[Federal Register Volume 87, Number 72 (Thursday, April 14, 2022)]
[Proposed Rules]
[Pages 22144-22146]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-07871]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2021-1017; Product Identifier AD-2021-00495-A]
RIN 2120-AA64


Airworthiness Directives; True Flight Holdings LLC Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Proposed rule; withdrawal.

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SUMMARY: The FAA is withdrawing a notice of proposed rulemaking (NPRM) 
that proposed to adopt a new airworthiness directive (AD) for all True 
Flight Holdings LLC Model AA-1, AA-1A, AA-1B, AA-1C, AA-5, AA-5A, and 
AA-5B airplanes. The NPRM was prompted by the report of an accident of 
an airplane with bondline corrosion and delamination of the horizontal 
stabilizers. The NPRM proposed to require inspecting the wings, 
fuselage,

[[Page 22145]]

and stabilizers for bondline separation, corrosion, and previous 
repair. The NPRM also proposed to require repairing or replacing parts 
and applying corrosion inhibitor as necessary. Since issuance of the 
NPRM, the FAA has determined that there is not an unsafe condition, but 
instead incorrectly followed maintenance procedures. Accordingly, the 
NPRM is withdrawn.

DATES: As of April 14, 2022, the proposed rule, which published in the 
Federal Register on December 1, 2021 (86 FR 68171), is withdrawn.

ADDRESSES: 

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 AD action, any 
comments received, and other information. The street 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: Fred Caplan, Aviation Safety Engineer, 
Atlanta ACO Branch, FAA, 1701 Columbia Avenue, College Park, GA 30337; 
phone: (404) 474-5507; email: [email protected].

SUPPLEMENTARY INFORMATION:

Background

    The FAA issued AD 2021-14-12, Amendment 39-21639 (86 FR 36491, July 
12, 2021) (AD 2021-14-12), for True Flight Holdings LLC Model AA-1, AA-
1A, AA-1B, AA-1C, and AA-5 airplanes. AD 2021-14-12 was prompted by an 
accident involving a 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 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. Multiple field reports identified additional instances of 
corrosion and delamination of skin bondlines around the horizontal 
stabilizer and other primary structures.
    AD 2021-14-12 stated that Model AA-1, AA-1A, AA-1B, AA-1C, and AA-5 
airplanes have horizontal stabilizers that are similar in design and 
use the same 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 structure. The FAA determined that a more 
thorough inspection was necessary to reliably identify corrosion and 
delamination of bondlines in these critical areas, including the 
horizontal stabilizer. As a result, AD 2021-14-12 requires a one-time 
inspection of the horizontal stabilizers, paying particular attention 
to the bondlines, for cracks, buckles, corrosion, delamination, rust, 
or previous repair.
    The FAA issued an NPRM that proposed to amend 14 CFR part 39 by 
adding an AD for all True Flight Holdings LLC Model AA-1, AA-1A, AA-1B, 
AA-1C, AA-5, AA-5A, and AA-5B airplanes. The NPRM published in the 
Federal Register on December 1, 2021 (86 FR 68171). In the NPRM, the 
FAA proposed to require a repetitive inspection of the wings, 
stabilizers, and aft fuselage for bondline separation, corrosion, and 
previous repair. While AD 2021-14-12 requires only inspecting the 
bondlines on the horizontal stabilizers, in the NPRM, the FAA proposed 
to require inspecting all of the bondlines on the airplane, including 
the bondlines on the wings and aft fuselage. In the NPRM, the FAA also 
proposed to add Model AA-5A and AA-5B airplanes to the applicability 
due to the similar bonded construction of all models.
    The original decision to pursue corrective action was based upon 
multiple field reports, including direct observation of two airplanes, 
of issues related to inspection of bonded structure. The first was the 
originating accident airplane, and the second was another same model 
airplane located in the same hangar as the first airplane. Both of 
these airplanes exhibited damage (bondline delamination) in an area 
believed to be the source of the accident, at the attachment of the 
elevator bearing to the horizontal stabilizer. The construction in this 
area is similar among the applicable models in AD 2021-14-12. The issue 
specific to this area was addressed in AD 2021-14-12.
    The FAA proposed the NPRM to address inspection for bondline 
delamination on the entire airplane based on an understanding that 
standard maintenance actions were insufficient to detect an issue. 
Because more models than those covered by AD 2021-14-12 share a similar 
bonded construction for the airplane as a whole, the NPRM proposed to 
also apply to True Flight Holdings LLC Model AA-5A and AA-5B airplanes.

Comments

    The FAA received comments from 41 commenters. The commenters were 
the Aircraft Owners and Pilots Association (AOPA), the Grumman Owners & 
Pilots Association (GOPA), Fortnight Aviation Maintenance, and many 
individual airplane owners and pilots.
    All commenters opposed the NPRM. Most commenters stated that the 
actions proposed in the NPRM are already addressed by existing 
maintenance practices or included in maintenance documents such as the 
Grumman maintenance manual, the annual inspection checklist, service 
bulletins, and AD 2021-14-12. The commenters noted that the January 
2021 accident resulted from poor maintenance practices and failure to 
adequately follow these existing procedures, not from any fault with 
the procedures themselves. For this reason, some commenters requested 
the FAA withdraw the NPRM due to lack of supporting data and issue a 
special airworthiness information bulletin (SAIB) instead.
    Several commenters requested that the FAA remove Model AA-5, AA-5A, 
and AA-5B airplanes from the applicability because these models have a 
different design than the accident airplane. Many commenters noted that 
the proposed AD is overly broad because the delamination issue is 
limited to pre-1977 models manufactured with a ``purple glue'' for 
adhesive. AOPA, GOPA, and a few individuals stated the proposed 
requirement to tap test all bondlines on the airplane annually would 
damage the paint and lead to corrosion. Lastly, AOPA, GOPA, and two 
individuals requested the FAA increase its estimated labor rate of $85 
per hour.
    The FAA agrees that the instructions in the airplane maintenance 
manual are sufficient to detect the type of damage that is believed to 
have led to the originating accident, as well as similar damage on the 
rest of the airplane. The FAA further agrees that the original findings 
were not indicative of an unsafe condition, but instead indicative of 
incorrectly followed maintenance procedures. Based on this assessment, 
the proposed inspection in the NPRM would exceed what is sufficient to 
detect the main issue of bondline delamination. The FAA has determined 
that additional AD action is not warranted and the proposal should be 
withdrawn.

[[Page 22146]]

    The FAA acknowledges the comments unrelated to whether there is an 
unsafe condition. However, because the FAA is withdrawing the NPRM, 
those commenters' requests are no longer necessary.
    Withdrawal of the NPRM constitutes only such action and does not 
preclude the FAA from further rulemaking on this issue, nor does it 
commit the FAA to any course of action in the future.

Regulatory Findings

    Since this action only withdraws an NPRM, it is neither a proposed 
AD nor a final rule. This action, therefore, is not covered under 
Executive Order 12866 or the Regulatory Flexibility Act.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Withdrawal

    Accordingly, the notice of proposed rulemaking, Docket No. FAA-
2021-1017; Project Identifier AD-2021-00495-A, published in the Federal 
Register on December 1, 2021 (86 FR 68171), is withdrawn.

    Issued on April 7, 2022.
Lance T. Gant,
Director, Compliance & Airworthiness Division, Aircraft Certification 
Service.
[FR Doc. 2022-07871 Filed 4-13-22; 8:45 am]
BILLING CODE 4910-13-P


