The revelation of Boeing's production problems with the cockpit devices designed to combat on-board condensation puts new focus on a Swedish system now entering airline service and designed to kill off the long-standing issue of excess water on airliners.

Condensation is a fact of life for jet operators and is due to passenger exhalation and perspiration of water vapour which condenses on the cold aluminium skin of the fuselage.

CTT Systems' Zonal Drying product is already installed or being installed on large airliners of Martinair, KLM, Austrian Airlines, LTU, Jet Aviation, and Swissair.

The eight-year-old publicly-owned company, based in Nykoping, also has a deal to try the system on a single Bombardier Canadair Regional Jet (CRJ) of a leading European operator - almost certainly Lufthansa CityLine - leading to a potential order for 63 aircraft if all options are exercised.


It signed with SAS to develop and install a more sophisticated "Moisture Management System" in a Boeing 767 with an option to equip up to 20 long-range aircraft - more 767s or whatever type SAS chooses for its new long-haul fleet, which is expected to be the Airbus A330/340 family.

That programme is in collaboration with long-established Swedish dehumidification specialist Munters.

CTT already has US FAA supplemental type certificates (STC) for the Boeing 767-200/300 and 757-200 and a Netherlands STC for the Boeing MD-11. It is working on further approvals for the MD-11, MD-80 and A330/340.

The Zonal Drying system, which weighs no more than 30kg, makes use of basic dehumidification principles and consists primarily of a rotating glassfibre honeycomb rotor impregnated with silica-gel and surrounded by flowing air.

Two separate streams of air are drawn into the unit by a fan and the humidity from one absorbed by the rotor leaving dry air to emerge on the other side. About 20% of the air in the other stream is electrically heated before passing through the rotor and then absorbs the humidity from the rotor.

The dry air then goes to parts of the aircraft subject to condensation, such as the crown, and the remainder is returned to the aircraft recirculation system or straight into the cabin.

CTT says benefits include: stopping condensation and 'rain in the plane' syndrome; drying out insulation blankets which can typically contain up to 0.5t of water that contributes to the aircraft weight; improved cabin air quality, particularly in premium class; reduced corrosion; and a reduction of safety hazards associated with water ingress into electronics.

The same technology can in principle be used, as in the SAS Moisture Management System, to control humidity carefully and increase it in premium class cabins or on executive jets to a more comfortable level, while still gaining the advantages of the basic system.

Source: Flight Daily News