Document ID: FAA-2017-0522-0004
Agency: faa
Document Type: Rule
Title: Airworthiness Directives: Northrop Grumman LITEF GmbH LCR-100 Attitude and Heading Reference System Units
Posted Date: 2019-04-24T04:00Z

[Federal Register Volume 84, Number 79 (Wednesday, April 24, 2019)]
[Rules and Regulations]
[Pages 17062-17064]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-08157]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2017-0522; Product Identifier 2015-SW-068-AD; Amendment 
39-19621; AD 2019-07-10]
RIN 2120-AA64

Airworthiness Directives; Northrop Grumman LITEF GmbH LCR-100 
Attitude and Heading Reference System Units

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: We are adopting a new airworthiness directive (AD) for 
Northrop Grumman LITEF GmbH LCR-100 Attitude and Heading Reference 
System (AHRS) units installed on various aircraft. This AD requires 
removing certain LCR-100 AHRS units from service. This AD was prompted 
by test results showing loss of or invalid data. The actions of this AD 
are intended to prevent an unsafe condition on these products.

DATES: This AD is effective May 29, 2019.

ADDRESSES: For service information identified in this final rule, 
contact Northrop Grumman LITEF GmbH, Customer Service--Commercial 
Avionics, Loerracher Str. 18, 79115 Freiburg, Germany; telephone +49 
(761) 4901-142; fax +49 (761) 4901-773; email [email protected]. 
You may review the referenced service information at the FAA, Office of 
the Regional Counsel, Southwest Region, 10101 Hillwood Pkwy., Room 6N-
321, Fort Worth, TX 76177.

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-2017-
0522; 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 AD, the European Aviation Safety Agency (EASA) AD, the economic 
evaluation, any comments received, and other information. The street 
address for Docket Operations (phone: 800-647-5527) is U.S. Department 
of Transportation, Docket Operations Office, M-30, West Building Ground 
Floor, Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: Nick Rediess, Aviation Safety 
Engineer, Boston ACO Branch, Compliance and Airworthiness Division, 
1200 District Avenue, Burlington, Massachusetts 01803; telephone (781) 
238-7763; email [email protected].

SUPPLEMENTARY INFORMATION:

Discussion

    On June 5, 2017, at 82 FR 25742, the Federal Register published our 
notice of proposed rulemaking (NPRM), which proposed to amend 14 CFR 
part 39 by adding an AD that would apply to airplanes and helicopters 
with a Northrop Grumman LITEF GmbH LCR-100 AHRS unit part number (P/N) 
145130-2000, 145130-2001, 145130-7000, 145130-7001, or 145130-7100 
installed that uses analog outputs for primary flight information 
display or autopilot functions without automatic output comparison. A 
primary flight information display includes any device that displays to 
the pilot primary flight information such as attitude, airspeed, and 
altitude. Such displays include primary flight displays, standby 
instruments, and multifunction displays that provide a secondary 
display of primary flight information. The NPRM proposed to require 
removing these LCR-100 AHRS units from service and to prohibit 
installing them on any aircraft.
    These units are often used to supply attitude and heading data to 
Primary Flight Displays (PFDs), autopilots, and other avionics. 
Northrop Grumman LITEF GmbH discovered erroneous behavior of an AHRS 
unit when the unit's continuous built-in test detects a failure and 
then does not correctly reset. When this occurs, the analog outputs of 
attitude and heading data freeze and the transmission of digital 
outputs of attitude and heading stops. The effect of the errors 
(display of misleading information, providing an alert if the attitude 
and heading data is frozen) depends on how the AHRS unit outputs are 
used in a particular installation. For instance, if the AHRS unit 
analog outputs are used by a PFD without any automatic comparison with 
another source of data, the PFD will display misleading information, 
which could lead to loss of control of the aircraft. Other 
installations using the analog outputs might include an automatic 
comparison feature that detects and provides an alert if the attitude 
and heading data is frozen. A similar situation would occur in 
installations that use the digital outputs since the erroneous behavior 
would be detected. The NPRM proposed to only apply to installations of 
the AHRS units using analog outputs for the display of

[[Page 17063]]

primary flight information or for input to an autopilot without 
automatic output comparison since these installations do not provide 
any warning indication of the erroneous behavior.
    The proposed requirements were intended to prevent an AHRS unit's 
analog outputs of attitude and heading data freezing without detection 
or warning, which could result in misleading attitude and heading 
information, anomalous autopilot behavior, and loss of control of the 
aircraft.
    The NPRM was prompted by AD No. 2015-0093, dated May 27, 2015, 
issued by EASA, which is the Technical Agent for the Member States of 
the European Union, to correct an unsafe condition for the Northrop 
Grumman LITEF GmbH LCR-100 AHRS units. EASA advises that laboratory 
tests of the AHRS units discovered that when the built-in test detects 
failures and resets the system, the units are not executing the system 
reset properly, which results in a freeze of analog attitude and 
heading output data without detection or warning to the pilot. EASA 
states that installations vary, but if there is no automatic comparison 
of analog output to detect unit failure, this condition, if not 
corrected, could lead to undetected attitude and heading errors, 
possibly resulting in loss of control of the aircraft.
    The NPRM also advised that the proposed AD would affect AD 2010-26-
09 (75 FR 81424, December 28, 2010) (``AD 2010-26-09''), which applies 
to Sikorsky Model S-76A, B, and C helicopters with an AHRS unit P/N 
145130-7100 installed. Since the NPRM proposed to require the removal 
of P/N 145130-7100, compliance with the proposed would make AD 2010-26-
09 no longer valid for those Sikorsky helicopters.
    Since the NPRM was issued, the FAA's Aircraft Certification Service 
has changed its organizational structure. The new structure replaces 
product directorates with functional divisions. We have revised some of 
the office titles and nomenclature throughout this Final rule to 
reflect the new organizational changes. Additional information about 
the new structure can be found in the Notice published on July 25, 2017 
(82 FR 34564).

Comments

    After our NPRM was published, we received comments from one 
commenter.

Request

    The commenter suggested we made an error in the Discussion section 
where it states, ``A similar situation would occur in installations 
that use the digital outputs since the erroneous behavior would be 
detected.'' The commenter states the loss of digital data would be 
detected, and therefore the sentence should state instead that a 
similar situation would not occur.
    We disagree. The commenter is correct that an installation that 
uses digital outputs would detect the erroneous behavior and provide an 
alert. The ``similar situation'' referred to is the alert provided by 
installations that use analog outputs with automatic comparison, which 
also detect the attitude and heading data becoming frozen. Because both 
types of installations detect the erroneous behavior, they result in a 
similar situation. We did not change the AD based on this comment.

FAA's Determination

    We have reviewed the relevant information, considered the comment 
received, and determined that an unsafe condition exists and is likely 
to exist or develop on other products of these same type designs and 
that air safety and the public interest require adopting the AD 
requirements as proposed.

Differences Between This AD and the EASA AD

    This AD only applies to certain part-numbered AHRS units that use 
analog outputs for primary flight information display or autopilot 
functions without automatic output comparison. The EASA AD applies to 
all of these part-numbered units regardless of the type of 
installation. The EASA AD requires inserting a temporary revision into 
the flight manual for analog without automatic output comparison 
installations until the AHRS unit is replaced with a modified unit. 
This AD does not require temporarily revising the flight manual. The 
EASA AD requires replacing the AHRS units with particular part-numbered 
modified units, while this AD requires removing the AHRS units from 
service instead.

Related Service Information

    We reviewed Northrop Grumman LITEF GmbH Service Bulletin No. 
145130-0017-845, Revision D, dated April 1, 2015 (SB 145130-0017-845). 
SB 145130-0017-845 specifies returning the applicable part numbered 
AHRS units to certain repair stations for modification. The modified 
AHRS units, which have new part numbers, have an additional watchdog 
circuit in the electronic board that eliminates frozen analog outputs 
and digital output interruptions.

Costs of Compliance

    We estimate that this AD affects 50 aircraft of U.S. Registry. We 
estimate that operators may incur the following costs in order to 
comply with this AD. Labor costs are estimated at $85 per work-hour, 
and typical installations consist of two AHRS units. Replacing two AHRS 
units takes about 4 work-hours and $62,630 for required parts, for a 
total cost of $62,970 per aircraft and $3,148,500 for the U.S. fleet.

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.
    We are 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) Is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979);
    (3) Will not affect intrastate aviation in Alaska to the extent 
that it justifies making a regulatory distinction; and
    (4) 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.

[[Page 17064]]

    We prepared an economic evaluation of the estimated costs to comply 
with this AD and placed it in the AD docket.

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

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 (AD):

2019-07-10 Northrop Grumman LITEF GmbH LCR-100 Attitude and Heading 
Reference System: Amendment 39-19621; Docket No. FAA-2017-0522; 
Product Identifier 2015-SW-068-AD.

(a) Applicability

    This AD applies to airplanes and helicopters, certificated in 
any category, with a Northrop Grumman LITEF GmbH LCR-100 Attitude 
and Heading Reference System (AHRS) unit part number (P/N) 145130-
2000, 145130-2001, 145130-7000, 145130-7001, or 145130-7100 
installed using analog outputs for primary flight information 
display or autopilot functions without automatic output comparison. 
Aircraft known to have the subject AHRS units installed include but 
are not limited to the following:
    (1) Dornier Luftfahrt GmbH Model 228-100, 228-101, 228-200, 228-
201, 228-202, and 228-212 airplanes;
    (2) Learjet Inc. Model 31A airplanes;
    (3) Pilatus Aircraft Ltd. Model PC12, PC-12/45, and PC-12/47 
airplanes;
    (4) Polskie Zaklady Lotnicze Sp. z o.o. Model PZL M28 05 
airplanes;
    (5) Textron Aviation Inc. (type certificate previously held by 
Cessna Aircraft Company) Model 560XL airplanes;
    (6) Bell Helicopter Textron Canada Limited Model 407 
helicopters;
    (7) Bell Helicopter Textron Inc. Model 412 and 412EP 
helicopters; and
    (8) Sikorsky Aircraft Corporation Model S-76A, S-76-B, and S-76C 
helicopters.

(b) Unsafe Condition

    This AD defines the unsafe condition as the AHRS unit's analog 
outputs of attitude and heading data freezing without detection or 
warning. This condition could result in misleading attitude and 
heading information, anomalous autopilot behavior, and loss of 
control of the aircraft.

(c) Affected ADs

    This AD affects AD 2010-26-09, Amendment 39-16548 (75 FR 81424, 
December 28, 2010) (``AD 2010-26-09''). Accomplishing a certain 
requirement of this AD terminates the requirements of AD 2010-26-09.

(d) Effective Date

    This AD becomes effective May 29, 2019.

(e) Compliance

    You are responsible for performing each action required by this 
AD within the specified compliance time unless it has already been 
accomplished prior to that time.

(f) Required Actions

    (1) Within 25 hours time-in-service (TIS), remove the AHRS unit 
from service.
    (2) Removal from service of P/N 145130-7100 terminates the 
requirements of AD 2010-26-09 (75 FR 81424, December 28, 2010).
    (3) Do not install an AHRS unit P/N 145130-2000, 145130-2001, 
145130-7000, 145130-7001, or 145130-7100 on any aircraft.

(g) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Boston ACO Branch, FAA, may approve AMOCs for 
this AD. Send your proposal to: Nick Rediess, Aviation Safety 
Engineer, Boston ACO Branch, Compliance and Airworthiness Division, 
1200 District Avenue, Burlington, Massachusetts 01803; telephone 
(781) 238-7763; email [email protected].
    (2) For operations conducted under a 14 CFR part 119 operating 
certificate or under 14 CFR part 91, subpart K, we suggest that you 
notify your principal inspector, or lacking a principal inspector, 
the manager of the local flight standards district office or 
certificate holding district office, before operating any aircraft 
complying with this AD through an AMOC.

(h) Additional Information

    (1) Northrop Grumman LITEF GmbH Service Bulletin No. 145130-
0017-845, Revision D, dated April 1, 2015, which is not incorporated 
by reference, contains additional information about the subject of 
this AD. For service information identified in this AD, contact 
Northrop Grumman LITEF GmbH, Customer Service--Commercial Avionics, 
Loerracher Str. 18, 79115 Freiburg, Germany; telephone +49 (761) 
4901-142; fax +49 (761) 4901-773; email [email protected]. 
You may review a copy of the service information at the FAA, Office 
of the Regional Counsel, Southwest Region, 10101 Hillwood Pkwy., 
Room 6N-321, Fort Worth, TX 76177.
    (2) The subject of this AD is addressed in European Aviation 
Safety Agency (EASA) AD No. 2015-0093, dated May 27, 2015. You may 
view the EASA AD on the internet at http://www.regulations.gov in 
Docket No. FAA-2017-0522.

(i) Subject

    Joint Aircraft Service Component (JASC) Code: 3420, Attitude and 
Directional Data System.

    Issued in Fort Worth, Texas, on April 16, 2019.
Lance T. Gant,
Director, Compliance & Airworthiness Division, Aircraft Certification 
Service.
[FR Doc. 2019-08157 Filed 4-23-19; 8:45 am]
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