Craig Amadeo 

General Manager 

Engineering Standards & 

Chief Engineer

Delta Air Lines, Inc.

1775 Aviation Blvd 

Atlanta, Ga. 30320 

T. +1 404 714 1312 

F. +1 404 773 3675 

craig.amadeo@delta.com 

 

September 30, 2011 

U.S. Department of Transportation 

Docket Operations, M-30, West Building Ground Floor, Room W12-140 

1200 New Jersey Avenue SE 

Washington, DC 20590 

Fax: (202) 493-2251 

Subject: Docket No. FAA-2011-0836; Directorate Identifier 2010-NE-38-AD: RB211-Trent 800 Series 

Turbofan Engines – Inspection of LP Fuel Tubes for wear from clamps – Proposed Rule 

Reference: (A) Notice of Proposed Rule Making (NPRM): Docket No. FAA-2011-0836; Directorate 

Identifier 2010-NE-38-AD. 

(B) Rolls Royce Service Bulletin RB.211-73-D685 Revision 5, dated August 18, 2010. 

(C) Rolls Royce Service Bulletin RB.211-73-D685 Revision 6, dated February 21, 2011. 

 

SUMMARY:

Reference (A) proposes a Trent 800 Series Engine Airworthiness Directive (AD) that would require initial and 

repetitive visual inspections of Low Pressure (LP) fuel tubes for evidence of fretting wear from the securing clamps that 

hold them in place on the engine fan case. The inspections are to be accomplished per certain steps of Reference (B). If 

wear is severe enough, the tube wall thickness is compromised and tube may fracture resulting in fuel loss. Tubes 

failing the inspection are to be removed from service. 

DELTA’S COMMENTS

Delta agrees with the need to mitigate the LP fuel tube wear and leakage issue. However, we have the following 

comments on the NPRM language as proposed: 

Service Bulletin Reference Questions: 

1) The latest version of Reference B service bulletin is now Revision 6 dated February 21, 2011. Delta would 

request the final rule reference this latest SB version and numbering. 

NOTE: Paragraphs (f)(1), (f)(2), and (g) list the SB number as RB.211-73-D685 (the ‘A’ was 

inadvertently omitted). DAL requests that the “A’ be added so the current service bulletin number is 

actually RB.211-73-AD685, Revision 6 dated February 21, 2011. 

2) Delta would request the final rule allow that engines previously inspected per SB RB.211-73-D685 Revision 3, 

4, or 5 to have met the “initial inspection” requirements of proposed rule. 

Inspection Procedure Questions: 

1) In the proposed rule paragraph (f), one of the interval options is to do initial inspection before 3,000 hrs since 

last inspection. Delta would like the final rule to provide the references by which the last inspection could 

have been done to be considered acceptable to use this option. 

2) Proposed rule paragraph (f)(1) requires inspecting both the LP fuel tubes and the clips that hold the tube in 

place using Reference B, Paragraphs 3.A.(2) and 3.A.(3) (On-wing) or Paragraphs 3.B.(2) and 3.B.(3) (In 

shop). When looking at these service bulletin paragraphs, there are no inspection criteria for the clips. There 
October 10, 2011 

Page 2 of 2 

are only inspection criteria for the wear on the tube. There are, instead, requirements in Reference B for 

replacement of the clips with new. Delta would like the final rule to provide clear direction for handling the 

clips (either require inspection per a particular reference or require clip replacement with new/serviceable part 

per the note in Paragraph 3.A of the SB). 

3) Paragraph (g) of proposed rule requires repeat inspections and, if necessary, replacement of fuel tubes and 

clips. Delta believes there is a chance to misinterpret the instructions as written and would propose the change 

in language given below to help clarify. The concern is the existing language might be perceived as requiring 

both the inspection and tube replacement to be accomplished per Ref B paragraphs 3.A(2) and 3.A(3) and 

3.B(2) and 3.B(3). Since these paragraphs are only applicable for the inspections and do not pertain to 

replacement of the tubes, Delta believes the language could be clarified to something similar to the following: 

“Following accomplishment of the initial inspection in compliance with the requirements of paragraph 

(f)(1) or (f)(2) of this AD, repeat the inspection at intervals not exceeding 3,000 hours. Accomplish the 

inspections per SB RB.211-73-AD685 Revision 6, paragraphs 3.A(2) and 3.A(3) for on wing and 3.B(2) 

and 3.B(3) for in shop. If the inspection results indicate that either the fuel tubes (P/N FK22617, 

FK19213, and FK23986) or the clips that hold them in place do not meet requirements, they must be 

replaced before further flight.” 

4) The proposed rule paragraphs (f)(1) and (f)(2) do not contain any statements about replacing tubes/clips when 

necessary as a result of the inspections. This is contrasted against paragraph (g) which currently does discuss 

replacement of these parts when necessary. For consistency, Delta believes these paragraphs should have 

similar information related to tube/clip replacement when the final rule is issued. 

5) The proposed rule currently does not require inspection of the Fuel Oil Heat Exchanger (FOHE) mounts during 

initial or repetitive inspections even though the Reference B service bulletin does emphasize this action and 

has this requirement. By contrast, the EASA AD 2010-0188 does require this FOHE mount inspection because 

it requires accomplishment of the entire service bulletin when doing the inspection. For clarity, Delta would 

request the final rule include a comment that the inspection requirements of the proposed AD do not mandate 

the FOHE mount inspections of Reference B, Paragraphs 3.A.(4) and 3.B.(4). This would eliminate any 

ambiguity in the inspection requirements. 

If you have any further questions or require additional information, please contact Steven Botts – Principal Engineer, 

Propulsion Engineering, at (612) 266-3876 or email at steven.botts@delta.com. 

Thank you, 

Peter Lauria 

Acting Chief Engineer; ODA administrator 

for 

Craig Amadeo 

General Manager – Engineering Standards & Chief Engineer 

Dept. 567 

Cc: Amber Krchnavy 

 Maggie Broder 

 Alan Strom, FAA Engine Certification Office