RB211 Trent 700 LP Fuel Tubes, Clips, and FOHE Mounting Hardware – Inspection for Frettage
1. Scope and Applicability
This article provides inspection and maintenance instructions for low-pressure (LP) fuel tubes, clips, and Fuel/Oil Heat Exchanger (FOHE) mounting hardware on RB211 Trent 700 series engines, specifically for Airbus A330 aircraft with post-SB73-F343 engines.
2. Background and Reason
In-service incidents of LP fuel leaks have been traced to excessive wear of P-Clips and subsequent frettage between exposed metal bands and fuel tubes. This can lead to fuel tube fracture and significant fuel leakage, potentially causing in-flight shutdowns (IFSD) and diversions. The bulletin provides proactive mitigation and inspection requirements to address these risks.
3. Compliance Requirements
- On-wing: Inspect within 4,000 hours from new delivery or last inspection. If over 3,200 hours have elapsed, inspect within 800 hours. Repeat at intervals not exceeding 4,000 hours.
- In-shop: Inspect at every engine shop visit.
- Note: This Service Bulletin may be subject to EASA/FAA Airworthiness Directive.
4. Manpower and Tooling
- On-wing: 0.5 hours (access), 1 hour (inspection), 2 hours (replacement).
- In-shop: 2 hours (inspection), 3 hours (replacement).
- No special tools required.
5. Inspection Instructions
5.1 On-wing Inspection
- Open fan cowl doors and ensure safe access.
- Visually inspect all clip positions (CP4881, CP2607, CP2427) on fuel tube FW53576 for damage or wear.
- Remove and replace clips as per Aircraft Maintenance Manual (AMM) 70-12-01. Do not reuse clips.
- Inspect FOHE mounts and associated hardware for damage or excessive wear. Manipulate mounts to check for play in spherical bearings.
- Apply acceptance/rejection criteria:
- Frettage depth > 0.1 mm on bends: Reject
- Frettage depth > 0.2 mm elsewhere: Reject
- Play or seizure in bearings: Replace within 800 flight hours
- Bent/twisted hardware: Replace within 800 flight hours
- Reassemble and perform leak test if any tube was replaced.
- Document findings and report to Rolls-Royce as per Appendix 3.
5.2 In-shop Inspection
- Visually inspect LP fuel tubes (FW26587, FW36335, FW26589, FW53576, FW53577) and all relevant clips for damage or wear.
- Remove and replace clips one at a time to avoid stressing the system. Do not reuse clips.
- Inspect FOHE mounts and associated hardware as per on-wing instructions.
- Apply the same acceptance/rejection criteria as above.
- Replace unserviceable tubes and hardware as required.
- Document findings and report to Rolls-Royce as per Appendix 2.
6. Material and Parts
A comprehensive list of part numbers for bolts, brackets, nuts, washers, tubes, clips, and mounting hardware is provided in the original bulletin. Only replace parts if rejected during inspection.
7. Safety and Cautions
- Engine components may remain hot for up to one hour after shutdown. Use appropriate gloves and PPE.
- Do not perform maintenance on multiple engines simultaneously unless necessary. Apply additional controls if unavoidable.
8. Documentation and Reporting
- Complete the relevant proforma (Appendix 2 for in-shop, Appendix 3 for on-wing) for each inspection.
- Forward inspection results to Rolls-Royce Field Service Office (FSO).
- Maintain records in accordance with local Service Bulletin tracking procedures.
9. References
- Rolls-Royce RB211 Service Bulletin 73-F343
- Rolls-Royce RB211 Non-Modification Service Bulletin 73-G848
- Airbus A330 Aircraft Maintenance Manuals (AMM)
- Engine and Aircraft Illustrated Parts Catalogues
10. Figures and Diagrams
Refer to the original Service Bulletin for detailed diagrams of fuel tube arrangements, clip positions, and FOHE mounting hardware (Figures 1–17).
Disclaimer: This article is a concise technical summary for Dynamics Customer Service and is intended to support Copilot indexing. For detailed procedures, always refer to the full Service Bulletin and applicable maintenance manuals.