Federal Aviation Administration (FAA), Department of Transportation (DOT).
Notice of proposed rulemaking (NPRM).
The FAA proposes to adopt a new airworthiness directive (AD) for all Boeing Model 737-600, -700, -700C, -800, and -900 series airplanes. This proposed AD would require repetitive inspections of the aft pressure bulkhead web for fatigue cracks, crack indications, discrepant holes, and corrosion, and repair if necessary. This proposed AD is prompted by reports of fatigue cracks in the aft pressure bulkhead web. We are proposing this AD to detect and correct such fatigue cracks, which could result in a rapid decompression of the airplane.
We must receive comments on this proposed AD by June 16, 2005.
Use one of the following addresses to submit comments on this proposed AD.
- DOT Docket Web Site: Go to http://dms.dot.gov and follow the instructions for sending your comments electronically.
- Government-wide Rulemaking Web Site: Go to http://www.regulations.gov and follow the instructions for sending your comments electronically.
- Mail: Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street SW., Nassif Building, room PL-401, Washington, DC 20590.
- By Fax: (202) 493-2251.
- Hand Delivery: Room PL-401 on the plaza level of the Nassif Building, 400 Seventh Street SW., Washington, DC, 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, P.O. Box 3707, Seattle, Washington 98124-2207.
You can examine the contents of this AD docket on the Internet at http://dms.dot.gov, or in person at the Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street SW., room PL-401, on the plaza level of the Nassif Building, Washington, DC. Start Printed Page 22621This docket number is FAA-2005-21086; the directorate identifier for this docket is 2004-NM-217-AD.Start Further Info
FOR FURTHER INFORMATION CONTACT:
Howard Hall, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 917-6430; fax (425) 917-6590.End Further Info End Preamble Start Supplemental Information
We invite you to submit any relevant written data, views, or arguments regarding this proposed AD. Send your comments to an address listed under ADDRESSES. Include “Docket No. FAA-2005-21086; Directorate Identifier 2004-NM-217-AD” in the subject line of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. We will consider all comments submitted by the closing date and may amend the proposed AD in light of those comments.
We will post all comments we receive, without change, to http://dms.dot.gov, including any personal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this proposed AD. Using the search function of that Web site, anyone can find and read the comments in any of our dockets, including the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). You can review DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78), or you can visit http://dms.dot.gov.
Examining the Docket
You can examine the AD docket on the Internet at http://dms.dot.gov, or in person at the Docket Management Facility office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Management Facility office (telephone (800) 647-5227) is located on the plaza level of the Nassif Building at the DOT street address stated in the ADDRESSES section. Comments will be available in the AD docket shortly after the DMS receives them.
We have received reports indicating that fatigue cracks were found in the aft pressure bulkhead web on Boeing Model 737-200 and -300 series airplanes. The fatigue cracks ran in the circumferential direction along the aft row of fasteners connecting the web assembly to the bulkhead “Y” chord. Fatigue cracks in the aft pressure bulkhead web, if not detected and corrected in a timely manner, could result in a rapid decompression of the airplane.
The aft pressure bulkhead webs on Model 737-600, -700, -700C, -800, and -900 series airplanes are identical to those on the affected Model 737-200 and -300 series airplanes. Therefore, the 737-600, -700, -700C, -800, and -900 models may be subject to the same unsafe condition.
Other Relevant Rulemaking
We have previously issued AD 99-08-23, amendment 39-11132 (64 FR 19879, April 26, 1999), applicable to Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. That AD requires repetitive inspections to detect cracking in the web of the aft pressure bulkhead at body station 1016 at the aft fastener row attachment to the “Y” chord; and corrective actions, if necessary.
Relevant Service Information
We have reviewed Boeing Alert Service Bulletin 737-53A1248, dated September 9, 2004. The service bulletin describes procedures for doing inspections (i.e., detailed inspection and either low-or high-frequency eddy current inspections) of the aft pressure bulkhead web for fatigue cracks, crack indications, discrepant holes, and corrosion, and contacting the manufacturer for repair instructions. The inspections are in the aft pressure bulkhead web along the aft row of fasteners where it attaches to the “Y” chord of the body station 1016 bulkhead. The service bulletin specifies initial compliance times of 25,000 total flight cycles and 66,000 total flight cycles, based on which area is to be inspected. Repetitive inspection intervals are every 1,200, 3,800, 6,000, or 12,000 flight cycles. The repetitive intervals are based on which area is inspected and which inspection method is used for that area. 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 exist or develop on other airplanes of this same type design. Therefore, we are proposing this AD, which would require accomplishing the actions specified in the service information described previously, except as discussed under “Difference Between the AD and the Service Bulletin.”
Differences Between Proposed Rule and Service Bulletin
The service bulletin specifies that you may contact the manufacturer for instructions on how to repair certain conditions, but this proposed AD would require you to repair 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 Delegation Option Authorization Organization who has been authorized by the FAA to make those findings.
Costs of Compliance
There are about 978 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:Start Printed Page 22622
|Action||Work hours||Average labor rate per hour||Parts||Cost per airplane||Number of U.S.-registered airplanes||Fleet cost|
|LFEC and detailed inspection per inspection, cycle||8||$65||None||$520 per inspection cycle||630||$327,600 inspection per cycle.|
|HFEC and detailed inspection (in lieu of LFEC and detailed inspection), per inspection cycle||2||65||None||130 per inspection cycle||630||81,900 per cycle inspection.|
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.
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. See the ADDRESSES section for a location to examine the regulatory evaluation.Start List of Subjects
List of Subjects in 14 CFR Part 39End List of Subjects
The Proposed Amendment
Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part 39 as follows:Start Part
PART 39—AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
2. The FAA amends § 39.13 by adding the following new airworthiness directive (AD):
Boeing: Docket No. FAA-2005-21086; Directorate Identifier 2004-NM-217-AD.
Comments Due Date
(a) The Federal Aviation Administration (FAA) must receive comments on this AD action by June 16, 2005.
(c) This AD applies to all Boeing Model 737-600, -700, -700C, -800, and -900 series airplanes, certificated in any category.
(d) This AD was prompted by reports of fatigue cracks in the aft pressure bulkhead web. We are issuing this AD to detect and correct such fatigue cracks, which could result in rapid decompression of the airplane.
(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.
(f) At the applicable “Inspection Threshold” in the table in Part 1.E. “Compliance” of Boeing Alert Service Bulletin 737-53A1248, dated September 9, 2004, or within 18 months after the effective date of this AD, whichever occurs later, and thereafter at intervals not to exceed the applicable “Inspection Repeat Interval” in that table: Do the inspections (i.e., detailed inspection and either high-or low-frequency eddy current inspections) of the aft pressure bulkhead web for fatigue cracks, crack indications, discrepant holes, and corrosion, in accordance with the Accomplishment Instructions of the service bulletin.
Corrective Action Difference
(g) If any fatigue crack, crack indication, discrepant hole, or corrosion is found during any inspection required by this AD, before further flight, repair the fatigue crack, crack indication, discrepant hole, and corrosion according to a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA; or according to data meeting the certification basis of the airplane approved by an Authorized Representative (AR) for the Boeing Delegation Option Authorization (DOA) Organization who has been authorized by the Manager, Seattle ACO, to make those findings. For a repair method to be approved, the approval must specifically reference this AD.
(h) Although the service bulletin references a reporting requirement in the Accomplishment Instructions, that reporting is not required by this AD.
Alternative Methods of Compliance (AMOCs)
(i)(1) The Manager, Seattle ACO, FAA, has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19.
(2) An AMOC that provides an acceptable level of safety may be used for corrective actions, if it is approved by an AR for the Boeing DOA 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 April 25, 2005.
Manager, Transport Airplane Directorate, Aircraft Certification Service.
[FR Doc. 05-8654 Filed 4-29-05; 8:45 am]
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