AD 94-09-11

The Civil Aviation Authority (CAA), which is the airworthiness authority for the United Kingdom, recently notified the FAA that an unsafe condition may exist on certain Raytheon Corporate Jets Model BAe 125-1000A and Hawker 1000 series airplanes. The CAA advises that the manufacturer of the thrust reversers on these airplanes has conducted a reassessment of the failure modes and effects analysis for the thrust reverser system, and has provided to the airplane manufacturer additional recommendations for repetitive inspection intervals of the system. Results of that reassessment revealed that failure of the drive links (or attachments) on the thrust reversers can occur due to the single link design concept of the thrust reverser link and lock system. This condition, if not corrected, can result in inadvertent deployment of a thrust reverser during flight, which could result in a significant reduction in the controllability of the airplane.

Raytheon Corporate Jets, Inc., has issued Service Bulletin SB 78-12, dated January 24, 1994, that describes procedures for a detailed visual inspection of the thrust reverser drive mechanism to detect wear and abrasion and to ensure the security of the attachment of the actuator to its drive links, of the drive links to the thrust reverser structure, and of the ends of the drive link and link hinges. The service bulletin also describes procedures for repetitive inspections of the thrust reverser system for structural integrity. Accomplishment of these inspections will ensure the continued structural integrity of the thrust reverser system. The CAA classified this service bulletin as mandatory.

This airplane model is manufactured in the United Kingdom and is type certificated for operation in the United States under the provisions of Section 21.29 of the Federal Aviation Regulations and the applicable bilateral airworthiness agreement. Pursuant to this bilateral airworthiness agreement,the CAA has kept the FAA informed of the situation described above. The FAA has examined the findings of the CAA, 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 deployment of a thrust reverser in flight and subsequent reduced controllability of the airplane. This AD requires repetitive inspections of the thrust reverser system for integrity, and correction of any discrepancy found. The inspections are required to be accomplished in accordance with the service bulletin described previously. Correction of any discrepancy found is required to be accomplished in accordance with procedures described in the airplane maintenance manual.

This is considered interim action.The airplane manufacturer currently is developing a secondary locking feature on the thrust reverser doors. Once this modification is developed, approved, and available, the FAA may consider further rulemaking to require its installation.

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.

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 notice must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket Number 94-NM-33-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 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 thatthis 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 14 CFR part 39 of the Federal Aviation Regulations as follows:

PART 39 - AIRWORTHINESS DIRECTIVES 1. The authority citation for part 39 continues to read as follows: Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89.

39.13 - [Amended] 2. Section 39.13 is amended by adding the following new airworthiness directive: