European safety regulators are proposing regulatory changes which would require operators of aircraft with Class D cargo or baggage compartments to convert them to a higher fire-resistant standard.
Close to 500 large aircraft registered in EASA member states are fitted with Class D compartments, the European Union Aviation Safety Agency estimates.
EASA had previously examined the issue in 2013 but decided that the overall cost-benefit of mandatory conversion – to either Class C or Class E – was too low to warrant a regulatory change.
But the increasing fire risk posed by thermal runaway of lithium batteries in baggage or cargo has spurred a rethink.
Class D compartments are designed to contain a fire completely without endangering the aircraft, and rely on oxygen starvation and resistance of liners to penetration.
EASA estimates that some 470 aircraft with such compartments remain in service within Europe, including over 150 Airbus A320-family jets and more than 150 Boeing 737s.
Another 100 aircraft comprise Boeing MD-80s, BAE Systems Avro RJs, Fokker 100s and 70s, and Embraer ERJ-145s, with regional turboprops accounting for the rest.
Class C and Class E compartments offer better protection through the installation of detectors or fire-extinguishing systems.
The probability of containing a fire initiated by thermal runaway of a large portable electronic device is “greater” in such compartments than in Class D aircraft, while pilots would also be alerted earlier, says EASA.
EASA has proposed a timetable which would require compliance with a mandatory conversion by the beginning of 2025.
It estimates that, by this point, some 260 aircraft from the affected fleet will have been retired leaving around 200 in service – the last of which would be retired by 2047.
EASA is seeking comments on the proposal for Class D compartment conversions by 1 June.