[Federal Register Volume 61, Number 91 (Thursday, May 9, 1996)] [Rules and Regulations] [Pages 21068-21070] From the Federal Register Online via the Government Publishing Office [www.gpo.gov] [FR Doc No: 96-11407] ----------------------------------------------------------------------- DEPARTMENT OF TRANSPORTATION 14 CFR Part 39 [Docket No. 96-NM-84-AD; Amendment 39-9611; AD 96-10-06] RIN: 2120-AA64 Airworthiness Directives; Boeing Model 737 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 series airplanes. This action requires repetitive inspections to detect cracks of the lower gate hinge of the forward galley service door, and replacement of any cracked hinge. This action also provides an optional terminating replacement for the repetitive inspections. This amendment is prompted by reports of fatigue cracks found in the lower gate hinge on the forward galley service door. The actions specified in this AD are intended to prevent such fatigue cracking, which could lead to the failure of the lower gate hinge on the forward galley service door and subsequent loss of cabin pressure. If the hinge fails, the hinge and its associated mechanisms and the emergency escape slide could separate from the airplane and be ingested into the engine, or could strike and damage the flight control surfaces. DATES: Effective May 24, 1996. The incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of May 24, 1996. Comments for inclusion in the Rules Docket must be received on or before July 8, 1996. ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-103, Attention: Rules Docket No. 96-NM-84-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: Roy Boffo, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington; telephone (206) 227-2780; fax (206) 227-1181. SUPPLEMENTARY INFORMATION: The FAA has received several reports of cracks found in the lower gate hinge on the forward galley service door on Boeing Model 737 series airplanes. In two of these cases, the hinge was severed completely and the lower gate separated from the airplane while in flight, which resulted in loss of cabin pressure. In one of these cases, the emergency escape slide was slowly pulled through the gate opening, and, subsequently, it separated from the airplane. These airplanes had accumulated between 13,700 and 66,000 total flight cycles. Investigation revealed that the cause of such cracking was due to fatigue. The effects of such fatigue cracking could lead to the failure of the lower gate hinge on the forward galley service door and subsequent loss of cabin pressure. If the hinge fails, the hinge and its associated mechanisms and the emergency escape slide could separate from the airplane and be ingested into the engine, or could strike and damage the flight control surfaces. Explanation of Relevant Service Information The FAA has reviewed and approved Boeing Alert Service Bulletin 737-52A1124, dated January 11, 1996, which describes procedures for repetitive detailed visual inspections to detect cracks of the lower gate hinge of the forward galley service door, and replacement of any cracked hinge found. The service bulletin also describes procedures for replacement of the lower gate hinge of the forward galley service door with an improved hinge, which will eliminate the need for the repetitive inspections. Explanation of the Requirements of the AD Since an unsafe condition has been identified that is likely to exist or develop on other Boeing Model 737 series airplanes of the same type design, this AD is being issued to prevent fatigue cracking and subsequent failure of the lower gate hinge on the forward galley service door. This AD requires repetitive detailed visual inspections to detect cracks of the lower gate hinge of the forward galley service door, and replacement of any cracked hinge found. This AD also provides for an optional replacement of the lower gate hinge of the forward galley service door with an improved hinge, which constitutes terminating action for the repetitive inspection requirements. The actions are required to be accomplished [[Page 21069]] in accordance with the alert service bulletin described previously. Differences Between the AD and the Relevant Service Information Operators should note that, unlike the various recommended compliance times specified in the alert service bulletin for accomplishing the initial inspection of airplanes (specified as 1,200 flight cycles after receipt of the service bulletin for airplanes with 10,000 to 12,000 total flight cycles; 800 flight cycles after receipt for airplanes with 12,000 to 13,000 total flight cycles; and 400 flight cycles after receipt for airplanes with 13,000 or more total flight cycles), this AD requires that all airplanes be inspected within 400 flight cycles after the effective date of the AD. In consideration of not only the manufacturer's recommendation, but the degree of urgency associated with addressing the subject unsafe condition, the average utilization of the affected fleet, and the time necessary to perform the inspection (3 hours), the FAA has determined that the various intervals specified in that alert service bulletin would not address the identified unsafe condition in a timely manner. In addition, the FAA has reviewed the available data and determined that the length of cracking is not necessarily related to the airplane's flight cycles, but instead is related to the number of door cycles. In light of all of these factors, the FAA finds that a 400-flight cycle compliance time for initiating the required actions is warranted, in that it represents an appropriate interval of time allowable for affected airplanes to continue to operate without compromising safety. 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 filed in 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 96-NM-84-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 1. The authority citation for part 39 continues to read as follows: Authority: 49 USC 106(g), 40113, 44701. Sec. 39.13 [Amended] 2. Section 39.13 is amended by adding the following new airworthiness directive: 96-10-06 Boeing: Amendment 39-9611. Docket 96-NM-84-AD. Applicability: Model 737 series airplanes, as listed in Boeing Alert Service Bulletin 737-52A1124, dated January 11, 1996; on which the actions specified in Boeing Service Bulletin 737-52-1097, Revision 1, dated April 6, 1989, or Revision 2, dated January 11, 1990, have not been accomplished; certificated in any category. 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 (c) 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 lower gate hinge on the forward galley service door, accomplish the following: (a) Within 400 flight cycles after the effective date of this AD, perform a detailed visual inspection to detect cracks of the lower gate hinge of the forward galley service door, in accordance with Boeing Alert Service Bulletin 737-52A1124, dated January 11, 1996. (1) If no cracks are detected, repeat the inspection thereafter at intervals not to exceed 4,500 flight cycles. (2) If any crack is detected, prior to further flight, replace the lower gate hinge with a new hinge, in accordance with the alert service bulletin. Accomplishment of the replacement constitutes terminating action for this AD. [[Page 21070]] (b) Replacement of the lower gate hinge of the forward galley service door with an improved hinge, in accordance with Boeing Alert Service Bulletin 737-52A1124, dated January 11, 1996, constitutes terminating action for the requirements of this AD. (c) 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 Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. 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 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO. (d) 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. (e) The inspection and replacement shall be done in accordance with Boeing Alert Service Bulletin 737-52A1124, dated January 11, 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. (f) This amendment becomes effective on May 24, 1996. Issued in Renton, Washington, on May 1, 1996. Darrell M. Pederson, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 96-11407 Filed 5-8-96; 8:45 am] BILLING CODE 4910-13-U