E8-25903. Airworthiness Directives; Boeing Model 737-600, -700, -700C, -800, and -900 Series Airplanes

AGENCY:

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

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to supersede an existing airworthiness directive (AD) that applies to all Boeing Model 737-600, -700, -700C, -800, and -900 series airplanes. The existing AD 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. This proposed AD would require the same actions for airplanes on which the engine has not been previously removed. This proposed 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 proposing 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.

DATES:

We must receive comments on this proposed AD by December 15, 2008.

ADDRESSES:

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 AD, contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207.

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:

Allen Rauschendorfer, 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

On January 21, 2003, we issued AD 2003-03-01, amendment 39-13025 (68 FR 4367, January 29, 2003), for all Boeing Model 737-600, -700, -700C, -800, and -900 series airplanes. That AD 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, that AD requires an inspection of the aft engine mount to determine if the center link assembly is correctly installed, and follow-on actions if necessary. That AD resulted from reports indicating that operators found that the center link assembly for the aft engine mount was reversed on several airplanes. We issued that 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.

Actions Since Existing AD Was Issued

Since we issued AD 2003-03-01, the manufacturer informed us that it is possible that some center links were incorrectly installed in an aft engine mount before the airplane was delivered. In AD 2003-03-01 inspection of the aft engine mounts was required only for airplanes that had an engine change after the airplane was delivered to the operator. The inspection is now necessary for all airplanes, line numbers 1 through 1277 inclusive.

Relevant Service Information

We have reviewed Boeing Alert Service Bulletin 737-71A1462, Revision 3, dated May 20, 2004. The procedures in Revision 3 of the service bulletin are essentially the same as those in Boeing Alert Service Bulletin 737-71A1462, Revision 1, dated November 7, 2002. We referred to Revision 1 of the service bulletin as the appropriate source of service information for accomplishing the actions required by AD 2003-03-01. However, Revision 3 of the service bulletin also specifies inspecting to determine if the center link assembly is installed correctly on any installed engine that has not been removed from the airplane since the airplane's delivery. Revision 3 of the service bulletin also specifies repeating the inspection during each subsequent engine change for each aft engine mount. Finally, Revision 3 also specifies that adding permanent part marks on the center link assembly and the hanger fitting ends the need for the repetitive inspections. Accomplishing the actions specified in the service information is intended to adequately address the unsafe condition.

FAA's Determination and Requirements of the Proposed AD

We have evaluated all pertinent information and identified an unsafe condition that is likely to develop on other airplanes of the same type design. For this reason, we are proposing this AD, which would supersede AD 2003-03-01 and would retain the requirements of the existing AD. This proposed AD would also require the same actions for airplanes on which the engine has not been previously removed. This proposed AD would also require accomplishing the actions specified in the service bulletin described previously, except as discussed under “Difference Between the Proposed AD and the Service Bulletin.”

Difference Between the Proposed AD and the Service Bulletin

Boeing Alert Service Bulletin 737-71A1462, Revision 3 specifies contacting the part manufacturer (CFMI) for more instructions if damage is found to the engine mounting lugs and the adjacent engine turbine rear frame. (Damage includes cracking, yielding, buckling, and wear.) However, this proposed AD would require repairing those conditions in one of the following ways:

• Using a method that we approve; or
• Using data that meet the certification basis of the airplane, and that have been approved by an Authorized Representative for the Boeing Commercial Airplanes Delegation Option Authorization (DOA) Organization whom we have authorized to make those findings.

Clarification of Certain Actions

Revision 3 of the service bulletin specifies repeating the inspection during each subsequent engine change for each aft engine mount. This proposed AD does not specify a repetitive inspection but instead specifies in paragraph (n), “Parts Installation,” that no person may install an engine on any airplane unless the center link assembly of the aft engine mount is found to be installed correctly.

Revision 3 of the service bulletin also specifies that adding permanent part marks on the center link assembly and the hanger fitting ends the need for the repetitive inspections. As noted above, this proposed AD would not include a repetitive inspection requirement. In addition, because the affected parts are rotable, the repetitive inspections referred to in the service bulletin would be terminated only as long as the engine stays on the airplane.

Changes to Existing AD

This proposed AD would retain the requirements of AD 2003-03-01. Since AD 2003-03-01 was issued, the AD format has been revised, and certain paragraphs have been rearranged. As a result, the corresponding paragraph identifiers have changed in this proposed AD, as listed in the following table:

Revised Paragraph Identifiers

Requirement in AD 2003-03-01	Corresponding requirement in this proposed AD
Paragraph (a)	Paragraph (f).
Paragraph (b)	Paragraph (g).
Paragraph (c)	Paragraph (h).
Paragraph (d)	Paragraph (i).
Paragraph (e)	Paragraph (m).
Paragraph (f)	Paragraph (n).

We have also removed Note 1 of the existing AD and re-numbered subsequent notes accordingly. We have also revised Note 2 and Note 3 of the existing AD (Note 1 and Note 2 of this proposed AD) to provide a more up-to-date definition of a general visual inspection and a detailed inspection.

Boeing Commercial Airplanes has received a DOA. We have revised paragraph (i) of this AD (paragraph (d) of AD 2003-03-01) to delegate the authority to approve an alternative method of compliance for any repair required by this proposed AD to an Authorized Representative for the Boeing Commercial Airplanes DOA rather than a Designated Engineering Representative (DER). We have also simplified paragraph (i) of this AD by referring to the “Alternative Methods of Compliance (AMOCs)” paragraph (o) of this proposed AD for repair methods, which includes a reference to the DOA.

Costs of Compliance

There are about 1,277 airplanes of the affected design in the worldwide fleet. This proposed AD would affect about 500 airplanes of U.S. registry. The average labor rate is $80 per work hour. The following table provides the estimated costs for U.S. operators to comply with this proposed AD.

Estimated Costs

Action	Work hours	Parts	Cost per airplane	Fleet cost
Maintenance records review (required by AD 2003-03-01)	1	$0	$80	$40,000
Inspection for correct installation of center link assembly (new proposed action)	1	0	80	40,000

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 proposed AD 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 Federal Aviation Administration (FAA) amends § 39.13 by removing amendment 39-13025 (68 FR 4367, January 29, 2003) and adding the following new airworthiness directive (AD):

Boeing: 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 December 15, 2008.

Affected ADs

(b) This AD supersedes AD 2003-03-01.

Applicability

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

Unsafe Condition

(d) 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

(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.

Restatement of the Requirements of AD 2003-03-01

Review of Maintenance Records

(f) 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; however paragraph (n) of this AD continues to apply.

Inspection To Determine if Center Link Assembly Is Installed Correctly

(g) For any installed engine that is found to have 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, per 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, as specified in the service bulletin, no further action is required by paragraph (g), (h), or (i) of this AD for that engine; however paragraph (n) of this AD continues to apply.

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, hangar 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

(h) For any center link assembly that is found installed incorrectly during the inspection required by paragraph (g) of this AD: Before further flight, do the actions in paragraphs (h)(1), (h)(2), and (h)(3) of this AD, per 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.

(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

(i) If any cracking, yielding, buckling, or wear damage is found during the inspections required by paragraphs (h)(2) and (h)(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 by the Manager, Seattle Aircraft Certification Office (ACO), FAA; or using 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

(j) For all airplanes identified in Boeing Alert Service Bulletin 737-71A1462, Revision 3, dated May 20, 2004: For any installed engine that 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.

Follow-on and Corrective Actions

(k) For any center link assembly that is found installed incorrectly during any inspection required by paragraph (j) of this AD: Before further flight, do the actions required by paragraphs (k)(1), (k)(2), and (k)(3) of this AD, per the Accomplishment Instructions of Boeing Alert Service Bulletin 737-71A1462, Revision 3, dated May 20, 2004, except that it is not necessary to submit a report of findings to the airplane manufacturer.

(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.

Repair

(l) If any cracking, yielding, buckling, or wear damage is found during the inspections required by paragraphs (k)(2) and (k)(3) of this AD, and Boeing Alert Service Bulletin 737-71A1462, Revision 3, dated May 20, 2004, specifies to contact Boeing or the part manufacturer: Before further flight, replace the discrepant part (e.g., parts with cracking, yielding, buckling, and wear damage) with a new or serviceable part, or repair using a method approved in accordance with the procedures specified in paragraph (o) 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 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 Alert Service Bulletin	Revision	Date
737-71A1462	Original	Aug. 29, 2002.
737-71A1462	1	Nov. 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 unless the inspections specified in paragraph (g) or (j) of this AD are accomplished and the center link assembly of the aft engine mount is found to be installed correctly.

Alternative Methods of Compliance (AMOCs)

(o)(1) The Manager, Seattle Aircraft Certification Office (ACO) FAA, ATTN: Allen Rauschendorfer, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone [phone]; fax [phone]; has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19.

(2) 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 appropriate principal inspector (PI) in the FAA Flight Standards District Office (FSDO), or lacking a PI, your local FSDO.

(3) An AMOC that provides an acceptable level of safety may be used for any repair required by this AD, if it is approved by an Authorized Representative for the Boeing Commercial Airplanes Delegation Option Authorization Organization who 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 October 10, 2008.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.