Aircraft
Certification Service Washington, DC U.S. Department of Transportation Federal Aviation Administration
2024-01
February 13, 2024
This is information only. Recommendations
aren’t mandatory.
Introduction
This Special Airworthiness Information Bulletin (SAIB) is being issued
to ensure that aircraft occupants are not exposed to smoke or fumes
emitted from a thermal runaway (TR) event that could occur with the TCW
Technologies LLC Integrated Back-up Battery System (IBBS) Models
IBBS-12v-3ah-CRT, IBBS-12v-6ah-CRT, and IBBS-24v-3ah-CRT installed on
aircraft in accordance with Supplemental Type Certificate (STC)
SA04400NY, amended prior to June 29, 2023.
At this time, the airworthiness concern is not an unsafe condition that
would warrant airworthiness directive (AD) action under Title 14 of the
Code of Federal Regulations (14 CFR) part 39.
Background
Rechargeable lithium cells are capable of generating hazardous
emissions when defective or subject to physical or operational abuse.
Although the IBBS unit is protected from abusive failure conditions and
includes a variety of fail-safe mechanisms, conditions may occur that
could cause a TR event, which could result in the venting of smoke or
fumes and/or liquid from the base plate mounting corners or from around
the product fuse location. Although the FAA has received no reports of
this occurring in the field, the FAA is issuing this SAIB for operator
awareness and to prevent smoke/fumes exposure should a TR event occur.
Recommendations
The FAA recommends that all owners and operators using one of the
aforementioned TCW Technologies LLC IBBS units in aircraft modified in
accordance with STC SA04400NY, amended prior to June 29, 2023, should
provide a sealed secondary metal IBBS enclosure with a vent port and
vent hose to ensure aircraft occupants are not exposed to smoke or
fumes emitted from a TR event. The enclosed IBBS unit must be installed
in the horizontal axis with respect to the mounting base of the IBBS
unit and the vent port must be routed to the bottom or side exterior of
the aircraft via the vent hose.
The mounting area must provide sufficient clearance around the IBBS
unit for the wiring harness and vent hose, and ensure sufficient
clearance to fuel tanks, fuel lines, oxygen lines or any other critical
systems and the mounting area is accessible to allow for future battery
servicing. Enclosure installation details are provided in the TCW
Technologies LLC IBBS Installation Instructions, Document No. 725.0047,
Revision 1.5, dated September 18, 2023, or later revision. The IBBS
Installation Instructions can be obtained from the TCW Technologies
website: tcwtech.com/documentation.
It is recommended previous IBBS unit customers contact TCW Technologies
LLC to purchase the suitable secondary metal enclosure with venting
provision. Obtaining the secondary metal enclosure will entail the
owners or operators sending their existing IBBS unit to TCW
Technologies LLC to be installed into the secondary metal enclosure
assembly, part number 980.0020. This will ensure that the secondary
metal enclosure is properly sealed and the IBBS unit meets the current
standard of the IBBS-xx-xx-CRT-V for the current IBBS unit being
shipped.
For Further Information Contact
Steven Dzierzynski, Aviation Safety Engineer, Avionics & Electrical
Systems Section, East Certification Branch, FAA, 1600 Stewart Avenue,
Westbury, NY 11590; phone: (516) 228-7367; email:
steven.dzierzynski@faa.gov.
For Related Service Information Contact
TCW Technologies LLC, 2955 Main Road East, Emmaus, PA 18049; phone:
(610) 928-3420; website: tcwtech.com/documentation; email:
support@tcwtech.com.