DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2015-4497; Project Identifier 2016-SW-011-AD; Amendment
39-21450; AD 2021-05-07]
Airworthiness Directives; Airbus Helicopters Deutschland GmbH
(Type Certificate Previously Held by Eurocopter Deutschland GmbH)
AGENCY: Federal Aviation Administration (FAA), Department of
ACTION: Final rule.
SUMMARY: The FAA is adopting a new airworthiness directive (AD)
Airbus Helicopters Deutschland GmbH (Airbus Helicopters) Model BO-105A,
BO-105C, BO-105S, MBB-BK 117 A-1, MBB-BK 117 A-3, MBB-BK 117 A-4, MBB-
BK 117 B-1, MBB-BK 117 B-2, and MBB-BK 117 C-1 helicopters. This AD was
prompted by a report of a loss of electrical ground between the
starter-generator and the generator voltage regulator (regulator). This
AD requires inspecting the starter-generator electrical ground
connection, retrofitting the starter-generator wire harness, and
depending on model, revising the existing Rotorcraft Flight Manual
(RFM) for your helicopter. The FAA is issuing this AD to address the
unsafe condition on these products.
DATES: This AD is effective April 16, 2021.
The Director of the Federal Register approved the incorporation by
reference of certain publications listed in this AD as of April 16,
ADDRESSES: For Eurocopter service information identified in this
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 this service information at the FAA, Office of the Regional
Counsel, Southwest Region, 10101 Hillwood Pkwy., Room 6N-321, Fort
Worth, TX 76177. For information on the availability of this material
at the FAA, call 817-222-5110.
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-2015-
4497; 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
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 20590.
FOR FURTHER INFORMATION CONTACT: Ronnea L. Derby, Aerospace Engineer,
Denver ACO Branch, FAA, 26805 East 68th Ave., Room 214, Denver, CO
80249; telephone 303-342-1093; email ronnea.l.derby.@faa.gov.
The European Aviation Safety Agency (now European Union Aviation
Safety Agency) (EASA), which is the Technical Agent for the Member
States of the European Union, has issued EASA AD 2015-0098, dated June
2, 2015 (EASA AD 2015-0098), and EASA AD 2015-0220, dated November 9,
2015 (EASA AD 2015-0220) (also referred to as the Mandatory Continuing
Airworthiness Information, or the MCAI), to correct an unsafe condition
for all Airbus Helicopters Model MBB-BK117 A-1, MBB-BK117 A-3, MBB-
BK117 A-4, MBB-BK117 B-1, MBB-BK117 B-2, and MBB-BK117 C-1 helicopters;
and Airbus Helicopters Model BO105 A, BO105 C, BO105 D and BO105 S
helicopters with certain part-numbered voltage regulators.
The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 by adding an AD that would apply to certain Airbus
Helicopters Model BO-105A, BO-105C, and BO-105S helicopters; and all
Airbus Helicopters Model MBB-BK 117 A-1, MBB-BK 117 A-3, MBB-BK 117 A-
4, MBB-BK 117 B-1, MBB-BK 117 B-2, and MBB-BK 117 C-1 helicopters. The
NPRM published in the Federal Register on July 16, 2020 (85 FR 43153).
The NPRM was prompted by a report of a loss of electrical ground
between the starter-generator and the regulator. The NPRM proposed to
require inspecting the starter-generator electrical ground connection,
retrofitting the starter-generator wire harness, and depending on
model, revising the existing RFM for your helicopter.
The FAA is issuing this AD to address the loss of electrical ground
between the starter-generator and the regulator. This condition could
result in an overvoltage of electrical power, damage to electronic
equipment, and subsequent loss of control of the helicopter.
The FAA gave the public the opportunity to participate in
developing this final rule. The FAA received no comments on the NPRM or
on the determination of the cost to the public.
The FAA reviewed the relevant data and determined that air safety
and the public interest require adopting this final rule as proposed,
except for minor editorial changes. The FAA has determined that these
Are consistent with the intent that was proposed in the
NPRM for addressing the unsafe condition; and
Do not add any additional burden upon the public than was
already proposed in the NPRM.
Related Service Information Under 1 CFR Part 51
Eurocopter (now Airbus Helicopters) issued Alert Service Bulletin
ASB-MBB-BK117-90-118, Revision 2, dated May 4, 2009, for certain Model
MBB-BK117 helicopters and Alert Service Bulletin ASB BO105-90-103,
Revision 4, dated June 21, 2010, for certain Model BO105 helicopters.
This service information specifies a visual inspection for damage,
corrosion, and cracks and measuring the resistance of the left-hand and
right-hand electrical ground connections between each starter-generator
and the regulator. If there is damage or suspected damage, or if the
resistance is out of tolerance, this service information specifies
replacing the wire terminal. This service information also specifies
performing the visual inspection and resistance measurement each time
the starter generator is removed or the wiring is disconnected until a
retrofit ground connection is installed. These documents are distinct
since they apply to different models.
Eurocopter also issued Eurocopter Flight Manual BK117 A-3 Temporary
Revision 9, Eurocopter Flight Manual BK117 A-4 Temporary Revision 5,
Eurocopter Flight Manual BK117 B-1 Temporary Revision 6, Eurocopter
Flight Manual BK 117 B-2 Temporary Revision 1, and Eurocopter Flight
Manual BK 117 C-1 Temporary Revision 2, all dated September 22, 2006,
to provide updated procedures in the event of a generator failure.
These documents are distinct since they apply to different models.
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
Eurocopter (now Airbus Helicopters) issued Service Bulletin SB
BO105-90-104, Revision 1, dated June 21, 2010, for certain Model BO105
helicopters. This service information specifies procedures for
installing a retrofit ground connection of the starter-generator.
Eurocopter issued Alert Service Bulletin ASB-BO 105-80-118,
Revision 1, dated November 29, 1995, and Service Bulletin SB-BO105-80-
119, dated November 7, 1994, both for certain Model BO105 helicopters.
This service information specifies retrofitting certain helicopters
with voltage regulators that incorporate overvoltage protection by
modifying the main relay box, modifying the overhead panel, and
performing a functional test.
Eurocopter issued Information Notice 2370-I-24, Revision 0, dated
November 15, 2011, for certain Model BO105 helicopters to provide
notice that a modified starter-generator may only be installed on
helicopters that have also been modified. This service information
states that combining modified with non-modified can cause overvoltage
in the electrical system during the first ground run following engine
replacement and subsequent damage to electronic equipment. This service
information also recommends retrofitting all helicopters approved to
only fly under visual flight rules.
Differences Between This AD and the EASA ADs
The EASA ADs require visually inspecting the wire terminals for
damage, corrosion, and cracks. This AD requires visually inspecting for
a crack, a kink, fraying, looseness, missing material, and corrosion.
The EASA ADs require repeating the visual inspection and resistance
measurement each time a starter-generator is removed or the wiring is
disconnected from a starter-generator. This AD does not because such a
compliance time would be difficult to enforce.
EASA AD 2015-0220 requires additional actions for Model BO-105
helicopters with a serial number up to 0160 than for helicopters with
serial number 0161 and larger. This AD requires the same actions for
all Model BO-105 helicopters regardless of serial number.
EASA AD 2015-0220 allows credit for complying with Eurocopter Alert
Service Bulletin ASB BO105-90-103, Revision 2 or Revision 3, whereas
this AD does not.
Costs of Compliance
The FAA estimates that this AD affects 40 Model BO-105 helicopters
and 44 Model MBB-BK 117 helicopters of U.S. Registry. The FAA estimates
that operators may incur the following costs in order to comply with
this AD using an estimated labor cost of $85 per work-hour.
Performing a visual inspection and resistance measurement of the
electrical ground connection takes about 2 work-hours for an estimated
cost of $170 per helicopter and $14,280 for the U.S. fleet per
inspection and measurement.
Performing the retrofit of the wiring harness takes about 10 work-
hours. Required parts for a Model BO-105 helicopter cost $2,509 for an
estimated replacement cost of $3,359 per helicopter and $134,360 for
the U.S. fleet. Required parts for a Model MBB-BK 117 helicopter cost
$1,730 for an estimated replacement cost of $2,580 per helicopter and
$113,520 for the U.S. fleet. Revising the existing RFM for Model MBB-BK
117 helicopters takes about 0.5 work-hour, for an estimated cost of $43
per helicopter and $1,892 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.
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.
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
(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