The Direction Generale de l'Aviation Civile (DGAC), which is the airworthiness authority for France, recently notified the FAA that an unsafe condition may exist on all Airbus Model A330 and A340 series airplanes. The DGAC advises that, during a C-check on a Model A330 series airplane, a crack was discovered in the upper part of the left-hand bogie beam of the main landing gear (MLG), in the area of the forward bogie stop pad. The crack was 120 mm (6 inches) long and 12 mm (0.4 inch) deep, and extended longitudinally along the bogie, underneath the stop pad. The airplane had accumulated a total of approximately 10,000 flight hours and 6,000 flight cycles.
The retraction link on that MLG had previously failed, leading to an undamped extension of the MLG. The failure occurred approximately 1,000 flight cycles and 11 months before the crack was discovered in the bogie beam. Analysis has shown that, due to the retraction link failure, loading in this area ofthe bogie is significantly greater than normally expected. Detailed analysis has not identified any other situation in which the load would cause such damage.
There have been four in-service retraction link failures. In two cases, the affected landing gears were replaced. There was a similar visible crack discovered on one of the bogies, which was installed on an airplane that had accumulated approximately 16,000 total flight hours and 7,000 total flight cycles. Another was put in storage following the retraction failure and was subsequently inspected, revealing a crack. Inspection of a number of spare bogies that had been removed from service and had not been involved in retraction link failure incidents has revealed no similar cracks. It should be noted, however, that no proven connection has been made between failure of the retraction links and cracking in the bogie beams.
Cracking of the MLG bogie beam could result in failure of the beam and consequent loss of the landing gear wheels and brakes, and structural damage to the MLG strut and airframe.
Explanation of Relevant Service Information
Airbus has issued All Operators Telex (AOT) A330-32A3137, dated July 19, 2001; and AOT A340-32A4174, dated July 19, 2001. The AOTs describe procedures for a one-time visual inspection to detect cracking of the bogie beams of the MLG, in the area around the bogie stop pad. The AOTs also describe procedures for follow-on actions for certain conditions, if necessary. The DGAC classified these AOTs as mandatory and issued French telegraphic airworthiness directive T2001-320(B), dated July 20, 2001, to ensure the continued airworthiness of these airplanes in France.
FAA's Conclusions
These airplane models are manufactured in France and are type certificated for operation in the United States under the provisions of Sec. 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the applicable bilateral airworthiness agreement. Pursuant to this bilateral airworthiness agreement, the DGAC has kept the FAA informed of the situation described above. The FAA has examined the findings of the DGAC, reviewed all available information, and determined that AD action is necessary for products of this type design that are certificated for operation in the United States.
Explanation of Requirements of Rule
Since an unsafe condition has been identified that is likely to exist or develop on other airplanes of the same type design registered in the United States, this AD is being issued to detect and correct cracking of the MLG bogie beams, which could result in failure of the beams and consequent loss of the landing gear wheels and brakes, and structural damage to the MLG strut and airframe. This AD requires accomplishment of the actions specified in the AOTs described previously, except as discussed below.
Difference Between AD and AOTs
Although the AOTs specify that the manufacturer may be contacted for disposition of certaininspection findings, this AD requires follow-on actions to be accomplished in accordance with a method approved by either the FAA or the DGAC (or its delegated agent).
Interim Action
This is considered to be interim action. The manufacturer has indicated its intent to investigate the cracked MLG bogie beams and any additional findings to confirm the cause of the cracking. If final action is developed in the future to address the identified unsafe condition, 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.
Submit comments using the following format:
Organize comments issue-by-issue. For example, discuss a request to change the compliance time and a request to change the service bulletin reference as two separate issues.
For each issue, state what specific change to the AD is being requested.Include justification (e.g., reasons or data) for each request.
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 2001-NM-257-AD." The postcard will be date stamped and returned to the commenter.
Regulatory Impact
The regulations adopted herein will not have a substantial direct effect 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, it is determined that this final rule does not have federalism implications under Executive Order 13132.
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 U.S.C. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new airworthiness directive: