DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2020-0831; Project Identifier 2019-CE-031-AD; Amendment
39-21471; AD 2021-06-04]
RIN 2120-AA64

Airworthiness Directives; Gulfstream Aerospace Corporation Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for all
Gulfstream Aerospace Corporation (Gulfstream) Model GV airplanes. This
AD was prompted by notification of corrosion present in floor beam
support links. This AD requires inspecting the right butt line 6 floor
beam inboard support links and bushings for corrosion. The FAA is
issuing this AD to address the unsafe condition on these products.

DATES: This AD is effective May 4, 2021.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of May 4, 2021.

ADDRESSES: For service information identified in this final rule,
contact Gulfstream Aerospace Corporation, Technical Publications Dept.,
P.O. Box 2206, Savannah, GA 31402-2206; phone: (800) 810-4853; fax:
(912) 965-3520; email: pubs@gulfstream.com; website: https://www.gulfstream.com/en/customer-support/. You may view this service
information at the FAA, Airworthiness Products Section, Operational
Safety Branch, 901 Locust, Kansas City, MO 64106.
For information on the availability of this material at the FAA,
call (816) 329-4148. It is also available at https://www.regulations.gov by
searching for and locating Docket No. FAA-2020-0831.

Examining the AD Docket

You may examine the AD docket at https://www.regulations.gov by
searching for and locating Docket No. FAA-2020-0831; 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, 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: Ronald Wissing, Aviation Safety
Engineer, Atlanta ACO Branch, FAA, 1701 Columbia Avenue, College Park,
GA 30337; phone: (404) 474-5552; fax: (404) 474-5606; email:
ronald.wissing@faa.gov.

SUPPLEMENTARY INFORMATION:

Background

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 by adding an AD that would apply to all Gulfstream Model GV
airplanes. The NPRM published in the Federal Register on December 10,
2020 (85 FR 79443). The NPRM was prompted by notification of a failed
floor beam support link at right butt line (RBL) 6 on a Gulfstream
Model GV airplane, resulting from seizure of the retaining sleeve and
bushing at the lower attachment point due to undetected corrosion.
The floor beam support links at RBL 6, fuselage stations (FS) 499,
531, and 569.5 have a two-piece installation with straight bushings
rather than spherical bearings in the inboard link lower end. Design of
the support links allows floor beam movement when the cabin is
pressurized. Seizure of the lower bushing will not allow the link
assembly to move as designed, resulting in bending stress and potential
failure of the link, which may compromise the integrity of the pressure
vessel floor. Gulfstream determined that the procedures for the
existing Aircraft Maintenance Manual (AMM) inspection do not reliably
detect corrosion in the floor beam support link lower bushings.
Accordingly, Gulfstream has revised the airworthiness limitation
requirements to the AMM by adding a detailed inspection with an initial
and repetitive inspections at intervals of 96 months and including
references for removal and installation instructions for RBL 6 Floor
Beam Support Links.
In the NPRM, the FAA proposed to require inspecting the right butt
line 6 floor beam inboard support links and bushings for corrosion. The
FAA is issuing this AD to prevent link failure, which can compromise
the integrity of the pressure vessel floor and lead to loss of
pressurization of the airplane.

Discussion of Final Airworthiness Directive

Comments

The FAA received one comment from Gulfstream. The following
presents the comment received on the NPRM and the FAA's response to the
comment.

Request for Clarification on Reporting

Gulfstream requested the FAA clarify whether the AD requires or
recommends reporting the CB 231A inspection results to Gulfstream.
Gulfstream noted a discrepancy in the NPRM, where the section titled
``Proposed AD Requirements'' states that the proposed AD recommends
sending the inspection results to Gulfstream, but the section titled
``Differences Between this Proposed AD and the Service Information''
states that the proposed AD would not require reporting the results of
the inspection to Gulfstream.
The FAA agrees. This AD does not require reporting the results of
the inspection. This AD is not an interim action; mandating a report of
the inspection results is not necessary to correct the unsafe
condition. The FAA should not have included conflicting language in the
NPRM to this effect. The FAA has revised the preamble of this final
rule to correct this discrepancy.

Conclusion

The FAA reviewed the relevant data, considered any comments
received, and determined that air safety requires adopting this AD as
proposed. Accordingly, the FAA is issuing this AD to address the unsafe
condition on these products. Except for minor editorial changes, this
AD is adopted as proposed in the NPRM. None of the changes will
increase the economic burden on any operator.

Related Service Information Under 1 CFR Part 51

The FAA reviewed Gulfstream GV Customer Bulletin Number 231,
Revision A, dated July 30, 2019 (Gulfstream CB 231A). The service
information contains procedures for the inspection of the RBL 6, FS
499, 531, and 569.5, and the bushing in the lower end of the link and
all attachments for corrosion.
The FAA reviewed Table 13: Fuselage Inspection Table in Section 05-
10-10 of Chapter 5--Time Limits/Maintenance Checks of Gulfstream GV
Aircraft Maintenance Manual, Revision 51, dated February 28, 2020. The
service information identifies tasks for a recurring detailed
inspection of the floor beam and wing links FS 465 through FS 576.
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.

Differences Between This AD and the Service Information

Gulfstream CB 231A specifies reporting the results of the
inspection to Gulfstream, and this AD does not.

Costs of Compliance

The FAA estimates that this AD affects 148 airplanes of U.S.
registry.
The FAA estimates the following costs to comply with this AD:

Estimated Costs

The FAA estimates the following costs to do any necessary
replacements that would be required based on the results of the
inspection. The FAA has no way of determining the number of airplanes
that might need these replacements:

On-Condition Costs

The FAA has included all known costs in its cost estimate.
According to the manufacturer, however, some of the costs of this AD
may be covered under warranty, thereby reducing the cost impact on
affected operators.

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.

Regulatory Findings

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.

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 adding the following new airworthiness
directive: