DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2021-0156; Project Identifier AD-2020-01594-T]
RIN 2120-AA64

Airworthiness Directives; Gulfstream Aerospace Corporation Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD)
for certain Gulfstream Aerospace Corporation (Gulfstream) Model GVII-
G500 airplanes. This proposed AD results from flap yoke fittings with
design features that cause decreased fatigue life. This proposed AD
would require replacing the flap inboard and outboard yoke fitting
assemblies and establishing a 20,000 flight cycle life limit for the
fittings. The FAA is proposing this AD to address the unsafe condition
on these products.

DATES: The FAA must receive comments on this proposed AD by June 21,
2021.

ADDRESSES: You may send comments, using the procedures found in 14 CFR
11.43 and 11.45, by any of the following methods:

Federal eRulemaking Portal: Go to https://www.regulations.gov. Follow the
instructions for submitting comments.

Fax: (202) 493-2251.

Mail: U.S. Department of Transportation, Docket
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New
Jersey Avenue SE, Washington, DC 20590.

Hand Delivery: Deliver to Mail address above between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays.

For service information identified in this NPRM, contact Gulfstream
Aerospace Corporation, Technical Publications Dept., P.O. Box 2206,
Savannah, GA 31402; phone: (800) 810-4853; email: pubs@gulfstream.com;
website: https://www.gulfstream.com/en/customer-support/. You may view
this service information at the 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.

Examining the AD Docket

You may examine the AD docket at https://www.regulations.gov by
searching for and locating Docket No. FAA-2021-0156; 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 NPRM, any comments
received, and other information. The street address for Docket
Operations is listed above.

FOR FURTHER INFORMATION CONTACT: Jeff Johnson, Aviation Safety
Engineer, Atlanta ACO Branch, FAA, 1701 Columbia Ave., College Park, GA
30337; phone: (404) 474-5554; fax: (404) 474-5606; email:
jeffrey.d.johnson@faa.gov.

SUPPLEMENTARY INFORMATION:

Comments Invited

The FAA invites you to send any written relevant data, views, or
arguments about this proposal. Send your comments to an address listed
under ADDRESSES. Include "Docket No. FAA-2021-0156; Project Identifier
AD-2020-01594-T" at the beginning of your comments. The most helpful
comments reference a specific portion of the proposal, explain the
reason for any recommended change, and include supporting data. The FAA
will consider all comments received by the closing date and may amend
this proposal because of those comments.

Except for Confidential Business Information (CBI) as described in
the following paragraph, and other information as described in 14 CFR
11.35, the FAA will post all comments received, without change, to
https://www.regulations.gov, including any personal information you
provide. The agency will also post a report summarizing each
substantive verbal contact received about this NPRM.

Confidential Business Information

CBI is commercial or financial information that is both customarily
and actually treated as private by its owner. Under the Freedom of
Information Act (FOIA) (5 U.S.C. 552), CBI is exempt from public
disclosure. If your comments responsive to this NPRM contain commercial
or financial information that is customarily treated as private, that
you actually treat as private, and that is relevant or responsive to
this NPRM, it is important that you clearly designate the submitted
comments as CBI. Please mark each page of your submission containing
CBI as "PROPIN." The FAA will treat such marked submissions as
confidential under the FOIA, and they will not be placed in the public
docket of this NPRM. Submissions containing CBI should be sent to Jeff
Johnson, Aviation Safety Engineer, Atlanta ACO Branch, FAA, 1701
Columbia Ave., College Park, GA 30337. Any commentary that the FAA
receives which is not specifically designated as CBI will be placed in
the public docket for this rulemaking.

Background

During flight testing of a Gulfstream Model GVII-G500 airplane,
when the aircraft was configuring for a steep approach test point, the
crew received a flap failure message. After landing, inspection
revealed that the left-hand flap track `B' yoke had become disconnected
due to structural failure. Gulfstream's investigation to determine the
root cause of the failure revealed that the flap yoke fittings for
certain serial-numbered Gulfstream Model GVII-G500 airplanes have
design features that cause decreased fatigue life. The unsafe design
features include insufficient shaft diameter, a small fillet radius
detail at the top of the shaft, and a rough surface finish allowance,
which collectively attribute to a potential yoke fitting failure. These
design features ultimately cause higher stress concentrations leading
to premature and fast-fracture overload of the flap actuator yoke at
the junction of the fitting shaft and yoke clevis.

This condition, if not addressed, could result in failure of the
flap yoke fitting during flap transition, which could cause the flaps
to stop moving. This, combined with additional failures in the flap
actuator force limiter or flap yoke actuator disconnect, could result
in asymmetric flap positions, leading to a loss of airplane control.

FAA's Determination

The FAA is issuing this NPRM after determining that the unsafe
condition described previously is likely to exist or develop on other
products of the same type design.

Related Service Information Under 1 CFR Part 51

The FAA reviewed Gulfstream GVII-G500 Aircraft Service Change No.
032, Initial Issue, dated November 20, 2020 (Gulfstream ASC No. 032).
This service information specifies procedures for replacing the flap
inboard and outboard yoke fitting assemblies and upper bushings. 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 ADDRESSES.

Other Related Service Information

The FAA also reviewed Gulfstream GVII-500 Customer Bulletin No.
045, Initial Issue, dated November 20, 2020. This service information
specifies the compliance time and additional information for Gulfstream
ASC No. 032. The FAA also reviewed Gulfstream Aerospace GVII-G500
Aircraft Maintenance Manual (AMM) Document Number GAC-AC-GVII-G500-AMM-
0001, Revision 7, dated December 15, 2020. This document contains
revised airworthiness limitations, maintenance checks, and inspections.

Proposed AD Requirements in This NPRM

This proposed AD would require replacing the flap inboard and
outboard yoke fitting assemblies and updating chapter 5 of your
existing AMM to incorporate a 20,000 flight cycle life limit.

Differences Between This Proposed AD and the Service Information

Gulfstream ASC No. 032 contains actions labeled "Required for
Compliance" (RC), and the language in the ASC and in paragraph (h)(3)
of this AD indicates that operators must comply with all actions
labeled RC for compliance with this AD. However, this AD does not
require all of the steps in Gulfstream ASC No. 032 that are labeled as
RC. Operators only need to comply with the RC steps specified in
paragraph (g) of this AD.

Costs of Compliance

The FAA estimates that this AD, if adopted as proposed, would
affect 85 airplanes of U.S. registry.

The FAA estimates the following costs to comply with this proposed AD:

Estimated Costs

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

The FAA determined that this proposed AD would not have federalism
implications under Executive Order 13132. This proposed AD 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.

For the reasons discussed above, I certify this proposed
regulation:

(1) Is not a "significant regulatory action" under Executive
Order 12866,

(2) Would not affect intrastate aviation in Alaska, and

(3) Would 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 Proposed Amendment

Accordingly, under the authority delegated to me by the
Administrator, the FAA proposes to amend 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: