UK investigators develop methods to handle electric aircraft wreckage hazards

UK accident investigators are developing new techniques to handle the hazards electric and hybrid-electric aircraft present when wreckage is examined, according to the Air Accidents Investigation Branch.

The branch says the rapid growth of eVTOLs, electric general aviation models and unmanned air systems creates what it calls a clear and present risk. Electric motor systems rely on large high-capacity batteries, and the organisation is concerned about how those batteries may react.

It points out that problems of this kind are already appearing in other modes of transport. Conventional hydrocarbon fuels can be drained and moved into safe containers, but that is not an option for a large charged battery. Portable steel cases built to contain thermal-runaway events in personal devices are not large enough, or capable enough, to hold or restrain propulsion batteries running at 350-400V or more, the branch says. Such voltages are lethal by electrocution and can generate enough heat to melt metals and alloys.

Several techniques are under examination. They include collecting information on battery design and assembling a database of manufacturers' power systems, along with understanding how impact protection might be compromised in an accident. The branch also says it needs to understand aircraft monitoring systems and how they might show battery condition.

A battery may have been damaged or heated and now be unstable, so that if first responders or investigators later disturb it, it transitions into thermal runaway. When attending an accident, investigators will aim to visually identify such conditions.