The FAA has received reports of smoke in the cockpit caused by electrical short circuits between the pilot's and copilot's foot warmers and the composite floorboards. A short circuit in a foot warmer causes electrical current to flow through the metal heelplate of the foot warmer to the composite floorboards. Due to the high resistance of the composite floorboards, the circuit breaker may not open, or the opening could be significantly delayed.
After the first incident, that occurred on an older design of the foot warmer, the manufacturer re-designed the foot warmer to minimize the potential for this failure mode. After the latest incident, the re- designed foot warmer was evaluated, and was found to have the same potential for an electrical short circuit. This condition, if not corrected, could result in outgassing of the faceply material of the composite floorboard, and consequent smoke in the cockpit.
Explanation of Relevant Service InformationWe have reviewed and approved Learjet Alert Service Bulletin SB A45-21-14, dated May 3, 2002, which describes procedures for pulling the FOOT WARM circuit breaker located on the copilot's circuit breaker panel. The alert service bulletin also describes procedures for installation of a collar on the foot warmer circuit breaker to prevent the FOOT WARM circuit breaker from being activated.
Explanation of the Requirements of the Rule
Since an unsafe condition has been identified that is likely to exist or develop on other airplanes of the same type design, this AD is being issued to prevent an electrical short circuit in the pilot's and copilot's foot warmers, which could result in outgassing of the faceply material of the composite floorboard, and consequent smoke in the flightdeck. This AD requires pulling the FOOT WARM circuit breaker located on the copilot's circuit breaker panel, and installing a collar on that circuit breaker. The actions are required to be accomplishedin accordance with the alert service bulletin described previously.
Interim Action
This is considered to be interim action. The manufacturer has advised that it currently is developing a modification that will address the unsafe condition addressed by this AD. Once this modification is developed, approved, and available, we 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 writtendata, 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 2002-NM-167-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 ruledoes 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.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new airworthiness directive: