This article describes the fire-related risks that are related to the toilet compartments of an aircraft and gives an idea about the legal requirements that are imposed in order to mitigate those risks.
The toilet compartments have some specifics that set them aside from other parts of the aircraft and therefore require special attention when fire detection and suppression is involved:
Toilet compartments do not offer a clear view to the flight crew. Therefore, in case a fire starts, it might remain undetected for a considerably long period of time, thus allowing it to spread.
Toilet compartments contain highly combustible materials (e.g. paper) which are susceptible to ignition by objects discarded by passengers.
Toilet compartments offer the passengers privacy, which may result in the use of tobacco products even on a non-smoking flight.
Provisions regarding the requirements for toilet compartment fire detection and suppression equipment are contained in the relevant documents (e.g. for the EU such a document is “Certification Specifications and AMC for Large Aeroplanes CS-25” by EASA). Although there may be slight differences from country to country, the main points usually are:
Lavatory fire protection requiremets apply to aeroplanes with a passenger capacity of 20 or more.
Installation of smoke detectors that provide warning signals in the cockpit and in the passenger cabin. It is worth noting that these detectors are not considered critical for the flight safety and therefore the flight continues normally in case of detector malfunction.
Installation of automatic fire extinguishers in the lavatory trash receptacles.
Placing “no smoking” signs on both sides of lavatory doors.
Informing the passengers during the in-flight briefing that smoking is prohibited in the lavatories.
Placing ashtrays at conspicuous locations both inside and outside the lavatories regardless of whether smoking is allowed in any other part of the aeroplane.
The use of Halon in lavatory fire extinguishers is restricted. For the EU, the cut-off date is 31st December 2011 and the end date is 31st December 2020. Research and testing have shown that there are suitable alternatives meeting the standards for effectiveness, volume, weight and toxicology.