Lufthansa is working on initiatives to reduce cabin fume events on its fleet of Airbus A380s. The measures include alterations to the Rolls-Royce Trent 900 engines, procedural changes and better surveillance of cabin air quality.

The airline says it has experienced an unusual number of cabin fume events on its A380 services, particularly when outbound from Singapore. In the events, cabin crew and passengers reported unusual odors in the cabin, but the problems did not cause health problems, the airline states. Because many of the events were reported on return flights from Singapore, the airline suspects climatic conditions may play a role in the causal chain.

Cabin air is supplied through the bleed air system with air taken in from inside the engines. The industry says that the system is safe, but there also have been reports--and even lawsuits—filed by cabin crew and pilots who claim to have suffered serious health problems from toxic fumes. The only passenger aircraft that does not use the bleed air system is the Boeing 787. Other types that have been linked to more frequent fume events include the BAe-146 and the A340-600.

Lufthansa has started to install protective covers in front of the bleed air inlets inside the Trent 900s to keep fumes from being circulated throughout the cabin. TCPs or tricresyl phosphates, toxic substances added to kerosene to ensure a mostly consistent state, are suspected of being linked to the more serious fume events, although a 2011 Cranfield University study concluded that fume events in aircraft cabins do not cause danger for passengers and crew.

Nevertheless, the airline also proposes a new procedure where the bleed air system is turned off during engine startup, when often small quantities of leaked kerosene are burned off. The procedure still awaits approval by Airbus, Rolls-Royce (R-R) and the European Aviation Safety Agency.

Separately, the carrier has commissioned the development of sensors that will be installed in the cockpit. They will record concentrations of substances in the cabin air once pilots notice an unusual odor. But given the lack of scientific certainty about what quantities are dangerous, the sensors will not be equipped with a warning mechanism. Lufthansa says development is at an “advanced stage,” but cannot say when the sensors will be ready to use.

R-R says in a statement, “We can confirm that we are working with Lufthansa on a specific cabin odor issue the airline has experienced on a small number of A380 flights. A solution to this issue has been identified and is being implemented.” The engine maker also says it is “working with a number of aviation regulatory and academic organizations to help in the understanding and prevention of cabin odor events.”

Singapore Airlines, another Trent 900 operator, says it is “checking internally any bleed air issues on the A380 as reported, but at this point we are not aware of similar incidents.”