DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2020-0561; Product Identifier 2019-SW-019-AD; Amendment
39-21251; AD 2020-19-08]
Airworthiness Directives; Bell Textron Inc. (Type Certificate
Previously Held by Bell Helicopter Textron Inc.) Helicopters
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final rule.
SUMMARY: The FAA is adopting a new airworthiness directive (AD)
Bell Textron Inc. (Type Certificate previously held by Bell Helicopter
Textron Inc.) (Bell), Model 204B, 205A-1, and 212 helicopters. This AD
was prompted by reports of corrosion on main rotor hub tension-torsion
strap (TT strap) assemblies. This AD requires reducing the life limit
of a certain part-numbered TT strap assembly and prohibits installing
this TT strap assembly on any helicopter. The FAA is issuing this AD to
address the unsafe condition on these products.
DATES: This AD is effective October 21, 2020.
ADDRESSES: For service information identified in this final rule,
contact Bell Textron Inc., P.O. Box 482, Fort Worth, TX 76101;
telephone 817-280-3391; fax 817-280-6466; or at https://www.bellcustomer.
com. You 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.
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-
0561; 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 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: Kuethe Harmon, Safety Management
Program Manager, DSCO Branch, FAA, 10101 Hillwood Pkwy., Fort Worth, TX
76177; telephone 817-222-5198; email email@example.com.
The FAA issued a notice of proposed rulemaking (NPRM) to amend 14
CFR part 39 by adding an AD that would apply to Bell Model 204B, 205A-
1, and 212 helicopters with TT strap assembly part number (P/N) 204-
012-112-005 installed. The NPRM published in the Federal Register on
June 9, 2020 (85 FR 35227). The NPRM was prompted by three incidents of
fatigue cracking in TT strap assembly P/N 206-010-105-3 installed on
Model 206 helicopters. These TT strap assemblies have stainless steel
filament windings (wires) encased in a urethane cover, which was
manufactured using Caytur 21 (also known as Cature 21) as the urethane-
curing accelerator. Caytur 21 contains chlorides, which are retained in
urethane cover after curing and result in premature failure of the urethane
and subsequent corrosion and failure of the encased wires of the TT strap
assemblies. As a result, Bell changed the curing accelerator in the manufacturing
Due to manufacturing process similarities of the urethane cover, TT
strap assembly P/N 204-012-112-005, which is installed on Model 204B,
205A-1, and 212 helicopters, is affected by the same unsafe condition.
Accordingly, the NPRM proposed to require reducing the life limit
of the TT strap assembly from 2,400 total hours time-in-service (TIS)
to 1,200 total hours TIS or 18 months since initial installation on any
helicopter, whichever occurs first, and creating a component history
card or equivalent record. The NPRM also proposed to prohibit
installing the affected TT strap assembly on any helicopter.
The actions of this AD are intended to prevent the TT strap
assembly from remaining in service beyond its fatigue life. This
condition, if not addressed, could result in failure of a TT strap,
loss of a main rotor blade, and subsequent loss of control of the
The FAA gave the public the opportunity to participate in
developing this final rule. The FAA received one comment in support of
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 Service Information
The service information specifies replacing TT strap assemblies
with less than 1,200 hours TIS no later than January 1, 1979, and
replacing TT strap assemblies with more than 1,200 hours TIS no later
than September 1, 1978. This AD requires reducing the life limit of the
TT strap assembly to 1,200 total hours TIS or 18 months since initial
installation on any helicopter, whichever occurs first, instead. This
AD also prohibits installing the TT strap assembly on any helicopter
after the effective date of this AD.
Related Service Information
The FAA reviewed Bell Helicopter Textron Alert Service Bulletin
(ASB) No. 204-78-3 for Model 204B helicopters, ASB No. 205-78-2 for
Model 205A-1 helicopters, and ASB No. 212-78-4 for Model 212
helicopters, all dated April 19, 1978. This service information
specifies replacing TT strap assembly P/N 204-012-112-005 at 1,200
hours TIS but no later than January 1, 1979. For any TT strap assembly
P/N 204-012-112-005 that already has accumulated 1,200 hours TIS, this
service information specifies replacing it no later than September 1,
Costs of Compliance
The FAA estimates that this AD affects 143 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
Determining the total hours TIS and the total months since initial
installation of each TT strap assembly takes about .5 work-hours for an
estimated cost of $43 per helicopter.
Replacing each TT strap assembly takes about 10 work-hours and
parts cost about $9,000, for an estimated cost of $9,850 per TT strap
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