E9-18642. Airworthiness Directives; Boeing Model 737-600, -700, -700C, -800 and -900 Series Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

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

SUMMARY:

We are revising an earlier proposed airworthiness directive (AD) for certain Boeing Model 737-600, -700, -700C, -800 and -900 series airplanes. The original NPRM would have required repetitive lubrication of the left and right main landing gear (MLG) forward trunnion pins; and an inspection for discrepancies of the transition radius, lead-in chamfer, and cross bolt bore of the MLG forward trunnion pins, and repair or replacement if necessary. Doing the applicable inspections and repairs/replacements, or overhauling the trunnion pins as proposed in the original NPRM, would end the repetitive lubrication requirements of this proposed AD. The original NPRM resulted from a report that the protective finishes on the forward trunnion pins for the left and right MLG might have been damaged during final assembly. This action revises the original NPRM by changing the inspection of the trunnion pins to allow inspection in-situ. If a certain repair is done, this action would require repetitive inspections for discrepancies of the transition radius. We are proposing this supplemental NPRM to prevent cracking of the forward trunnion pin, which could result in fracture of the pin and consequent collapse of the MLG.

DATES:

We must receive comments on this supplemental NPRM by August 31, 2009.

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 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 ht tps://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 or 425-227-1152.

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:

Nancy Marsh, 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-2007-29087; Directorate Identifier 2007-NM-094-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 issued a notice of proposed rulemaking (NPRM) (the “original NPRM”) to amend 14 CFR part 39 to include an airworthiness directive (AD) that would apply to certain Boeing Model 737-600, -700, -700C, -800 and -900 series airplanes. That original NPRM was published in the Federal Register on August 31, 2007 (72 FR 50292). That original NPRM proposed to require repetitive lubrication of the left and right main landing gear (MLG) forward trunnion pins; and an inspection for discrepancies of the transition radius, lead-in chamfer, and cross bolt bore of the MLG forward trunnion pins, and repair or replacement if necessary. The NPRM specified that the applicable inspections and repairs/replacements, or overhauling the trunnion pins, ends the repetitive lubrication requirements of this AD.

Actions Since Original NPRM Was Issued

We referred to Boeing Service Bulletin 737-32-1376, Revision 1, dated March 19, 2007, as the appropriate source of service information for accomplishing the actions proposed in the original NPRM. Since we issued the original NPRM, Boeing issued Service Bulletin 737-32-1376, Revision 2, dated August 6, 2008, to provide procedures for an in-situ detailed inspection for discrepancies of transition radius of the MLG forward trunnion pins, and for in-situ repair of the protective finish of the forward trunnion pin transition radius. Revision 2 of the service bulletin also provides procedures for inspecting the lead-in chamfer and the cross bolt bore with the MLG removed. Revision 2 of the service bulletin also includes new cost information. For airplanes on which the repair specified in Part 4 of Revision 2 of the service bulletin is done, the service bulletin provides procedures for repetitive inspections of the transition radius until the trunnion pin is overhauled or replaced.

Boeing Service Bulletin 737-32-1376, Revision 2, dated August 6, 2008, specifies that no more work is necessary on airplanes changed in accordance with Boeing Service Bulletin 737-32-1376, Revision 1, dated March 19, 2007.

In Boeing Service Bulletin 737-32-1376, Revision 2, dated August 6, 2008, the threshold has been changed to 120 months for doing the in-situ detailed inspection of the lead-in chamfer and cross-bolt bore for any airplane on which a trunnion pin is not replaced.

Clarification of Service Bulletin

In paragraph 1.E., “Compliance” of Boeing Service Bulletin 737-32-1376, Revision 2, dated August 6, 2008, note (d) of Table 1 and note (a) of Table 2 state that repair of the trunnion pin in accordance with the Boeing 737 Component Maintenance Manual (CMM) 57-15-01 meets “all compliance requirements of this service bulletin for that pin only.” However, operators should note that an overhaul of the entire pin rather than a local repair is necessary to comply with the requirements of this proposed AD.

Explanation of Additional Paragraph in the Supplemental NPRM

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

Comments

We gave the public the opportunity to participate in developing this AD. We considered the comments received.

Agreement with Lubrication Task

Air Transport Association (ATA), on behalf of its member American Airlines (AA), agrees with the lubrication task required every 30 days.

Requests to Reduce Burden on Operators

We received several comments regarding the burden on operators imposed by the actions proposed in the original NPRM. These commenters note the difficulty and expense of accomplishing certain inspections, and request we reduce that burden as follows:

• Southwest Airlines and Continental Airlines request that we clarify the original NPRM to note that the inspections of the transition radius do not require removing the MLG. Southwest also requests that we revise the compliance time from 96 months to 120 months for some inspections of the trunnion pin, and that we postpone the issuance of the final rule pending development of a new inspection procedure. Continental states that the complexity of the inspections will affect the operation of the airline by removing multiple airplanes from service.
• ATA, on behalf of AA, states that the cost impact is grossly underestimated, and that the costs to AA alone will be over $1.7 million, including out-of-service revenue costs.

We agree that requiring operators to remove the MLG in order to do the actions proposed in the original NPRM could impose an undue burden. The proposed requirement to remove the MLG could severely affect the airlines by forcing multiple airplanes to be out of service at the same time. As a result of the comments we received, we held a multi-operator meeting. Boeing, the FAA, and several operators attended the meeting. Operators provided Boeing with new inspection data from airplanes that had already been inspected. Boeing evaluated the data and, in cooperation with the airlines, developed an alternative inspection procedure that does not require removal of the MLG. That alternative procedure is specified in Boeing Service Bulletin 737-32-1376, Revision 2, dated August 6, 2008, described above. We have included that alternative procedure in this supplemental NPRM. In addition, we have revised paragraph (h) of the original NPRM (paragraph (i) of this supplemental NPRM) from 96 months to 120 months in this supplemental NPRM, as recommended in Boeing Service Bulletin 737-32-1376, Revision 1, dated March 19, 2007.

Request to Remove Certain Inspections

Continental Airlines requests that we delete paragraph (h) of the original NPRM (paragraph (i) of this supplemental NPRM). Paragraph (h) of the original NPRM specifies doing a detailed inspection for discrepancies of the lead-in chamfer and cross-bolt bore, and repairing or replacing the trunnion pin if any discrepancy is found. The commenter believes there is no propensity for stress corrosion to exist in certain areas of the trunnion pin.

We partially agree with the commenter. We agree that the inspections specified in Boeing Service Bulletin 737-32-1376, Revision 1, dated March 19, 2007, can be modified. However, we do not agree that the inspections can be deleted entirely. Additional information provided to Boeing during the multi-operator meeting discussed previously resulted in revised inspections that are included in Boeing Service Bulletin 737-32-1376, Revision 2, dated August 6, 2008. The revised inspections are included in paragraph (i) of this supplemental NPRM.

Request to Revise Compliance Time for Certain Airplanes

Boeing requests that the AD specify a separate compliance time for Boeing Model 737-BBJ, C40A, and C40B airplanes. Boeing notes that these airplanes might not enter service immediately upon delivery and, therefore, their exposure to the effects of the environment is reduced.

We disagree with the request to specify a separate compliance time for these airplanes. The circumstances surrounding when these airplanes enter service are variable; therefore, defining a consistent compliance time for all of these airplanes is not possible. However, under the provisions of paragraph (l) of this supplemental NPRM, we will consider requests for adjustments to the compliance time if data are submitted to substantiate that such an adjustment would provide an acceptable level of safety. We have not changed the AD in this regard.

FAA's Determination and Proposed Requirements of the Supplemental NPRM

We are proposing this supplemental NPRM because we evaluated all pertinent information and determined an unsafe condition exists and is likely to exist or develop on other products of the same type design. The changed inspections described above expand the scope of the original NPRM. As a result, we have determined that it is necessary to reopen the comment period to provide additional opportunity for the public to comment on this supplemental NPRM.

Costs of Compliance

There are about 890 airplanes of the affected design in the worldwide fleet. The following table provides the estimated costs for U.S. operators to comply with this proposed AD. The average labor rate is $80 per work hour.

Estimated Costs

Action	Work hours	Cost per airplane	Number of U.S.-registered airplanes	Fleet cost
Repetitive lubrication	2	$160 per lubrication cycle	300	$48,000 per lubrication cycle.
Inspections (in situ)	2	$160	300	$48,000.

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 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 this 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.

You can find our regulatory evaluation and the estimated costs of compliance in the AD Docket.

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 adding the following new AD:

Boeing: Docket No. FAA-2007-29087; Directorate Identifier 2007-NM-094-AD.

Comments Due Date

(a) We must receive comments by August 31, 2009.

Affected ADs

(b) None.

Applicability

(c) This AD applies to Boeing Model 737-600, -700, -700C, -800 and -900 series airplanes, certificated in any category, as identified in Boeing Service Bulletin 737-32-1376, Revision 2, dated August 6, 2008.

Subject

(d) Air Transport Association (ATA) of America Code 32: Landing Gear.

Unsafe Condition

(e) This AD results from a report that the protective finishes on the forward trunnion pins for the left and right main landing gear (MLG) might have been damaged during final assembly. We are issuing this AD to prevent cracking of the forward trunnion pin, which could result in fracture of the pin and consequent collapse of the MLG.

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.

Lubrication or Overhaul

(g) Within 30 days after the effective date of this AD: Lubricate the left and right MLG forward trunnion pins in accordance with the Accomplishment Instructions of Boeing Service Bulletin 737-32-1376, Revision 2, dated August 6, 2008. Repeat the lubrication at intervals not to exceed 30 days until all applicable requirements of paragraphs (h) and (i) of this AD have been accomplished. Overhauling the trunnion pin in accordance with the Accomplishment Instructions of Boeing Service Bulletin 737-32-1376, Revision 2, dated August 6, 2008, ends the repetitive lubrication requirements of this paragraph for that pin.

Inspection and Corrective Actions

(h) Within 60 months after the date of issuance of the original airworthiness certificate or date of issuance of the original export certificate of airworthiness, or within 6 months after the effective date of this AD, whichever occurs later: Do a detailed inspection for discrepancies (corrosion, finish damage, surface deformation, or scratches) of the transition radius of the left and right MLG trunnion pins; and if any discrepancy is found, repair or replace the trunnion pin before further flight. Do all actions in accordance with the Accomplishment Instructions of Boeing Service Bulletin 737-32-1376, Revision 2, dated August 6, 2008. If the repair specified in Part 4 of the service bulletin is done, within 24 months after doing the repair, do the detailed inspection of the transition radius, and do the inspection thereafter at intervals not to exceed 24 months until the trunnion pin is overhauled or replaced in accordance with the Accomplishment Instructions of Boeing Service Bulletin 737-32-1376, Revision 2, dated August 6, 2008.

(i) For airplanes on which the trunnion pin has not been replaced or overhauled: Within 120 months after the date of issuance of the original airworthiness certificate or date of issuance of the original export certificate of airworthiness, or within 6 months after the effective date of this AD, whichever occurs later, do a detailed inspection for discrepancies of the lead-in chamfer and cross-bolt bore; and if any discrepancy is found, repair or replace the trunnion pin before further flight. Do all actions in accordance with the Accomplishment Instructions of Boeing Service Bulletin 737-32-1376, Revision 2, dated August 6, 2008.

No Report Required

(j) Although Boeing Service Bulletin 737-32-1376, Revision 2, dated August 6, 2008, specifies to send inspection reports to the manufacturer, this AD does not include that requirement.

Credit for Actions Done Using Previous Issue of Service Information

(k) Actions done before the effective date of this AD in accordance with Boeing Service Bulletin 737-32-1376, dated May 12, 2005; or Revision 1, dated March 19, 2007; are acceptable for compliance with the corresponding actions of this AD.

Alternative Methods of Compliance (AMOCs)

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

(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 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.

(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 July 24, 2009.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.