2011-367. Airworthiness Directives; The Boeing Company Model 737-600, -700, -700C, -800, -900, and -900ER Series Airplanes

AGENCY:

Federal Aviation Administration (FAA), Department of Transportation (DOT).

ACTION:

Supplemental notice of proposed rulemaking (NPRM); reopening of comment period.

SUMMARY:

The FAA is revising an earlier NPRM for an airworthiness directive (AD) that applies to all Boeing Model 737-600, -700, -700C, -800, and -900 series airplanes. The original NPRM would have superseded an existing AD that currently requires reviewing the airplane maintenance records to determine whether an engine has been removed from the airplane since the airplane was manufactured. For airplanes on which an engine has been removed, the existing AD also requires an inspection of the aft engine mount to determine if the center link assembly is correctly installed, and follow-on actions if necessary. The original NPRM proposed to require the same actions for airplanes on which the engine has not been previously removed. The original NPRM resulted from reports indicating that operators found that the center link assembly for the aft engine mount was reversed on several airplanes that had not had an engine removed since delivery. This new action revises the original NPRM by expanding the applicability to include Model 737-900ER airplanes. We are proposing this supplemental NPRM to prevent increased structural loads on the aft engine mount, which could result in failure of the aft engine mount and consequent separation of the engine from the airplane.

ADDRESSES:

We must receive comments on this supplemental NPRM by February 25, 2011.

DATES:

You may send comments 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: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., Washington, DC 20590, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

For service information identified in this proposed AD, contact Boeing Commercial Airplanes, Attention: Data & Services Management, P.O. Box 3707, MC 2H-65, Seattle, Washington 98124-2207; telephone [phone], extension 1; fax [phone]; e-mail [e-mail]; Internet https://www.myboeingfleet.com. You may review copies of the referenced service information at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington. For information on the availability of this material at the FAA, call 425-227-1221.

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 (telephone [phone]) is in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT:

Alan Pohl, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone [phone]; fax [phone].

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-2008-1118; Directorate Identifier 2007-NM-318-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

We proposed to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) with a notice of proposed rulemaking (NPRM) for an AD (the “original NPRM”) to supersede AD 2003-03-01, Amendment 39-13025 (68 FR 4367, January 29, 2003). The original NPRM applied to all Model 737-600, -700, -700C, -800, and -900 series airplanes. The original NPRM was published in the Federal Register on October 30, 2008 (73 FR 64568). The original NPRM would have superseded an existing AD that currently requires reviewing the airplane maintenance records to determine whether an engine has been removed from the airplane since the airplane was manufactured. For airplanes on which an engine has been removed, the existing AD also requires an inspection of the aft engine mount to determine if the center link assembly is correctly installed, and follow-on actions if necessary. The original NPRM proposed to require the same actions for airplanes on which the engine has not been previously removed.

Actions Since Original NPRM Was Issued

Since we issued the original NPRM, the manufacturer has informed us that Model 737-900ER airplanes should be included in the applicability of the supplemental NPRM. Model 737-900ER airplanes were not being produced in May 2004 when Revision 3, dated May 20, 2004, of Boeing Alert Service Bulletin 737-71A1462, was issued. (Revision 3 was referred to as an appropriate source of service information for accomplishing the proposed actions in the original NPRM.) Following production it was determined that the affected aft engine mount is interchangeable with Model 737-900ER airplanes; however, those airplanes were inspected in production to ensure that the center link was properly installed. Therefore, the requirements in the existing AD do not apply to those airplanes. However, since we are including airplanes on which the engines have been removed since production, we have added Model 737-900ER airplanes to the applicability section of this supplemental NPRM.

Comments

We have considered the following comments on the original NPRM.

Request for Exemption From AD Requirements

American Airlines (AA) asks that all operators that have performed the actions specified in Boeing Alert Service Bulletin 737-71A1462, Revision 3, dated May 20, 2004, be exempt from repeating maintenance actions in accordance with the original NPRM for a maintenance program that is already in place and proven effective. AA states that it has exceeded the requirements of AD 2003-03-01 by inspecting both engine aft mount center link assemblies, regardless of the stipulation in the existing AD, which limited the inspection requirement to engines removed since the airplane date of manufacture. AA adds that the inspections revealed that none of its installed or spare engines had incorrectly installed aft mount center link assemblies. AA notes that it is doing Part 2 of the Accomplishment Instructions of the service bulletin at every engine shop visit, and has implemented maintenance task documentation to verify the proper aft mount center link configuration at every engine change. AA concludes that it has not accepted delivery of any additional Model 737 airplanes since the release of the existing AD and Boeing Alert Service Bulletin 737-71A1462, Revision 3, dated May 20, 2004.

We acknowledge the commenter's request. Actions done in accordance with Boeing Alert Service Bulletin 737-71A1462, Revision 3, before the effective date of this AD are acceptable for compliance with the AD, as indicated by the phrase “unless the actions have already been done” in paragraph (f) of this AD. We have made no change to the supplemental NPRM in this regard.

Request To Change Paragraph (d)

Boeing asks that paragraph (d) of the original NPRM be changed to indicate that the center link assembly for the aft engine mount was reversed on one airplane that had not had an engine removed since delivery. Boeing is aware of only one such report.

We do not agree with the commenter. We have received another report indicating that some airplanes were found with the engine mounts installed incorrectly on engines that had not been removed since airplane delivery. Therefore, we have not changed paragraph (d) of the NPRM (paragraph (e) of the supplemental NPRM).

Request To Change Paragraph (n)

Boeing asks that paragraph (n) of the original NPRM be changed to clarify parts not affected by the “Parts Installation” paragraph by including the permanent part marking on the center link assembly, as specified in Part 2 of the Work Instructions of Boeing Alert Service Bulletin 737-71A1462, Revision 3, dated May 20, 2004. Boeing states that this change would be equivalent to an existing alternative method of compliance (AMOC) for AD 2003-03-01, requiring the installation of marked engine mounts, as specified in the approved section of Boeing Alert Service Bulletin 737-71A1462, Revision 3, dated May 20, 2004.

We agree with the commenter for the reasons provided. We have changed paragraph (n) of the supplemental NPRM to include permanent part marking on the center link assembly, as specified in Part 2 of the Work Instructions of Boeing Alert Service Bulletin 737-71A1462, Revision 3, dated May 20, 2004.

Request To Clarify Requirements in Paragraph (n)

Japan Airlines (JAL) asks for clarification whether the requirement in paragraph (n) of the original NPRM applies only to airplanes affected by Boeing Alert Service Bulletin 737-71A1462, Revision 3, dated May 20, 2004; or to all Model 737-600, -700, -700C, -800, and -900 series airplanes. JAL states that if the requirement in paragraph (n) applies to all Model 737NG (next generation) airplanes then a change should be made to paragraph (n) of the supplemental NPRM for clarification.

We acknowledge the commenter's concern and provide the following clarification. As noted under “Actions Since Original NPRM Was Issued,” we have added Model 737-900ER airplanes to the applicability section of this supplemental NPRM; therefore, the requirement in paragraph (n) of the supplemental NPRM applies to all Model 737NG airplanes. No change to paragraph (n) of the supplemental NPRM is necessary.

Request To Change Paragraphs (i) and (o)

CFM International states that the acronym CFMI is not accurate and recommends using CFM International (CFM) throughout the NPRM.

We agree that the correct acronym should be used in the supplemental NPRM and in future rulemaking. However, CFMI is not referred to anywhere in this supplemental NPRM; therefore, no change is necessary.

CFM also asks that paragraphs (i) and (o) of the original NPRM be changed to include the Engine and Propeller Directorate, Engine Certification Office (ECO), as an approved source for obtaining repair procedures. CFM states that the engine mounting lugs and adjacent engine turbine rear frame are under the responsibility of CFM as part of the engine type certificate. CFM notes that it is in charge of approval of repairs by delegation of both engine authorities, which are the FAA and European Aviation Safety Agency (EASA); CFM is a joint certification. CFM adds that for any part problems it contacts the ECO, in Burlington, Massachusetts, and the EASA Engine Certification Office, in Cologne, Germany. In light of this, CFM does not recommend the parts be repaired under approval of a Boeing Representative.

We partially agree with the commenter for the reasons provided. We agree that the appropriate office for approval of certain repairs specified in the original NPRM is the ECO. Paragraph (i) of the original NPRM is a restatement of the requirements in AD 2003-03-01. However, paragraph (i) of the supplemental NPRM does refer to paragraph (o) of the supplemental NPRM for AMOC approval. We have changed paragraph (o) of this supplemental NPRM to allow for certain AMOC approvals by the ECO.

Explanation of Additional Changes Made to This Supplemental NPRM

We have changed this supplemental NPRM to identify the legal name of the manufacturer as published in the most recent type certificate data sheet for the affected airplane models.

We have added a new paragraph (d) to this supplemental NPRM to provide the Air Transport Association (ATA) of America subject code 71: Powerplant. This code is added to make this supplemental NPRM parallel with other new AD actions. We have reidentified subsequent paragraphs accordingly.

FAA's Determination and Proposed Requirements of the Supplemental NPRM

Certain changes discussed above expand the scope of the original NPRM; therefore, we have determined that it is necessary to reopen the comment period to provide additional opportunity for public comment on this supplemental NPRM.

Explanation of Change to Costs of Compliance

Since issuance of the original NPRM, we have increased the labor rate in the Costs of Compliance from $80 per work hour to $85 per work hour. The Costs of Compliance information, below, reflects this increase in the specified hourly labor rate.

Costs of Compliance

There are about 1,846 airplanes of the affected design in the worldwide fleet. We estimate that 854 airplanes of U.S. registry would be affected by this proposed AD. There are no new requirements in this proposed AD; however, we have expanded the applicability as noted under “Actions Since Original NPRM Was Issued.” The current costs for this proposed AD are recalculated for the convenience of affected operators, as follows:

Estimated Costs

Action	Work hours	Parts	Cost per airplane	Fleet cost
Maintenance records review (required by AD 2003-03-01)	1	$0	$85	$72,590
Inspection for correct installation of center link assembly (new proposed action)	1	0	85	72,590

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); 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 regulatory evaluation of the estimated costs to comply with this supplemental NPRM and placed it in the AD docket. See the ADDRESSES section for a location to examine the regulatory evaluation.

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 amendment 39-13025 (68 FR 4367, January 29, 2003) and adding the following new AD:

The Boeing Company: Docket No. FAA-2008-1118; Directorate Identifier 2007-NM-318-AD.

Comments Due Date

(a) The FAA must receive comments on this AD action by February 25, 2011.

Affected ADs

(b) This AD supersedes AD 2003-03-01, Amendment 39-13025.

Applicability

(c) This AD applies to all The Boeing Company Model 737 -600, -700, -700C, -800, -900, and -900ER series airplanes, certificated in any category.

Subject

(d) Air Transport Association (ATA) of America Code 71: Powerplant.

Unsafe Condition

(e) This AD results from reports indicating that operators found that the center link assembly for the aft engine mount was reversed on several airplanes that had not had an engine removed since delivery. We are issuing this AD to prevent increased structural loads on the aft engine mount, which could result in failure of the aft engine mount and consequent separation of the engine from the airplane.

Compliance

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

Restatement of the Requirements of AD 2003-03-01

Review of Maintenance Records

(g) For Model 737-600, -700, -700C, -800, and -900 series airplanes: Within 90 days after February 13, 2003 (the effective date of AD 2003-03-01), review the airplane maintenance records to determine whether either engine has been removed since the airplane's date of manufacture. If neither engine has been removed since the airplane's date of manufacture, no further action is required by this paragraph.

Inspection of Engines That Have Been Removed to Determine if Center Link Assembly is Installed Correctly

(h) For Model 737-600, -700, -700C, -800, and -900 series airplanes on which any installed engine has been removed from the airplane since the airplane's date of manufacture: Within 90 days after February 13, 2003, do a one-time general visual inspection to determine if the center link assembly of the aft engine mount is installed correctly, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-71A1462, Revision 1, dated November 7, 2002; or Revision 3, dated May 20, 2004. If the center link assembly is installed correctly, no further action is required by paragraph (h) or (i) of this AD for that engine. As of the effective date of this AD, use only Boeing Alert Service Bulletin 737-71A1462, Revision 3.

Note 1:

For the purposes of this AD, a general visual inspection is: “A visual examination of an interior or exterior area, installation, or assembly to detect obvious damage, failure, or irregularity. This level of inspection is made from within touching distance unless otherwise specified. A mirror may be necessary to ensure visual access to all surfaces in the inspection area. This level of inspection is made under normally available lighting conditions such as daylight, hanger lighting, flashlight, or droplight and may require removal or opening of access panels or doors. Stands, ladders, or platforms may be required to gain proximity to the area being checked.”

Follow-on and Corrective Actions

(i) For airplanes on which any center link assembly is found installed incorrectly during any inspection required by paragraph (h), (k), or (l) of this AD: Before further flight, do the actions specified in paragraphs (i)(1), (i)(2), and (i)(3) of this AD, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-71A1462, Revision 1, dated November 7, 2002; or Revision 3, dated May 20, 2004; except that it is not necessary to submit a report of findings to the airplane manufacturer. As of the effective date of this AD, use only Boeing Alert Service Bulletin 737-71A1462, Revision 3.

(1) Remove the center link assembly and install it correctly.

(2) Perform a detailed inspection of the engine mounting lugs and engine turbine rear frame for cracking, yielding, buckling, or wear damage.

(3) Perform a detailed inspection of the hardware for the aft engine mount; including the center link assembly, right link assembly, aft mount hanger assembly, and link pins; for cracking, yielding, buckling, or wear damage.

Note 2:

For the purposes of this AD, a detailed inspection is: “An intensive examination of a specific item, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at an intensity deemed appropriate. Inspection aids such as mirror, magnifying lenses, etc., may be necessary. Surface cleaning and elaborate procedures may be required.”

Repair

(j) If any cracking, yielding, buckling, or wear damage is found during the inspections required by paragraphs (i)(2) and (i)(3) of this AD: Before further flight, replace the discrepant part with a new or serviceable part, or repair in accordance with a method approved in accordance with the procedures specified in paragraph (o) of this AD.

New Requirements of This AD

Inspection of Engines That Have Not Been Removed To Determine if Center Link Assembly Is Installed Correctly

(k) For airplanes identified in Boeing Alert Service Bulletin 737-71A1462, Revision 3, dated May 20, 2004, on which any installed engine has not been removed from the airplane since the airplane's date of manufacture: Within 90 days after the effective date of this AD, do a detailed inspection to determine if the center link assembly of the aft engine mount is installed correctly, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-71A1462, Revision 3, dated May 20, 2004. If the center link is installed correctly, no further action is required by this paragraph for that engine.

Follow-on and Corrective Actions

(l) For airplanes on which any center link assembly is found installed incorrectly during the inspection required by paragraph (k) of this AD: Before further flight, do the follow-on and corrective actions required by paragraph (i) of this AD.

Credit for Actions Done Using Previous Service Information

(m) Inspections and corrective actions done before the effective date of this AD in accordance with a Boeing service bulletin listed in Table 1 of this AD are acceptable for compliance with the corresponding requirements of this AD.

Table 1—Previous Service Bulletins

Boeing service bulletin	Revision—	Dated—
737-71A1462	Original	August 29, 2002.
737-71A1462	1	November 7, 2002.
737-71A1462	2	May 29, 2003.

Parts Installation

(n) As of the effective date of this AD, no person may install an engine on any airplane identified in paragraph (c) of this AD unless the actions required by paragraph (n)(1) or (n)(2) of this AD are accomplished.

(1) The inspection is accomplished in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-71A1462, Revision 3, dated May 20, 2004, and the center link assembly of the aft engine mount is found to be installed correctly.

(2) The hanger fitting and center link assembly are marked and part marked in accordance with Part 2 of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-71A1462, Revision 3, dated May 20, 2004.

Note 3:

For hanger fittings and center link assemblies marked and part marked in production, as specified in Part 2 of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-71A1462, Revision 3, dated May 20, 2004, the actions specified in paragraph (n)(2) of this AD do not apply.

Alternative Methods of Compliance (AMOCs)

(o) The certification office specified in paragraph (o)(1) or (o)(2) of this AD, as applicable, has the authority to approve AMOCs for paragraphs (i) and (j) of this AD, if requested using the procedures found in 14 CFR 39.19.

(1) For the structure identified in paragraph (i)(2) of this AD: The Manager, Engine Certification Office (ECO), FAA. Send information to ATTN: Antonio Cancelliere, Aerospace Engineer, ANE-141, FAA, ECO, 12 New England Executive Park, Burlington, MA 01803-5299; telephone [phone]; fax [phone].

(2) For the structure identified in paragraph (i)(3) of this AD: The Manager, Seattle Aircraft Certification Office (ACO), FAA. Send information to ATTN: Alan Pohl, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle ACO, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone [phone]; fax [phone]. Information may be e-mailed to: [e-mail].

(3) To request a different method of compliance or a different compliance time for this AD, follow the procedures in 14 CFR 39.19. Before using any approved AMOC on any airplane to which the AMOC applies, notify your principal maintenance inspector (PMI) or principal avionics inspector (PAI), as appropriate, or lacking a principal inspector, your local Flight Standards District Office. The AMOC approval letter must specifically reference this AD.

(4) An AMOC that provides an acceptable level of safety may be used for any repair required by paragraph (i)(3) of this AD if it is approved by Boeing Commercial Airplanes Organization Designation Authorization (ODA) that has been authorized by the Manager, Seattle ACO, to make those findings. For a repair method to be approved, the repair must meet the certification basis of the airplane, and the approval must specifically refer to this AD.

Issued in Renton, Washington, on December 17, 2010.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.

Peter A. White,

Assistant Directorate Manager, Engine and Propeller Directorate, Aircraft Certification Service.