
[Federal Register Volume 80, Number 46 (Tuesday, March 10, 2015)]
[Notices]
[Pages 12698-12699]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2015-05501]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration


Underwater Locating Devices (Acoustic) (Self-Powered)

AGENCY: Federal Aviation Administration, FAA, DOT.

ACTION: Notice to extend the revocation date of Technical Standard 
Order (TSO) C-121 and C-121a, Underwater Locating Devices (ULD) 
(Acoustic) (Self-Powered).

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SUMMARY: This Notice extends the planned revocation date of Technical 
Standard Order (TSO) authorization for the production of Underwater 
Locating Devices (ULD) (Acoustic) (Self-Powered) manufactured to TSO-
C121 and TSO C-121a specifications. This action is necessary to 
facilitate an efficient transition to UDLs with a 90-day minimum 
battery operating life manufactured to the TSO-C121b specifications.

FOR FURTHER INFORMATION CONTACT: Mr. John Barry, AIR-130, Federal 
Aviation Administration, 470 L'Enfant Plaza, SW., Suite 4102, 
Washington, DC 20024. Telephone 202-267-1665, Fax 202-267-8589, email: 
john.barry@faa.gov.

SUPPLEMENTARY INFORMATION:

Background

    The FAA published a Notice in the Federal Resister, 76 FR 52734, 
August 23, 2011, announcing the planned revocation of TSO-C121 and TSO-
C121a. Notice of that conformation was published in the Federal 
Register, 77 FR 13174, March 5, 2012. Thus far, only two manufacturers 
currently hold TSO authorizations (TSOAs) under TSO-C121 or TSO-C121a; 
both are domestic. Both manufacturers are now authorized to produce 
longer duration TSO-C121b units as envisioned by the March 5, 2012 
Federal Register notice. One manufacturer received its TSO-C121b 
authorization in December 2014, the other in February 2015. Although 
both manufacturers received approval to manufacture devices meeting the 
current standard, the TSOA by itself does not authorize installation in 
an aircraft. Recent events have driven additional testing requirements 
for installation of lithium batteries, which these devices contain. 
Prior to the FAA's issuing the TSOAs to the two applicants, testing of 
the lithium batteries produced satisfactory results, such that the 
newly approved TSO-C121b devices will contain the effects of 
catastrophic battery failures. The ULD manufacturer's data may be used 
to support installations of the device on an aircraft, but each 
installer must analyze their design for safety impacts on their 
aircraft. A major aircraft manufacturer requested additional time to 
complete testing and analysis of the TSO-C121b device's installation. 
They also requested additional time to update their part numbers and 
drawings in their various Type Certificated (TC) aircraft once the 
analysis is complete. Granting this additional time will prevent a 
disruption in aircraft production as the necessary documentation 
changes are updated to reflect the current production of TSO-C121b 
devices.

Conclusion

    Based on the recent award of TSO-C121b authorizations, additional 
testing and analysis of lithium battery

[[Page 12699]]

installations and the lead time required to update required 
documentation, the FAA has delayed the revocation of TSO-C121 and TSO-
C121a authorizations to December 1, 2015.

    Issued in Washington, DC. on March 4, 2015.
Susan J. M. Cabler,
Assistant Manager, Design, Manufacturing and Airworthiness Division, 
Aircraft Certification Service.
[FR Doc. 2015-05501 Filed 3-9-15; 08:45 am]
 BILLING CODE 4910-13-P


