DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. FAA-2021-1017; Project Identifier AD-2021-00495-A]
Airworthiness Directives; True Flight Holdings LLC Airplanes
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed rulemaking (NPRM).
SUMMARY: The FAA proposes to adopt a new airworthiness directive
for all True Flight Holdings LLC Model AA-1, AA-1A, AA-1B, AA-1C, AA-5,
AA-5A, and AA-5B airplanes. This proposed AD was prompted by the report
of an accident of an airplane with bondline corrosion and delamination
of the horizontal stabilizers. This proposed AD would require
inspecting the wings, fuselage, and stabilizers for bondline
separation, corrosion, and previous repair. This AD would also require
repairing or replacing parts and applying corrosion inhibitor as
necessary. 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 January
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
for submitting comments.
Fax: (202) 493-2251.
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 True
Flight Holdings LLC, 2300 Madison Highway, Valdosta, GA 31601; phone:
(229) 242-6337; email: email@example.com. You may view this
service information at the FAA, Airworthiness Products Section,
Operational Safety Branch, 901 Locust, Kansas City, MO 64106. For
information on the availability of this material at the FAA, call (816)
329-4148. It is also available at https://www.regulations.gov by
searching for and locating Docket No. FAA-2021-1017.
Examining the AD Docket
You may examine the AD docket at https://www.regulations.gov by
searching for and locating Docket No. FAA-2021-1017; 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.
FOR FURTHER INFORMATION CONTACT: Fred Caplan, Aviation Safety Engineer,
Atlanta ACO Branch, FAA, 1701 Columbia Avenue, College Park, GA 30337;
phone: (404) 474-5507; fax: (404) 474-5606; email:
The FAA invites you to send any written relevant data, views, or
arguments about this proposal. Send your comments to an address listed
under ADDRESSES. Include ``Docket No. FAA-2021-1017; Project Identifier
AD-2021-00495-A'' at the beginning of your comments. The most helpful
comments reference a specific portion of the proposal, explain the
reason for any recommended change, and include supporting data. The FAA
will consider all comments received by the closing date and may amend
this proposal because of those comments.
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 post all comments received, without change, to
https://www.regulations.gov, including any personal information you
provide. The agency will also post a report summarizing each
substantive verbal contact received about this NPRM.
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 Fred
Caplan, Aviation Safety Engineer, Atlanta ACO Branch, FAA, 1701
Columbia Avenue, College Park, GA 30337. Any commentary that the FAA
receives which is not specifically designated as CBI will be placed in
the public docket for this rulemaking.
The FAA received a report of an accident involving a True Flight
Holdings LLC Model AA-5 airplane that occurred on January 19, 2021.
During flight, the outboard elevator attach bracket on the horizontal
stabilizer detached, causing loss of elevator control, flutter, and
significant damage to the airplane. An investigation identified
corrosion and delamination of the airplane skin bondlines around the
area of the horizontal stabilizer where the elevator attach bracket was
attached, as well as on the trailing edge of the elevator trim tab.
Field reports have identified additional instances of corrosion and
delamination of skin bondlines around the horizontal stabilizer and
other primary structures.
Model AA-1, AA-1A, AA-1B, AA-1C, AA-5, AA-5A, and AA-5B airplanes
are similar in design and are constructed using a metal-to-metal
bonding process. While the bond adhesive remains structurally sound
throughout the aging process, factors such as corrosion and freezing
moisture may compromise the structural integrity of some of the bond
joints. This can lead to delamination of the skin from the primary
Field reports indicate that bondline inspections are not being
adequately performed during routine inspections, which emphasize a
visual scanning for problem areas. However, damage can exist with no
visual indications, and a mechanic might miss damage in a hidden area.
The FAA has determined that a more thorough inspection procedure is
necessary to reliably identify corrosion and delamination of bondlines
in these critical areas.
This condition, if not addressed, could result in reduced
structural integrity of the affected airplane component, with
consequent loss of control of the airplane. The FAA is proposing this
address the unsafe condition on these products.
The FAA is issuing this NPRM after determining that the unsafe
condition described previously is likely to exist or develop on other
products of the same type design.
Related Service Information Under 1 CFR Part 51
The FAA reviewed True Flight Aerospace Service Bulletin SB-195,
Revision A, dated June 1, 2021 (True Flight SB-195A). This service
information specifies procedures for inspecting the primary structure
and flight controls for bondline separation and corrosion and repairing
or replacing parts and applying corrosion inhibitor as necessary.
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 ADDRESSES.
Other Related Service Information
The FAA also reviewed True Flight Aerospace Service Kit 125,
Revision B. This service information specifies procedures for repairing
bondline delamination of flight controls and structures.
Proposed AD Requirements in This NPRM
This proposed AD would require accomplishing the actions specified
in True Flight SB-195A as already described, except as discussed under
``Differences Between the AD and the Service Information.''
Differences Between This Proposed AD and the Service Information
This proposed AD would only require the Part A inspections, and not
the Part B inspection, from True Flight SB-195A. In addition, True
Flight SB-195A specifies reporting information to the manufacturer, and
this proposed AD would not.
Costs of Compliance
The FAA estimates that this AD, if adopted as proposed, would
affect 2,466 airplanes of U.S. registry.
The FAA estimates the following costs to comply with this proposed
|Inspect for delamination and
||8 work-hours x $85 per hour =
$680 per inspection cycle
||$680 per inspection
||$1,676,880 per inspection
The FAA estimates that it would take
3 work-hours at $85 per work-
hour to do the proposed corrosion inhibitor treatment. Parts would cost
$104 for a total proposed cost of $359 per airplane. In addition, there
could be a wide range of areas that may require repair (fuselage,
stabilizers, and wings) for the delaminated bondlines and/or corrosion
with potential replacement of the entire component. The FAA has no way
of determining the number of airplanes that might need these repairs or
the exact costs for corrective actions needed as a result of the
proposed inspection, as the damage may vary significantly from airplane
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) Would not affect intrastate aviation in Alaska, and
(3) Would 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