Transport Canada Aviation, which is the airworthiness authority for Canada, recently notified the FAA that an unsafe condition may exist on certain Canadair Model CL-215-1A10 and CL-215-6B11 series airplanes. Transport Canada Aviation advises that there have been reports of fatigue cracking found on several main landing gear (MLG) wheel axles on in-service airplanes. In three cases, such cracking has resulted in complete failure of the axle and subsequent separation of the wheel from the airplane. Investigation has revealed that this cracking occurs only on axles that have been reworked by chromium plating the wheel inner bearing surface. Such cracking, if not detected and corrected in a timely manner, can lead to failure of the axle and separation of the wheel from the airplane. Since each MLG has only a single wheel, loss of the wheel could result in reduced controllability of the airplane during take-off or landing.
The number of reworked axlescurrently in the fleet is unknown; however, at least nine MLG axles were reworked by chromium plating during manufacture prior to their installation on the airplane. In light of this, Transport Canada Aviation has advised that, irrespective of the number of flight hours accumulated on the airplane or axle, the potential for cracking exists in all of these affected airplanes.
Canadair has issued Alert Service Bulletin 215-A462, dated June 2, 1993, which describes procedures for conducting an eddy current or chemical inspection of the inner bearing surface area of the left and right MLG axles to determine whether they have been reworked using chromium plating. For axles that have been so reworked, the service bulletin provides instructions for conducting repetitive ultrasonic inspections to detect cracks in the chromium-plated inner bearing surface. The service bulletin also describes procedures for removing cracked axles and replacing them with serviceable units. Transport Canada Aviation classified this service bulletin as mandatory and issued Canadian Airworthiness Directive CF-93-08R2, dated June 20, 1994, in order to assure the continued airworthiness of these airplanes in Canada.
This airplane model is manufactured in Canada and is type certificated for operation in the United States under the provisions of section 21.29 of the Federal Aviation Regulations (14 CFR 21.19) and the applicable bilateral airworthiness agreement. Pursuant to this bilateral airworthiness agreement, Transport Canada Aviation has kept the FAA informed of the situation described above. The FAA has examined the findings of Transport Canada Aviation, 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.
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 prevent cracking of the chromium-plated inner bearing surface of the MLG axle. Such cracking can lead to failure of the axle, separation of the wheel from the aircraft, and consequent reduced controllability of the airplane during takeoff or landing. This AD requires an eddy current or chemical inspection of the inner bearing surface area of the left and right MLG axles to determine if they have been reworked using chromium plating. For axles that have been reworked, this AD requires repetitive ultrasonic inspections to detect cracking in the chromium-plated inner bearing surface. If cracking is found, the cracked axle must be removed and replaced with a serviceable unit. The actions are required to be accomplished in accordance with the service bulletin described previously.
Additionally, operators must submit a report of all ultrasonic inspection findings to the manufacturer.
None of the Model CL-215-1A10 or CL-215-6B11 series airplanes affected by this action is on the U.S. Register. All airplanes included in the applicability of this rule currently are operated by non-U.S. operators under foreign registry; therefore, they are not directly affected by this AD action. However, the FAA considers that this rule is necessary to ensure that the unsafe condition is addressed in the event that any of these subject airplanes are imported and placed on the U.S. Register in the future.
Should an affected airplane be imported and placed on the U.S. Register in the future, it would require approximately 2 work hours to accomplish the required inspection actions, at an average labor charge of $60 per work hour. Based on these figures, the total cost impact of this AD would be $120 per airplane per inspection.
If a cracked axle is found and replaced, that action would require 8 work hours per airplane to accomplish, at an average labor charge of $60 per work hour. Required parts are estimated to cost $13,000 per assembly. Based on these figures, the total cost impact of necessary replacement required by this AD would be $13, 480 per airplane.
Since this AD action does not affect any airplane that is currently on the U.S. register, it has no adverse economic impact and imposes no additional burden on any person. Therefore, notice and public procedures hereon are unnecessary and the amendment may be made effective in less than 30 days after publication in the Federal Register.
Comments Invited
Although this action is in the form of a final rule and was not preceded by notice and 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-173-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.
For the reasons discussed above, I certify that this action (1) is not a "significant regulatory action" under Executive Order 12866; (2) is not a "significant rule" under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. A final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it 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), 40101, 40113, 44701.
39.13 - [Amended]
2. Section 39.13 is amended by adding the following new airworthiness directive: