Consultation expired with comments. The Proposed Special Condition (SC) has been updated based on the comments received, and the corresponding Comment-Response Document (CRD) has been completed by EASA.
Details
Identification of issue
In recent years, EASA has made significant efforts to address the threat associated to thermal runaways of rechargeable and non-rechargeable lithium batteries that are certified as part of the aircraft design.
Nonetheless, a significant amount of lithium batteries not included in the design configuration of the certified aircraft, are brought on board by crew members, passengers, or as part of the cargo.
Personal Electronic Devices (PEDs) powered by lithium batteries are commonly transported on the flight deck of Large Aeroplanes, e.g. electronic flight bags (EFB) or devices carried by the flight crew for personal convenience (mobile phones, tablets, laptop computers, e-cigarettes, etc.). Transportation of PEDs on Large Aeroplanes is addressed in the EASA Air Ops rules. EFBs are considered as controlled PEDs (C-PEDs). A ‘Controlled portable electronic device (C-PED)’ is a PED subject to administrative control by the operator that uses it. This includes tracking the allocation of the devices to specific aircraft or persons and ensuring that no unauthorised changes are made to the hardware, software, or databases. In addition to PEDs, also power banks or spare batteries may be transported on the flight deck by flight crew members.
Lithium batteries, including the ones that power PEDs, can go into thermal runaway. A thermal runaway may result in the release of heat, smoke, flames and in some cases in explosion. FAA report DOT/FAA/TC-16/37 shows how a lithium cell in thermal runaway may experience a rapid and uncontrolled temperature rise, with peaks that may exceed 760° C.
The increasing number of lithium batteries contained in PEDs carried by the flight crew on commercial transport aircraft results in a higher risk of in-flight lithium battery fire on the flight deck.
Typical locations for PEDs on the flight deck may be the available stowage compartments or mounting brackets. PEDs lithium batteries may be connected to a power supply unit available on the flight deck, or even to a power bank.
On certain aircraft, the flight deck storage boxes may be located in close proximity to critical systems, such as flight control and oxygen lines routed on the flight deck.
In case of a battery/cell thermal runaway, the flight deck would become potentially affected by generation of heat, smoke and flames, as well as by explosions. Additionally, a battery fire affecting critical aircraft systems (e.g. flight controls and oxygen lines) may be catastrophic.
While CS 25.1585(a)(3) already request that “Operating procedures must be furnished for –
…
(3) Emergency procedures for foreseeable but unusual situations in which immediate and precise action by the crew may be expected to substantially reduce the risk of catastrophe”, the existing specifications included in CS-25 do not explicitly address the battery fire risk described above.
EASA has acknowledged that the use of PEDs on the flight deck is a common practice and, to address the risk of PED battery fire on the flight deck, has developed the special conditions and the related means of compliance that are detailed below.
EASA is aware that future evolution of the design of PEDs may have an impact on the risk associated to their use/stowage on the flight deck. This may result in the need to reconsider and update the content of these special conditions and the associated means of compliance.
