement fuel hoses. Previous rubber fuel hoses are now replaced with Teflon hoses. Reports of accidents and incidents indicate that a significant number of 206L and 206L-1 operators have not replaced the P/N 206 flow switches with the newer P/N 205 flow switches per T.B. 206L Rev. A. The old style P/N 206 fuel flow switches, which activate the L/FUEL PUMP and R/FUEL PUMP caution lights, may fail due to contaminants in the fuel system. Page 1 of 26

2 Contaminants in the fuel system can also render the fuel transfer system inoperative by clogging the manifold and dual ejector pump nozzles. Operations Safety Notice 206L-81-3, was issued to advise pilots to heed the FUEL LOW warning light, despite indications of having an adequate fuel quantity on board for continued flight operations. Operations Safety Notice 206L was issued to inform operators of an incident that resulted from fuel starvation caused by fuel contamination. Information Letter 206L was also issued to explain in detail the operation of the fuel system. The Model 205/212 helicopter flow switches have been found to be less susceptible to contaminants. These switches are larger in capacity and are the Venturi type rather than the poppet valve type as were earlier switches. The installation of the new switches and the relocation of the in-line filters will enhance the reliability of the fuel transfer system. Personnel are again cautioned to ensure that fuel supplies, servicing equipment and the helicopter fuel tanks are kept clean and free of contaminants at all times. Compliance with this A.S.B. supersedes T.B Rev. A and cancels T.B and T.B. 206L Rev. A. 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 16.0 man-hours are required to complete this bulletin. An additional 3.0 man-hours may be required for flushing the aft fuel tank. Man-hours are based on hands-on time, and may vary with personnel and facilities available. WARRANTY: There is no warranty credit applicable for parts or labor associated with this bulletin. Page 2 of 26

3 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 Retrofit Kit, Fuel Flow Switches 1 kit Consists of the following parts: Nut 2 ea Switch, Flow 2 ea Stiffener 1 ea Stiffener 1 ea Tube 1 ea Tube 1 ea Clip Assy 2 ea Clip Assy 2 ea V000A080A Hose Assy 2 ea (Note 1) V000A136A Hose Assy 1 ea (Note 2) V000A157A Hose Assy 1 ea (Note 3) 85T4-1 Insulation Tube (4 inch) 2 ea 85T4-7 Insulation Tube (6 inch) 2 ea 85T4-7 Insulation Tube (8 inch) 2 ea 85T Insulation Tube (9 inch) 2 ea 869A6TT Check Valve 2 ea AN832-6D Union 2 ea AN833-6D Elbow 2 ea AN924-6D Nut 6 ea AN960JD10L Washer 7 ea M A Splice 4 ea MS Strap 18 ea MS20426AD4-4 Rivet 6 ea MS20470AD4-4 Rivet 22 ea MS21042L3 Nut 2 ea MS21919WDG2 Clamp 2 ea MS21919WDG3 Clamp 1 ea MS21919WDG6 Clamp 1 ea MS Screw 1 ea MS Screw 6 ea MS Packing 6 ea Note 1: For spare part replacement use CR-0085 for the forward left-hand side (going to the left side flow switch) and V000D80 in the aft position (going to the in-line filter). Page 3 of 26

4 Note 2: For spare part replacement use V000D136 hose assy. Note 3: For spare part replacement use CR-0157 hose assy. 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 ,TY III (MIL-S-8774) Sealant, Type A or B (Proseal 706, PRC 1321 GG200, GG700 or CS3300) See Figure 2 Packings (In-line filter) A/R See Figure 3 Packings (Ejector pump) A/R See Figure 4 Packings (Manifold) A/R A/R SPECIAL TOOLS: None required. WEIGHT AND BALANCE: Longitudinal Weight Change Arm Moment Lbs 90 inch in-lbs ELECTRICAL LOAD DATA: Not affected. REFERENCES: 206L Maintenance Manual, Volume 1 206L Maintenance Manual, Volume 2 206L Illustrated Parts Catalog 206L-1 Maintenance Manual, Volume 1 206L-1 Maintenance Manual, Volume 2 206L-1 Illustrated Parts Catalog OSN 206L-81-3, Engine Flameouts Due to Fuel System Contaminates. OSN 206L-87-22, Installation of P/N Fuel Flow Switches. ASB 206L-77-2, Installation of Fuel Ejector Pump Filters, P/N TB 206L-78-2, Low Fuel Indicator Switch, P/N Page 4 of 26

5 TB 206L RA. In-Line Fuel Filters, P/N , Relocation of TB 206L-81-65, Fuel System Flow Switches, P/N , , -003, and -101, Replacement of. TB 206L RA, Fuel System Flow Switches, P/N , , -003, -101 and -103, Replacement of. Allison 250-C20 Series Operation and Maintenance Manual, 10W2. Allison 250-C28 Series Operation and Maintenance Manual, 16W2. IL 206L-86-39, Model 206L/L-1/L-3 Fuel System "Flameouts/Starvation". PUBLICATIONS AFFECTED: 206L Maintenance Manual, Volume 1, Chapters 28 and L Maintenance Manual, Volume 2, Chapter L Illustrated Parts Catalog. 206L-1 Maintenance Manual, Volume 1, Chapter 28 and L-1 Maintenance Manual, Volume 2, Chapter L-1 Illustrated Parts Catalog. ACCOMPLISHMENT INSTRUCTIONS: 1. Prepare helicopter for maintenance. Disconnect battery and/or external power supply. 2. Defuel helicopter. Ref. 206L Maintenance Manual and 206L-1 Maintenance Manual. 3. Remove passenger aft facing seat backs and cushions. Ref. 206L Maintenance Manual and 206L-1 Maintenance Manual. 4. Remove molded plastic cover from aft side of vertical control tunnel (broom closet). 5. Remove seat installation cover, P/N or -105, between left and right aft facing passenger seats and cover P/N NOTE- Faying surfaces of fume cover, tunnel and web panel are coated with sealant for fume tightness. Use care to prevent damage during parts removal. 6. Remove fume cover, P/N , tunnel, P/N , and web panel, P/N , (which attaches to tunnel at forward bulkhead) to gain access to fuel flow switches and attaching parts. 7. Disconnect electrical connectors from flow switches and disconnect clamp installation attaching wires to inboard flow switch tube. Move wire harness forward of T shaped interconnect tube so it is free of work area. Page 5 of 26

6 8. Helicopters S/N through which do not incorporate T.B. 206L (See Figure 1, sheet 1). a. Remove clamp installations at Sta. 100 and 116. b. Remove tube, P/N or , and tube, P/N or c. Remove tubes, P/N , , and d. Remove tubes, elbow, P/N AN833-6D, nut, P/N AN924-6D, and union, P/N AN815-6D, from in-line filters, P/N Retain filters for cleaning and re-use. 9. Helicopters, S/N through which do incorporate T.B. 206L (See Figure 1, sheet 2). a. Remove clamp installation at Sta b. Remove tubes, P/N and , with in-line filters, P/N , and hoses, P/N V000A094 and 157. c. Remove sleeve material, P/N 85T4-1000, from in-line filters and remove attaching tubes and hoses, including unions, P/N AN815-6D. (See View A-A). Retain filters for cleaning and re-use. d. Remove tubes, P/N and , from forward side of flow switches and ejector pump. 10. Install protective covers over openings on the aft flow tubes, P/N and -003, and over nozzles at ejector pump. 11. Remove existing flow switches from floor panel by removing attaching screws, washers and spacers. 12. Disassemble and clean the removed in-line filters, P/N (See Figure 2 for filter types). a. Remove fitting or head/filter from end of case or housing and discard packing. Withdraw element or filter assembly if required. b. Clean parts ultrasonically. If equipment is not available, agitate parts in dry cleaning solvent (P-D-680) until free of contaminates. Dry parts using clean, dry, low pressure shop air. c. Install element or filter into case or housing as shown in Figure 2. Place new packing, P/N (See Figure 2), on fitting or head/filter and install in case. Page 6 of 26

7 d. Install protective covers over opening in filters. 13. Remove protective covers from ejector pump nozzles. Remove nozzles from pump and clean using a stiff fiber brush. Do not distort nozzle jet. (See Figure 3, Sheet 1 and Sheet 2, for ejector pump types). Place new packings on nozzles and install in pumps. Reinstall protective covers over pump nozzles. 14. Helicopters S/N through If the in-line filters (Step 12) were contaminated with foreign matter the fuel manifold, P/N , shall be removed and cleaned. (See Figure 4). a. Remove aft passenger seat backs and cushions. Reference: 206L Maintenance Manual and 206L-1 Maintenance Manual. b. From aft fuel cell door remove the two screws, P/N MS , and washers, P/N AN960JD416L, which retain fuel cell to door. (See Figure 4, View A-A). c. Remove the 24 screws, P/N MS , and washers, P/N AN960JD10L, which retain the cell door to the bulkhead assembly. d. Open fuel cell at split line by removing the 18 bolts, P/N AN4-4A, and washers, P/N AN960JD416L. (See Figure 4, View A-A). e. Gain access to manifold and tag the 5 attaching hoses to ensure correct reinstallation. (See Figure 4, for part numbers). On the 4 lower hoses, recommend a string be tied near each fitting and retained outside the cell. This will prevent hoses from falling to bottom of cell. Disconnect the 5 hoses from unions on manifold. Install protective caps in each hose fitting. f. Disconnect clamp installation attaching transfer system interconnect tube to manifold. Leave hardware in place on tube. g. Remove manifold from fuel cell by removing the two attaching bolts, P/N AN3-13A, and washers, P/N AN960JD10L. h. Disassemble, clean and reassemble manifold. Page 7 of 26

8 -NOTE- It is not necessary to remove the 5 union fittings from manifold ports for cleaning. Index mark valve assembly positions prior to removal. Do not intermix valve parts, positions, or remove the spring guides which are press fitted inside the manifold inlet ports. Do not disassemble poppet valves. (1) Cut lockwire and remove valve assemblies from manifold. Remove plug, P/N AN814-D6, and discard all packings. (See Figure 4, Sheet 2) (2) Clean parts ultrasonically. If equipment is not available, agitate parts in dry cleaning solvent (P-D-680) until free of contaminates. Dry parts using clean, dry, low pressure shop air. i. Place new packing, P/N MS , on plug, P/N AN814-D6, and install in manifold. j. Place two new packings, P/N MS AND MS , on valve body and one new packing, P/N MS , on poppet valve. k. Place poppet valve with new packing into valve body and spring on top of poppet valve. Holding both manifold and valve assembly upright and vertical, carefully thread valve into manifold. Tighten valve assembly into manifold to a torque of 27 to 33 foot pounds. Repeat procedure for installation of opposite valve assembly. l. Using a 4 to 5 inch length of weld rod or equivalent, 1/8 inch or smaller diameter, carefully insert into inlet of valve assembly and lightly depress poppet valve approximately 1/16 inch into open position, then release. Poppet valve is lightly spring loaded and must return to the closed position. In the event the valve does not return to the closed position, disassemble valve assembly and check valve for binding and spring for proper seating in spring seat. m. Safety valve assemblies to manifold using or inch lockwire, P/N MS20995C20 or C32. n. If removed, install five unions, P/N AN815-6D, with new packings, P/N MS o. Install manifold into fuel cell and secure with previously removed two bolts, P/N AN3-13A, and washers, P/N AN960JD10L. Page 8 of 26

9 p. Connect interconnect tube to manifold with previously disconnected hardware left on tube. q. Recover fuel transfer hoses, P/N V000V232 and V260. Connect hose, P/N V232, to union on bottom left side of manifold and, P/N V260, to union on right bottom side of manifold. (See Figure 4, Sheet 1). r. Recover fuel boost pump hoses, P/N V225C175. Connect hose from forward boost pump to union on aft left side of manifold and the other hose to union on the aft right side of manifold. s. Recover fuel supply hose, P/N V000V265. Connect hose to union on top of manifold. Check torque on all hose fittings to ensure tightness and that interconnect tube is securely clamped. t. Prior to closing fuel cell, recommend that, at this time, aft fuel cell be thoroughly flushed and cleaned in accordance with Step 15. u. Close aft fuel cell at split line using the previously removed 18 bolts, P/N AN4-4A, and washers, P/N AN960JD-416L. Evenly torque bolts to 50 to 70 inchpounds. v. Install cell door to bulkhead with the previously removed 24 screws, P/N MS , and washers, P/N AN960JD10L. w. Install aft passenger seat cushions and backs. Ref: 206L Maintenance Manual or 206L-1 Maintenance Manual. 15. Helicopters S/N through If the in-line filters (Step 12) were contaminated with foreign matter, the aft fuel cell shall be thoroughly flushed. a. Remove boost pump assembly from aft fuel cell. Ref: 206L Maintenance Manual or 206L-1 Maintenance Manual. b. Remove fuel cell filler cap and thoroughly flush cell interior with dry cleaning solvent (P-D-680). After flushing, wipe the bottom cell interior dry using soft lint free cloths. c. Install boost pump assembly into aft fuel cell. Ref: 206L Maintenance Manual or 206L-1 Maintenance Manual. 16. Modify the removed fume cover, P/N to (See Figure 5.) a. Locate stiffeners, P/N and -115, to lower side of cover as shown in Figure 4. Index mark location for rivet holes. b. Drill rivet holes in cover and stiffeners. Deburr rivet holes. Secure stiffeners to cover with rivets, P/N MS20426AD4-4 and MS20470AD4-4. Page 9 of 26

10 c. Drill four 0.31 inch diameter holes through cover and stiffeners at locations shown in Figure 5. Deburr holes and touch up with primer. 17. On helicopters S/N through which incorporate interconnect hose, P/N , secure clip, P/N , with screw, P/N MS , and washer, P/N AN960JD10L. Location for screw is at forward mounting point for the removed inboard flow switch. (See Figure 6, View A, Sheet 1 and Sheet 2). 18. Assemble the two new flow switches, P/N (See Figure 6). a. Locate switch "flow" arrow. (See Figure 6, Sheet 1, View B). To each switch outlet port install union, P/N AN832-6D, with clip (nutplate flange forward) P/N , two nuts, P/N AN924-6D, and packing, P/N MS Do not tighten nuts at this time. b. To each switch inlet port install elbow, P/N AN833-6D, with nut, P/N AN924-6D, clip (nutplate flange forward) P/N , nut, P/N , and packing, P/N MS Do not tighten nuts at this time. c. Temporarily mount each switch to lower side of fume cover, P/N , through clips with two screws, P/N MS , and washers, P/N AN960JDlOL. d. Adjust unions, elbows and torque nuts to secure switches in mounting clips and seat packings. Elbows should be pointing down and approximately 30 degrees to 45 degrees inboard when viewed from rear. e. Remove switches from fume cover and pencil mark each switch for location (left and right). Remove protective covers from nozzles of dual ejector pumps. 19. Locate left switch into position and install new tube, P/N (See Figure 6, Sheet 1). Install right switch and new tube, P/N Temporarily place fume cover over switches to check alignment of screw holes with clips, loosen tubes and adjust as required. Do not install cover at this time. 20. Assemble and install new hoses to left flow switch and connect to lower flow tube at main tank. (See Figure 6, Sheet 3, Views C-C and D-D.) a. Place new packing, P/N MS , on check valve, P/N 869A-6TT, and install into outlet side of one in-line filter, P/N Check to ensure flow arrows are in the same direction. b. Install new hose, P/N V000A080A (replaced by CR-0085), to check valve and hose, P/N V000A136 (replaced by V000D136), to opposite end of in-line filter. Page 10 of 26

11 c. Slide a length of sleeve material, P/N 85T4-1000, onto hoses so that check valve and in-line filter are covered. Secure sleeve with two straps, P/N MS , at outboard ends of check valve and in-line filter. d. Connect hose, P/N V000A080A (replaced by CR-0085) to elbow on left flow switch and hose, P/N V000A136A (replaced by V000D136), to lower flow tube at main fuel tank. 21. Assemble and install new hoses to right flow switch and connect to main fuel tank upper flow tube. (See Figure 6, Sheet 3, Views C-C and D-D). a. Place new packing, P/N MS , onto remaining check valve, P/N 869A- 6TT, and install into in-line filter. Check to ensure flow arrows are in the same direction. b. Install new hose, P/N V000A157A (replaced by CR-0157), to check valve and hose, P/N V000A080A (replaced by V000D80) to in-line filter. c. Slide remaining length of sleeve material, P/N 85T5-1000, onto hoses so that check valve and in-line filter are covered. Secure sleeve with two straps, P/N MS , at outboard ends of check valve and in-line filter. d. Connect hose, P/N V000A157A (replaced by CR-0157), to elbow on right flow switch and hose, P/N V000A080A (replaced by V000D80), to upper flow tube at main fuel tank. e. Secure the hose assemblies together with four straps, P/N MS Locate one strap at aft end of each in-line filter and two at the forward crossing point of the two forward hoses. 22. Modify flow switch wiring harness and flow switch wires as follows: (See Figure 7). a. Clamp wiring harness to tube, P/N , with new clamp hardware as shown in Figure 7. b. On helicopters equipped with ejector pump, vendor P/N 612E109, which has a retaining bolt across upper surface, clamp wiring harness to bolt with new clamp hardware shown in Figure 7. c. Remove electrical connectors from flow switch wiring harness and terminals from wiring on flow switches. d. Slide an 8 inch length of insulation tubing, P/N 85T4-7, over each pair of wiring harness wires Nos. E90A22, E89A22N and E88A22, E87A22N. Trim wires, as required, and install splices, P/N M81714/11-20A, to each wire end. Page 11 of 26

12 e. Slide a 4 inch length of insulation tubing, P/N 85T4-1, over each pair of splices, do not secure at this time. f. Slide a 6 inch length of insulation tubing, P/N 85T4-7, over each pair of flow switch wires, red and white. Trim wires as required, and install into splices. Refer to wiring diagram shown in Figure 7. g. Reposition the large 4 inch length of insulation tubing, P/N 85T4-1, to cover splices. Secure tubing at each end using four straps, P/N MS h. Secure small tubing, P/N 85T4-7, at each end using four straps, PIN MS i. Fold loose wiring into bundle and secure with two straps, P/N MS , near clamp location on ejector pump bolt or at tube, P/N Ensure work area is clear and clean of foreign objects and all connections are tight and secure. 24. Prepare helicopter for refueling and application of electrical power. a. Check that the CAUTION LIGHT circuit breaker is closed and open FUEL BOOST LEFT and RIGHT circuit breakers. Check that FUEL VALVE switch is OFF, then turn BATTERY switch on. b. Press CAUTION LT test switch and verify all caution segments illuminate. Check that FUEL, LOW, R/FUEL PUMP and L/FUEL PUMP caution segments remain illuminated. -NOTE- For installation of the FUEL LOW indicator switch and circuit on helicopters S/N through 45111, refer to T.B. 206L c. Refuel helicopter with approximately 9 to12 gallons of fuel. Ref: 206L Maintenance Manual or 206L-1 Maintenance Manual. d. Check that FUEL LOW caution light extinguishes when tank is serviced with approximately 9.5 gallons (62 to 65 pounds) of useable fuel. e. Service helicopter until fuel level in main tank remains approximately 1 to 2 inches above the 1.5 inch diameter interconnect tube (as viewed through filler cap opening). This will ensure that the forward fuel tanks are full. Thoroughly check all fuel lines and fittings for leakage, correct as required. f. Defuel main tank (only) until fuel level is approximately 1 to 2 inches above boost pumps (as viewed through filler cap opening). Page 12 of 26

13 25. Perform an operational check of the boost pumps and flow switches as follows: a. Check that FUEL BOOST LEFT and FUEL BOOST RIGHT circuit breakers are open. b. Check that CAUTION LIGHTS circuit breaker is closed. Turn BATTERY switch on. R/FUEL PUMP and L/FUEL PUMP caution light segments must be illuminated. c. Close FUEL BOOST LEFT and FUEL BOOST RIGHT circuit breakers and turn FUEL VALVE switch ON. Check that R/FUEL PUMP AND L/FUEL PUMP caution lights extinguish and that the lights are correlated with pump breakers. d. Allow both boost pumps to operate several minutes and note the fuel flow return from the forward tanks into the main tank through the 0.75 inch diameter return tube (as viewed through filler cap opening). (1) For future reference and troubleshooting note the fuel flow volume that is returning through the 0.75 inch diameter tube. Check with both boost pumps operating and then with one pump inoperative. (2) Possible causes for a reduction to return fuel flow are: empty or blocked forward cell inlets or outlets; clogged nozzle in the ejector pump; inoperative boost pump; clogged fuel line, in-line filter, or flow switch. Clogged check valves in the fuel manifold will cause an increase in return fuel flow. e. Turn FUEL VALVE and BATTERY switch OFF. 26. Refuel helicopters to maximum or operational capacity. Thoroughly check all fuel lines and fittings for leaks, correct as required. 27. Install fume cover, tunnel and web panel as follows: CAUTION Faying surface of fume cover, tunnel and web panel over fuel system components must be sealed for fume tightness. a. Mix sealant, P/N Type III, 100 parts to 12 parts by weight per manufacturers' instructions. b. Apply a film of sealant to faying surfaces of fume cover, tunnel and web panel that mate with structure. Page 13 of 26

14 c. Install fume cover to structure. Secure the flow switch to cover with screws, P/N MS , and washers, P/N AN960JD10L. d. Install web panel, tunnel and seat installation cover to structure with previously removed hardware. Fill all gaps and voids around entire periphery of web panel, tunnel and fume cover to ensure fume tightness. 28. Install passenger compartment floor carpeting and molded plastic cover aft side of vertical control tunnel (broom closet). 29. Install passenger aft facing seat backs and cushions. Ref: 206L Maintenance manual or 206L-1 Maintenance Manual. 30. Prior to initial engine ground run up, bleed trapped air from the fuel control assembly. Ensure that the fuel being delivered to the engine fuel nozzle is free of air. Reference: Allison 250-C20 Series Operation and Maintenance Manual, 10W3. Allison 250-C28 Series Operation and Maintenance manual, 16W Prepare helicopter for flight operations. Page 14 of 26

15 Figure 1 - Flow switch and in-line filter installation effectivity through (sheet 1 of 2). Page 15 of 26

16 Figure 1 - Flow switch and in-line filter installation effectivity: and subsequent. (sheet 2) Page 16 of 26

17 Figure 2 - In-line fuel filters, P/N Page 17 of 26

18 Figure 3 - Dual fuel ejector pump (sheet 1 of 2) Page 18 of 26

19 Figure 3 - Dual fuel ejector pump (sheet 2) Page 19 of 26

20 Figure 4 - Fuel manifold, P/N (sheet 1 of 2) Page 20 of 26

21 Figure 4 - Fuel manifold, P/N (sheet 2) Page 21 of 26

22 Figure 5 - Modification of fume cover, P/N to -111 Page 22 of 26

23 Figure 6 - Installation of flow switches, P/N (sheet 1 of 3) Page 23 of 26

24 Figure 6 - Installation of flow switches, P/N (sheet 2) Page 24 of 26

25 Figure 6 - Installation of flow switches, P/N (sheet 3) Page 25 of 26

26 Figure 7. Modification of flow switch wiring harness Page 26 of 26