The Departmento de Aviacao Civil (DAC) , which is the airworthiness authority for Brazil, recently notified the FAA that an unsafe condition may exist on all Empresa Brasileira de Aeronautica S.A. (EMBRAER) Model EMB-135 and -145 series airplanes. The DAC advises that cases of internal corrosion have been found on the stow/transit switches installed in the engine thrust reversers of EMBRAER Model EMB-145 series airplanes. Erroneous messages of "ENG ( ) REV DISAGREE" or "ENG ( ) REV FAIL" have been displayed in the Engine Indicating and Crew Alerting System (EICAS) because of this corrosion. In one case, a transit switch severely contaminated by corrosion resulted in an uncommanded engine rollback to idle in flight. Several cases of aborted takeoffs have also been reported due to "ENG ( ) REV DISAGREE" messages during takeoff. This internal corrosion condition, if not corrected, could result in erroneous signals of the thrust reverser stow/transit switches, which could result in uncommanded loss of engine power in flight, or unnecessary aborted takeoffs on the ground.
Explanation of Relevant Service Information
EMBRAER has issued Service Bulletin 145-78-0029, dated February 2, 2001, which describes procedures for repetitive inspections of the stow/transit switches for possible internal corrosion by means of a field check with a megohmmeter for insulation resistance; and corrective action, if applicable. The DAC classified this service bulletin as mandatory and issued Brazilian airworthiness directive 2001-05-03, dated June 8, 2001, 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 section 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 erroneous signals from being displayed on the EICAS, caused by internal corrosion of the thrust reverser stow/transit switches, which could result in uncommanded loss of engine power in flight, or unnecessary aborted takeoffs on the ground. This AD requires accomplishment of the actions specified in the service bulletin described previously, except as discussed below.
Interim Action
This is considered to be an interim action until final action is identified, at which time the FAA may consider further rulemaking.
Differences Between Proposed Rule and Foreign Airworthiness Directive
This AD differs from the parallel Brazilian airworthiness directive in that it requires repetitive inspections every 1,200 flight hours after the initial inspection, as recommended by EMBRAER Service Bulletin 145-78-0029, dated February 2, 2001. The parallel Brazilian airworthiness directive contains only a note that makes reference to a future revision of the airplane Maintenance Review Board (MRB) that will include periodic re-inspection.
Mandating the repetitive inspections specified in the service bulletin is based on the FAA's determination that, in this case, long- term continued operational safety would be better assured by continued monitoring until a design change can be made to remove the source of the problem.
Determination of Rule's Effective Date
Since a situation exists that requires the immediate adoption of this regulation, it isfound 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 Number 2001-NM-248-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 emergencyregulation 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: