[Federal Register Volume 86, Number 34 (Tuesday, February 23, 2021)]
[Proposed Rules]
[Pages 10875-10878]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-03483]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2020-0994; Project Identifier AD-2020-00687-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-
G600 airplanes. This proposed AD was prompted by a report that a 
failure mode

[[Page 10876]]

in the data concentration network (DCN) software causes the pitch 
attitude value to freeze on the primary flight display (PFD) for up to 
20 seconds. This proposed AD would require updating the DCN and flight 
deck master operating system (MOS) software. 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 April 9, 
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 proposed rule, 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 FAA, 
Airworthiness Products Section, Operational Safety Branch, 901 Locust, 
Kansas City, Missouri 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-2020-0994; 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: Myles Jalalian, Aviation Safety 
Engineer, Atlanta ACO Branch, FAA, 1701 Columbia Avenue, College Park, 
GA 30337; phone: (404) 474-5572; fax: (404) 474-5606; email: 
myles.jalalian@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-2020-0994; Project Identifier 
AD-2020-00687-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 AD 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 AD, 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 AD. Submissions containing CBI should be sent to Myles 
Jalalian, Aviation Safety Engineer, Atlanta ACO Branch, FAA, 1701 
Columbia Avenue, 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

    The FAA received a report that on certain Gulfstream Model GVII-
G600 airplanes a failure mode in the DCN software causes the pitch 
attitude value to freeze on the PFD for up to 20 seconds.
    During implementation of the DCN software update version 10.10.10 
for certain Model GVII-G500 airplane configurations (``Block 1''), it 
was discovered the software supplier had incorrectly implemented one of 
Gulfstream's design requirements. At the time of this discovery on 
Model GVII-G500 Block 1 configurations, the DCN software version 
10.10.10 had already been implemented on Model GVII-G600 airplanes in 
service. This airplane has three independent inertial reference systems 
(IRSs), identified as IRS1, IRS2, and IRS3, which are expected to 
provide identical pitch data. During flight testing, the GVII-G600 IRS1 
was found to indicate a slightly different pitch from IRS2 and IRS3, at 
the same actual airplane pitch attitude. A DCN embedded function was 
created to correct the very minor pitch difference between IRS1, IRS2, 
and IRS3. DCN software version 10.10.10 implemented the new embedded 
function which computes a ``PITCH_DELTA correction factor'' (pitch 
difference correction factor) between the IRS pitch angles being used 
by the PFDs. The system calculates pitch correction based in part on 
the IRS1 pitch angle. If the IRS1 is lost, it causes the embedded 
function to invalidate the ``PITCH_DELTA output.'' During this failure 
mode, the pitch attitude value freezes on the display for up to 20 
seconds, which results in temporarily incorrect pitch indications. The 
effect is evident only if the pitch of the airplane changes during the 
20 second reset window. After 20 seconds, the system returns to normal. 
The standby flight display and heads up display are unaffected by this 
failure mode and continue to display the correct pitch attitude.
    There is not an alert or annunciation that informs the flight crew 
of a stale (frozen) pitch display or potentially misleading flight 
information.
    This condition, if not addressed, could result in loss of control 
of the airplane in certain phases of flight during instrument 
meteorological conditions.

Related Service Information Under 1 CFR Part 51

    The FAA reviewed Gulfstream GVII-G600 Aircraft Service Change No. 
901, Initial Issue, dated May 12, 2020. This service document specifies 
procedures for installing the MOS software update part number 
EB60001034-0106 and operationally checking the installation.
    The FAA also reviewed Gulfstream GVII-G600 Aircraft Service Change 
No. 020, Initial Issue, dated May 12, 2020. This service document 
specifies procedures for updating the DCN software level to version 
10.10.12, updating system software in support of the MOS software 
update, and operationally checking the installation.
    This service information is reasonably available because the 
interested parties have access to it through their normal

[[Page 10877]]

course of business or by the means identified in the ADDRESSES section.

FAA's Determination

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

Proposed AD Requirements in This NPRM

    This proposed AD would require accomplishing the actions specified 
in the service information described previously.

Costs of Compliance

    The FAA estimates that this AD, if adopted as proposed, would 
affect 43 airplanes of U.S. registry.
    The FAA estimates the following costs to comply with this proposed 
AD:

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                     Cost per      Cost on U.S.
                Action                         Labor cost           Parts cost        product        operators
----------------------------------------------------------------------------------------------------------------
Update DNC software...................  30 work-hours x $85 per              $52          $2,602        $111,886
                                         hour = $2,550.
Update MOS software...................  10 work-hours x $85 per               52             902          38,786
                                         hour = $850.
----------------------------------------------------------------------------------------------------------------

    The FAA has included all known costs in its cost estimate. 
According to the manufacturer, however, some of the costs of this 
proposed 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 proposing 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

0
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]

0
2. The FAA amends Sec.  39.13 by adding the following new airworthiness 
directive:

Gulfstream Aerospace Corporation: Docket No. FAA-2020-0994; Project 
Identifier AD-2020-00687-T.

(a) Comments Due Date

    The FAA must receive comments on this airworthiness directive 
(AD) by April 9, 2021.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to Gulfstream Aerospace Corporation Model GVII-
G600 airplanes, serial numbers 73001 through 73043, certificated in 
any category.

(d) Subject

    Joint Aircraft System Component Code 3400, Navigation System.

(e) Unsafe Condition

    This AD was prompted by reports of software causing pitch 
attitude value freezing on the Primary Flight Display (PFD) for up 
to 20 seconds. The FAA is issuing this AD to prevent a stale pitch 
display or potentially misleading flight information. The unsafe 
condition, if not addressed, could result in loss of control of the 
airplane in certain phases of flight during instrument 
meteorological conditions.

(f) Compliance

    Comply with this AD within the compliance times specified, 
unless already done.

(g) Update Software

    Within 24 months after the effective date of this AD, update the 
data concentration network and flight deck master operating system 
software by using the Modification Instructions, Steps III. A 
through I, in Gulfstream GVII-G600 Aircraft Service Change No. 901, 
Initial Issue, dated May 12, 2020, concurrently with the 
Modification Instructions, Steps III. A through D, in Gulfstream 
GVII-G600 Aircraft Service Change No. 020, Initial Issue, dated May 
12, 2020.

(h) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Atlanta ACO Branch, FAA, has the authority to 
approve AMOCs for this AD, if requested using the procedures found 
in 14 CFR 39.19. In accordance with 14 CFR 39.19, send your request 
to your principal inspector or local Flight Standards District 
Office, as appropriate. If sending information directly to the 
manager of the certification office, send it to the attention of the 
person identified in Related Information.
    (2) Before using any approved AMOC, notify your appropriate 
principal inspector, or lacking a principal inspector, the manager 
of the local flight standards district office/certificate holding 
district office.

(i) Related Information

    (1) For more information about this AD, contact Myles Jalalian, 
Aviation Safety Engineer, Atlanta ACO Branch, FAA, 1701 Columbia 
Avenue, College Park, GA 30337; phone: (404) 474-5572; fax: (404) 
474-5606; email: myles.jalalian@faa.gov.
    (2) For service information identified in this AD, contact 
Gulfstream Aerospace Corporation, Technical Publications Dept., P.O. 
Box 2206, Savannah, GA 31402; phone:

[[Page 10878]]

(800) 810-4853; email: pubs@gulfstream.com; website: https://www.gulfstream.com/en/customer-support/. You may view this 
referenced service information at the FAA, Airworthiness Products 
Section, Operational Safety Branch, 901 Locust, Kansas City, 
Missouri 64106. For information on the availability of this material 
at the FAA, call (816) 329-4148.

    Issued on January 29, 2021.
Gaetano A. Sciortino,
Deputy Director for Strategic Initiatives, Compliance & Airworthiness 
Division, Aircraft Certification Service.
[FR Doc. 2021-03483 Filed 2-22-21; 8:45 am]
BILLING CODE 4910-13-P


