AD 2004-23-03

The FAA is adopting a new airworthiness directive (AD) for Rolls-Royce plc (RR) RB211 Trent 700 series turbofan engines. This AD requires initial and repetitive borescope inspections of the high pressure-and-intermediate pressure (HP-IP) turbine internal and external oil vent tubes for coking and carbon buildup, and cleaning or replacing the vent tubes if necessary. This AD results from a report of a RB211 Trent 700 series engine experiencing a disk shaft separation, overspeed of the IP turbine rotor, and multiple blade release of IP turbine blades. Preliminary findings suggest these events resulted from an internal oil fire in the HP-IP turbine oil vent tubes due to coking and carbon buildup. This fire led to a second fire in the internal air cavity below the IP turbine disk drive shaft. We are issuing this AD to prevent internal oil fires due to coking and carbon buildup, that could cause uncontained engine failure and damage to the airplane.

Final rule; request for comments.

2004-23-03 Rolls-Royce plc: Amendment 39-13858. Docket No. FAA-2004- 19559; Directorate Identifier 2004-NE-03-AD.

Effective Date

(a) This AD becomes effective November 23, 2004.

Affected ADs

(b) None.

Applicability

(c) This AD applies to Rolls-Royce plc (RR) RB211 Trent 768-60, RB211 Trent 772-60, and RB211 Trent 772B-60 series turbofan engines. These engines are installed on, but not limited to, Airbus A330-243, -341, -342 and -343 series airplanes.

Unsafe Condition

(d) This AD results from a report of a RB211 Trent 700 series engine experiencing a disk shaft separation, overspeed of the IP turbine rotor, and multiple blade release of IP turbine blades. Preliminary findings suggest these events resulted from an internal oil fire in the HP-IP turbine oil vent tubes due to coking and carbon buildup. This fire led to a second fire in the internal air cavity below the IP turbine disk drive shaft. We are issuing this AD to prevent internal oil firesdue to coking and carbon buildup, that could cause uncontained engine failure and damage to the airplane.

Compliance

(e) You are responsible for having the actions required by this AD performed within the compliance times specified unless the actions have already been done.

Initial Visual Inspection

(f) Using the inspection schedule in Table 1 of this AD, perform an initial borescope inspection of the high pressure-and- intermediate pressure (HP-IP) turbine internal and external oil vent tubes for coking and carbon buildup as follows:

(1) Insert an 8 mm diameter flex borescope to see if it will pass along the full length of the vent tube into the bearing chamber

(2) If the vent tube prevents an 8 mm diameter flex borescope from passing along the full length of the tube into the bearing chamber, repeat the action using a 6mm flex borescope.

(3) If the 6 mm diameter flex borescope passes through to the bearing chamber, continue using the engine in service, and perform the repetitive inspections in this AD at the required intervals.

(4) If the vent tube prevents the 6 mm diameter flex borescope from passing along the full length of the tube into the bearing chamber, clean or replace the vent tube. Information on oil vent tube cleaning or replacement can be found in Rolls-Royce plc Alert Service Bulletin No. RB.211-72-AE302, Revision 1, dated May 25, 2004.

Table 1.--Initial Inspection Schedule

If the engine or the 05 module:
Then initially inspect:

Has reached 10,000 hours time-since-new (TSN) or
reached 2,500 cycles-since-new (CSN) on the effective date of this AD.
Within 3 months after the effective date of this AD.

Has fewer than 10,000 hours TSN or fewer than 2,500 CSN on the effective date of this AD.
Within 3 months after reaching 10,000 hours TSN or 2,500 CSN, whichever occurs first.

Repetitive Visual Inspections

(g) Using the inspection schedule in Table 2 of this AD and paragraphs(f)(1) through (f)(4) of this AD, perform repetitive borescope inspections of the HP-IP turbine internal and external oil vent tubes for coking and carbon buildup.

Table 2.--Repetitive Inspection Schedule

If at the previous inspection, before any cleaning
Then:
was performed:

(1) There was no coking and carbon buildup of a visible thickness; or an 8 mm diameter flex borescope could pass along the full length of the internal vent tube into the bearing chamber.
Reinspect within 6,400 hours time-since-last-inspection (TSLI) or within 1,600 cycles-since-last-inspection (CSLI), whichever occurs first.

(2) The coking or carbon buildup prevented an 8 mm
diameter flex borescope from passing through the
internal vent tube, but a 6 mm diameter flex borescope could pass along the full length of the internal vent tube into the bearing chamber.
Reinspect within 1,600 hours TSLI or within 400 CSLI, whichever occurs first.

(3) The coking or carbon buildup prevented the 6 mm
diameter flex borescope from passing through the full
length of the internal vent tube and into the bearing
chamber.
Clean or replace the vent tubes within 10 CSLI. Information on oil vent tube cleaning or replacement can be found in Rolls-Royce plc Alert Service Bulletin No. RB.211-72-
AE302, Revision 1, dated May 25, 2004.

Alternative Methods of Compliance

(h) The Manager, Engine Certification Office, has the authority to approve alternative methods of compliance for this AD if requested using the procedures found in 14 CFR 39.19.

Material Incorporated by Reference

(i) None.

Related Information

(j) CAA airworthiness directive No. G-2004-0016, dated June 20, 2004, also addresses the subject of this AD.

As a member of the National Transportation Safety Board (NTSB) investigation team, we are investigating an incident event and possible unsafe condition on RR RB211 Trent 700 series engines. The Civil Aviation Authority (CAA), which is the airworthiness authority for the United Kingdom (UK) is helping us investigate. A report was received of a RB211 Trent 700 series engine experiencing a disk shaft separation, overspeed of the IP turbine rotor, and multiple blade release of IP turbine blades. Preliminary findings suggest these events resulted from an internal oil fire in the HP-IP turbine oil vent tubes due to coking and carbon buildup. This fire led to a second fire in the internal air cavity below the IP turbine disk drive shaft. Because the oil vent tubes on the event engine were destroyed, the partner engine on the same airplane was inspected. That inspection revealed heavy coking and carbon buildup, with partial blockage of the HP-IP turbine oil vent tubes. Both engines had the same on-wing life of 15,169 hours with 2,344 cycles-since-new. Both engines contained Mobil Jet Oil 291, which also is suspect and will be removed from the list of approved oils for these engines. The NTSB investigation is ongoing and a finding of probable cause has not yet been made. The fire, disk overspeed, and blade release appear to be the result of the coking and carbon buildup, evident in the sister engine and linked by cycles and oil use to the event engine.

Relevant Service Information

We have reviewed and approved the technical contents of RR Alert Service Bulletin (ASB) No. RB.211-72-AE302, Revision 1, dated May 25, 2004, that describes procedures for:

Initial and repetitive borescope inspections for coking and carbon buildup in the HP-IP turbine oil vent tubes; and
Cleaning the tubes if necessary, and removing the engine from service to clean or replace the tubes.

This ASB requires that all operators submit inspection data to themanufacturer. The CAA classified this ASB as mandatory and issued AD G- 2004-0016, dated June 20, 2004, in order to ensure the airworthiness of these RB211 Trent 700 series engines in the UK.

Bilateral Airworthiness Agreement

These engine models are manufactured in the UK and are type certificated for operation in the United States under the provisions of section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the applicable bilateral airworthiness agreement. Under this bilateral airworthiness agreement, the CAA kept the FAA informed of the situation described above. As a member of the NTSB investigation team, we have examined the findings with the CAA, reviewed all available information, and determined that AD action is necessary for products of this type design that are certificated for operation in the United States.

FAA's Determination and Requirements of This AD

Although no airplanes that are registered in the United States use these engines, the possibility exists that the engines could be used on airplanes that are registered in the United States in the future. The unsafe condition described previously is likely to exist or develop on other RB211 Trent 700 series turbofan engines of the same type design. We are issuing this AD to prevent internal oil fires due to coking and carbon buildup, that could cause uncontained engine failure and damage to the airplane. This AD requires:

Initial and repetitive borescope inspections of the HP-IP turbine oil vent tubes for coking and carbon buildup; and
Cleaning or replacing the oil vent tubes if they fail the inspection.

FAA's Determination of the Effective Date

Since there are currently no domestic operators of this engine model, notice and opportunity for public comment before issuing this AD are unnecessary. A situation exists that allows the immediate adoption of this regulation.

Interim Action

These actions are interim actions and we may take further rulemaking actions in the future.

Comments Invited

This AD is a final rule that involves requirements affecting flight safety and was not preceded by notice and an opportunity for public comment; however, we invite you to submit any written relevant data, views, or arguments regarding this AD. Send your comments to an address listed under ADDRESSES. Include "AD Docket No. FAA-2004-19559; Directorate Identifier 2004-NE-03-AD" in the subject line of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify it.

We will post all comments we receive, without change, to http://dms.dot.gov , including any personal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this AD. Using the search function of the DMS Web site, anyone can find and read the comments in any of our dockets, including the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). You may review the DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78) or you may visit http://dms.dot.gov.

Examining the AD Docket

You may examine the docket that contains the AD, any comments received, and any final disposition in person at the DMS Docket Offices between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Office (telephone (800) 647-5227) is located on the plaza level of the Department of Transportation Nassif Building at the street address stated in ADDRESSES. Comments will be available in the AD docket shortly after the DMS receives them.

Regulatory Findings

We have determined that this AD will not have federalism implications under Executive Order 13132. This AD will not have a substantial direct effect on the States, on the relationship between the national Government and the States, or on the distribution of power and responsibilities among the various levels of government.

For the reasons discussed above, I certify that the regulation:

1. Is not a "significant regulatory action" under Executive Order 12866;

2. Is not a "significant rule" under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and

3. Will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act.

We prepared a summary of the costs to comply with this AD and placed it in the AD Docket. You may get a copy of this summary by sending a request to us at the address listed under ADDRESSES.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Safety.

Adoption of the Amendment

Under the authority delegated to me by the Administrator, the FAA amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows:

PART 39--AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.

39.13 [Amended]

2. The Federal Aviation Administration (FAA) amends 39.13 by adding the following new airworthiness directive (AD):