TECHNICAL BULLETIN 407-20-134
BELL 407GX · Service Bulletins
Overview
This technical bulletin provides instructions for modifying the engine torque indication system of the Bell 407 GXi helicopter. It addresses an issue where the system is over-indicating by 1.6% and outlines the installation of balancing resistors to stabilize the torque signal output.
- Affected model: Bell 407 GXi.
- Modification addresses over-indication of engine torque by 1.6%.
- Installation of balancing resistors is required.
- Compliance is at the customer's option.
- Approximately 24 man-hours needed for completion.
- No warranty credit for parts or labor.
- Engineering design approved by Transport Canada.
- Contact Bell Product Support for questions.
Document
Source
Originally published by bellcustomer.com. Sprinkle hosts a reference copy with an added summary, specifications and searchable full text.
Document details
- Type ·
- Service Bulletins
- Year ·
- 2023
- File size ·
- 461 KB
- Publisher ·
- bellcustomer.com
- Language ·
- en
Specifications & performance
Extracted from this document.
Specifications
- Length of wire 1250-00308-00 (ft) ·
- 7
- Length of wire 1250-00309-00 (ft) ·
- 28
- Length of insulation tubing 2530-00368-00 (ft) ·
- 2
Weight & balance
- Weight balance impact ·
- Negligible
What is the TECHNICAL BULLETIN 407-20-134?
The TECHNICAL BULLETIN 407-20-134 is a service bulletins for the BELL 407GX, dated 2023.
Where does the TECHNICAL BULLETIN 407-20-134 come from?
This copy of the TECHNICAL BULLETIN 407-20-134 was originally published by bellcustomer.com and is hosted on Sprinkle as a free, searchable reference copy.
What year was the TECHNICAL BULLETIN 407-20-134 published?
The TECHNICAL BULLETIN 407-20-134 — the BELL 407GX service bulletins on file — is dated 2023.
Most owners only have the POH. Here's the essential set for the BELL 407GX.
- Pilot's Operating Handbook / AFM
- Checklist
- Maintenance Manual
- Parts Catalog (IPC)
- Systems & Wiring
- Service Bulletins on file
- Type Certificate (TCDS)
More BELL 407GXmanuals & documents
In this document
Description
The bulletin describes the over-indication issue in the engine torque indication system and provides modification instructions.
Compliance
Compliance with the bulletin is optional for customers.
Required Material
Lists materials needed for the modification, including specific part numbers and quantities.
Accomplishment Instructions
Step-by-step instructions for modifying the engine torque indication system.
Special Tools
Lists special tools required to complete the modification.
Publications Affected
Identifies the manuals and publications that are affected by this bulletin.
Safety notes
- Obey all safety precautions when performing maintenance on or near electrical/electronic equipment.
Full document text
TB 407-20-134 Page 1 of 9 Approved for public release. TECHNICAL BULLETIN 407-20-134 7 June 2023 MODEL AFFECTED: 407 SUBJECT: ENGINE TORQUE INDICATION SYSTEM, MODIFICATION OF HELICOPTERS AFFECTED: Serial numbers 54304, 54567, 54805 through 54903, 54905 through 54906, 54908 through 54910 and 54912. [Serial numbers 54904, 54907, 54911, 54913 and subsequent will have the intent of this bulletin accomplished prior to delivery.] COMPLIANCE: At customer’s option. DESCRIPTION: Bell has discovered that the 407 GXi helicopter engine torque indication system is over indicating by 1.6% on the whole span of the engine torque measurement. This technical bulletin provides the instructions to modify the engine torque indication system with the installation of balancing resistors to the engine torque transducer circuitry. The function of the balancing resistors is to stabilize the engine torque signal output. Applicability of this bulletin to any spare part shall be determined prior to its installation on an affected helicopter. APPROVAL: The engineering design aspects of this bulletin are Transport Canada Civil Aviation (TCCA) approved. TB 407-20-134 Page 2 of 9 Approved for public release. CONTACT INFO: For any questions regarding this bulletin, please contact: Bell Product Support Engineering Tel: 1-450-437-2862 / 1-800-363-8023 / productsupport@bellflight.com MANPOWER: Approximately 24 man-hours are required to complete this bulletin. This estimate is 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. MATERIAL: Required Material: The following material is required for the accomplishment of this bulletin and may be obtained through your Bell Supply Center. Part Number Nomenclature Qty (Note) 1250-00308-00 Wire 7 feet (2.13m)(1) 1250-00309-00 Wire 28 feet (8.53m)(1) 110-182H1004TAM Resistor 2 130-057-04B2 Insulation Sleeving 1 130-061-02W2 Insulation Tubing 2 20-108-1 Band 1 31-065-8TB4 Decal 1 DCR-1A-05 Rail 1 2530-00368-00 Insulation Tubing 2 feet (0.61m)(1) M39029/22-191 Contact 1 M39029/56-348 Contact 2 M81824/1-1 Splice 1 M81714/60-22-05 Terminal block 1 M85049/93-10 Shield support ring 1(2) S200-2-W1-22-9 Shield Terminator 2 S200-3-00 Shield Terminator 1 S200-3-01-100HN Shield Terminator 1 S200-3-W1-22-9 Shield Terminator 1 NOTES: 1. Part number is for quantities sold by the foot. Actual quantity required must be specified in the order. TB 407-20-134 Page 3 of 9 Approved for public release. 2. Only required if the replacement is needed. 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 Supply Center. Part Number Nomenclature Qty (Note) Reference * 2000-00731-00 Insulation tape. 1Roll (1) C-548 2000-09120-00 Adhesive Tape 1Roll (1) C-460 PLT2S-C702Y Cable Tie AR C-292 * C-XXX numbers refer to the consumables list in the BHT-ALL-SPM, Standard Practices Manual NOTE 1: Quantity indicated is the format that the product is delivered in. Actual quantity required to accomplish the instructions in this bulletin may be less than what has been delivered. SPECIAL TOOLS: M81969/14-01 Insertion/Extraction tool M81969/16-04 Insertion/Extraction tool M22520/7-01 Crimp tool (or equivalent) M22520/7-05 Turret/Positioner M22520/7-11 Turret/Positioner M81714/69-02 Module extractor A40199 Band crimper (or equivalent) AD-1377 Raychem crimper HT-900 Raychem heat gun (or equivalent) 45-1987 Wire stripper (or equivalent) WEIGHT AND BALANCE: Negligible. ELECTRICAL LOAD DATA: Not affected. REFERENCES: 407-IPB, Illustrated Parts Breakdown, chapter 95 407-MM, Maintenance Manual, chapter 95 407-MM, Maintenance Manual, chapter 98 BHT-ELEC-SPM, Electrical Standard Practices Manual BHT-ALL-SPM, Standard Practices Manual TB 407-20-134 Page 4 of 9 Approved for public release. PUBLICATIONS AFFECTED: 407-IPB, Illustrated Parts Breakdown, chapter 95 407-MM, Maintenance Manual, chapter 98 ACCOMPLISHMENT INSTRUCTIONS: 1. Prepare the helicopter for maintenance. 2. Make sure all electrical power is removed from helicopter. WARNING OBEY ALL THE SAFETY PRECAUTIONS WHEN YOU DO MAINTENANCE ON OR NEAR ELECTRICAL/ELECTRONIC EQUIPMENT (407-MM, chapter 96). -NOTE- Refer to the 407-MM, DMC-407-A-96-00-00-00A-028A-A to identify the exact location of applicable electrical and electronic components. 3. Gain access to the terminal blocks 8TB1 and 8TB4 by removing the left upper and lower console panel, and left upper door.(407-MM, chapter 95 and BHT-ALL-SPM). 4. Gain access to the connector 6J1 and the wire harness between the terminal block 8TB4 and the connector 6J1 by removing the hat bin, the cockpit and cabin headliners, and the instrument panel shroud assemblies (407-MM, chapter 25, and chapter 95). 5. Remove the terminal blocks 8TB4K, 8TB4L, 8TB4M and 8TB4N from the terminal block rail 8TB4 (BHT-ELEC-SPM). 6. Remove and discard the rail. Retain the hardware for the installation of the new rail. 7. Install the new rail (1, Figure 1) with the hardware that was retained in step 6, and bond the decal (2), as shown in figure 1. 8. Install the new terminal block 8TB4P (3) on the rail (1) and reinstall the terminal blocks 8TB4K, 8TB4L, 8TB4M and 8TB4N that were removed in step 5 (BHT-ELEC- SPM). TB 407-20-134 Page 5 of 9 Approved for public release. -NOTE- Refer to BHT-ELEC-SPM to complete the following step. Refer to Figure 1 for wire routing and Figure 2 for the wiring diagram. -NOTE- Actions specified in the “ACTION” column of the Wiring Modifications Instruction Table (Table 1) are as follows: Reterminate – Reposition one end of the specified wire FROM its previous location TO a new location. Add – A new wire or resistor is required between the two
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locations listed in TO and FROM 9. Wire harness modifications instructions (BHT-ELEC-SPM). a. Disconnect connector 6P1 from connector 6J1 (AFT Section). b. Disconnect wire E572C22 from connector 6J1 (AFT Section). Re-route the existing wire E572C22 from connector 6J1 to terminal block 8TB4P. Trim the wire E572C22 to proper length for termination. c. Cut one piece of wire 1250-00309-00 to the length specified in table 1. Mark the wire number E572D22 every 6 to 12 inches (152.4 to 304.8 mm) using M23053/5- 105-9 heat shrink and a permanent ink marker. d. Route wire E572D22 from 8TB4P to connector 6J1 (AFT section). e. Terminate wire E572D22 to connector 6J1 using contact M39029/56-348, insulation tube 130-057-04B2 and shield terminator S200-3-01-100HN. Insert the white and blue wire to connector 6J1 position 67 and 68 respectively. Join the shield wire with connector 6J1 shield. f. Rebuild connector 6J1 and reconnect connector 6P1. g. Cut one piece of wire 1250-00308-00 to the length specified in table 1. Mark the wire number E571F22 every 6 to 12 inches (152.4 to 304.8 mm) using M23053/5- 105-9 heat shrink and a permanent ink marker. TB 407-20-134 Page 6 of 9 Approved for public release. h. Terminate wire E571F22 to terminal block 8TB1K using contact M39029/22-191. Shield wire E571F22, E571C22, E571D22 and E571E22 shall be terminated together at the terminal block 8TB1K. Splice M81824/1-1 and shield terminator S200-2-W1-22-9 can be used to modify the shield wires. Insert the wire to terminal block 8TB1K position Z. i. Terminate wire E572C22, E571F22 and E572D22 to terminal block 8TB4P using contact M39029/22-191. Shield wires E572C22, E571F22 and E572D22 shall be terminated together at the terminal block 8TB4P using shield terminator S200-3- 00, S200-2-W1-22-9 and S200-3-W1-22-9 respectively. j. Insert wire E572C22 white and blue to terminal block 8TB4P position G and J respectively. k. Insert wire E571F22 to terminal block 8TB4P position B. l. Insert wire E572D22 white and blue to terminal block 8TB4P position H and K respectively. m. Identify 6341R1 and 6341R2 to the resistors 110-182H1004TAM by using the insulation tube 130-061-02W2 and a permanent ink marker. n. Insert resistor 6341R1 to terminal block 8TB4P position D and E o. Insert resistor 6341R2 to terminal block 8TB4P position C and L. 10. Reinstall the left upper and lower console panel, and left upper door. (407-MM, chapter 95 and BHT-ALL-SPM) 11. Reinstall the hat bin, the cockpit and cabin headliner interior and the shroud assembly (407-MM, chapter 25 and chapter 95). 12. Do a torque indication operational check (DMC-407-A-95-65-00-00A-320C-A). 13. Make an entry in the helicopter logbook and historical service records indicating compliance with this Technical Bulletin. TB 407-20-134 Page 7 of 9 Approved for public release. Table 1 – Wiring Modifications Instruction Table Action Wire# Length (feet) From (Pin location) Hardware To (Pin location) Hardware Notes Reterminate E572C22 WHT 6J1 (67) M39029/56-348 8TB4P (G) M39029/22-191 1,4,5,9 E572C22 BLU 6J1 (68) M39029/56-348 8TB4P (J) M39029/22-191 1,4,5,9 E572C22 SHLD 6J1 SHLD 8TB4P S200-3-00 5,6 Add E572D22 WHT 28 8TB4P (H) M39029/22-191 6J1 (67) M39029/56-348 1,3,5, 9,10 E572D22 BLU 8TB4P (K) M39029/22-191 6J1 (68) M39029/56-348 1,3,5, 9,10 E572D22 SHLD 8TB4P S200-3-W1-22-9 6J1 SHLD S200-3-01- 100HN 5,6,7, 11 Add E571F22 7 8TB4P (B) M39029/22-191 8TB1K (Z) M39029/22-191 1,3,9 E571F22 SHLD 8TB4P S200-2-W1-22-9 8TB1K S200-2-W1-22-9 6,8,12 Add 6341R1 8TB4P (D) M39029/22-191 8TB4P (E) M39029/22-191 2 Add 6341R2 8TB4P (C) M39029/22-191 8TB4P (L) M39029/22-191 2 NOTES: 1. Cut to length. 2. Identify the resistors by using the insulation tube 130-061-02W2 and a permanent ink marker. 3. Mark the wire number every 6 to 12 inches (152.4 to 304.8 mm) using M23053/5- 105-9 heat shrink and a permanent ink marker. 4. Reposition one end of the specified wire from its previous location to a new location. 5. Remove and reinstall the back shell of connector 6J1 to add or delete the wire. 6. Shield of wires E572C22, E571F22 and E572D22 shall be terminated together at the terminal block 8TB4P. 7. Shield of wire E572D22 shall be terminated with connector 6J1 shield. 8. Shield of wires E571F22, E571C22, E571D22 and E571E22 shall be terminated together at the terminal block 8TB1K. Splice M81824/1-1 can be used to modify the shield of the wires. 9. For the contact PN: M39029/22-191 use crimping tool M22520/7-01 and positioner M22520/7-11. The insert/extract tool is M81969/16-04. 10. For the contact PN: M39029/56-348 use crimping tool M22520/7-01 and positioner M22520/7-05. The insert/extract tool is M81969/14-01 11. For the shield termination band 20-108-1 use crimping tool A40199. 12. For the splice M81824/1-1 use crimping tool AD-1377. TB 407-20-134 Page 8 of 9 Approved for public release. FIGURE 1 – Terminal block, rail, and wire harness installation TB 407-20-134 Page 9 of 9 Approved for public release. Pre TB 407-20-134 Post TB 407-20-134 FIGURE 2 – Torque transducer modification wiring diagram