DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2019-1099; Product Identifier 2018-SW-026-AD; Amendment
39-21164; AD 2020-15-01]
Airworthiness Directives; Airbus Helicopters
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final rule.
SUMMARY: The FAA is adopting a new airworthiness directive (AD)
Airbus Helicopters Model EC 155B and EC155B1 helicopters. This AD
requires modifying the wiring of the attitude and heading reference
system (AHRS) connector. This AD was prompted by a report of wiring of
the AHRS contrary to approved design specifications. The actions of
this AD are intended to address an unsafe condition on these products.
DATES: This AD is effective August 17, 2020.
The Director of the Federal Register approved the incorporation by
reference of certain documents listed in this AD as of August 17, 2020.
ADDRESSES: For service information identified in this final rule,
contact Airbus Helicopters, 2701 N Forum Drive, Grand Prairie, TX
75052; telephone 972-641-0000 or 800-232-0323; fax 972-641-3775; or at
may view the referenced service information at the FAA, Office of the
Regional Counsel, Southwest Region, 10101 Hillwood Pkwy., Room 6N-321,
Fort Worth, TX 76177. It is also available on the internet at https://www.
regulations.gov by searching for and locating Docket No. FAA-2019-1099.
Examining the AD Docket
You may examine the AD docket on the internet at https://www.regulations.
gov by searching for and locating Docket No. FAA-2019-
1099; 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 (now European Union
Aviation Safety Agency) (EASA) AD, any service information that is
incorporated by reference, any comments received, and other
information. The street 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
FOR FURTHER INFORMATION CONTACT: George Schwab, Aviation Safety
Engineer, Safety Management Section, Rotorcraft Standards Branch, FAA,
10101 Hillwood Pkwy., Fort Worth, TX 76177; telephone 817-222-5110;
On February 28, 2020, at 85 FR 11879, the FAA published a notice of
proposed rulemaking (NPRM) in the Federal Register, which proposed to
amend 14 CFR part 39 by adding an AD that would apply to Airbus
Helicopters Model EC 155B and EC155B1 helicopters. The NPRM proposed to
require modifying the wiring at connector 11 ALPHA based on the
helicopter configuration and in accordance with specified portions of
the applicable service information. The proposed requirements were
intended to correct the AHRS wiring, and prevent the display of
misleading attitude and vertical speed information and subsequent loss
of control of the helicopter in instrument meteorological conditions
The NPRM was prompted by EASA AD No. 2018-0069, dated March 26,
2018, issued by EASA, which is the Technical Agent for the Member
States of the European Union, to correct an unsafe condition for Airbus
Helicopters Model EC 155 B and EC 155 B1 helicopters. EASA advises that
the AHRS1 and AHRS2 on Model EC 155-series helicopters use the same
flight/ground signal contrary to the approved design specification,
which requires the AHRS1 and AHRS2 to use independent signals to ensure
redundancy. EASA states that if AHRS1 and AHRS2 both receive an
incorrect ``ground'' status due to a single failure while in flight, it
will generate an error in the computation of the attitude and vertical
speed and, as a result, an incorrect display of these indications to
the flight crew. EASA advises that this condition, if not corrected,
could lead to erroneous attitude and vertical speed indications,
resulting in increased workload for the flight crew and reduced control
of the helicopter during flight in IMC.
Accordingly, the EASA AD requires modifying the connection of
connector 11 ALPHA, and based on the helicopter configuration, also
modifying the wiring to connector 11 ALPHA.
The FAA gave the public the opportunity to participate in
developing this final rule. The FAA received comments from one
commenter. The commenter commented in support of the NPRM.
The FAA has reviewed the relevant information and determined that
an unsafe condition exists and is likely to exist or develop on other
helicopters 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
The compliance time for the EASA AD is within 7 or 12 months
depending on helicopter configuration. The compliance time for this AD
is before further flight in IMC or within 660 hours time-in-service,
whichever occurs first.
Related Service Information Under 1 CFR Part 51
The FAA reviewed Airbus Helicopters Alert Service Bulletin (ASB)
No. EC155-34A033, Revision 2, dated January 30, 2018. This service
information specifies re-allocating the electronic board output
connections by modifying the wiring of connector 11 ALPHA for
helicopters with modification (MOD) 0722B51 installed and modifying the
wiring to connector 11 ALPHA for those helicopters that also have a
combined voice and flight data recording system (MOD 0731B89)
The FAA also reviewed Airbus Helicopters ASB No. EC155-34A037,
Revision 0, dated February 19, 2018. This service information specifies
installing MOD 0722B51 by modifying the wiring of connector 11 ALPHA to
separate the flight/ground information so the left-hand landing gear
flight information is also used by the automatic pilot system as well
as but separately from the right-hand landing gear flight information.
This service information also specifies re-allocating the electronic
board output connections by modifying the wiring of connector 11 ALPHA.
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.
Other Related Service Information
The FAA also reviewed Airbus Helicopters ASB No. EC155-34A033,
Revision 0, dated July 19, 2017, and Airbus Helicopters ASB No. EC155-
34A033, Revision 1, dated October 9, 2017. Revisions 0 and 1 of this
service information contain the same procedures for modifying the
wiring as Revision 2. However, Revision 1 clarifies the applicable
helicopter configurations and updates the post-modification testing
procedures, and Revision 2 clarifies the post-modification test
procedures and updates a figure.
Costs of Compliance
The FAA estimates that this AD affects 17 helicopters of U.S.
Registry. The FAA estimates that operators may incur the following
costs in order to comply with this AD. Labor costs are estimated at $85
Modifying the wiring takes about 4 work-hours and parts cost about
$20 for an estimated cost of $360 per helicopter and $6,120 for the
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 helicopters identified in this rulemaking action.
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
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
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
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