Notice2026-16019
Denial of Motor Vehicle Defect Petition
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
August 6, 2026
Issuing agencies
Transportation DepartmentNational Highway Traffic Safety Administration
Abstract
This notice sets forth the reasons for the denial of a petition, DP26-001, submitted by Mr. Christopher Mammarella (the Petitioner) to the Administrator of NHTSA (the "Agency") by a letter dated January 9, 2026, under 49 U.S.C. 30162 and 49 CFR part 552. The Petitioner requests the Agency initiate a safety defect investigation into allegations of a mechanical failure that results in the loss of All Wheel Drive (AWD) in certain Model Year (MY) 2021 to 2023 Acura TLX and MY 2022 to 2023 Acura MDX vehicles (the "Subject Vehicles") equipped with Acura's Super Handling All Wheel Drive (SH-AWD). As a result of the failure, these vehicles permanently lose the ability to transfer drive torque to the rear wheels effectively making them front wheel drive only. NHTSA's Office of Defects Investigation (ODI) has determined that the issues raised in the Petition are not likely to result in a finding that a defect related to motor vehicle safety exists. This determination is based on a technical review by ODI of available information, which included: (1) consumer complaints submitted by the petitioner; (2) consumer complaint information in the agency's databases; and (3) other relevant information in possession of the agency. As a result, further investigation of the issue raised by the Petition is not warranted and the Agency, accordingly, has denied the Petition.
Full Text
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<title>Federal Register, Volume 91 Issue 150 (Thursday, August 6, 2026)</title>
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[Federal Register Volume 91, Number 150 (Thursday, August 6, 2026)]
[Notices]
[Pages 50916-50917]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-16019]
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DEPARTMENT OF TRANSPORTATION
National Highway Traffic Safety Administration
Denial of Motor Vehicle Defect Petition
AGENCY: National Highway Traffic Safety Administration (NHTSA),
Department of Transportation.
ACTION: Denial of a petition to open a defect investigation.
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SUMMARY: This notice sets forth the reasons for the denial of a
petition, DP26-001, submitted by Mr. Christopher Mammarella (the
Petitioner) to the Administrator of NHTSA (the ``Agency'') by a letter
dated January 9, 2026, under 49 U.S.C. 30162 and 49 CFR part 552. The
Petitioner requests the Agency initiate a safety defect investigation
into allegations of a mechanical failure that results in the loss of
All Wheel Drive (AWD) in certain Model Year (MY) 2021 to 2023 Acura TLX
and MY 2022 to 2023 Acura MDX vehicles (the ``Subject Vehicles'')
equipped with Acura's Super Handling All Wheel Drive (SH-AWD). As a
result of the failure, these vehicles permanently lose the ability to
transfer drive torque to the rear wheels effectively making them front
wheel drive only. NHTSA's Office of Defects Investigation (ODI) has
determined that the issues raised in the Petition are not likely to
result in a finding that a defect related to motor vehicle safety
exists. This determination is based on a technical review by ODI of
available information, which included: (1) consumer complaints
submitted by the petitioner; (2) consumer complaint information in the
agency's databases; and (3) other relevant information in possession of
the agency. As a result, further investigation of the issue raised by
the Petition is not warranted and the Agency, accordingly, has denied
the Petition.
FOR FURTHER INFORMATION CONTACT: Mr. Richard K. Lawrence, Vehicle
Defect Division A, Office of Defects Investigation, NHTSA 1200 New
Jersey Avenue SE, Washington, DC 20590. Telephone: 202-366-7818. Email:
<a href="/cdn-cgi/l/email-protection#394b505a51584b5d17521755584e4b5c575a5c795d564d175e564f"><span class="__cf_email__" data-cfemail="26544f454e475442084d084a475154434845436642495208414950">[email protected]</span></a>.
SUPPLEMENTARY INFORMATION:
1. Introduction
Any interested person may petition NHTSA to request that the Agency
initiate an investigation to determine whether a motor vehicle or item
of replacement equipment complies with an applicable motor vehicle
safety standard or contains a defect that relates to motor vehicle
safety. 49 U.S.C. 30162(a)(2); 49 CFR 552.3. Upon receipt of a properly
filed petition, the Agency conducts a technical review of the petition,
material submitted with the petition, and any additional information.
49 CFR 552.6. The technical review may consist solely of a review of
information already in the possession of the Agency or it may include
the collection of information from the motor vehicle manufacturer and/
or other sources. Id. After conducting the technical review and
considering appropriate factors, which may include, but are not limited
to, the nature of the complaint, allocation of agency resources, agency
priorities, the likelihood of uncovering sufficient evidence to
establish the existence of a defect, and the likelihood of success in
any necessary enforcement litigation, the agency will grant or deny the
petition. See 49 U.S.C. 30162(a)(2); 49 CFR 552.8.
2. Defect Petition Summary
In a letter dated January 9, 2026, the Petitioner requested that
NHTSA ``open a Preliminary Evaluation (PE) to investigate the
metallurgy and design of the Power Take-off Unit (PTU) to transaxle
splined connection'' of the Subject Vehicles, to ``review warranty
claim data from American Honda Motor Co. for part numbers related to
the PTU (Transfer Assembly) and the transaxle output shaft for the
2021-2023 model years,'' and to ``Direct Acura to issue a safety recall
to remedy the defect, providing owners with a revised, high-strength
component that can withstand the torque requirements of the 2.0L. 3.0L
and 3.5L engines.'' Mr. Mammarella supported his request by citing
multiple online complaints in various user forums as well as 48
consumer complaints found on NHTSA's website.
Mr. Mammarella states that a critical mechanical failure occurs at
the interface where the transaxle output shaft meets the PTU input
shaft. The metal splines on the transaxle and PTU shafts strip or shear
completely flat making torque transfer to the rear wheels impossible.
Mr. Mammarella states that there is no clear indication to the driver
that their vehicle is no longer functioning as an AWD vehicle. Mr.
Mammarella alleges that fluid inspections by technicians frequently
reveal ``orange/discolored liquid'' and metal shavings within the PTU
housing. Because the damaged shafts are not available for replacement
separately, the complete transaxle and PTU must be replaced when this
failure occurs. Mr. Mammarella states that the cost of this repair can
range from $13,000 to $19,000. NHTSA has based its decision on a review
of the material cited by the Petitioner, pertinent information in
NHTSA's databases, and other relevant information in possession of the
agency.
3. Office of Defects Investigation Analysis
Most traditional AWD systems utilize mechanical and passive
measures. These systems have the tendency to distribute torque along
the path of least resistance, such as a wheel that has lost contact
with the ground or is on a low friction surface such as ice. To
compensate for this, many manufacturers use the brake system to
redirect torque to the wheels with more traction. However, in this
style of AWD system, a failed drive shaft or similar disconnection
prior to the brakes often results in drive power being lost to the
disconnected component. The consequence of this loss is the inability
to maintain speed with surrounding traffic which increases the risks of
collisions and injuries to the vehicle occupants.
The Subject Vehicles are built upon a platform that was designed
primarily as Front Wheel Drive (FWD). The SH-AWD system functions more
as a performance enhancement feature rather than a stability feature.
Even if the SH-AWD is nonoperational, the vehicles retain full mobility
via FWD. In addition, the Vehicle Stability Assist (VSA) remains
functional, ensuring directional stability through traditional engine
and brake-based traction control. As a result, although the condition
raised by the Petitioner may degrade the vehicle's performance
characteristics, there is insufficient information to indicate a
potential unreasonable safety risk.
ODI reviewed 62 Vehicle Owner Questionnaires (VOQs) and several
TREAD (Transportation Recall Enhancement, Accountability and
Documentation) Field Reports alleging the loss of SH-AWD and its impact
on the driving dynamics of the subject vehicles. During its analysis,
ODI determined that the failure is localized to the mechanical
interface between the FWD transaxle and the PTU. Specifically, the
failure is the shearing or stripping of the interfacing splined
[[Page 50917]]
shafts between the FWD transaxle and the PTU, resulting in a permanent
loss of torque transfer to the rear of the vehicle. Upon reviewing the
technical details of SH-AWD, ODI has found that this failure does not
result in any loss of motive power or lead to a loss of vehicle
control.
Several complaints indicated that the operators were unaware of the
mechanical fault until encountering a low friction surface or the
condition was identified by a technician during routine maintenance.
The SH-AWD system lacks any form of direct feedback for monitoring real
time torque transfer to the rear wheels. Therefore, the system will
continue to display information indicating power is being supplied to
the rear wheels even when power is actually only supplied to the front
wheels.
ODI's review did not identify sufficient evidence to indicate that
the misinformation has presented a safety issue in the field. ODI did
not identify any reports of loss of motive power or vehicle control
that could be attributed to the loss of SH-AWD. ODI is not aware of any
crashes involving the Subject Vehicles that resulted from the loss of
SH-AWD.
The Agency has thoroughly assessed the material submitted by the
Petitioner, consumer complaint information in NHTSA's databases, and
other relevant information already in possession of the Agency. NHTSA
does not believe that the issues presented by the Petitioner indicate
the likelihood of a safety related defect that would warrant a formal
investigation. After full consideration of the available information,
and in view of NHTSA's enforcement priorities, the Petition is denied.
(Authority: 49 U.S.C. 30162(d) and 49 CFR part 552; delegation of
authority at 49 CFR 1.95(a).) \1\
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\1\ The authority to determine whether to approve or deny defect
petitions under 49 U.S.C. 30162(d) and 49 CFR part 552 has been
further delegated to the Associate Administrator for Enforcement.
Eileen Sullivan,
Associate Administrator for Enforcement.
[FR Doc. 2026-16019 Filed 8-5-26; 8:45 am]
BILLING CODE 4910-59-P
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</html>Indexed from Federal Register on August 6, 2026.
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