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 Federal Register Information
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39 [60 FR 53109 NO. 197 10/12/95]
Docket No. 95-NM-190-AD; Amendment 39-9398; AD 95-20-51
Airworthiness Directives; Boeing Model 767-200 and -300 Series Airplanes
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Preamble Information
AGENCY: Federal Aviation Administration, DOT
ACTION: Final rule; request for comments
SUMMARY: This document publishes in the Federal Register an amendment adopting Airworthiness Directive (AD) T95-20-51 that was sent previously to all known U.S. owners and operators of Boeing Model 767-200 and -300 series airplanes by individual telegrams. This AD requires inspections of the lower half of the aft trunnion of the main landing gear (MLG) to detect damage, cracking, missing pieces, or corrosion; and correction of discrepancies. This amendment is prompted by a report indicating that the MLG collapsed on an airplane due to fracture of the aft trunnion outer cylinder that was caused by stress corrosion cracking. The actions specified by this AD are intended to prevent the collapse of the MLG due to the problems associated with stress corrosion cracking in the aft trunnion assembly; collapse of the MLG could lead to loss of control of the airplane during landing, taxiing, and takeoff.
DATES: Effective October 17, 1995.
To all persons except those persons to whom it was made
immediately effective by telegraphic AD T95-20-51, issued September 25, 1995, which contained the requirements of this amendment.
Comments for inclusion in the Rules Docket must be received on or before December 11, 1995.
ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA),
Transport Airplane Directorate, ANM-103, Attention: Rules Docket No. 95-NM-190-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.
Information concerning this AD may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington.
FOR FURTHER INFORMATION CONTACT: James G. Rehrl, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206) 227-2783; fax (206) 227-1181.
SUPPLEMENTARY INFORMATION: On September 7, 1995, the FAA issued AD 95-19-10, amendment 39-9372 (60 FR 47689, September 14, 1995), applicable to all Boeing Model 767 series airplanes. That AD requires operators to perform visual inspections of the outer cylinder aft trunnion on the main landing gear (MLG) to determine if the fillet seal is cracked or missing, and to correct any discrepancy or to perform follow-on actions, if necessary. That action was prompted by reports of fractures of the outer cylinder aft trunnion due to stress corrosion cracking.
Since the issuance of that AD, the FAA has received an additional report indicating that the MLG collapsed on a Model 767-300 series airplane due to fracture of the aft trunnion outer cylinder that was caused by stress corrosion cracking. In this reported incident, the right-hand MLG separated from the aft and forward trunnion support structure and penetrated the wing trailing edge. The airplane rolled to the right and came to rest on the right engine nacelle. Extensive damage occurred to the right-hand MLG and its support structure, the wing trailing edge, and the right engine and its support structure. Investigation revealed that this fracture differed from those reported previously in that it initiated at the crossbolt hole, approximately five inches from the aft trunnion bushing flange.
Stress corrosion cracking in the outer cylinder of the aft trunnion, if not corrected, could result in the collapse of the MLG under certain loading conditions. Such a collapse could lead to the loss of control of the airplane during landing, taxiing, and takeoff.
Consequently, the FAA has determined that the problem of stress corrosion cracking is not limited solely to the aft trunnion bushing, which was addressed in AD 95-19-10. The FAA finds that additional inspections must be performed in an expanded area of the aft trunnion assembly to ensure the safety of the affected fleet. These additional inspections must be performed in addition to, not in lieu of, the inspections required by AD 95-19-10.
Since the unsafe condition described is likely to exist or develop on other airplanes of the same type design, the FAA issued Telegraphic AD T95-20-51 to prevent the collapse of the MLG due to the problems associated with stress corrosion cracking in the aft trunnion assembly. The AD requires operators to perform an external general visual inspection of the lower half of the aft trunnion of the MLG to detect damage, cracking, missing pieces, or corrosion emanating from the aft trunnion bushing fillet seal or from the aft trunnion crossbolt hole. (This inspection is to be performed repetitively on airplanes having MLG's that are 4 years old or older.) Discrepancies are to be repaired in accordance with a method approved by the FAA.
Since it was found that immediate corrective action was required, notice and opportunity for prior public comment thereon were impracticable and contrary to the public interest, and good cause existed to make the AD effective immediately by individual telegrams issued on September 25, 1995, to all known U.S. owners and operators of Boeing Model 767-200 and -300 series airplanes. These conditions still exist, and the AD is hereby published in the Federal Register as an amendment to section 39.13 of the Federal Aviation Regulations (14 CFR 39.13) to make it effective to all persons.
The FAA considers this AD to be interim action until final action is identified, at which time the FAA may consider further rulemaking.
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 95-NM-190-AD." The postcard will be date stamped and returned to the commenter.
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, 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), 40101, 40113, 44701. § 39.13 - [Amended]
2. Section 39.13 is amended by adding the following new airworthiness directive:
Regulatory Information
95-20-51 BOEING: Amendment 39-9398. Docket 95-NM-190-AD.
Applicability: All Model 767-200 and 767-300 series airplanes, 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 use the authority provided in paragraph (d) of this AD 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.
Compliance: Required as indicated, unless accomplished previously.
To prevent the collapse of the main landing gear due to stress corrosion cracking in the outer cylinder of the aft trunnion, accomplish the following:
NOTE 2: The inspections required by this AD are in addition to, not in lieu of, the inspections required by AD 95-19-10, amendment 39-9372.
(a) Within 48 clock hours (not flight hours) after the effective date of this AD, perform an external general visual inspection of the lower half of the aft trunnion of the main landing gear (MLG) to detect obvious signs of damage, cracking, missing pieces; or obvious visible corrosion emanating from the aft trunnion bushing fillet seal or from the aft trunnion crossbolt hole.
NOTE 3: For the purpose of this AD, "external general visual inspection" means that the inspection is to be conducted within one foot of the area to be inspected. If necessary, the area should be wiped clean with a rag. Finally, mirrors and additional lighting should be used, as needed, to increase the probability of visually detecting discrepancies. This inspection does not require disassembly of the MLG.
(b) Prior to four years from the date the MLG is placed in service or overhauled, or within 48 clock hours (not flight hours) after the inspection required by paragraph (a) of this AD is accomplished, whichever occurs later, repeat the inspection required by paragraph (a) of this AD. Thereafter, repeat the inspection at intervals not to exceed 48 clock hours.
(c) If any discrepancy is detected during any inspection required by this AD, prior to further flight, repair in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate.
(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) This amendment becomes effective on October 17, 1995, to all persons except those persons to whom it was made immediately effective by telegraphic AD T95-20-51, issued on September 25, 1995, which contained the requirements of this amendment.
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