[Federal Register Volume 86, Number 65 (Wednesday, April 7, 2021)]
[Rules and Regulations]
[Pages 17902-17905]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-07015]



Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2020-0915; Project Identifier AD-2020-00661-Q; 
Amendment 39-21501; AD 2021-08-07]
RIN 2120-AA64

Airworthiness Directives; Rockwell Collins, Inc., Global 
Positioning Systems

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.


SUMMARY: The FAA is adopting a new airworthiness directive (AD) for 
certain Rockwell Collins, Inc. (Rockwell Collins), GPS-4000S Global 
Positioning Systems (GPS) installed on airplanes. This AD was prompted 
by an un-annunciated GPS position error, which could cause a misleading 
localizer performance with vertical guidance (LPV) glidepath, resulting 
in controlled flight into terrain (CFIT). This AD requires upgrading 
the GPS-4000S. The FAA is issuing this AD to address the unsafe 
condition on these products.

DATES: This AD is effective May 12, 2021.

ADDRESSES: For service information identified in this final rule, 
contact Rockwell Collins, Inc., 400 Collins Road NE, Cedar Rapids, IA 
52498; phone: (319) 295-5000; email: 
[email protected]; website: www.rockwellcollins.com. 
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.

Examining the AD Docket

    You may examine the AD docket at https://www.regulations.gov by 
searching for and locating Docket No. FAA-2020-0915; 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: Paul Rau, Aviation Safety Engineer, 
Wichita ACO Branch, FAA, 1801 Airport Road, Wichita, KS 67209; phone: 
(316) 946-4149; fax: (316) 946-4107; email:

[[Page 17903]]

[email protected] or [email protected].



    The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 
CFR part 39 by adding an AD that would apply to Rockwell Collins GPS-
4000S GPS installed on airplanes. The NPRM published in the Federal 
Register on October 29, 2020 (85 FR 68501). The NPRM was prompted by 
the FAA being notified of a software error in GPS P/N 822-2189-100 that 
can result in an un-annunciated inaccurate GPS position in the region 
within approximately 1,000 miles (+/-20 degrees) of 180 degrees west 
longitude. The software improperly applies the wide area augmentation 
system ionospheric delay corrections to the GPS signal from satellites 
located across the 180th meridian. Due to this anomaly, the position 
accuracy may be diminished such that the GPS-4000S P/N 822-2189-100 
will not support LPV approaches in the affected region. In the NPRM, 
the FAA proposed to require removing P/N 822-2189-100 GPS-4000S GPS 
from the airplane and installing P/N 811-2189-101 GPS-4000S GPS. The 
FAA is issuing this AD to prevent a misleading glidepath on an affected 
LPV approach, resulting in CFIT.

Discussion of Final Airworthiness Directive


    The FAA received comments from five commenters. The commenters were 
the Air Line Pilots Association, International (ALPA), Bombardier 
Aviation (Bombardier), Delta Air Lines, Inc. (Delta), Airbus Canada, 
and Transport Canada Civil Aviation (Transport Canada). The following 
presents the comments received on the NPRM and the FAA's response to 
each comment.

Supportive Comment

    ALPA supported the AD without change.

Request Regarding the Unsafe Condition

    Bombardier requested the FAA clarify paragraph (e) because it does 
not describe the unsafe condition accurately. Bombardier stated that 
the reference to a GPS vertical error is misleading and recommended 
rewording it to state that a GPS software anomaly causes an 
undetectable and inaccurate horizontal position from the Global 
Navigation Satellite System (GNSS).
    The FAA disagrees. The software error in the GPS-4000 produces both 
horizontal and vertical position inaccuracies in the affected region. 
The FAA determined the vertical error results in an unsafe condition as 
it could cause the airplane to follow a glidepath below the obstacle 
clearance surface of the LPV approach.

Request Regarding Replacement of the GPS-4000S

    Delta requested the FAA change the proposed requirement in 
paragraph (g)(1) to replace GPS-4000S P/N 822-2189-100 so that the AD 
does not prevent installation of a GPS P/N that is unaffected by the 
unsafe condition. Delta stated GPS-4000S P/N 822-2189-011 is two-way 
interchangeable with P/N 822-2189-100 as a set and is not affected by 
the unsafe condition. Delta also stated that Rockwell Collins could 
develop new GPS P/Ns that are not subject to the unsafe condition, 
which operators could not install without obtaining approval for an 
alternative method of compliance (AMOC), based on the proposed 
paragraph (g)(1). Delta requested the FAA change paragraph (g)(1) to 
require replacing GPS-4000S GPS P/N 822-2189-100 with ``an improved 
part number.''
    The FAA agrees. It is not necessary for the AD to require 
installing P/N 822-2189-101 because requiring the removal of P/N 822-
2189-100 will resolve the unsafe condition. Operators may replace GPS 
P/N 822-2189-100 with any other system approved for installation in 
their aircraft, although the FAA expects installation of P/N 822-2189-
101 will be the most common method.
    The FAA has revised the AD to only require removing GPS-4000S GPS 
P/N 822-2189-100 from service without requiring replacement with a 
specific P/N GPS.

Requests Regarding Installation Prohibition

    Airbus Canada and Transport Canada commented on the FAA's proposal 
to prohibit the installation of the GPS-4000S GPS P/N 822-2189-100 as 
of the effective date of the AD instead of once P/N 822-2189-101 has 
been installed. The commenters stated that this may create dispatch 
issues for operators depending on the number of available parts.
    The FAA agrees and has changed the prohibition of installation to 
take effect 24 months after the effective date of the AD. Operators may 
install a GPS-4000S GPS P/N 822-2189-100 to address maintenance/repair 
issues prior to complying with the AD. Once an operator has removed 
GPS-4000S GPS P/N 822-2189-100 to comply with the AD, the operator must 
maintain that configuration and may not change it to install a GPS-
4000S GPS P/N 822-2189-100 without an approved AMOC.

Request Regarding Applicability

    Delta requested the FAA change the applicability to specify only 
those aircraft types with the affected software installed. Delta stated 
that as proposed, the AD would require all operators to review records 
to verify whether the affected GPS P/N is installed on all of their 
airplane fleets, regardless of whether it is type certificated or 
supplemental type certificated.
    The FAA disagrees. The FAA issues an AD against an appliance when, 
as in this case, the unsafe condition exists in the appliance. If 
known, the FAA will list the aircraft models that the appliance might 
be installed on. However, this would not be an all-inclusive list and 
would still require all operators to check their airplanes for the 
affected appliance, regardless of whether the model of their airplane 
is listed.
    The FAA did not change this AD based on this comment.

Requests Regarding Reinstatement of LPV Approaches

    Airbus Canada stated that the NPRM does not mention that Rockwell 
Collins removed the LPV approaches from the impacted airports. Airbus 
Canada requested that the AD provide credit for this. Transport Canada 
asked whether Rockwell Collins and the FAA will return the affected 
Alaska LPV procedures to the Navigation database for customers who have 
updated their entire fleet with the P/N 822-2189-101 version of the 
    The FAA disagrees with this comment. The FAA infers that the 
commenters are referencing Rockwell Collins' removal of the affected 
LPV approaches from the Rockwell Collins Navigation database beginning 
in February 2020. This LPV approach removal was initiated by Rockwell 
Collins as a temporary mitigation, but it affects all versions of the 
GPS-4000S that use the database, including those (such as the -101 
version) that do not have the unsafe condition. Accordingly, the FAA 
did not base its determination and the corrective actions of this AD on 
the removal of affected LPV approaches.
    The FAA did not change this AD based on this comment.

[[Page 17904]]


    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 the changes described 
previously, this AD is adopted as proposed in the NPRM. None of the 
changes will increase the economic burden on any operator.

Related Service Information

    The FAA reviewed Rockwell Collins Service Information Letter GPS-
4X00( )-19-3, Revision No. 2, dated March 25, 2020. The service letter 
describes the unsafe condition and provides operating limitations for 
approaches to airports in the affected region until the software is 
    The FAA also reviewed Rockwell Collins Service Bulletin GPS-4X00( 
)-34-510, Revision No. 1, dated March 6, 2020. The service bulletin 
specifies procedures for upgrading the GPS-4000S software, which 
removes P/N 822-2189-100 and installs P/N 822-2189-101.

Costs of Compliance

    The FAA estimates that this AD affects 3,500 airplanes of U.S. 
registry. The FAA estimates that 2,000 airplanes have two GPS-4000S 
units installed and 1,500 airplanes have one GPS-4000S unit installed.
    The FAA estimates the following costs to comply with this AD:

                                                 Estimated Costs
                                                                                     Cost per      Cost on U.S.
                Action                         Labor cost           Parts cost        product        operators
Replace GPS-4000S (airplanes with 2     7 work-hours x $85 per         $4,540.00          $5,135     $10,270,000
 units installed).                       hour = $595.
Replace GPS-4000S (airplanes with       3.50 work-hours x $85              2,270        2,567.50       3,851,250
 single unit installed).                 per hour = $297.50.

    The FAA has included all known costs in this 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:


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 

2021-08-07 Rockwell Collins, Inc.: Amendment 39-21501; Docket No. 
FAA-2020-0915; Project Identifier AD-2020-00661-Q.

(a) Effective Date

    This airworthiness directive (AD) is effective May 12, 2021.

(b) Affected ADs


(c) Applicability

    This AD applies to Rockwell Collins, Inc. GPS-4000S Global 
Positioning System (GPS) part number (P/N) 822-2189-100 installed on 
airplanes, certificated in any category.

(d) Subject

    Joint Aircraft System Component (JASC)/Air Transport Association 
(ATA) of America Code 3400, NAVIGATION SYSTEM.

(e) Unsafe Condition

    This AD was prompted by an un-annunciated GPS vertical error 
that could result in a hazardously misleading localizer performance 
vertical (LPV) glidepath. The FAA is issuing this AD to prevent a 
misleading GPS position on an LPV approach. The unsafe condition, if 
not addressed, could result in a misleading GPS position on an LPV 
approach resulting in controlled flight into terrain.

(f) Compliance

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

(g) Actions

    (1) Within 24 months replace each GPS-4000S GPS P/N 822-2189-100 
with a GPS that does not have P/N 822-2189-100.
    (2) As of 24 months after the effective date of this AD, do not 
install GPS-4000S GPS P/N 822-2189-100 on any airplane.

(h) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Wichita 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.

[[Page 17905]]

    (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 Paul Rau, 
Aviation Safety Engineer, Wichita ACO Branch, FAA, 1801 Airport 
Road, Wichita, KS 67209; phone: (316) 946-4149; fax: (316) 946-4107; 
email: [email protected] or [email protected].
    (2) Rockwell Collins Service Information Letter GPS-4X00( )-19-
3, Revision No. 2, dated March 25, 2020; and Rockwell Collins 
Service Bulletin GPS-4X00( )-34-510, Revision No. 1, dated March 6, 
2020, contain information related to this AD. For this service 
information, you may contact Rockwell Collins, Inc., at 400 Collins 
Road NE, Cedar Rapids, IA 52498; phone: (319) 295-5000; email: 
[email protected]; website: 

    Issued on March 30, 2021.
Lance T. Gant,
Director, Compliance & Airworthiness Division, Aircraft Certification 
[FR Doc. 2021-07015 Filed 4-6-21; 8:45 am]