The Departmento de Aviacao Civil (DAC), which is the airworthiness authority for Brazil, notified the FAA that an unsafe condition may exist on certain EMBRAER Model EMB-135 and -145 series airplanes. The DAC advises that one report indicated that the aft baffle assembly separated from the shell assembly of auxiliary power unit (APU) exhaust silencer, part number 4503801B. This separation was caused by the poor quality of some spot welds used in the aft joint of the APU exhaust silencer. This condition, if not corrected, could result in consequent separation of the aft baffle assembly from the airplane, which could cause damage to other airplanes during takeoff and landing operations, or injury to people on the ground.
Explanation of Relevant Service Information
EMBRAER has issued Alert Service Bulletin 145-49-A021, Change 01, dated May 13, 2002, which describes procedures for determining whether a defective APU exhaust silencer is installed on the airplane; and corrective actions, if necessary. If a defective APU exhaust silencer is found installed, corrective actions include reinforcing the spot welds on the exhaust silencer assembly with fasteners to ensure that the components are secure. Accomplishment of the action specified in the service bulletin is intended to adequately address the identified unsafe condition.
The EMBRAER service bulletin references Hamilton Sundstrand ASB- 4503801-49-2, Revision 01, dated May 13, 2002, as a secondary source of information for the corrective actions required by this AD.
The DAC classified the EMBRAER service bulletin as mandatory and issued Brazilian airworthiness directive 2002-05-01, dated May 17, 2002, in order to assure the continued airworthiness of these airplanes in Brazil.
FAA's Conclusions
These airplane models are manufactured in Brazil 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 DAC has kept the FAA informed of the situation described above. The FAA has examined the findings of the DAC, 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 prevent separation of the aft baffle assembly from the APU exhaust silencer and consequent separation of the assembly from the airplane, which could cause damage to other airplanes during takeoff and landing operations, or injury to people on the ground. This AD requires determining whether a defective exhaust silencer for the auxiliary power unit is installed on the airplane; and corrective actions, if necessary. The actions are required to be accomplished in accordance with the EMBRAER service bulletin described previously, except as discussed below.
Difference Between the Service Bulletin/Brazilian Airworthiness Directive and This AD
Operators should note that the EMBRAER service bulletin and Brazilian airworthiness directive specify certain serial numbers and airplanes on which the APU cowling was replaced during maintenance between January and April 2002. Regarding the specified dates, we contacted the Brazilian airworthiness authorities about why the applicability was limited to certain dates, and whether there was a change in maintenance practices after April 2002 that would prevent the installation of a defective APU exhaust silencer. In response, we were informed that no change was made to the maintenance practices after April 2002. For that reason, we cannot be sure that a defective assembly was not installed after that date. Therefore, the applicability of this AD also includes those airplanes on which the APU cowling has been replaced between January 1, 2002, and the effective date of this AD.
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. Allcommunications 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 Number 2002-NM-166-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 DIRECTIVES1. 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: