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Proposed Rule

Airworthiness Directives; Boeing Model 737-100, -200, -200C, -300, -400, and -500 Series Airplanes

Document Details

Information about this document as published in the Federal Register.

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Start Preamble

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for certain Boeing Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. This proposed AD would require repetitive inspections of the intercostal webs, attachment clips, and stringer splice channels for cracks; and corrective action if necessary. This proposed AD is prompted by reports of fatigue cracks on several Boeing Model 737-200 series airplanes. We are proposing this AD to detect and correct fatigue cracking of the intercostals on the forward and aft sides of the forward entry door, which could result in loss of the forward entry door and rapid decompression of the airplane.

DATES:

We must receive comments on this proposed AD by September 20, 2004.

ADDRESSES:

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 at the Docket Management Facility, U.S. Department Start Printed Page 47809of Transportation, 400 Seventh Street SW., room PL-401, on the plaza level of the Nassif Building, Washington, DC.

Start Further Info

FOR FURTHER INFORMATION CONTACT:

Technical Information: 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.

Plain Language Information: Marcia Walters, marcia.walters@faa.gov.

End Further Info End Preamble Start Supplemental Information

SUPPLEMENTARY INFORMATION:

Docket Management System (DMS)

The FAA has implemented new procedures for maintaining AD dockets electronically. As of May 17, 2004, new AD actions are posted on DMS and assigned a docket number. We track each action and assign a corresponding directorate identifier. The DMS AD docket number is in the form “Docket No. FAA-2004-99999.” The Transport Airplane Directorate identifier is in the form “Directorate Identifier 2004-NM-999-AD.” Each DMS AD docket also lists the directorate identifier (“Old Docket Number”) as a cross-reference for searching purposes.

Comments Invited

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-2004-18788; Directorate Identifier 2003-NM-203-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 may visit http://dms.dot.gov.

We are reviewing the writing style we currently use in regulatory documents. We are interested in your comments on whether the style of this document is clear, and your suggestions to improve the clarity of our communications that affect you. You can get more information about plain language at http://www.faa.gov/​language and http://www.plainlanguage.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.

Discussion

We have received a report indicating that eleven operators have found fatigue cracks in the intercostal web at body station (BS) 358.5 and stringer (S) S-16L on several Boeing Model 737-200 series airplanes. The cracks extended from the inboard edge of the intercostal through tooling or fastener holes and terminated at the two-inch diameter lightening hole. Three operators have also reported four airplanes with cracks in the intercostals at S-11L, S-12L, and S-13L on the forward and aft sides of the forward entry door. All additional cracks are in the radius of return flanges of the webs and attachment clips. One operator has reported one airplane with cracks in the stringer splice channels at S-14L and S-15L on the aft side of the forward entry door. The cracks were in the intercostal web attachment flange at the aft end of the intercostal. Such fatigue cracking, if not detected and corrected in a timely manner, could result in loss of the forward entry door and rapid decompression of the airplane.

The intercostal webs, attachment clips, and stringer splice channels on certain Boeing Model 737-100, -200C, -300, -400, and -500 series airplanes are identical to those on the affected Boeing Model 737-200 series airplanes. Therefore, all of these models may be subject to the same unsafe condition.

Relevant Service Information

We have reviewed Boeing Special Attention Service Bulletin 737-53-1204, dated June 19, 2003. The service bulletin describes procedures for detailed and high frequency eddy current inspections (as applicable) of the intercostal webs, attachment clips, and stringer splice channels for cracks; and corrective actions if necessary. The corrective actions include repairing cracks and contacting Boeing for certain repair instructions.

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 repetitive inspections of the intercostal webs, attachment clips, and stringer splice channels for cracks; and corrective action if necessary. The proposed AD would require you to use the service information described previously to perform these actions, except as discussed under “Differences Between the Proposed AD and the Service Bulletin.”

Differences Between the Proposed AD and the Service Bulletin

Although the service bulletin specifies that operators may contact the manufacturer for disposition of certain repair conditions, this proposed AD would require operators to repair those conditions per a method approved by the FAA, or per data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative who has been authorized by the FAA to make such findings.

The service bulletin specifies to repair any crack found at the S-16L intercostal (BS 348.2-360) on Boeing Model 737-400 series airplanes per 737-400 Structural Repair Manual (SRM) 53-10-04, Figure 202. Figure 202 does not exist; the correct figure is 737-400 SRM 53-10-04, Figure 201. Note 2 of this proposed AD points out this error in the service bulletin.

Paragraphs 3. and 4. of the “Part 1 for Group 1 passenger airplanes” section of the Work Instructions of the service bulletin do not give instructions for repairing cracks found in the attachment clip or stringer splice channel during the inspections. Other paragraphs of the service bulletin give instructions for similar attachment clips and stringer splice channels. This proposed AD would require operators to contact the FAA or an FAA-authorized Boeing Delegated Engineer Representative (DER) for repair instructions and do the repair before further flight if any crack is found in the attachment clip or stringer splice channel during the inspections specified in “Part 1 for Group 1 passenger airplanes.” If no crack is found in the attachment clip or Start Printed Page 47810stringer splice channel during the inspections, this proposed AD would require the repetitive inspections.

The differences discussed above have been coordinated with Boeing.

Costs of Compliance

This proposed AD would affect about 3,113 airplanes worldwide and 876 airplanes of U.S. registry. The proposed actions would take about 2 work hours per airplane, at an average labor rate of $65 per work hour. Based on these figures, the estimated cost of the proposed AD for U.S. operators is $113,880, or $130 per airplane, per inspection cycle.

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. See the ADDRESSES section for a location to examine the regulatory evaluation.

Start List of Subjects

List of Subjects in 14 CFR Part 39

End 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:

Start Authority

Authority: 49 U.S.C. 106(g), 40113, 44701.

End Authority
[Amended]

2. The FAA amends § 39.13 by adding the following new airworthiness directive (AD):

Boeing: Docket No. FAA-2004-18788; Directorate Identifier 2003-NM-203-AD.

Comments Due Date

(a) The Federal Aviation Administration (FAA) must receive comments on this AD action by September 20, 2004.

Affected ADs

(b) None.

Applicability

(c) This AD applies to Model 737-100, -200, -200C, -300, -400, and -500 series airplanes, as listed in Boeing Special Attention Service Bulletin 737-53-1204, dated June 19, 2003; certificated in any category.

Unsafe Condition

(d) This AD was prompted by reports of fatigue cracks on several Boeing Model 737-200 series airplanes. We are issuing this AD to detect and correct fatigue cracking of the intercostals on the forward and aft sides of the forward entry door, which could result in loss of the forward entry door and rapid decompression of 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.

Service Bulletin Definition

(f) The term “service bulletin,” as used in this AD, means Boeing Special Attention Service Bulletin 737-53-1204, dated June 19, 2003.

Initial Compliance Time

(g) Before the accumulation of 15,000 total flight cycles, or within 4,500 flight cycles after the effective date of this AD, whichever occurs later: Do the inspections specified in paragraph (h) or (i) of this AD, as applicable.

Inspection for Passenger Configuration Airplanes

(h) For Group 1 passenger airplanes identified in the service bulletin: Perform a detailed inspection of the intercostal web, attachment clips, and stringer splice channels for cracks; and a high frequency eddy current inspection of the stringer splice channels, located forward and aft of the forward entry door, for cracks; per Parts 1 and 2 of the Work Instructions of the service bulletin.

Inspection for Cargo Configuration Airplanes

(i) For Group 2 cargo airplanes identified in the service bulletin: Perform a detailed inspection of the intercostal webs and attachment clips located forward of the forward entry door for cracks, per Part 3 of the Work Instructions of the service bulletin.

Repetitive Inspections

(j) If no crack is found during any inspection required by paragraph (h) or (i) of this AD, repeat the inspections at the applicable time specified in Table 1 of this AD, except as provided by paragraph (k) of this AD.

Table 1.—Repetitive Inspection Interval

Airplane group number in Service BulletinFor intercostal location—Repeat inspections at intervals not to exceed—
Group 1S-16L, from BS 348.2 to BS 360 (aft of door)4,500 flight cycles.
Group 1S-7L through S-15L, from BS 348.2 to BS 360 (aft of door)25,000 flight cycles.
Group 1 and 2S-7L through S-16L, from BS 294.5 to BS 303.9 (forward of door)25,000 flight cycles.

Deferral of Certain Repetitive Inspections

(k) For intercostal webs at S-16L from BS 348.2 to BS 360: Installation of the repair as a preventative modification or corrective action per Part 1 of the Work Instructions of the service bulletin defers the repetitive inspections to intervals not to exceed 25,000 flight cycles. Use 737-400 SRM 53-10-04, Figure 201 instead of Figure 202, as applicable.

Corrective Actions

(l) If any crack is found during any inspection required by paragraph (h) or (i) of this AD, perform the actions specified in paragraphs (l)(1) through (l)(3) of Table 2 of this AD, as applicable. Repeat the inspections at the applicable time specified in Table 1 of this AD, except as provided by paragraph (k) of this AD. Start Printed Page 47811

Table 2.—Corrective Actions

During any inspection specified in—If any crack is found in—At intercostal location—Before further flight—
(1) Part 1 of the Work Instructions of the service bulletin(i) The intercostal webStringer (S)-16L, from body station (BS) 348.2 to BS 360 (aft of door)Repair per Part 1 of the the Work Instructions of the service bulletin, except where the service bulletin specifies to contact Boeing for repair instructions, before further flight, do the repair specified in paragraph (m) of this AD. Use 737-400 Structural Repair Manual (SRM) 53-10-04, Figure 201 instead of Figure 202, as applicable (see note 2).
(ii) An attachment clip or stringer splice channelS-16L, from BS 348.2 to BS 360 (aft of door)Do the repair specified in paragraph (m) of this AD.
(2) Part 2 of the Work Instructions of the service bulletinAn intercostal web, attachment clip, or stringer splice channelS-7L through S-16L, from BS 294.5 to BS 303.9 (forward of door); and S-7L through S-15L, from BS 348.2 to BS 360 (aft of door)Do the repair specified in paragraph (m) of this AD.
(3) Part 3 of the Work Instructions of the service bulletinAn intercostal web or attachment clipS-7L through S-16L, from BS 294.5 to BS 303.9 (forward of door)Do the repair specified in paragraph (m) of this AD.

Note 2:

The service bulletin specifies to repair any crack found at the S-16L intercostal (BS 348.2-360) on Boeing Model 737-400 series airplanes per 737-400 SRM 53-10-04, Figure 202. Figure 202 does not exist; the correct figure is 737-400 SRM 53-10-04, Figure 201.

Repair

(m) At the time specified in Table 2 of this AD, repair per a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA; or per data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative who has been authorized by the Manager, Seattle ACO, to make such findings. For a repair method to be approved, the approval must specifically reference this AD.

Alternative Methods of Compliance (AMOCs)

(n)(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 a Boeing Company Designated Engineering Representative who has been authorized by the Manager, Seattle ACO, to make those findings.

Start Signature

Issued in Renton, Washington, on July 30, 2004.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.

End Signature End Part End Supplemental Information

[FR Doc. 04-17988 Filed 8-5-04; 8:45 am]

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