DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2020-0561; Product Identifier 2019-SW-019-AD]
Airworthiness Directives; Bell Textron Inc. (Type Certificate
Previously Held by Bell Helicopter Textron Inc.) Helicopters
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed rulemaking (NPRM).
SUMMARY: The FAA proposes to adopt a new airworthiness directive
for Bell Textron Inc. (Type Certificate previously held by Bell
Helicopter Textron Inc.) (Bell), Model 204B, 205A-1, and 212
helicopters. This proposed AD was prompted by reports of corrosion on
main rotor hub tension-torsion strap (TT strap) assemblies. This
proposed AD would require reducing the life limit of a certain part-
numbered TT strap assembly and prohibit installing this TT strap
assembly on any helicopter. The FAA is proposing this AD to address the
unsafe condition on these products.
DATES: The FAA must receive comments on this proposed AD by July
ADDRESSES: You may send comments, using the procedures found in
11.43 and 11.45, by any of the following methods:
Federal eRulemaking Portal: Go to https://www.regulations.gov. Follow
instructions for submitting comments.
Mail: U.S. Department of Transportation, Docket
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New
Jersey Avenue SE, Washington, DC 20590.
Hand Delivery: Deliver to Mail address above between 9
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
For service information identified in this NPRM, 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 NPRM, any comments received, and other information. The street
address for Docket Operations is listed above. Comments will be
available in the AD docket shortly after receipt.
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 firstname.lastname@example.org.
The FAA invites you to send any written relevant data, views, or
arguments about this proposal. Send your comments to an address listed
under the ADDRESSES section. Include "Docket No. FAA-2020-0561;
Product Identifier 2019-SW-019-AD" at the beginning of your comments.
The FAA specifically invites comments on the overall regulatory,
economic, environmental, and energy aspects of this NPRM. The FAA will
consider all comments received by the closing date and may amend this
NPRM because of those comments.
The FAA will post all comments received, without change, to https://www.
regulations.gov, including any personal information you provide.
The FAA will also post a report summarizing each substantive verbal
contact the FAA receives about this NPRM.
The FAA proposes to adopt a new AD for Bell Model 204B, 205A-1, and
212 helicopters with TT strap assembly part-number (P/N) 204-012-112-
005 installed. This proposed AD 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 the urethane cover
after curing and result in premature failure of the urethane cover and
subsequent corrosion and failure of the encased wires of the TT strap
assemblies. As a result, Bell changed the curing accelerator in the
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
and is therefore included in this NPRM.
Accordingly, this proposed AD would 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. This proposed AD would also prohibit
installing the affected TT strap assembly on any helicopter.
The proposed actions 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 helicopter.
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,
The FAA is proposing this AD because the FAA evaluated all the
relevant information and determined the unsafe condition described
previously is likely to exist or develop in other products of the same
Proposed AD Requirements
Within 25 hours TIS, this proposed AD would require determining the
total hours TIS and the total months since initial installation on any
helicopter of each TT strap assembly P/N 204-012-112-005. If the TT
strap assembly has reached or exceeded the new life limit by
accumulating 1,200 or more total hours TIS or reaching 18 months since
initial installation on any helicopter, whichever occurs first, this
proposed AD would require removing the affected TT strap assembly from
service before further flight. If the new life limit has not been
reached, this proposed AD would require creating a component history
card or equivalent record indicating the new life limit and removing
the TT strap assembly from service before reaching the new life limit.
This proposed AD would also prohibit the installation of TT strap
assembly P/N 204-012-112-005 on any helicopter.
Differences Between This Proposed 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 proposed AD would require 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 proposed AD would also prohibit installing the TT
strap assembly on any helicopter after the effective date of this
Costs of Compliance
The FAA estimates that this proposed AD would affect 143
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.
Determining the total hours TIS and the total months since initial
installation of each TT strap assembly would take about .5 work-hours
for an estimated cost of $43 per helicopter.
Replacing each TT strap assembly would take about 10 work-hours and
parts would cost about $9,000, for an estimated cost of $9,850 per
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 above, I certify this proposed
(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
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