RADAR ALTIMETER CABLES, REPLACEMENT OF. HELICOPTERS AFFECTED: Serial numbers through

Transcription

1 TECHNICAL BULLETIN October 207 MODEL AFFECTED: SUBJECT: 42EP RADAR ALTIMETER CABLES, REPLACEMENT OF. HELICOPTERS AFFECTED: Serial numbers through [Serial number 3704 and subsequent will have the intent of this bulletin accomplished prior to delivery.] COMPLIANCE: At customer s option. DESCRIPTION: Bell Helicopter has received reports of fluctuations and incorrect altitude information being provided by the Radar Altimeter (RAD ALT) system. On power up, the RAD ALT may display erroneous altitude information before indicating zero foot. The investigation revealed that the length of the RAD ALT coax cables between the RAD ALT transceiver and the tailboom disconnect was incorrect. This Technical Bulletin provides instruction to replace the existing coax cables (P/N: /-05) with longer cable assemblies (P/N: /-). 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 FAA approved. Page of 0

2 CONTACT INFO: For any questions regarding this bulletin, please contact: MANPOWER: Bell Helicopter Product Support Engineering - Medium Helicopters Tel: / / psemedium@bh.com Approximately 8.0 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 Helicopter Textron Supply Center. Part Number Nomenclature Qty (Note) NAS NAS NAS NAS49DO332J MS299WDG7 MS299WDG NAS43DD3-24N NAS43DD3-40N NAS43DD3-48N NAS43DD3-72N MS20470AD4-XX Cable Assembly Cable Assembly Screw Screw Screw Washer Clamp Clamp Spacer Spacer Spacer Spacer Rivet Nut () 2 NOTE : Rivet MS20470AD4 length to be determined at installation. Page 2 of 0

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 (Note) Reference * AS00026 Safety Wire AR C-508 * C-XXX numbers refer to the consumables list in the BHT-ALL-SPM, Standard Practices Manual SPECIAL TOOLS: None required. WEIGHT AND BALANCE: No significant effect. ELECTRICAL LOAD DATA: Not affected. REFERENCES: BHT-42-IPBS-EPI, Illustrated Parts Breakdown Supplement BHT-42-MMS-EPI, Maintenance Manual Supplement BHT-ELECT-SPM, Electrical Standard Practice BHT-ALL-SRM, Structural Repair Manual PUBLICATIONS AFFECTED: BHT-42-IPBS-EPI, Illustrated Parts Breakdown Supplement BHT-42-MMS-EPI, Maintenance Manual Supplement ACCOMPLISHMENT INSTRUCTIONS:. Prepare the helicopter for maintenance. 2. Disconnect battery and external DC power from the helicopter. 3. Gain access to left side aft avionics compartment. Refer to Figure, View A. 4. Locate Radar Altimeter transceiver 3408TR (5, View B). Page 3 of 0

4 5. Disconnect connectors 3408TRP2 and 3408TRP3 (3 and 4, View B) from Radar Altimeter transceiver 3408TR (5, View B). 6. Gain access to the tailboom forward bulkhead from the right hand aft access panel (View C). NOTE Connector 3408P2 and 3408P3 in View C are shown disconnected for clarity. 7. Disconnect 3408P2 and 3408P3 (6 and 7, View C) from tailboom receptacle 3408J2 and 3408J3 respectively. 8. Remove and discard existing cable assemblies ( and 2 View B) by loosening applicable clamps. 9. Locate and install nuts () using rivets (2) as shown in View D, Detail E and F. 0. Install new cable assemblies ALT-0B (, View B) P/N and ALT-02A (2, View B) P/N following new routing using existing clamps and new clamping arrangements with hardware as shown in View D, View G, Details E, F, H and I.. Connect new cable assembly ALT-02A (2, View B) connector 3408TRP2 (3, View B) to Radar Altimeter transceiver 3408TR (5, View B) to the XMIT antenna receptacle. 2. Connect new cable assembly ALT-0B (, View B) connector 3408TRP3 (4, View B) to 3408TR (5, View B) to the RCVR antenna receptacle. 3. Secure both connectors (3 and 4, View B) with safety wire C Connect new cable assembly ALT-02A (2, View B) connector 3408P2 (6, View C) to tailboom receptacle 3408J2. 5. Connect new cable assembly ALT-0B (, View B) connector 3408P3 (7, View C) to tailboom receptacle 3408J3. 6. Secure both connectors (6 and 7, View C) with safety wire C Clean, inspect and close L/H avionics bay and R/H aft access panel. Page 4 of 0

5 8. Connect battery and apply external DC power to the helicopter. 9. Perform Radar Altimeter transceiver operational check as per BHT-42-MMS-EPI, Chapter Return helicopter to flight status. 2. Make an entry in the helicopter logbook and historical service records indicating compliance with this Technical Bulletin. Page 5 of 0

6 Figure (sheet of 5) Page 6 of 0

7 Figure (sheet 2 of 5) Page 7 of 0

8 Figure (sheet 3 of 5) Page 8 of 0

9 Figure (sheet 4 of 5) Page 9 of 0

10 Figure (sheet 5 of 5) Page 0 of 0