AD 95-14-09

This amendment adopts a new airworthiness directive (AD) that is applicable to certain Learjet Model 60 airplanes. This action requires inspection to detect bends in or damage to the fuel crossflow tube; inspection to determine clearance between the fuel crossflow tube and the flight control cables; and replacement or repair of the tube, if necessary. This amendment is prompted by reports of damage to the fuel crossflow tube and inadequate clearance between the fuel crossflow tube and the flight control cables due to bends in the fuel crossflow tube. The actions specified in this AD are intended to prevent chafing and eventual failure of the fuel crossflow tube due to inadequate clearance between the tube and the flight control cables; this condition could result in loss of fuel from one fuel tank during normal operating conditions or loss of fuel from both main fuel tanks during fuel cross feeding operations.

Final rule; request for comments

95-14-09 LEARJET: Amendment 39-9303. Docket 95-NM-119-AD.

Applicability: Model 60 airplanes having serial numbers 60-001 through 60-058 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 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 use the authority provided in paragraph (c) of this AD to request approval from the FAA. This approval may address either no action, if the current configuration eliminates the unsafe condition; or different actions necessary to address the unsafe condition described in this AD. Such a request should include an assessment of the effect of the changed configuration on the unsafe condition addressed by this AD. In no case does the presence of any modification, alteration, or repair remove any airplane from the applicability of this AD.

Compliance: Required as indicated, unless accomplished previously.

To prevent loss of fuel from one fuel tank during normal operating conditions or loss of fuel from both main fuel tanks during fuel cross feeding operations, due to chafing and eventual failure of the fuel crossflow tube, accomplish the following:

(a) Within 10 hours time-in-service after the effective date of this AD, perform a visual inspection to detect bends in or damage to the fuel crossflow tube, and perform an inspection to determine whether the clearance between the fuel crossflow tube and the flight control cables is at least 0.150 inch; in accordance with Learjet Alert Service Bulletin SB A60-28-3, dated May 12, 1995.

(1) If the tube is not found to be bent or damaged, and a minimum clearance of 0.150 inch exists, no further action is required by this AD.

(2) If the tube is not foundto be bent or damaged, and a minimum clearance of 0.150 inch does not exist, within 10 hours time-in-service after the effective date of this AD, replace the tube with a new tube in accordance with either paragraph (a)(2)(i) or (a)(2)(ii) of this AD, as applicable. Prior to further flight following replacement of the tube, perform an inspection to determine whether the clearance between the fuel crossflow tube and the flight control cables is at least 0.150 inch, in accordance with Learjet Alert Service Bulletin SB A60-28-3, dated May 12, 1995.

(i) For airplanes having serial numbers 60-001 through 60-055, inclusive: Replace the fuel crossflow tube with a new tube in accordance with Learjet Service Bulletin SB 60-28-4, dated May 12, 1995.

(ii) For airplanes having serial number 60-056 through 60-058, inclusive: Replace the fuel crossflow tube with a new tube in accordance with paragraph 2.B. of Learjet Alert Service Bulletin SB A60-28-3, dated May 12, 1995.

(3)If the tube is found to be bent or damaged, prior to further flight, replace the tube with a new tube in accordance with either paragraph (a)(3)(i) or (a)(3)(ii) of this AD, as applicable. Prior to further flight following replacement of the tube, perform an inspection to determine whether the clearance between the fuel crossflow tube and the flight control cables is at least 0.150 inch, in accordance with Learjet Alert Service Bulletin SB A60-28-3, dated May 12, 1995.

(i) For airplanes having serial numbers 60-001 through 60-055, inclusive: Replace the fuel crossflow tube with a new tube in accordance with Learjet Service Bulletin SB 60-28-4, dated May 12, 1995.

(ii) For airplanes having serial number 60-056 through 60-058, inclusive: Replace the fuel crossflow tube with a new tube in accordance with paragraph 2.B. of Learjet Alert Service Bulletin SB A60-28-3, dated May 12, 1995.

(b) If a minimum clearance of 0.150 inch does not exist on the new fuel crossflow tube that was installed in accordance with the requirements of paragraph (a) of this AD, prior to further flight, repair in accordance with a method approved by the Manager, Wichita Aircraft Certification Office (ACO), FAA, Small Airplane Directorate.

(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 ACO. 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 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Wichita ACO.

(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.(e) The inspections and certain replacements shall be done in accordance with Learjet Alert Service Bulletin SB A60-28-3, dated May 12, 1995; and certain other replacements shall be done in accordance with Learjet Service Bulletin SB 60-28-4, dated May 12, 1995. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Learjet, P.O. Box 7707, Wichita, Kansas 67277-7707. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Wichita Aircraft Certification Office, Small Airplane Directorate, 1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

(f) This amendment becomes effective on August 3, 1995.

Recently, the FAA has received reports from operators of Learjet Model 60 airplanes that the fuel crossflow tube in the underwing keelbeam area was bent slightly upward. In two instances, the fuel crossflow tube was found to be chafed by the flight control cables due to inadequate clearance between the flight control cables and the fuel crossflow tube. Investigation revealed that the tube was installed improperly. Chafing and eventual failure of the fuel crossflow tube due to inadequate clearance between the tube and the flight control cables, if not corrected, could result in loss of fuel from one fuel tank during normal operating conditions or loss of fuel from both main fuel tanks during fuel cross feeding operations.

The FAA has reviewed and approved Learjet Alert Service Bulletin SB A60-28-3, dated May 12, 1995, which describes procedures for inspection to detect bends in or damage to the fuel crossflow tube, and replacement of bent or damagedtubes with new tubes; and inspection to determine the clearance between the fuel crossflow tube and the flight control cables, and replacement of tubes with new tubes if inadequate clearance exists. This alert service bulletin describes procedures for replacement of the fuel crossflow tube with a new tube for a certain group of airplanes. Replacement procedures for the remaining group of airplanes is described in Learjet Service Bulletin SB 60-28-4, dated May 12, 1995, which the FAA has reviewed and approved.

Since an unsafe condition has been identified that is likely to exist or develop on other Learjet Model 60 airplanes of the same type design, this AD is being issued to prevent chafing and eventual failure of the fuel crossflow tube due to inadequate clearance between the tube and the flight control cables; this condition could result in loss of fuel from one fuel tank during normal operating conditions or loss of fuel from both main fuel tanks during fuel cross feeding operations. This AD requires inspection to detect bends in or damage to the fuel crossflow tube, inspection to determine clearance between the fuel crossflow tube and the flight control cables, and replacement of tubes, if necessary. The actions are required to be accomplished in accordance with the service bulletins described previously.

This AD differs from the service bulletin in that the AD requires replacement of the tube if the tube is not bent or damaged and minimum clearance does not exist. This AD also requires the repair of certain fuel crossflow tubes in accordance with a method approved by the FAA.

As a result of recent communications with the Air Transport Association (ATA) of America, the FAA has learned that, in general, some operators may misunderstand the legal effect of AD's on airplanes that are identified in the applicability provision of the AD, but that have been altered or repaired in the area addressed by the AD. The FAA points out that all airplanes identified in the applicability provision of an AD are legally subject to the AD. If an airplane has been altered or repaired in the affected area in such a way as to affect compliance with the AD, the owner or operator is required to obtain FAA approval for an alternative method of compliance with the AD, in accordance with the paragraph of each AD that provides for such approvals. A note has been included in this rule to clarify this long-standing requirement.

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 tocomment 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 rule must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket Number 95-NM-119-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 that it is not a "significant regulatoryaction" 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. 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: