[Federal Register Volume 77, Number 43 (Monday, March 5, 2012)]
[Pages 13174-13175]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2012-5213]



Federal Aviation Administration

Underwater Locating Devices (Acoustic) (Self-Powered)

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of revocation of Technical Standard Orders (TSO) C-121 
and C-121a, Underwater Locating Devices (ULD).


SUMMARY: This is a confirmation notice for the planned revocation of 
all Technical Standard Order authorizations issued for the production 
of Underwater Locating Devices (Acoustic) (Self-Powered) manufactured 
to the TSO-C121 and TSO-C121a specifications. These actions are 
necessary because the planned issuance of TSO-C121b, Underwater 
Locating Devices (Acoustic) (Self-Powered), minimum performance 
standard (MPS) will increase the minimum operating life of Underwater 
Locating Devices from 30 days to 90 days.

FOR FURTHER INFORMATION CONTACT: Mr. Gregory Borsari, AIR-130, Federal 
Aviation Administration, 470 L'Enfant Plaza, Suite 4102, Washington, DC 
20024. Telephone (202) 385-4578, fax (202) 385-4651, email to: 
[email protected].



    On August 23, 2011, the Federal Aviation Administration (FAA) 
published a Notice in the Federal Register, Volume 76, page 52734, 
announcing the planned revocation of TSO-C121 and TSO-C121a 
authorizations and requested comments. The FAA proposed revising TSO-
C121a to invoke the new SAE standard AS8045A which improves ULD 
performance, including increasing the battery operating life from 30 
days to 90 days. When TSO-C121b is published, the FAA proposed 
withdrawing TSO-C121 and TSO-C121a authorizations no later than March 
1, 2014. All Underwater Locating Devices (Acoustic) (Self-Powered) 
equipment manufacturers seeking TSO authorization would then need to 
obtain a new authorization to manufacture in accordance with TSO-C121b.


    The FAA received four comments in response to the August 23, 2011, 
Federal Register Notice. The first comment, by Boeing Commercial 
Airplanes (Boeing), stated that the effective date of the planned 
withdrawal, March 1, 2014, appeared to have been calculated to provide 
two years between the publication date of the new TSO (approximately 
March 2012) and the withdrawal of the TSO authorizations. In order to 
allow orderly compliance, however, Boeing stated that industry needs 
the FAA to ensure at least three full years will be provided. Boeing 
stated that three years is the minimal time required for affected 
industry to address technical, business, and certification aspects of a 
new underwater locating device (ULD) before the existing devices can no 
longer be manufactured. Boeing urged the FAA take into consideration 
the fact that there are multiple flight data recorder suppliers with 
varying procurement methods and contractual details that will be 
necessary to address. Additionally, Boeing noted that the new SAE 
performance standards referenced in proposed TSO-C121b include new 
testing requirements. Boeing commented that one ULD manufacturer has 
already indicated that its existing 90-day ULD will not meet the 
requirements of the new SAE specification called out in the TSO, and 
therefore, a complete re-design of the unit will be necessary. The FAA 
agrees with Boeing's comment. TSO-C121b was published on February 28, 
2012 and as such we have changed the withdrawal date to March 1, 2015. 
Boeing also stated that the effect of the planned TSO revocation would 
be to eliminate the manufacture of ULDs based on an older SAE Aerospace 
Standard that calls for a 30-day life, and requires the use of only 
ULDs based on a newer SAE standard that calls for a 90-day life. While 
Boeing recognized the current 14 CFR part 25 design regulations 
applicable to ULDs specified in 14 CFR 25.1457(g)(3) do not require a 
specific battery life, Boeing noted that the associated 14 CFR part 121 
operating rules states in Sec.  121.359(c)(2)(iii), the aircraft have 
an ``approved'' underwater locating device. By revising the TSO to 
require different performance standards of the new SAE specification, 
Boeing argued that it appears the FAA may essentially be implementing a 
new operating requirement without rulemaking to precede it. Boeing 
asked the FAA to review this process and clarify the intent.
    The FAA acknowledges this comment. The TSO process is one method to 
gain approval for an underwater locating device, but not the only 
method. The FAA notes that it is within its authority to revoke, or 
withdraw, previous TSO-C121 and

[[Page 13175]]

TSO-C121a approvals. The intent of revoking TSO-C121 and TSO-C121a and 
only authorizing TSO-C121b is to enable future ULD designs that have a 
minimum operating life of 90 days. The FAA expects attrition of TSO-
C121 and TSO-C121a approved ULDs to occur as older ULDs are replaced by 
TSO-C121b approved ULDs.
    L-3 Communications Aviation Recorders (L-3) commented that a ULD 
designed to meet the 90-day performance criteria in SAE AS8045A will 
have a lithium battery large enough that it will be considered 
hazardous material. L-3 stated that it will need to follow DOT 
Hazardous Material Class 9 regulations to ship recorders outfitted with 
the 90-day beacon. L-3 noted this places considerable constraints on 
available carriers and the destinations to which they will ship. L-3 
stated this would negatively impact their customers.
    The FAA acknowledges that shipping regulations for hazardous 
material with regard to lithium batteries will need to be complied 
    L-3 Communications indicated its concern with the FAA plan of 
attrition for the 30-day beacon and what repercussions this has for 
configuration control for thousands of recorder part numbers and the 
field reparability of their beacons. Since it may take up to 6 years to 
replace a beacon battery, L-3 estimated that there will be years of 
both 30-day and 90-day beacons in service once the new TSO-C121b is in 
effect and TSO-C121 and TSO-C121a authorizations are revoked. In the 
event of a crash, L-3 noted that there will be unnecessary time 
required to determine if a 90-day beacon was onboard to warrant an 
extended search effort.
    The FAA disagrees with this comment. Regardless whether or a not a 
planned retrofit program was invoked, both pre and post TSO-C121b 
configuration, control documentation requirements and process remain 
the same. The FAA acknowledges that today's action will introduce a 
mixed ULD equipage across the fleet. However, manufacturers currently 
produce both a 30-day and 90-day ULD that is recorded in the 
configuration control documentation. The FAA believes that no 
additional burden is imposed, to identify if a 30-day or a 90-day ULD 
is installed on an aircraft for an operator during an over-water 
accident investigation.


    Based on the comments received, the FAA will revise TSO-C121a to 
invoke the SAE Minimum Performance Standard AS8045A, dated August 2011. 
Once TSO-C121b is published, the FAA will revoke TSO-C121 and TSO-C121a 
authorizations no later than March 1, 2015.

    Issued in Washington, DC, on February 29, 2012.
Susan J. M. Cabler,
Assistant Manager, Aircraft Engineering Division, Aircraft 
Certification Service.
[FR Doc. 2012-5213 Filed 3-2-12; 8:45 am]