The FAA has proposed a set of special conditions that would apply to a set of certification projects involving an inflatable restraint system with non-rechargeable lithium batteries. These special conditions could have far-reaching effect that goes beyond the STC projects for which they are intended.
The special conditions would apply to the aircraft listed on the approved model list in an AmSafe STC. The proposal does not list those aircraft – and as the AmSafe STC is not available to the general public, the list is a ‘secret’ list. This could make specific application of the special condition tricky to identify. This is concerning because special conditions become part of the type certificate basis, so konwing hich aircraft are potentially affected would be important.
It is possible that anyone attempting to obtain PMA for articles on those aircraft that are affected by the AmSafe STC (or by the non-rechargeable lithium batteries special conditions) would also be expected to comply with the special conditions. Therefore anyone with an interest in battery PMAs or seat PMAs/TSOAs ought to examine this proposal to establish whether it could affect their business – now or in the future.
The FAA proposed the following special conditions for Non-Rechargeable Lithium Battery Installations, which would take the place of the current storage battery standards under the regulations:
In lieu of Sec. 25.1353(b)(1) through (4) at Amendment 25-123, each non-rechargeable lithium battery installation must:
1. Be designed to maintain safe cell temperatures and pressures under all foreseeable operating conditions to prevent fire and explosion.
2. Be designed to prevent the occurrence of self-sustaining, uncontrollable increases in temperature or pressure.
3. Not emit explosive or toxic gases, either in normal operation or as a result of its failure, that may accumulate in hazardous quantities within the airplane.
4. Meet the requirements of Sec. 25.863.
5. Not damage surrounding structure or adjacent systems, equipment, or electrical wiring from corrosive fluids or gases that may escape in such a way as to cause a major or more severe failure condition.
6. Have provisions to prevent any hazardous effect on airplane structure or systems caused by the maximum amount of heat it can generate due to any failure of it or its individual cells.
7. Have a failure sensing and warning system to alert the flightcrew if its failure affects safe operation of the airplane.
8. Have a means for the flightcrew or maintenance personnel to determine the battery charge state if the battery’s function is required for safe operation of the airplane.
Note: A battery system consists of the battery and any protective, monitoring, and alerting circuitry or hardware inside or outside of the battery. It also includes vents (where necessary) and packaging. For the purpose of these special conditions, a “battery” and “battery system” are referred to as a battery.
The discussion associated with the proposed special conditions states that the special conditions are “necessary to establish a level of safety equivalent to that established by the existing airworthiness standards.” Because of their special application to non-rechargeable lithium battery installations, it is possible that this could serve as the model for a regulation that applies to non-rechargeable lithium batteries.