DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2019-0046; Product Identifier 2018-CE-040-AD; Amendment
39-19721; AD 2019-17-01]
RIN 2120-AA64

Airworthiness Directives; Learjet, Inc. Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: The FAA is superseding Airworthiness Directive (AD) 2017-11-09
for certain Learjet, Inc. (Learjet), Model 60 airplanes. AD 2017-11-09
required a one-time fluorescent dye penetrant inspection of the
fuselage skin for corrosion, additional related inspections and
corrective actions as necessary, and reporting the inspection results
to the FAA. This AD clarifies the compliance time for the inspection
and corrects an error in the inspection area of the fuselage skin. This
AD was prompted by the identification of an error in the fluorescent
dye penetrant inspection of the fuselage skin and an ambiguity in the
compliance time for the fluorescent dye penetrant inspection. The FAA
is issuing this AD to address the unsafe condition on these products.

DATES: This AD is effective October 2, 2019.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of May 22, 2017
(82 FR 18084, April 17, 2017).

ADDRESSES: For service information identified in this final rule,
contact Learjet, Inc., One Learjet Way, Wichita, KS 67209-2942;
telephone: 316-946-2000; fax: 316-946-2220; email:
ac.ict@aero.bombardier.com; internet: http://www.bombardier.com. You
may view this service information at the FAA, Policy and Innovation
Division, 901 Locust, Kansas City, Missouri 64106. For information on
the availability of this material at the FAA, call (816) 329-4148. It
is also available on the internet at http://www.regulations.gov by
searching for and locating Docket No. FAA-2019-0046.

Examining the AD Docket

You may examine the AD docket on the internet at http://www.regulations.
gov by searching for and locating Docket No. FAA-2019-
0046; or in person at Docket Operations between 9 a.m. and 5 p.m.,
Monday through Friday, except Federal holidays. The AD docket contains
this final rule, the regulatory evaluation, any comments received, and
other information. The address for Docket Operations is U.S. Department
of Transportation, Docket Operations, M-30, West Building Ground Floor,
Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: Tara Shawn, Aerospace Engineer,
Wichita ACO Branch, 1801 Airport Road, Room 100, Wichita, Kansas 67209;
telephone: (316) 946-4141; fax: (316) 946-4107; email:
tara.shawn@faa.gov or Wichita-COS@faa.gov.

SUPPLEMENTARY INFORMATION:

Discussion

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 to supersede AD 2017-11-09, Amendment 39-18908 (82 FR
24462, May 30, 2017) (``AD 2017-11-09''). AD 2017-11-09 applied to
certain serial-numbered Learjet Model 60 airplanes with either a
dorsal-mounted oxygen bottle or with a retained oxygen line fairing
installed on top of the fuselage after removing the dorsal-mounted
oxygen bottle. AD 2017-11-09 required a one-time fluorescent dye
penetrant inspection of the fuselage skin for corrosion and reporting
the results of the inspection to the FAA. AD 2017-11-09 resulted from
an evaluation by the design approval holder that indicated the upper
fuselage skin under the aft oxygen line fairing is subject to multi-
site damage. The FAA issued AD 2017-11-09 to detect and correct
corrosion of the fuselage skin, which could result in reduced
structural integrity of the airplane.
AD 2017-11-09 superseded AD 2017-08-07, Amendment 39-18856 (82 FR
18084, April 17, 2017) (``2017-08-07''). AD 2017-11-09 retained all of
the actions of AD 2017-08-07 but revised the applicability to include
only those airplanes with a dorsal-mounted oxygen bottle or airplanes
with a retained the oxygen line fairing installed on top of the
fuselage after removing the dorsal-mounted oxygen bottle. AD 2017-11-09
was prompted by the FAA's determination that only certain airplanes
listed in the applicability of AD 2017-08-07 were affected by the
unsafe condition.
The NPRM published in the Federal Register on February 8, 2019 (84
FR 2793). The NPRM was prompted by the FAA's identification of an error
in the area of the fluorescent dye penetrant inspection requirement. AD
2017-11-09 required a fluorescent penetrant inspection of the fuselage
skin between stringer (S)-2L and S-2R. Bombardier Learjet 60 Service
Bulletin (SB) 60-53-19, Revision 3, dated August 29, 2016, specifies
inspecting only out to the fairing end caps, which is a smaller area.
The FAA also identified an ambiguity in the compliance time for the
inspection of the fuselage skin. Paragraphs (g)(1) through (3) of AD
2017-11-09 do not specify that the date used for compliance is either
the date of issuance of the original airworthiness certificate or the
date of issuance of the original export certificate of airworthiness,
whichever date is earlier.
The FAA is issuing this AD to correct the error of the inspection
area and clarify the compliance times for the fluorescent dye penetrant
inspection of the fuselage skin. The actions of this AD will detect and
correct corrosion of the fuselage skin, which could result in reduced
structural integrity of the airplane.

Comments

The FAA gave the public the opportunity to participate in
developing this AD. The FAA received no comments on the NPRM or on the
determination of the cost to the public.

Conclusion

The FAA reviewed the relevant data and determined that air safety
and the public interest require adopting this AD as proposed except for
minor editorial changes. It has determined that these minor changes:
Are consistent with the intent that was proposed in the
NPRM for addressing the unsafe condition; and
Do not add any additional burden upon the public than was
already proposed in the NPRM.

Related Service Information Under 1 CFR Part 51

The FAA reviewed Bombardier Learjet 60 Service Bulletin (SB) 60-53-
19, Revision 3, dated August 29, 2016. This service information was
previously approved for incorporation by reference in AD 2017-08-07 and
retained in AD 2017-11-09. The service information describes procedures
for inspections of the fuselage crown skin for corrosion and, as
necessary, related investigative inspections and corrective actions.
This service information is reasonably available because the interested
parties have access to it through their normal course of business or by
the means identified in the ADDRESSES section.

Costs of Compliance

The FAA estimates that this AD affects 284 airplanes of U.S.
registry.
The FAA estimates the following costs to comply with this AD:

Estimated Costs

This AD adds no additional economic burden. The FAA has not
received definitive data that would enable us to provide cost estimates
for the on-condition actions specified in this AD. According to the
manufacturer, some of the costs of this AD may be covered under
warranty, thereby reducing the cost impact on affected individuals. The
FAA does not control warranty coverage for affected individuals. As a
result, it has included all known costs in the cost estimate.

Paperwork Reduction Act

A federal agency may not conduct or sponsor, and a person is not
required to respond to, nor shall a person be subject to a penalty for
failure to comply with a collection of information subject to the
requirements of the Paperwork Reduction Act unless that collection of
information displays a currently valid OMB Control Number. The OMB
Control Number for this information collection is 2120-0056. Public
reporting for this collection of information is estimated to be
approximately 1 hour per response, including the time for reviewing
instructions, searching existing data sources, gathering and
maintaining the data needed, completing and reviewing the collection of
information. All responses to this collection of information are
mandatory. Send comments regarding this burden estimate or any other
aspect of this collection of information, including suggestions for
reducing this burden to: Information Collection Clearance Officer,
Federal Aviation Administration, 10101 Hillwood Parkway, Fort Worth, TX
76177-1524.

Authority for This Rulemaking

Title 49 of the United States Code specifies the FAA's authority to
issue rules on aviation safety. Subtitle I, Section 106, describes the
authority of the FAA Administrator. Subtitle VII, Aviation Programs,
describes in more detail the scope of the Agency's authority.
The FAA is issuing this rulemaking under the authority described in
Subtitle VII, Part A, Subpart III, Section 44701, General requirements.
Under that section, Congress charges the FAA with promoting safe flight
of civil aircraft in air commerce by prescribing regulations for
practices, methods, and procedures the Administrator finds necessary
for safety in air commerce. This regulation is within the scope of that
authority because it addresses an unsafe condition that is likely to
exist or develop on products identified in this rulemaking action.
This AD is issued in accordance with authority delegated by the
Executive Director, Aircraft Certification Service, as authorized by
FAA Order 8000.51C. In accordance with that order, issuance of ADs is
normally a function of the Compliance and Airworthiness Division, but
during this transition period, the Executive Director has delegated the
authority to issue ADs applicable to small airplanes, gliders,
balloons, airships, domestic business jet transport airplanes, and
associated appliances to the Director of the Policy and Innovation
Division.

Regulatory Findings

The FAA determined that this AD will not have federalism
implications under Executive Order 13132. This AD 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.
For the reasons discussed above, I certify that this AD:
(1) Is not a ``significant regulatory action'' under Executive
Order 12866,
(2) Will not affect intrastate aviation in Alaska, and
(3) 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.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Incorporation by
reference, Safety.

Adoption of the Amendment

Accordingly, under the authority delegated to me by the
Administrator, the FAA amends 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. The FAA amends Sec. 39.13 by removing Airworthiness Directive (AD)
2017-11-09, Amendment 39-18908 (82 FR 24462, May 30, 2017), and adding
the following new AD: