Source: https://www.federalregister.gov/documents/2004/08/06/04-17988/airworthiness-directives-boeing-model-737-100--200--200c--300--400-and--500-series-airplanes
Timestamp: 2017-11-18 00:13:59
Document Index: 431514662

Matched Legal Cases: ['art 1', 'art 1', 'art 3', 'art 1', 'art 1', 'art 1', 'art 2', 'art 3']

69 FR 47808
47808-47811 (4 pages)
Docket No. FAA-2004-18788
04-17988
https://www.federalregister.gov/d/04-17988 https://www.federalregister.gov/d/04-17988
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.
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.
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 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.
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.
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.”
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.
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.
Boeing: Docket No. FAA-2004-18788; Directorate Identifier 2003-NM-203-AD.
(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.
(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
(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.
(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.
Group 1 S-16L, from BS 348.2 to BS 360 (aft of door) 4,500 flight cycles.
(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.
(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
(1) Part 1 of the Work Instructions of the service bulletin (i) The intercostal web Stringer (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 channel S-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 bulletin An intercostal web, attachment clip, or stringer splice channel S-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 bulletin An intercostal web or attachment clip S-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.
(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.
(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.
[FR Doc. 04-17988 Filed 8-5-04; 8:45 am]