Airworthiness directives: Boeing,
[Federal Register: December 9, 1998 (Volume 63, Number 236)]
[Rules and Regulations]
[Page 67769-67771]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr09de98-1]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 98-NM-291-AD; Amendment 39-10931; AD 98-25-06]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 737-200, -200C, -300, and -400 Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule; request for comments.
SUMMARY: This amendment adopts a new airworthiness directive (AD) that is applicable to certain Boeing Model 737-200, -200C, -300, and -400 series airplanes. This action requires repetitive inspections to detect cracking of the corners of the door frame and the cross beams of the aft cargo door, and corrective actions, if necessary. This action also provides an optional terminating action for the repetitive inspection requirement of this AD. This amendment is prompted by reports indicating that fatigue cracks have been detected in the corners of the door frame and the cross beams of the aft cargo door on several in- service airplanes, and by another report indicating that rapid depressurization occurred during flight on one of those airplanes. The actions specified in this AD are intended to prevent fatigue cracking of the corners of the door frame and the cross beams of the aft cargo door, which could result in rapid depressurization of the airplane.
DATES: Effective December 24, 1998.
The incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of December 24, 1998.
Comments for inclusion in the Rules Docket must be received on or before February 8, 1999.
ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 98-NM-291-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.
The service information referenced in this AD may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.
FOR FURTHER INFORMATION CONTACT: Rick Kawaguchi, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-1153; fax (425) 227-1181.
SUPPLEMENTARY INFORMATION: The FAA has received reports indicating that fatigue cracks have been detected in the corners of the door frame and the cross beams of the aft cargo door on several in-service Boeing Model 737-200, -200C, -300, and -400 series airplanes. Such fatigue cracking results from cabin pressurization cycles. The FAA also has received a report indicating that an incident of rapid depressurization occurred during flight on one of the affected Boeing Model 737-200 series airplanes. Investigation of that incident revealed fatigue cracks in the corners of the frame of the aft cargo door of the airplane. These conditions, if not corrected, could result in rapid depressurization of the airplane.
Explanation of Relevant Service Information
The FAA has reviewed and approved Boeing Service Bulletin 737-52- 1079, Revision 5, dated May 16, 1996. That service bulletin describes procedures for repetitive internal detailed visual inspections to detect cracking of the corners of the door frame and the upper and lower cross beams of the aft cargo door, and corrective actions, if necessary. Those corrective actions include repair, replacement of the damaged frame, and modification of the aft cargo door. The modification entails installation of a steel reinforcement angle at each corner of the door and installation of reinforcements on the upper and lower cross beams of the door. Accomplishment of such modification eliminates the need for the repetitive internal detailed visual inspections.
Explanation of the Requirements of the Rule
Since an unsafe condition has been identified that is likely to exist or develop on other airplanes of the same type design, this AD is being issued to prevent fatigue cracking of the corners of the door frame and the cross beams of the aft cargo door, which could result in rapid depressurization of the airplane. This AD requires accomplishment of the actions specified in the service bulletin described previously, except as discussed below.
Other Relevant Rulemaking
The FAA previously has issued AD 90-06-02, amendment 39-6489 (55 FR 8372, March 7, 1990), applicable to certain Boeing Model 737 series airplanes. AD 90-06-02 requires accomplishment of certain structural modifications, which constitutes terminating action for the repetitive inspection requirements of this AD.
Differences Between Service Bulletin and This AD
Operators should note that, unlike the procedures described in the service bulletin, this AD does not permit further flight with stop- drilled cracks in the frame of the aft cargo door. The FAA has determined that, because of the safety implications and consequences associated with such cracking, any subject aft cargo door frame that is found to be cracked must be permanently repaired and modified prior to further flight.
Operators also should note that, although the service bulletin specifies that the manufacturer may be contacted for disposition of certain repair conditions, this AD requires the repair of those conditions to be accomplished in accordance with a method approved by the FAA.
Explanation of Applicability
Operators should note that the effectivity listing of the service bulletin includes Boeing Model 737-200 and
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-200C series airplanes having line numbers 6 through 873 inclusive. The applicability of this AD includes not only those airplanes listed in the effectivity listing of the service bulletin, but also Boeing Model 737-200, -200C, -300, and -400 series airplanes; having line numbers 874 through 1642 inclusive; that have certain replacement doors installed and that have not been modified in accordance with Boeing Service Bulletin 737-52-1079.
Explanation of Compliance Threshold
Although the service bulletin recommends that the initial inspection be performed prior to the accumulation of 12,000 total flight cycles, this AD requires that the initial inspection be performed within 90 days or 700 flight cycles after the effective date of this AD, whichever occurs later. The FAA has determined that the number of total flight cycles for an airplane may not be a good indicator of the total cycle count for the subject aft cargo door, because a door may have been removed from an airplane with many total flight cycles and reinstalled on an airplane with relatively fewer total flight cycles. Also, the FAA finds that, in view of the reports indicating that rapid depressurization occurred on an airplane on which fatigue cracks were found in the frame of the aft cargo door, and because of the safety implications and consequences associated with such cracking, the initial compliance time specified in this AD is appropriate.
Interim Action
This is considered to be interim action until final action is identified, at which time the FAA may consider further rulemaking.
Determination of Rule's Effective Date
Since a situation exists that requires the immediate adoption of this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days.
Comments Invited
Although this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this rule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified under the caption ADDRESSES. All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed.
Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report that summarizes each FAA-public contact concerned with the substance of this AD will be filedin the Rules Docket.
Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this rule must submit a self-addressed, stamped postcard on which the following statement is made: ``Comments to Docket Number 98-NM-291-AD.'' The postcard will be date stamped and returned to the commenter.
Regulatory Impact
The regulations adopted herein will not have substantial direct effects 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. Therefore, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.
The FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and that it is not a ``significant regulatory action'' under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, may be obtained from the Rules Docket at the location provided under the caption ADDRESSES.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.
Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows:
PART 39--AIRWORTHINESS DIRECTIVES
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The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
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Section 39.13 is amended by adding the following new airworthiness directive:
98-25-06 Boeing: Amendment 39-10931. Docket 98-NM-291-AD.
Applicability: The following airplane models, certificated in any category:
‹bullet› Model 737-200 and -200C series airplanes, line numbers 6 through 873 inclusive;
‹bullet› Model 737-200, -200C, -300, and -400 series airplanes; line numbers 874 through 1642 inclusive; equipped with an aft cargo door having Boeing part number (P/N) 65-47952-1 or P/N 65-47952-524; except:
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Those airplanes on which that door has been modified in accordance with Boeing Service Bulletin 737-52-1079; or,
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Those airplanes on which the door assembly having P/N 65- 47952-524 includes four straps (P/N's 65-47952-139, 65-47952-140, 65-47952-141, and 65-47952-142) and a thicker lower cross beam web (P/N 65-47952-157).
Note 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been otherwise modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (d) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.
Compliance: Required as indicated, unless accomplished previously.
To prevent fatigue cracking of the corners of the door frame and the cross beams of the aft cargo door, which could result in rapid depressurization of the airplane, accomplish the following:
(a) Within 90 days or 700 flight cycles after the effective date of this AD, whichever occurs later, perform an internal detailed visual inspection to detect cracking of the
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corners of the door frame and the cross beams of the aft cargo door, in accordance with Boeing Service Bulletin 737-52-1079, Revision 5, dated May 16, 1996.
(1) If no cracking is detected, accomplish the requirements of either paragraph (a)(1)(i) or (a)(1)(ii) of this AD.
(i) Repeat the internal visual inspection thereafter at intervals not to exceed 4,500 flight cycles. Or,
(ii) Prior to further flight, modify the corners of the door frame and the cross beams of the aft cargo door in accordance with the service bulletin. Accomplishment of such modification constitutes terminating action for the repetitive inspection requirements of this AD.
(2) If any cracking is detected in the upper or lower cross beams, prior to further flight, modify the cracked beam in accordance with paragraph III.C. of Part I of the Accomplishment Instructions of the service bulletin. Accomplishment of such modification constitutes terminating action for the repetitive inspection requirements of this AD for the repaired beam.
(3) If any cracking is detected in the forward or aft upper door frame, prior to further flight, repair the frame and modify the corners of the door frame of the aft cargo door, in accordance with paragraph III.E. of Part I of the Accomplishment Instructions of the service bulletin, except as provided by paragraph (b) of this AD. Accomplishment of such modification constitutes terminating action for the repetitive inspection requirements of this AD for the upper door frame.
Note 2: Cracks of the forward or aft upper door frame, regardless of length, must be repaired prior to further flight in accordance with paragraph III.E. of Part I of the Accomplishment Instructions of the service bulletin.
(4) If any cracking is detected in the forward or aft lower door frame, prior to further flight, replace the damaged frame with a new frame, and modify the corners of the door frame of the aft cargo door, in accordance with paragraph III.F. of Part I of the Accomplishment Instructions of the service bulletin. Accomplishment of such modification constitutes terminating action for the repetitive inspection requirements of this AD for the lower door frame.
(b) Where Boeing Service Bulletin 737-52-1079, Revision 5, dated May 16, 1996, specifies that certain repairs are to be accomplished in accordance with instructions received from Boeing, this AD requires that, prior to further flight, such repairs be accomplished in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate.
(c) Modification of the corners of the door frame and the cross beams of the aft cargo door in accordance with Boeing Service Bulletin 737-52-1079, Revision 5, dated May 16, 1996, or in accordance with the requirements of AD 90-06-02, amendment 39-6489, constitutes terminating action for the repetitive inspection requirements of this AD.
Note 3: Modification of the corners of the door frame and the cross beams of the aft cargo door accomplished prior to the effective date of this AD in accordance with Boeing Service Bulletin 737-52-1079, dated December 16, 1983; Revision 1, dated December 15, 1988; Revision 2, dated July 20, 1989; Revision 3, dated May 17, 1990; or Revision 4, dated February 21, 1991; are considered acceptable for compliance with paragraph (c) of this AD.
(d) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Seattle ACO. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Seattle ACO.
Note 4: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO.
(e) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.
(f) Except as provided by paragraph (b) of this AD, the inspections, repair, replacement, and modification (if accomplished), shall be done in accordance with Boeing Service Bulletin 737-52-1079, Revision 5, dated May 16, 1996. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.
(g) This amendment becomes effective on December 24, 1998.
Issued in Renton, Washington, on November 30, 1998. Darrell M. Pederson, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.
[FR Doc. 98-32361Filed12-8-98; 8:45 am]
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