Click here to read VC’s position on contaminated cabin air in German.
In order to guarantee the greatest possible safety in air traffic and to protect the health of passengers and aircraft occupants, the Cockpit association calls for the avoidance of harmful substances in cabin air. What it’s all about The cabin air in modern commercial aircraft has been supplied unchanged with bleed air (bleed air) from the engines since the 1960s. The dispensing air serves to maintain the necessary pressure cabin, ie the oxygen supply to the passengers and the aircraft crew. This bleed air is thereby tapped directly from the engines and unfiltered into the aircraft cabin. In the case of the large loads occurring on engines, it can not be guaranteed that all seals fulfill their tasks to one hundred percent. Thus it happens again and again that equipment such as high-alloy engine oils and aggressive hydraulic fluids enter the pump air and thus the air in the cabin. These incidents are referred to as Fume Events. The liquids which enter the cabin are subjected to a thermal decomposition process (pyrolysis) upon contact with the very hot surfaces of the engines. The highly toxic constituents liberated thereby are inhaled by the people on board. These operating agents contain various chemical compounds, inter alia. Also organophosphates, which are admixed due to their very good thermal stability and have been found in various measurements to the quality of the cabin air. Investigations from Germany (Institute for Prevention and Occupational Medicine (IPA), BG Transport) have demonstrated 100% of a load on some of these organophosphates in human biomonitoring with flying personnel. A comparison value for the normal population is four percent. The load on some organophosphates is even quantitatively higher in the bodies of crewmembers than in the case of aircraft mechanics, who are equipped with protective equipment and selected labor protection measures in the constant handling of these equipment. The organophosphates detected by the flight crew have a lasting effect on various enzyme systems of the human body; They lead to central toxic effects. In addition to the potentially serious health consequences for all people on board, flight safety is also at risk, as is the case with numerous incidents Air accident investigation, BfU). Another complicating factor is that the working load is very high for the pilots during particularly intensive cabin air incidents, while the inhalation of the toxic substances at the same time greatly reduces their performance.
The exposure to the pyrolysis products takes place under the special conditions of the pressurized cabin: This means that there are reduced oxygen pressures and a markedly reduced humidity, which, combined with the mixtures of substances, do not make a toxicological assessment possible. In particular, it must be taken into consideration that limit values apply only to singular substances, and that the specialist companies also stipulate that these limit values do not apply to the pressure booth heights. In addition, there are no limit values for many of the pollutants to be expected as no hazardous level can be established. The specific characteristics of the inhaled route are not included in the limit values.
For these reasons, the avoidance of pollutants in the cabin air by means of technical solutions is indispensable. Therefore the most important requirement is:
Contamination of the cabin air must be technically excluded in the case of new developments.
Since this is not possible with existing aircraft, two approaches must be pursued in parallel:
Since a risk to the health of entering contaminated air into the cabin can not be reliably prevented with the currently used pump air system, filters are urgently required! It is only through such filters, whose technology is already developed and available, that it is possible to minimize the pollutants.
Sensors are urgently needed to minimize the effects of an acute seal failure! Sensors already available are, however, not yet installed in airplanes. An implementation of the already existing (!) Installation requirement is necessary! (EASA CS 25.831, 25.832, 25.1309).
Outside air is sucked in by the engines (1), the hot compressed air is cooled (2) and mixed with filtered air (3) from the cabin. The mixture of sucked outside air and “recycled” cabin air (recirculation circuit) is distributed in the cabin (4). As outside air enters, at the same time, used air is discharged from the cabin (5).Already today, extremely accurate and reliable products for detecting oil fumes are available on the German market. In some cases, the systems have several million hours of successful measurement runs for airports, pharmaceutical industries, etc. This is an indispensable prerequisite for allowing these techniques to be as fast as possible for aviation. The test of a manufacturer at an auxiliary power plant (APU) at a German technical university was able to demonstrate air pollution by engine oils, de-icing agents and hydraulic fluids reproducibly up to the ppb (parts per billion) range. Up to now, however, no German air carrier has participated in measurements on its own engines! The human nose is so far the only “instrument” to recognize Fume events. On the other hand, certain substances are odorless (e.g., carbon monoxide / carbon dioxide) in the dry air of the cabins. In addition, some people are “odorless” due to their genetics for certain groups of substances. All these circumstances make it difficult to recognize a fume event.The regulations for the admission of a commercial aircraft are defined by the European Aviation Safety Agency (EASA). The specifications EASA CS 25.831 and 25.832 stipulate the requirements that during the flight it must also be possible to demonstrate that no “dangerous substances” may be contained in the air. In addition, the corresponding construction specification 25.1309 provides that sensors must be installed in aircraft in order to enable the crew to take all necessary measures, such as the placement of oxygen masks for safe flight. As far back as 2002, the American Federal Aviation Administration (FAA) concluded that nothing had been implemented so far: “Due to the lack of air pollution control systems, no aircraft design meets the requirements of CS 25.831; These monitoring systems are intended to ensure that the air is free from hazardous pollutants for the occupants “(source: FAA). In 2014, the German air traffic control investigation authority (BfU) will be analyzing 663 reported events. To the following significant findings: “… There were clear indications pointing to health hazards in terms of occupational medicine for aircraft crews and cabin occupations …”, “… that standardized procedures for reporting and proofing (blood tests) are not available”, “In few cases were The safety reserves were so far reduced that a […] high accident probability existed “. For example, we would like to mention the interim report of the Spanish air accident investigation authorities, which has classified the disruption of a German air carrier as an accident in an cabin accident. According to our information, a total of four members of the aircraft crew suffered short-term health impairments. Two of the four employees are still affected by the disease. In addition to its work in various organizations and committees (German Institute for Standardization (DIN), American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) and SAE), the Association has taken cockpit with manufacturers of sensors and noted that it In Germany, suitable devices are available, which can also be installed in airplanes after modification.Current developmentsCurrent developments• EASA: After the EASA has long been strikingly silent with regard to this topic, there are now considerations for further studies on the toxicity of possible introduction of resources into the dispensing air. An urgently necessary step in the right direction from the point of view of the VC.• CEN (European Institute for Standardization): Through its membership in DIN (German Institute for Standardization), the VC was sent to CEN as part of a national expert group to assist in the improvement of health and environmental protection against chemicals.• ECA (European Cockpit Association): The ECA actively supports the ongoing European activities. In addition, ECA members are working on an ICAO initiative on the subject of CAQ after the international civil aviation organization has also identified the crews with information and information.• Berufsgenossenschaftsverkehr (BG Transport): The BG initiated the first attempt of a coordinated investigation of crews on the basis of a concerted procedure. In addition, the formation of so-called competence centers at German university clinics was agreed, where experience from the fields of toxicology and occupational medicine should be bundled.• In order to achieve a standardization of the reporting system – which means that the number of accident notifications or the reportable events is to be made reliable – the VC and the airlines are also working on a standardized reporting form, which is intended to facilitate the processing of the incidents.Demands of the association Cockpit We demand that, in the case of future aircraft designs, contamination of the cabin air is technically excluded, especially since a perfectly suitable alternative technology is available. In this case, the cabin air is taken from the normal ambient air of the aircraft without first passing it through the engines. The so-called air is called “RAM-Air”. This method is already used in the Boeing 787 aircraft type.
Because this requirement can not be implemented for the existing aircraft samples, we require the installation of filters in order to keep the cabin air as free of pollutants as possible. In order to prevent fatal effects during acute strong fume events, it is indispensable to incorporate sensors into today’s aircraft patterns, which enable the cockpit crew to react as quickly as possible. In addition to the self-protection (for example, the placement of the oxygen mask), a fast and effective fault analysis is also necessary in order to guarantee safe flight and thus to protect the health of all aircraft occupants. As long as no technical applications are used, which guarantee a clean cabin air and no sensors are installed to determine the quality of the cabin air, the minimization requirement applies.