The FAA has received a report indicating the occurrence of an uncommanded brake application condition that was not annunciated in the cockpit, in which the airplane experienced a dragging brake (uncommanded brake application condition) when the pilot released the parking brake. Not realizing the severity or cause of the problem, the pilot increased the thrust control to taxi the airplane. During takeoff, the airplane failed to accelerate properly, and the pilot performed a rejected takeoff. After the airplane returned to the ramp, investigation revealed that one or more brake pistons had failed, causing a small brake oil fire.
Explanation of Relevant Service Information
The manufacturer has issued Learjet Temporary Flight Manual (TFM) Changes TFM 2000-01, 2000-02, 2000-03, 2000-04, 2000-05, 2000-06, 2000-07, and 2000-08, each dated April 6, 2000. These TFM changes provide information for the flight crew with certain instructions to detect possible brake problems during exterior preflight inspections and ground operations.
Explanation of the Requirements of the Rule
Since an unsafe condition has been identified that is likely to exist or develop on other Learjet Model 45 airplanes of the same type design, this AD is being issued to provide the flight crew with procedures to detect an uncommanded brake application condition during taxi and takeoff. Such a condition could result in a possible wheel/brake fire and/or a high-speed rejected takeoff. This AD requires revising the Limitations and Normal Procedures Sections of the FAA-approved AFM to provide the flight crew with certain instructions to detect possible brake problems during exterior preflight inspections and ground operations.
Interim Action
This is considered to be interim action. The manufacturer has advised that it currently is developing a modification that will positively address the unsafe condition addressed by this AD. Once this modification is developed, approved, and available, the FAA may consider additional 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 rulemay 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 2000-NM-85-AD." The postcard will be date stamped and returnedto 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.
39.13 [Amended]
2. Section 39.13 is amended by adding the following new airworthiness directive: