DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2020-0907; Product Identifier 2017-SW-072-AD]
Airworthiness Directives; Airbus Helicopters
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed rulemaking (NPRM).
SUMMARY: The FAA proposes to adopt a new airworthiness directive
for Airbus Helicopters Model AS350B3 helicopters. This proposed AD
would require modifying the electrical system of the throttle twist
grip, inspecting the routing of a microswitch electrical harness, and
correcting the electrical harness routing if it is incorrect. This
proposed AD was prompted by reports of the engine remaining in idle
when the twist grip was turned from the "forced idle" position to the
"flight" position. The actions of this proposed AD are intended to
address an unsafe condition on these products.
DATES: The FAA must receive comments on this proposed AD by November
ADDRESSES: You may send comments by any of the following methods:
Federal eRulemaking Docket: Go to https://www.regulations.gov. Follow
online instructions for sending your comments electronically.
Mail: Send comments to the U.S. Department of
Transportation, Docket Operations, M-30, West Building Ground Floor,
Room W12-140, 1200 New Jersey Avenue SE, Washington, DC 20590-0001.
Hand Delivery: Deliver to the "Mail" address between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
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-2020-0907;
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
proposed AD, the European Aviation Safety Agency (now European Union
Aviation Safety Agency) (EASA) AD, any comments received and other infor-
mation. The street address for Docket Operations is listed above. Comments
will be available in the AD docket shortly after receipt.
For service information identified in this proposed 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.
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.
The FAA invites you to participate in this rulemaking by submitting
written comments, data, or views. The most helpful comments reference
specific portion of the proposal, explain the reason for any
recommended change, and include supporting data. To ensure the docket
does not contain duplicate comments, commenters should send only one
copy of written comments, or if comments are filed electronically,
commenters should submit only one time.
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 file in the docket all comments received, as well
as a report summarizing each substantive public contact with FAA
personnel concerning this proposed rulemaking. Before acting on this
proposal, the FAA will consider all comments received on or before the
closing date for comments. The FAA will consider comments filed after
the comment period has closed if it is possible to do so without
incurring expense or delay. The FAA may change this proposal in light
of the comments received.
Confidential Business Information
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 NPRM 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 NPRM, 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 NPRM. Submissions containing
CBI should be sent to George Schwab, Aviation Safety Engineer, Safety
Management Section, Rotorcraft Standards Branch, FAA, 10101 Hillwood
Pkwy., Fort Worth, TX 76177; telephone 817-222-5110. Any commentary
that the FAA receives which is not specifically designated as CBI will
be placed in the public docket for this rulemaking.
EASA, which is the Technical Agent for the Member States of the
European Union, has issued a series of ADs, most recently EASA AD No.
2017-0035, dated February 20, 2017 (EASA AD 2017-0035), to correct an
unsafe condition for Airbus Helicopters (formerly Eurocopter) Model AS
350 B3 helicopters with ARRIEL 2B engines installed. EASA advises of an
initial report of the microswitch pin jammed in the pushed-in position
resulting in the engine remaining in idle when the twist grip had been
turned back to the "flight" position during an autorotation training
exercise. This condition could also occur during governor failure
training when the twist grip is turned in the low flow rate direction.
EASA also advises of two later reports of this condition, with one of
those reports related to an incorrectly routed electrical harness. EASA
advises that this condition, if not detected and corrected, could lead
to reduced control of the helicopter.
EASA initially issued AD No. 2006-0094, dated April 21, 2006, which
required repetitive testing of the microswitch and established a life
limit for the microswitch. Subsequent EASA AD action required reducing
that life limit, inspecting the travel of the collective lever,
performing an additional check of the collective lever for free travel,
and installing a terminating action modification that was available for
certain helicopter configurations. That modification gave priority to
the HydroMechanical Unit (HMU) flight position when the microswitch
failed to operate correctly at forced idle. EASA most recently issued
AD 2017-0035, which prompted this AD action, to include all of the
previous AD requirements and expand the terminating action modification
to other helicopter configurations.
These helicopters have been approved by EASA and are approved for
operation in the United States. Pursuant to the FAA's bilateral
agreement with the European Union, EASA has notified the FAA of the
unsafe condition described in its AD. The FAA is proposing this AD
because the FAA evaluated all known relevant information and determined
that an unsafe condition is likely to exist or develop on other
products of the same type designs.
Related Service Information Under 1 CFR Part 51
The FAA reviewed Airbus Helicopters Alert Service Bulletin (ASB)
No. AS350-67.00.43, Revision 3, dated June 16, 2016, which specifies
procedures, based on different configurations, to modify the electrical
operation to give priority to the HMU flight position when the
microswitch does not operate correctly at forced idle (corresponds to
Airbus Helicopters Modification (MOD) 073357). This service information
also specifies instructions to inspect the routing of microswitch
electrical harness number "53K".
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 Eurocopter ASB No. 05.00.49, Revision 3,
dated March 8, 2012. This service information specifies procedures, for
helicopters without MOD 073357 installed, for repetitive testing of the
microswitch, a life limit for the microswitch, inspecting the travel of
the collective lever, and verifying correct wiring harness
Proposed AD Requirements
This proposed AD would require, based on helicopter configuration,
modifying the electrical system of the throttle twist grip. This
proposed AD would also require inspecting the routing of a microswitch
electrical harness, and depending on the routing of that electrical
harness, correcting the routing.
Differences Between This Proposed AD and the EASA AD
The EASA AD specifies a repetitive test of the microswitch, a life
limit for the microswitch, and inspecting the travel of the collective
lever, until the terminating action of modifying the electrical system
of the throttle twist grip and inspecting the routing of a microswitch
electrical harness are completed. This proposed AD would only require
modifying the electrical system of the throttle twist grip and
inspecting the routing of a microswitch electrical harness. The EASA AD
specifies performing that terminating action in a compliance time of
calendar months. This proposed AD would require performing the required
actions before the next practice autorotation, before the next
simulated governor failure, or within 330 hours time-in-service,
whichever occurs first.
Costs of Compliance
The FAA estimates that this proposed AD would affect 517
helicopters of U.S. Registry. The FAA estimates that operators may
incur the following costs in order to comply with this proposed AD.
Labor costs are estimated at $85 per work-hour.
Modifying the electrical system and inspecting the electrical
harness routing would take about 30 work-hours and parts would cost
about $9,692 for an estimated cost of $12,242 per helicopter and
$6,329,114 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.
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, I certify this proposed regulation:
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
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
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