[Federal Register Volume 68, Number 117 (Wednesday, June 18, 2003)]
[Proposed Rules]
[Pages 36502-36504]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-15339]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NM-408-AD]
RIN 2120-AA64


Airworthiness Directives; Learjet Model 60 Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the supersedure of an existing 
airworthiness directive (AD), applicable to certain Learjet Model 60 
airplanes, that currently 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 action would 
require a review of airplane maintenance records or an inspection to 
determine if a fuel crossflow tube having a certain part number is 
installed; and follow-on/corrective actions, as applicable. This action 
also would expand the applicability of the existing AD to include 
additional airplanes. The actions specified by the proposed AD are 
intended to prevent chafing and consequent failure of the fuel 
crossflow tube due to inadequate clearance between the tube and the 
flight control cables, which 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 action is 
intended to address the identified unsafe condition.

DATES: Comments must be received by August 4, 2003.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2000-NM-408-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: 
[email protected]. Comments sent via fax or the Internet must 
contain ``Docket No. 2000-NM-408-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 or 2000 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.

FOR FURTHER INFORMATION CONTACT: Jeffrey Janusz, Aerospace Engineer, 
Systems and Propulsion Branch, ACE-116W, FAA, Wichita Aircraft 
Certification Office, 1801 Airport Road, Room 100, Mid-Continent 
Airport, Wichita, Kansas 67209; telephone (316) 946-4148; fax (316) 
946-4407.

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 action may be changed in 
light of the comments received.
    Submit comments using the following format:
    [sbull] 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.
    [sbull] For each issue, state what specific change to the proposed 
AD is being requested.
    [sbull] 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 action must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 2000-NM-408-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-408-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    On June 28, 1995, the FAA issued airworthiness directive (AD) 95-
14-09, amendment 39-9303 (60 FR 36984, July 19, 1995), applicable to 
certain Learjet 60 airplanes, to require 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. That action was 
prompted by reports of chafing of the fuel crossflow tube by flight 
control cables. The requirements of that AD are intended to prevent 
chafing and consequent failure of the fuel crossflow tube due to 
inadequate clearance between the tube and the flight control cables, 
which 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.

Actions Since Issuance of Previous Rule

    Since the issuance of that AD, the manufacturer has implemented a 
design change to adequately preclude chafing or bending of the fuel 
crossflow tube. Although the minimum clearance required by AD 95-14-09 
was adequate, there was a possibility that the fuel crossflow tube 
could be installed incorrectly due to installation variables, including 
rotation of the fuel crossflow tube. The design change calls for an 
increased minimum clearance and the installation of a specific part 
number for the fuel crossflow tube, which can be installed in only one 
way.

Explanation of New Service Information

    The FAA has reviewed and approved Bombardier Learjet 60 Alert 
Service Bulletin SB A60-28-3, Revision 2, dated October 26, 1998. This 
service bulletin describes procedures for inspecting the fuel crossflow 
tube for damage (e.g., chafing and/or bends), measuring the clearance 
between the

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crossflow tube and flight control cables, and correcting incorrect 
clearance. For certain airplanes, this service bulletin also describes 
procedures for replacing existing fuel crossflow tubes with new fuel 
crossflow tubes. This service bulletin also adds certain airplanes to 
the effectivity listing.
    We also have reviewed and approved Bombardier Learjet 60 Service 
Bulletin SB 60-28-4, Revision 2, dated August 22, 2001. For certain 
airplanes, this service bulletin describes procedures for replacing 
existing fuel crossflow tubes with new fuel crossflow tubes, and 
measuring the clearance between the crossflow tube and flight control 
cables.
    Accomplishment of the actions specified in these service bulletins 
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 supersede AD 95-14-09 to require a review of 
maintenance records or an inspection to determine if a fuel crossflow 
tube having a certain part number is installed; and follow-on/
corrective actions, as applicable. Certain actions would be required to 
be accomplished in accordance with the service bulletins described 
previously, except as discussed below.

Differences Between Proposed Rule and Service Bulletins

    Operators should note the following differences between the 
proposed AD and the service bulletins:
    [sbull] Bombardier Learjet 60 Alert Service Bulletin SB A60-28-3, 
Revision 2, recommends that the fuel crossflow tube be inspected for 
bends and evidence of damage (e.g., contact with the flight control 
cables). It also recommends that the clearance between the fuel 
crossflow tube and flight control cables be measured to ensure that it 
is at least 0.150 inch. This proposed AD would not require those 
inspections because they pertain to the previous airplane design. In 
lieu of the previously described inspections for bends and evidence of 
damage, this proposed AD would require a review of the airplane 
maintenance records or an inspection to determine if a certain part 
number for the fuel crossflow tube is installed. In addition, the 
proposed AD would require measurement of the clearance between the fuel 
crossflow tube and flight control cables to ensure that it is at least 
0.35 inch. We have determined that an interval of 25 flight hours 
(after the effective date of this proposed AD) for accomplishment of 
the review of the airplane maintenance records/inspection would address 
the identified unsafe condition in a timely manner.
    [sbull] Alert Service Bulletin A60-28-3, Revision 2, also 
recommends a compliance time of 600 flight hours to replace the fuel 
crossflow tube, if necessary. This proposed AD would extend the 
compliance time to require replacement of any fuel crossflow tube not 
having the correct part number, with a new tube having the correct part 
number, within 90 days after the proposed inspection. In developing an 
appropriate compliance time for this proposed AD, we considered not 
only the manufacturer's recommendation, but the degree of urgency 
associated with addressing the subject unsafe condition, the average 
utilization of the affected fleet, and the time necessary to perform 
the inspection. In light of all of these factors, the FAA finds a 
longer compliance time for completing the proposed actions to be 
warranted, in that it represents an appropriate interval of time 
allowable for affected airplanes to continue to operate without 
compromising safety.
    [sbull] Bombardier Learjet 60 Service Bulletins SB A60-28-3, 
Revision 2, and SB 60-28-4, Revision 2, specify that if the correct 
fuel crossflow tube part number is installed and if the specified 
minimum clearance does not exist between the fuel crossflow tube and 
the flight control cables, the manufacturer may be contacted for 
disposition. This proposed AD would require that correction of any 
incorrect clearances be accomplished per a method approved by the FAA.

Clarification of Part Number for Installation

    Operators should note that, in Bombardier Learjet 60 Alert Service 
Bulletin SB A60-28-3, Revision 2, the fuel crossflow tube to be 
installed in the airplane is incorrectly identified as part number (P/
N) 6026020-001 in Figure 1, detail D; the correct P/N is 6026020-005. 
The FAA has been advised that the manufacturer will issue a revision to 
this alert service bulletin to correct the error.

Changes to the Applicability of the Existing AD

    This proposed AD would expand the applicability to include affected 
airplanes having serial numbers 60-056 through 60-145 inclusive, in 
addition to serial numbers 60-001 through 60-055 inclusive identified 
in the existing AD. All of these airplanes are subject to the 
identified unsafe condition of this AD.

Changes to 14 CFR Part 39/Effect on the Proposed AD

    On July 10, 2002, the FAA issued a new version of 14 CFR part 39 
(67 FR 47997, July 22, 2002), which governs the FAA's airworthiness 
directive system. The regulation now includes material that relates to 
altered products, special flight permits, and alternative methods of 
compliance (AMOC). Because we have now included this material in part 
39, only the office authorized to approve AMOCs is identified in each 
individual AD. Therefore paragraph (d) and Note 1 of AD 95-14-09 have 
not been included in this proposed AD. Paragraph (c) of AD 95-14-09 has 
been revised to only identify the office authorized to approve AMOCs, 
and is identified as paragraph (f) in this proposed AD.

Cost Impact

    There are approximately 145 Model 60 airplanes of the affected 
design in the worldwide fleet. The FAA estimates that 109 airplanes of 
U.S. registry would be affected by this proposed AD.
    It would take approximately 2 work hours per airplane to accomplish 
the review of airplane maintenance records/inspection proposed in this 
AD action, at an average labor rate of $60 per work hour. Based on 
these figures, the cost impact of the proposed requirements of this AD 
on U.S. operators is estimated to be $13,080, or $120 per airplane.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the current or proposed 
requirements of this AD action, and that no operator would accomplish 
those actions in the future if this 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

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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.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    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 (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 removing amendment 39-9303 (60 FR 
36984, July 19, 1995), and by adding a new airworthiness directive 
(AD), to read as follows:

Learjet: Docket 2000-NM-408-AD. Supersedes AD 95-14-09, Amendment 
39-9303.

    Applicability: Model 60 airplanes, serial numbers 60-001 through 
60-145 inclusive, certificated in any category.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent chafing and consequent failure of the fuel crossflow 
tube due to inadequate clearance between the tube and the flight 
control cables, which 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, accomplish the 
following:

Part Identification

    (a) Within 25 flight hours after the effective date of this AD, 
inspect the fuel crossflow tube to determine whether part number (P/
N) 5026020-005 is installed. Instead of inspecting the tube, a 
review of airplane maintenance records is acceptable if the P/N of 
the tube can be positively determined from that review.

Clearance Measurement and Corrective Action

    (b) For all airplanes: If P/N 6026020-005 is found installed 
during the review or inspection required by paragraph (a) of this 
AD, before further flight, measure the clearance between the fuel 
crossflow tube and the flight control cables to determine if it is 
at least 0.35 inch, per paragraph 2.B.(8) of the Accomplishment 
Instructions of Bombardier Learjet 60 Alert Service Bulletin SB A60-
28-3, Revision 2, dated October 26, 1998.
    (1) If the clearance is 0.35 inch or more, no further action is 
required by this paragraph.
    (2) If the clearance is less than 0.35 inch, before further 
flight, repair per a method approved by the Manager, Wichita 
Aircraft Certification Office (ACO), FAA.

Part Replacement, Measurement, and Repair

    (c) For airplanes having serial numbers 60-001 through 60-055: 
If P/N 6026020-005 is not found installed during the review or 
inspection required by paragraph (a) of this AD, within 90 days 
after accomplishing the review or inspection, replace the existing 
fuel crossflow tube with a new fuel crossflow tube having P/N 
6026020-005, and measure the clearance between the newly installed 
fuel crossflow tube and the flight control cables, per paragraph 
2.A. of the Accomplishment Instructions of Bombardier Learjet 60 
Service Bulletin SB 60-28-4, Revision 2, dated August 22, 2001.
    (1) If the clearance is 0.35 inch or more, no further action is 
required by this paragraph.
    (2) If the clearance is less than 0.35 inch, before further 
flight, repair per a method approved by the Manager, Wichita ACO, 
FAA.
    (d) For airplanes having serial numbers 60-056 through 60-145: 
If P/N 6026020-005 is not found installed during the review or 
inspection required by paragraph (a) of this AD, within 90 days 
after accomplishing the review or inspection, replace the existing 
fuel crossflow tube with a new fuel crossflow tube having P/N 
6026020-005, and measure the clearance between the newly installed 
fuel crossflow tube and the flight control cables to determine if 
the clearance is at least 0.35 inch, per paragraph 2.B. of the 
Accomplishment Instructions of Bombardier Learjet 60 Alert Service 
Bulletin SB 60-28-3, Revision 2, dated October 26, 1998.
    (1) If the clearance is 0.35 inch or more, no further action is 
required by this paragraph.
    (2) If the clearance is less than 0.35 inch, before further 
flight, repair per a method approved by the Manager, Wichita ACO, 
FAA.

    Note 1: Alert Service Bulletin SB A60-28-3, Revision 2, Figure 
1, detail D., incorrectly identifies the fuel crossflow tube to be 
installed as P/N 6026020-001. The manufacturer is aware of this 
error and plans to correct the part number in the next revision of 
the alert service bulletin.

Part Installation

    (e) As of the effective date of this AD, only fuel crossflow 
tubes having P/N 6026020-005 shall be installed on any airplane.

Alternative Methods of Compliance

    (f) In accordance with 14 CFR 39.19, the Manager, Wichita ACO, 
FAA, is authorized to approve alternative methods of compliance for 
this AD.

    Issued in Renton, Washington, on June 12, 2003.
Kalene C. Yanamura,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 03-15339 Filed 6-17-03; 8:45 am]
BILLING CODE 4910-13-P