2011-26821. Airworthiness Directives; Rolls-Royce plc (RR) Turbofan Engines

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

We propose to supersede an existing airworthiness directive (AD) that applies to all RR RB211-Trent 553-61, 553A2-61, 556-61, 556A2-61, 556B-61, 556B2-61, 560-61, 560A2-61, 768-60, 772-60, 772B-60, 875-17, 877-17, 884-17, 884B-17, 892-17, 892B-17, and 895-17 turbofan engines. The existing AD currently requires inspecting the intermediate-pressure (IP) compressor rotor shaft rear balance land for cracks. Since we issued that AD, we received reports of one RB211-Trent 700 and two additional RB211-Trent 800 IP compressor rotor shafts that have been found cracked. This proposed AD would continue to require initial inspections, add additional inspections, and an optional terminating action. The cracking identified above could lead to IP compressor rotor shaft failure, uncontained engine failure, and damage to the airplane. We are proposing this AD to correct the unsafe condition on these products.

DATES:

We must receive comments on this proposed AD by December 2, 2011.

ADDRESSES:

You may send comments, using the procedures found in 14 CFR 11.43 and 11.45, by any of the following methods:

• Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the instructions for submitting comments.
• Fax: [phone].
• Mail: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590.
• Hand Delivery: Deliver to Mail address above between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

For service information identified in this AD, contact Rolls-Royce plc, Corporate Communications, P.O. Box 31, Derby, England, DE248BJ; phone: [phone]; fax: [phone] or e-mail from http://www.rolls-royce.com/​contact/​civil_​team.jsp. You may review copies of the referenced service information at the FAA, Engine & Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803. For information on the availability of this material at the FAA, call 781-238-7125.

Examining the AD Docket

You may examine the AD docket on the Internet at http://www.regulations.gov;​; or in person at the Docket Management Facility between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this proposed AD, the regulatory evaluation, any comments received, and other information. The street address for the Docket Office (phone: [phone]) is in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT:

Alan Strom, Aerospace Engineer, Engine Certification Office, FAA, 12 New England Executive Park, Burlington, MA; phone: [phone]; fax: [phone]; e-mail: [e-mail].

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to send any written relevant data, views, or arguments about this proposed AD. Send your comments to an address listed under the ADDRESSES section. Include “Docket No. FAA-2007-28059; Directorate Identifier 2007-NE-13-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of this proposed AD. We will consider all comments received by the closing date and may amend this proposed AD because of those comments.

We will post all comments we receive, without change, to http://www.regulations.gov,, including any personal information you provide. We will also post a report summarizing each substantive verbal contact we receive about this proposed AD.

Discussion

On August 25, 2008, we issued AD 2008-18-08, Amendment 39-15665 (73 FR 52201, September 9, 2008), for all Rolls-Royce plc RB211-Trent 553-61, 553A2-61, 556-61, 556A2-61, 556B-61, 556B2-61, 560-61, 560A2-61, 768-60, 772-60, 772B-60, 875-17, 877-17, 884-17, 884B-17, 892-17, 892B-17, and 895-17 turbofan engines. That AD requires a onetime eddy current inspection (ECI) of the rear balance land of the IP compressor rotor shaft for cracks. That AD resulted from reports of cracking on the rear balance land of IP compressor rotor shafts. We issued that AD to detect cracking on the rear balance land of the IP compressor rotor shaft. Cracking on the rear balance land on the IP compressor rotor shaft can lead to failure of the rotor shaft and damage to the engine.

Actions Since Existing AD Was Issued

Since we issued AD 2008-18-08, (73 FR 52201, September 9, 2008), RR reports that they have introduced an optional terminating action to the repetitive inspections required by that AD. RR also reported that for those operators not adopting the optional terminating action, improved inspection methods for the RB211-Trent 700 and RB211-Trent 800 turbofan engines are necessary. Also, EASA issued AD 2010-0266, dated December 21, 2010, and AD 2010-0266R1, dated January 6, 2011, to require repetitive on-wing and in-shop ECIs on RB211-Trent 700 and RB211-Trent 800 engines and repetitive in-shop visual inspections on the RB211-Trent 500, RB211-Trent 700, and RB211-Trent 800 engines. EASA issued their ADs because RR had reported finding additional cracks on the IP compressor rotor shaft of two in-service RB211-Trent 800 engines and on one in-service RB211-Trent 700 engine. The cracking had initiated from frettage marks caused by balance weights. RR reports that stress analysis has shown that the cracking presents a possible threat to the rotor integrity. We evaluated the data supplied by EASA and RR, and concur that the improved inspections for cracks on the balance land of the IP compressor rotor shaft are required. We have evaluated the optional terminating action and determined it to be effective.

These cracks, if present, could result in an unsafe condition leading to IP compressor rotor shaft failure and damage to the engine.

Relevant Service Information

We reviewed RR Alert Service Bulletins (ASB) No. RB.211-72-AF260, Revision 5, dated July 7, 2011, ASB No. RB.211-72-AG085, Revision 2, dated July 7, 2011, ASB No. RB.211-72-AG264, Revision 5, dated March 21, 2011, ASB No. RB.211-72-AG270, Revision 4, dated March 21, 2011, and Service Bulletin No. RB.211-72-G448, Revision 3, dated July 7, 2011 which provide information for the inspections required by this AD.

FAA's Determination

We are proposing this AD because we evaluated all the relevant information and determined the unsafe condition described previously is likely to exist or develop in other products of these same type designs.

Proposed AD Requirements

This proposed AD would require:

• For the RB211-Trent 700 and RB211-Trent 800 engines, on wing initial and repetitive borescope inspections and when in the shop, repetitive ECIs for cracks on the rear balance land; and
• For the RB211-Trent 500 engines, initial and repetitive in-shop visual inspections or ECIs for cracks on the rear balance land.

This proposed AD would also add an optional terminating action to the repetitive inspection requirements for the RB211-Trent 700 and RB211-Trent 800 engines.

Costs of Compliance

We estimate that this proposed AD would affect about 136 engines installed on airplanes of U.S. registry. We also estimate that it would take about 6 work-hours per engine to perform the proposed inspections and that the average labor rate is $85 per work-hour. Based on these figures, we estimate the total cost of the proposed AD to U.S. operators to be $69,360.

Authority for This Rulemaking

Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, Section 106, describes the authority of the FAA Administrator. Subtitle VII, Aviation Programs, describes in more detail the scope of the Agency's authority.

We are issuing this rulemaking under the authority described in Subtitle VII, Part A, Subpart III, Section 44701, “General requirements.” Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.

Regulatory Findings

We have determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD would 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 proposed 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),

(3) Will not affect intrastate aviation in Alaska, and

(4) 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.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Incorporation by reference
• Safety

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 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 FAA amends § 39.13 by removing airworthiness directive (AD) 2008-18-08, Amendment 39-15665 (73 FR 52201, September 9, 2008), and adding the following new AD:

Rolls-Royce plc: Docket No. FAA-2007-28059; Directorate Identifier 2007-NE-13-AD.

(a) Comments Due Date

The FAA must receive comments on this AD action by December 2, 2011.

(b) Affected ADs

This AD supersedes AD 2008-18-08, Amendment 39-15665, (73 FR 52201, September 9, 2008).

(c) Applicability

This AD applies to Rolls-Royce plc (RR) RB211-Trent 553-61, 553A2-61, 556-61, 556A2-61, 556B-61, 556B2-61, 560-61, 560A2-61, 768-60, 772-60, 772B-60, 875-17, 877-17, 884-17, 884B-17, 892-17, 892B-17, and 895-17 turbofan engines.

(d) Unsafe Condition

We are superseding AD 2008-18-08 because additional cracking on RB211-Trent 700 and RB211-Trent 800 intermediate-pressure (IP) compressor rotor shafts has been found since that AD was issued. This cracking could lead to IP compressor rotor shaft failure, uncontained engine failure, and damage to the airplane.

(e) Compliance

Comply with this AD within the compliance times specified, unless already done.

(f) RB211-Trent 700 Series Engines—Rear Balance Land Inspections

(1) On-Wing Inspections

Perform on-wing inspections as follows:

(i) Within 625 cycles-in-service (CIS) after the effective date of this AD, borescope inspect the IP compressor rotor shaft rear balance land. Use RR Alert Service Bulletin (ASB) No. RB.211-72-AG270, Revision 4, dated March 21, 2011, sections 3.A.(2)(a) through 3.A.(2)(c) and 3.A.(3)(a) through 3.A.(3)(c), or 3.B.(2)(a) through 3.B.(2)(c) and 3.B.(4)(a) through 3.B.(4)(c), to do the inspection.

(ii) Thereafter, repeat the inspection within every 625 cycles-since-last inspection (CSLI). You may count CSLI from the last borescope inspection or the last eddy current inspection, whichever has occurred last.

(2) In-Shop Inspections

At each shop visit, eddy current inspect (ECI) and visually inspect the IP compressor rotor shaft rear balance land, and visually inspect the balance weights. Use RR ASB No. RB.211-72-AG085, Revision 2, dated July 7, 2011, sections 3.A. through 3.D.(3)(b)(v), except paragraphs 3.D.(3)(a)(ii) and 3.D.(3)(b)(iii) to do the inspections.

(3) RB211-Trent 800 Series Engines—Rear Balance Land Inspections

(1) On-Wing Inspections

(i) Within 475 CIS after the effective date of this AD, borescope inspect the IP compressor rotor shaft rear balance land. Use RR ASB No. RB.211-72-AG264, Revision 5, dated March 21, 2011, sections 3.B.(2)(a) through 3.B.(2)(c) and 3.B.(4)(a) through 3.B.(4)(c) to do the inspection.

(ii) Thereafter, repeat the inspection within every 475 CSLI. You may count CSLI from the last borescope inspection or the last eddy current inspection, whichever has occurred last.

(2) In-Shop Inspections

At each shop visit, ECI and visually inspect the IP compressor rotor rear shaft balance land, and visually inspect the balance weights. Use RR ASB No. RB.211-72-AG085, Revision 2, dated July 7, 2011, sections 3.A. through 3.D.(3)(b)(v), except paragraphs 3.D.(3)(a)(ii) and 3.D.(3)(b)(iii), to do the inspections.

(h) RB211-Trent 500 Series Engines—In-Shop Rear Balance Land Inspections

At each shop visit, ECI the IP compressor rotor shaft and visually inspect the balance weights. Use RR ASB No. RB.211-72-AF260, Revision 5, dated July 7, 2011 sections 3.A. through 3.B.(3)(a)(iii) to do the visual inspection, or RR SB No. RB.211-72-G448, Revision 3, dated July 7, 2011 section 3.D.(1) through 3.D.(14) to do the ECI.

(i) Definition

For the purposes of this AD, a shop visit is defined as introduction of an engine into a shop, and disassembly sufficient to expose the IP compressor module rear face.

(j) Optional Terminating Action for RB211-Trent 700 and RB211-Trent 800 Engines

(1) Modifying an RB211-Trent 700 engine as specified in RR SB No. RB.211-72-G402, Revision 2, dated July 7, 2011, or RR SB No. RB.211-72-G402, Revision 1, dated January 11, 2011, is terminating action for paragraph (f)(2) of this AD.

(2) Modifying an RB211-Trent 800 engine as specified in RR SB No. RB.211-72-G401, Revision 2, dated July 5, 2011, or SB No. RB.211-72-G401, Revision 1, dated January 11, 2011, is terminating action for paragraph (h)(2) of this AD.

(k) Previous Credit

(1) For RB211-Trent 700 series engines:

(i) On-wing inspections done before the effective date of this AD using RR ASB No. RB.211-72-AG270, Revision 1, dated December 14, 2009, or Revision 2, dated December 21, 2010, or Revision 3, dated February 25, 2011, meet the inspection requirements in paragraph (f) of this AD.

(ii) In-shop inspections done before the effective date of this AD using RR ASB No. RB.211-72-AG085, Revision 1, dated September 27, 2010, meet the inspection requirements in paragraph (g) of this AD.

(2) For RB211-Trent 800 series engines:

(i) On-wing inspections done before the effective date of this AD using RR ASB No. RB.211-72-AG264, Revision 3, dated December 21, 2010, or Revision 4, dated February 25, 2011, meet the inspection requirements in paragraph (h) of this AD.

(ii) In-shop inspections done before the effective date of this AD using RR ASB No. RB.211-72-AG085, Revision 1, dated September 27, 2010, meet the inspection requirements in paragraph (i) of this AD.

(3) For RB211-Trent 500 series engines:

(i) In-shop visual inspections done before the effective date of this AD using RR ASB No. RB.211-72-AF260, Revision 4, dated July 28, 2009, meet the inspection requirements in paragraph (j) of this AD.

(ii) In-shop ECIs done before the effective date of this AD using RR ASB No. RB.211-72-G448, Revision 2, dated December 23, 2010, meet the ECI requirements in paragraph (j) of this AD.

(l) Alternative Methods of Compliance (AMOCs)

The Manager, Engine Certification Office, FAA, may approve AMOCs for this AD. Use the procedures in 14 CFR 39.19 to request an AMOC.

(m) Related Information

(1) For more information about this AD, contact Alan Strom, Aerospace Engineer, Engine Certification Office, FAA, 12 New England Executive Park, Burlington, MA; phone: [phone]; fax: [phone]; e-mail: [e-mail].

(2) For service information identified in this AD, contact Rolls-Royce plc, Corporate Communications, P.O. Box 31, Derby, England, DE248BJ; phone: [phone]; fax: [phone]; or e-mail from http://www.rolls-royce.com/​contact/​civil_​team.jsp. You may review copies of the referenced service information at the FAA, Engine & Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803. For information on the availability of this material at the FAA, call 781-238-7125.

Issued in Burlington, Massachusetts, on October 6, 2011.

Peter A. White,

Manager, Engine & Propeller Directorate, Aircraft Certification Service.