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Proposed Rule

Airworthiness Directives; Learjet Model 60 Series Airplanes

Document Details

Information about this document as published in the Federal Register.

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AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Learjet Model 60 series airplanes. This proposal would require inspecting the routing of oxygen tubing to ensure that there is adequate clamping of the tubing and adequate clearance between the tubing and electrical wiring or electrical contacts, and taking corrective action, if necessary. The actions specified by the proposed AD are intended to prevent electrical arcing between the oxygen tubing and an electrical source which could result in an oxygen fire.

DATES:

Comments must be received by September 22, 2000.

ADDRESSES:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2000-NM-52-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9 a.m. and 3 p.m., Monday through Friday, except Federal holidays. Comments may be submitted via fax to (425) 227-1232. Comments may also be sent via the Internet using the following address: 9-anm-nprmcomment@faa.gov. Comments sent via fax or the Internet must contain “Docket No. 2000-NM-52-AD” in the subject line and need not be submitted in triplicate. Comments sent via the Internet as attached electronic files must be formatted in Microsoft Word 97 for Windows or ASCII text.

The service information referenced in the proposed rule may be obtained from Learjet, Inc., One Learjet Way, Wichita, Kansas 67209-2942. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington or at the FAA, Small Airplane Directorate, Wichita Aircraft Certification Office, 1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas.

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FOR FURTHER INFORMATION CONTACT:

Shane Bertish, Aerospace Engineer, Systems and Propulsion Branch, ACE-116W, FAA, Small Airplane Directorate, Wichita Aircraft Certification Office, 1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas 67209; telephone (316) 946-4156; fax (316) 946-4407.

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SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to participate in the making of the proposed 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 above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule.

The proposals contained in this notice may be changed in light of the comments received.

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 proposed 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 proposed 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 summarizing each FAA-public contact concerned with the substance of this proposal 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 2000-NM-52-AD.” The postcard will be date stamped and returned to the commenter.

Availability of NPRMs

Any person may obtain a copy of this NPRM by submitting a request to the FAA, Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 2000-NM-52-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

Discussion

The FAA has received a report of a fire resulting from the puncture of an oxygen tube by an electrical arc from the generator control unit. The arcing is the result of improper clamping and inadequate spacing between the oxygen tubing and electrical sources, such as wires and contacts. The incident occurred during a routine functional test of the oxygen system on the production line. Improper clamping and inadequate spacing, if not corrected, could cause electrical arcing between the oxygen tubing and an electrical source, which could result in an oxygen fire.

Explanation of Relevant Service Information

The FAA has reviewed and approved Bombardier Alert Service Bulletin (Learjet 60) SB A60-35-2, dated November 4, 1999, which addresses certain Learjet Model 60 airplanes. That service bulletin describes procedures for inspecting the oxygen tubing system for adequate clamping and adequate clearance between the tubing and electrical wiring or electrical contacts and for adjusting the clamping of the tubing or the clearance between the tubing and electrical wiring or electrical contacts, as necessary. Accomplishment of the actions specified in the service bulletin is intended to adequately address the identified unsafe condition.

Explanation of Requirements of Proposed Rule

Since an unsafe condition has been identified that is likely to exist or develop on other products of this same type design, the proposed AD would Start Printed Page 48400require accomplishment of the actions specified in the service bulletin described previously, except as discussed below.

Differences Between Alert Service Bulletin and Proposed AD

Operators should note that, although the service bulletin recommends accomplishing the required inspection within 15 days after receipt of the service bulletin, the proposed AD specifies a compliance time of 60 days or 80 flight hours after the effective date of the AD, whichever comes first.

In developing this compliance time, the FAA considered not only the manufacturer's recommendation, but also the degree of urgency associated with addressing the unsafe condition, the schedule of regular maintenance, and the average utilization of the affected fleet. In light of these factors, the FAA finds that the proposed compliance time represents an appropriate interval allowable for affected airplanes to continue to operate without compromising safety.

Cost Impact

There are approximately 58 airplanes of the affected design in the worldwide fleet. The FAA estimates that 40 airplanes of U.S. registry would be affected by this proposed AD, that it would take 1 work hour per airplane to accomplish the proposed inspection, and that the average labor rate is $60 per work hour. There would be no parts required. Based on these figures, the cost impact of the proposed inspection on U.S. operators is estimated to be $2,400, or $60 per airplane.

Should an operator be required to adjust the clamping or the clearance of the oxygen tubing, the FAA estimates that it would take approximately 3 work hours per airplane and that the average labor rate is $60 per work hour. The cost of required parts, such as clamps, nuts, bolts, and washers, would be negligible. Based on these figures, the cost impact of adjusting the clamping or the clearance of the tubing is estimated to be $7,200, or $180 per airplane.

The cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the proposed requirements of this AD action, and that no operator would accomplish those actions in the future if this proposed AD were not adopted. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions.

Regulatory Impact

The regulations proposed herein would 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 proposal would not have federalism implications under Executive Order 13132.

For the reasons discussed above, I certify that this proposed regulation (1) is not a “significant regulatory action” under Executive Order 12866; (2) is not a “significant rule” under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) if promulgated, will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. A copy of the draft regulatory evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ADDRESSES.

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List of Subjects in 14 CFR Part 39

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The Proposed Amendment

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Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend part 39 of the Federal Aviation Regulations (

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PART 39—AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

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Authority: 49 U.S.C. 106(g), 40113, 44701.

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[Amended]

2. Section 39.13 is amended by adding the following new airworthiness directive:

Learjet: Docket 2000-NM-52-AD.

Applicability: Model 60 airplanes, serial numbers 104 through 168 inclusive; certificated in any category.

Note 1:

This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been otherwise modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (c) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Required as indicated, unless accomplished previously.

To prevent electrical arcing between the oxygen tubing and an electrical source which could result in an oxygen fire, accomplish the following:

Inspection

(a) Within 60 days or 80 flight hours after issuance of this AD, whichever occurs first, perform a detailed visual inspection of the oxygen tubing for adequate clamping and adequate clearance from electrical wiring and electrical contacts, in accordance with the Accomplishment Instructions of Bombardier Alert Service Bulletin (Learjet 60) SB A60-35-2, dated November 4, 1999. If adequate clamping and adequate clearance, as specified in the service bulletin, is found, no further action is required by this AD.

Note 2:

For the purposes of this AD, a detailed visual inspection is defined as: “An intensive visual examination of a specific structural area, system, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at intensity deemed appropriate by the inspector. Inspection aids such as mirror, magnifying lenses, etc., may be used. Surface cleaning and elaborate access procedures may be required.”

Adjustment

(b) If clamping or clearance of the oxygen tubing from electrical wiring or contacts is not adequate as specified in Bombardier Alert Service Bulletin (Learjet 60) SB A60-35-2, dated November 4, 1999, the clamping or the clearance must be adjusted, in accordance with the Accomplishment Instructions of the service bulletin.

Alternative Methods of Compliance

(c) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Wichita Aircraft Certification Office (ACO), FAA, Small Airplane Directorate. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Wichita ACO.

Note 3:

Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Wichita ACO.

Special Flight Permits

(d) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.

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Issued in Renton, Washington, on August 2, 2000.

Donald L. Riggin,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.

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[FR Doc. 00-20003 Filed 8-7-00; 8:45 am]

BILLING CODE 4910-13-U