DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2020-0483; Product Identifier 2016-SW-066-AD; Amendment
39-21241; AD 2020-18-20]
Airworthiness Directives; MD Helicopters Inc. (MDHI), Helicopters
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final rule.
SUMMARY: The FAA is adopting a new airworthiness directive (AD)
certain MD Helicopters Inc. (MDHI) Model 369A, 369D, 369E, 369FF, 369H,
369HE, 369HM, 369HS, 500N, and 600N helicopters. This AD was prompted
by reports of abrasion strips departing the main rotor (MR) blade in-
flight. This AD requires tap inspecting each MR blade leading edge
abrasion strip. The FAA is issuing this AD to address the unsafe
condition on these products.
DATES: This AD is effective October 28, 2020.
The Director of the Federal Register approved the incorporation by
reference of a certain publication listed in this AD as of October 28,
ADDRESSES: For service information identified in this final rule,
contact Helicopter Technology Company, LLC, address 12902 South
Broadway, Los Angeles, CA 90061; telephone (310) 523-2750; email
firstname.lastname@example.org; or at http://www.helicoptertech.com. You
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. It is also available on the internet
at https://www.regulations.gov by searching for and locating Docket No.
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-
0483; 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 Docket Operations, 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: Payman Soltani, Aviation Safety
Engineer, Los Angeles ACO Branch, FAA, 3960 Paramount Blvd., Lakewood,
California 90712; telephone (562) 627-5313; email
The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 by adding an AD that would apply to MDHI Model 369A, 369D,
369E, 369FF, 369H, 369HE, 369HM, 369HS, 500N, and 600N helicopters with
a MR blade part number (P/N) 500P2100-105, P/N 500P2100-305, P/N
500P2300-505, P/N 369D21120-505, P/N 369D21121-505, or P/N 369D21123-
505 with a 1.25 inch chord length nickel abrasion strip (abrasion
strip) manufactured or installed by Helicopter Technology Company, LLC
(HTC), or where the manufacturer of the abrasion strip is unknown, except
abrasion strip has accumulated 700 or more hours time-in-service (TIS).
The NPRM published in the Federal Register on May 14, 2020 (85 FR
The NPRM was prompted by reports of leading edge abrasion strips
manufactured by HTC departing the MR blades during flight. An
investigation determined that the abrasion strips were manufactured
from electroformed nickel, have a chord length of 1.25 inch, and are
delaminating from the MR blade before departing from the helicopter.
HTC has determined that a repetitive tap inspection of the abrasion
strips should be performed on all blades with abrasion strips that have
less than 700 hours TIS to detect any voids, including blistering,
bubbling, or lifting of the abrasion strip. Identical looking
electroformed nickel abrasion strips with a chord length of 1.25 inch
manufactured by other repair stations have not departed in flight and
therefore were not proposed as the subject of this AD.
To address this unsafe condition, the NPRM proposed to require tap
inspecting the abrasion strip within 10 hours TIS and thereafter before
the first flight of each day until the abrasion strip has accumulated
700 or more hours TIS since installation.
The FAA gave the public the opportunity to participate in
developing this final rule. The following presents the comments
received on the NPRM and the FAA's response to each comment.
The FAA received one comment in support of the NPRM.
Request: HTC stated that the NPRM proposed to mandate its service
bulletin that was issued June 1, 2017, and that there has not been a
documented case of an abrasion strip departure related to this issue in
4 years. HTC further stated that the majority of affected operators
have either modified the abrasion strip or accumulated more than 700
hours TIS, such that the proposed AD would no longer apply. Although
HTC did not request any changes to the NPRM, the FAA infers that this
commenter would like the FAA to withdraw the proposed AD.
FAA's Response: The FAA partially agrees. The FAA has not received
any reports of an abrasion strip departure related to this issue since
issuance of the HTC service bulletin. In addition, about a third of the
abrasion strips have been modified and others have accumulated more
than 700 hours TIS, and therefore would not be affected by this AD.
However, because some affected abrasion strips are still in service or
may be stored as spare parts, the unsafe condition exists and
corrective action is necessary. The FAA has made no changes based on
Request: Wilson Construction requested that the FAA change the NPRM
to allow pilots to perform the tap test following proper training, to
avoid difficulties complying with the AD while away from base of
operations or during cross country flights. The commenter stated that
this would be consistent with AD 88-17-09 R1 (Amendment 39-6400; 54 FR
48583, November 24, 1989) (``AD 88-17-09 R1''), which allows a pilot to
perform a pre-flight check, and that the test itself is simple to
FAA's Response: The FAA disagrees. AD 88-17-09 R1 allows the pilot
to perform a check of the tail boom extension for security. This check
is an exception to the FAA's standard maintenance regulations and is
allowed in AD 88-17-09 R1 because it is a visual check that can be
performed equally well by a pilot or a mechanic and does not require
training or the use of tools. Since the tap inspection proposed in the
NPRM would require both training and the use of a tool, allowing a
pilot to perform it is not acceptable. The FAA made no changes in this
final rule based on this comment.
Request: Wilson Construction stated the inspection criteria in the
proposed AD are already specified by the manufacturer of the MR blades
(HTC) and by MDHI. The commenter stated if owners/operators would
follow the manufacturer's instructions, then an AD would not be
FAA's Response: The FAA agrees. Not all operators are required to
incorporate a manufacturer's maintenance instructions into the
operator's maintenance program. Where the FAA has determined that a
manufacturer's maintenance instructions are necessary to correct an
unsafe condition, the FAA must issue an AD to mandate those
instructions. The FAA made no changes in this final rule based on this
The FAA has reviewed the relevant information, considered the
comments 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 with minor editorial changes. These
minor changes are consistent with the proposals in the NPRM and will
not increase the economic burden on any operator nor increase the scope
of the AD.
Related Service Information Under 1 CFR Part 51
The FAA reviewed HTC Mandatory Service Bulletin Notice No. 2100-
8R4, dated June 1, 2017, which specifies a daily tap inspection of the
MR blade abrasion strip to detect voids. If there are any voids, this
service information specifies repairing or replacing the MR blade,
depending on the size, quantity, and location of any damage.
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.
Costs of Compliance
The FAA estimates that this AD affects 50 helicopters of U.S.
Registry. The FAA estimates that operators may incur the following
costs in order to comply with this AD.
At an average labor rate of $85 per hour, tap-testing the MR blades
requires about 0.25 work-hour, for a cost per helicopter of $22 per
inspection cycle. If required, replacing an MR blade requires about 1
work-hour and required parts cost up to $24,130, for a cost per
helicopter of $24,215.
According to HTC's service information, some of the costs of this
AD may be covered under warranty, thereby reducing the cost impact on
affected individuals. The FAA does not control warranty coverage by
HTC. Accordingly, the FAA has included all costs in this cost estimate.
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