AD 95-02-10

Active

Flap Track Structure

Key Information
95-02-10
Active
February 14, 1995
Not specified
94-NM-236-AD
39-9129
Applicability
["Aircraft"]
["Large Airplane"]
The Boeing Company
757-200 Series 757-200CB Series 757-200PF Series 757-300 Series
Summary

This amendment adopts a new airworthiness directive (AD) that is applicable to certain Boeing Model 757 series airplanes. This action requires replacement of the bolts, nuts, and washers that attach the support bracket at the Number 4 and Number 5 transmissions to the wing flap structure. This amendment is prompted by a report of damage to the left inboard trailing edge flap. The actions specified in this AD are intended to prevent these airplanes from taking off with broken bolts that attach the transmission bracket to the wing flap track structure, which could result in the airplane rolling at liftoff.

Action Required

Final rule; request for comments

Regulatory Text

95-02-10 BOEING: Amendment 39-9129. Docket 94-NM-236-AD. \n\n\tApplicability: Model 757 series airplanes having line numbers 181 through 647 inclusive, certificated in any category. \n\n\tNOTE 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been 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 use the authority provided in paragraph (b) to request approval from the FAA. This approval may address either no action, if the current configuration eliminates the unsafe condition; or different actions necessary to address the unsafe condition described in this AD. Such a request should include an assessment of the effect of the changed configuration on the unsafe condition addressed by this AD. In no case does the presence of any modification, alteration, or repair remove any airplane from the applicability of this AD. \n\n\tCompliance: Required as indicated, unless accomplished previously. \n\n\tTo prevent these airplanes from taking off with broken bolts that attach the transmission bracket to the flap track structure, which could result in the airplane rolling at liftoff, accomplish the following: \n\n\t(a)\tWithin 60 days after the effective date of this AD, remove the bolts, nuts, and washers that attach the support bracket at the Number 4 and Number 5 transmission for the inboard trailing edge flap system and install kit number 012N8037, in accordance with Boeing Alert Service Bulletin 757-27A0118, dated December 15, 1994. \n\n\t(b)\tAn 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. \n\n\tNOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO. \n\n\t(c)\tSpecial 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. \n\n\t(d)\tThe installation shall be done in accordance with Boeing Alert Service Bulletin 757-27A0118, dated December 15, 1994. 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.\n \n\t(e)\tThis amendment becomes effective on February 14, 1995.

Supplementary Information

Recently, the FAA has received a report of damage to the left inboard trailing edge flap on the wing of a Boeing Model 757 series airplane when the flaps were retracted after the airplane had landed. Investigation revealed that six bolts on the attachment bracket of the inboard flap drive had sheared off when the flaps were retracted. Further investigation revealed that the Number 3 inboard flap outboard drive had disconnected inside the angle gear box, while the Number 4 inboard flap inboard drive continued to retract. This caused a flap skew, which applied sufficient load on the drive screw to fracture the six bolts that attach the Number 4 transmission bracket to its mating flap track. Analysis showed that those six bolts, which were made of titanium, do not meet the designed limit load. If an airplane attempts to take off with broken bolts that attach the transmission bracket to the flap track structure, the result may be the airplane rolling at liftoff. \n\n\tThe FAA has reviewed and approved Boeing Alert Service Bulletin 757-27A0118, dated December 15, 1994, which describes procedures for replacement of the six bolts, nuts, and washers that attach the support bracket at the Number 4 and Number 5 transmission to the inboard trailing edge flap system. The replacement bolts, nuts, and washers (kit number 012N8037) are made of Inconel 718 material, which is stronger and will sustain the designed limit load. \n\n\tSince 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 these airplanes from taking off with broken bolts that attach the transmission bracket to the flap track structure, which could result in the airplane rolling at liftoff. This AD requires replacement of the bolts, nuts, and washers that attach the support bracket at the Number 4 and Number 5 transmission to the inboard trailing edge flap system, with items made ofInconel 718 material. The actions are required to be accomplished in accordance with the alert service bulletin described previously. \n\n\tThis AD applies only to airplanes having line numbers 181 through 647, inclusive. The subject six-bolt attachment configuration was incorporated on airplanes starting at line position 181. \n\n\tSince 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. \n\nComments Invited \n\n\tAlthough 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. \n\n\tComments 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. \n\n\tCommenters 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 94-NM-236-AD." The postcard will be date stamped and returned to the commenter. \n\n\tThe 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. \n\n\tThe 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 underDOT 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."\n\n List of Subjects in 14 CFR Part 39 \n\n\tAir transportation, Aircraft, Aviation safety, Incorporation by reference, Safety. \n\nAdoption of the Amendment \n\n\tAccordingly, 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:\n \nPART 39 - AIRWORTHINESS DIRECTIVES \n\n\t1.\tThe authority citation for part 39 continues to read as follows: Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89. § 39.13 - (Amended) \n\n\t2.\tSection 39.13 is amended by adding the following new airworthiness directive:

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Contact Information

Carrie Sumner, Aerospace Engineer, Airframe Branch, ANM-121S, FAA, Transport Airplane Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206) 227-2778; fax (206) 227-1181.

References
(Federal Register: January 30, 1995 (Volume 60, Number 19))
--- - Part 39 (60 FR 5566 NO. 19 01/30/95)
(Page 5566)
FAA Documents