SNV - SN EN 4618
Aerospace series - Aircraft internal air quality standards, criteria and determination methods
|Publication Date:||1 February 2010|
|ICS Code (Passenger and cabin equipment):||49.095|
This standard specifies requirements and determination methods for newly certificated commercial passenger aircraft programmes.
This standard applies to newly certificated commercial passenger aircraft programmes. It may also apply to current production aircraft if it does not carry significant penalties, i.e. if it can be shown to be technically feasible and economically justifiable.
This standard covers the period from first crew embarkation to last crew disembarkation.
NOTE 1 During embarkation and disembarkation, reduced temperatures in the cabin may be desirable due to increased metabolic activity of the occupants. In some ground cases, the aircraft environmental control system (ECS) may not be able to compensate for the external conditions influencing the cabin comfort conditions, such as open doors, extreme hot/cold ground/air temperatures or radiant heat. In this case, external air-conditioning systems, for example conditioned low-pressure ground air or high-pressure supply, may be used to supplement the aircraft ECS. If the temperature range stated in this standard is regularly exceeded (either above or below the stated range), changes to airline and/or airport procedures and/or aircraft design should be introduced.
NOTE 2 During ground operations, the external air quality may adversely influence the air quality within the aircraft cabin. Contamination produced as a result of servicing activities or ground operations vehicles may enter the aircraft directly, for example via open doors, and the ECS may not be able to effectively control contaminant levels in the cabin. Airline and airport operational procedures should be organised so as to avoid direct contamination of the cabin from these pollutant sources. If the contaminant ranges stated in this standard are regularly exceeded, changes to airline and/or airport procedures and/or aircraft design should be introduced.
Outside air quality levels would usually be regulated by national authorities.
The population under consideration - passengers and crew - excludes individuals with pre-existing infirmity or ill health conditions.
All values given in this document are sea-level equivalent (see Clause 4). According to the Air Quality Guidelines WHO 1999, paragraph 2.2.3, 'For gaseous pollutants, no increase in effects over those experienced at sea level would be expected as a result of the increase of the inhalation, as the partial pressures of the pollutant gases will fall in line with that of oxygen.' The limit concentrations at flight altitude can therefore be defined using pressure ratios.
Annex A provides the formula for calculating allowable concentrations at flight altitude.
There are many potential sources of contamination, which could affect the aircraft cabin environment. It would be impractical to set limits for all the chemical constituents of these sources.
The presence of marker compounds in concentrations that exceed the cabin air quality comfort, health or safety limits set in the standard may indicate that maintenance, procedural or operational change or design change is required to bring the air quality back within the limits set in this standard.
Several sources have been considered to identify contaminants produced during normal operation. The possible sources have been analysed to identify which chemical groupings are related to each one. At least one compound from each grouping identified for each potential source has been chosen as representative of that source.
To define the performance of the ECS, maximum contamination limits are given for the selected marker compounds. The marker compounds have been selected to be:
- Representative of contaminants produced during operation;
- Balanced across the chemical groupings of the potential contamination sources.
The selected marker compounds may occur in several of the selected potential sources. A full list of all compounds considered is given for completeness. Some of the compounds were subsequently disregarded because they were:
- Expected to appear only in very low concentrations, and/or
- Have low toxicity for given TLVs, and/or
- Below the quantification limit of measurement method.
Where this is the case is marked in Table 1. Additionally, while some compounds may be present in many of the identified potential sources, they are only relevant (under the guidelines given above) for some of the potential sources. In this case this is also marked in Table 1.
The potential sources under consideration are described below:
- Bio-effluents - compounds produced by the occupants;
- Cabin Interior - compounds that may be used during cabin servicing and cleaning;
- Solvents - compounds that may be present in the cabin due to, for example, cabin furnishing off-gassing;
- External Conditions - compounds likely to be present in the environment, specifically near the airport, either from natural or man made sources;
- Exhaust - compounds likely to be present in the engine or APU exhaust, which under certain environmental conditions may be ingested into the outside air intake;
- Oils, lubricants and hydraulic fluids - compounds present in these fluids, and/or their thermal breakdown products, that may enter the cabin under certain conditions;
- Fuel - compounds present in fuels that may enter the cabin under certain conditions.
Contaminants indicative of engine/APU lubricant or fuel leaks would enter the cabin through the bleed air system. The bleed air system may also carry ingested exhaust fumes, hydraulic fluid leaks and environmental pollution in to the cabin. On the ground, exhaust fumes and environmental pollution may also enter through open aircraft doors.
Criteria relative to environmental criteria concern:
- thermal comfort;
- pressure rate of change;
- cost of compliance.
Changes in costs related to the need to comply with a new standard may arise from the following factors:
- expenditure on R&D for the development of new technologies;
- non recurring costs for the development of new products;
- recurring costs in the production of new products;
- certification and compliance testing;
- operating costs for new products;
- the residual value of the current fleet.
However, for this proposed standard the programme of measurements in the sky carried out in the EC CabinAir project demonstrated that the values chosen for pollutants and comfort criteria can generally be met by technology currently available. As a result, the only increases in costs are likely to be associated with a limited extension of the certification process and possibly with through-life compliance testing. In both of these cases the overall impact on total costs is expected, at most, to be very much at the marginal level.