2012-20476. Airworthiness Directives; The Boeing Company Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

We propose to adopt a new airworthiness directive (AD) for certain The Boeing Company Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. This proposed AD was prompted by a report of an approximate 8-inch crack found in the fuselage skin under the aft drain mast. This proposed AD would require a detailed inspection for cracking and corrosion of the channel and fillers adjacent to the drain mast bolts, an inspection to determine the location of the bonding strap, a measurement of the washers under the drain mast bolts, and related investigative actions and repair if necessary. We are proposing this AD to detect and correct cracking in the fuselage skin and internal support structure, which could result in uncontrolled decompression of the airplane.

DATES:

We must receive comments on this proposed AD by October 5, 2012.

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 proposed AD, contact Boeing Commercial Airplanes, Attention: Data & Services Management, P.O. Box 3707, MC 2H-65, Seattle, WA 98124-2207; telephone [phone], extension 1; fax [phone]; 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, WA. 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 (phone: [phone]) is in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT:

Wayne Lockett, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue SW., Renton, WA 98057-3356; phone: [phone]; fax: [phone]; email: [e-mail].

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to send any written relevant data, views, or arguments about this proposal. Send your comments to an address listed under the ADDRESSES section. Include “Docket No. FAA-2012-0857; Directorate Identifier 2011-NM-244-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 received a report of an aft drain mast found loose on a Model 737-400 series airplane with approximately 30,500 total flight cycles. Further investigation revealed the fuselage skin and surrounding back-up structure were cracked. An 8-inch crack common to the fuselage skin was hidden under the drain mast. The crack was likely caused by incorrect installation of the drain mast. A drain mast that is not installed correctly can cause cracks in the fuselage skin and the internal support structure. The skin cracks cannot be seen because they are hidden by the drain mast. This condition, if not corrected, could result in uncontrolled decompression of the airplane.

Relevant Service Information

We reviewed Boeing Alert Service Bulletin 737-53A1318, dated October 31, 2011.

For airplanes identified as Group 1 in Boeing Alert Service Bulletin 737-53A1318, dated October 31, 2011, this service bulletin describes procedures for doing a detailed inspection for cracking and corrosion of the channel and fillers adjacent to the drain mast bolts, an inspection to determine the location of the bonding strap, a measurement of the washers under the drain mast bolts, and related investigative actions and repair if necessary. Related investigative actions include removing the drain mast and doing a high frequency eddy current (HFEC) and detailed inspection for cracking and corrosion of the skin, channel, and fillers. This service bulletin also specifies contacting Boeing for repair instructions and doing the repair.

For airplanes identified as Group 2 in Boeing Alert Service Bulletin 737-53A1318, dated October 31, 2011, this service bulletin specifies contacting Boeing for inspection and repair instructions and doing the actions.

The compliance time for the inspection is within 120 days, and before further flight for the repair.

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 accomplishing the actions specified in the service information described previously, except as discussed under “Differences Between the Proposed AD and the Service Information.”

Differences Between the Proposed AD and the Service Information

Boeing Alert Service Bulletin 737-53A1318, dated October 31, 2011, specifies to contact the manufacturer for instructions on how to inspect and repair certain conditions, but this proposed AD would require that those actions be accomplished in one of the following ways:

• In accordance with a method that we approve; or
• Using data that meet the certification basis of the airplane, and that have been approved by the Boeing Commercial Airplanes Organization Designation Authorization (ODA) whom we have authorized to make those findings.

Costs of Compliance

We estimate that this proposed AD affects 612 airplanes of U.S. registry.

We estimate the following costs to comply with this proposed AD:

Estimated Costs

Action	Labor cost	Parts cost	Cost per product	Cost on U.S. operators
Detailed inspection, bonding strap inspection, washer measurement	4 work-hours × $85 per hour = $340	$0	$340	$208,080

We estimate the following costs to do certain necessary conditional actions that would be required based on the results of the proposed inspection. We have no way of determining the number of aircraft that might need these actions:

On-condition Costs

Action	Labor cost	Parts cost	Cost per product
Drain mast removal, HFEC and detailed inspections, and drain mast installation	5 work-hours × $85 per hour = $425	$0	$425

We have received no definitive data that would enable us to provide a cost estimate for the repair specified in this proposed AD.

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),

(3) Will not affect intrastate aviation in, 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 adding the following new airworthiness directive (AD):

The Boeing Company: Docket No. FAA-2012-0857; Directorate Identifier 2011-NM-244-AD.

(a) Comments Due Date

We must receive comments by October 5, 2012.

(b) Affected ADs

None.

(c) Applicability

This AD applies to The Boeing Company Model 737-100, -200, -200C, -300, -400, and -500 series airplanes, certificated in any category, as identified in Boeing Alert Service Bulletin 737-53A1318, dated October 31, 2011.

(d) Subject

Joint Aircraft System Component (JASC)/Air Transport Association (ATA) of America Code 53, Fuselage.

(e) Unsafe Condition

This AD was prompted by a report of an approximate 8-inch crack found in the fuselage skin under the aft drain mast. We are issuing this AD to detect and correct cracking in the fuselage skin and internal support structure, which could result in uncontrolled decompression of the airplane.

(f) Compliance

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

(g) Inspection and Repair

(1) For airplanes identified as Group 1 airplanes in Boeing Alert Service Bulletin 737-53A1318, dated October 31, 2011: At the times specified in paragraph 1.E. “Compliance,” of Boeing Alert Service Bulletin 737-53A1318, dated October 31, 2011, do the actions specified in paragraphs (g)(1)(i), (g)(1)(ii), and (g)(1)(iii) of this AD, and do all related investigative actions and repair, as applicable, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1318, dated October 31, 2011, except as required by paragraph (h) of this AD. Related investigative actions and repairs must be done before further flight. If the drain mast is found to be installed correctly, no further action is required by this paragraph.

(i) Do a detailed inspection for cracking and signs of corrosion of the channel and the fillers adjacent to the drain mast bolts.

(ii) Inspect the bonding strap for the correct location.

(iii) Measure the diameter and thickness of the washers under the drain mast bolts.

(2) For airplanes identified as Group 2 airplanes in Boeing Alert Service Bulletin 737-53A1318, dated October 31, 2011: Within 120 days after the effective date of this AD, inspect and repair, as required, using a method approved in accordance with the procedures specified in paragraph (i) of this AD. Repairs must be done before further flight.

(h) Exception

(1) Where Paragraph 1.E., “Compliance,” of Boeing Alert Service Bulletin 737-53A1318, dated October 31, 2011, specifies a compliance time after the original issue date of Boeing Alert Service Bulletin 737-53A1318, dated October 31, 2011, this AD requires compliance within the specified compliance time after the effective date of this AD.

(2) For airplanes identified as Group 1 airplanes in Boeing Alert Service Bulletin 737-53A1318, dated October 31, 2011: If any cracking or sign of corrosion is found during any inspection required by this AD, and Boeing Alert Service Bulletin 737-53A1318, dated October 31, 2011, specifies to contact Boeing for appropriate action, before further flight, repair the crack or sign of corrosion using a method approved in accordance with the procedures specified in paragraph (i) of this AD.

(i) Alternative Methods of Compliance (AMOCs)

(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. In accordance with 14 CFR 39.19, send your request to your principal inspector or local Flight Standards District Office, as appropriate. If sending information directly to the manager of the ACO, send it to the attention of the person identified in the Related Information section of this AD. Information may be emailed to: [e-mail].

(2) Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the local flight standards district office/certificate holding district office.

(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 the 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.

(j) Related Information

(1) For more information about this AD, contact Wayne Lockett, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue SW., Renton, WA 98057-3356; phone: [phone]; fax: [phone]; email: [e-mail].

(2) For service information identified in this AD, contact Boeing Commercial Airplanes, Attention: Data & Services Management, P.O. Box 3707, MC 2H-65, Seattle, WA 98124-2207; telephone [phone], extension 1; fax [phone]; 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, WA. For information on the availability of this material at the FAA, call 425-227-1221.

Issued in Renton, Washington, on August 8, 2012.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.