ADR.OPS.C.015 Maintenance of visual aids and electrical systems

ELECTRICAL SYSTEMS

(a)Schedules of routine maintenance of the individual elements of the aerodrome’s electrical systems should be based on manufacturers' instructions, adjusted to the aerodrome operator's experience regarding the frequency of malfunctions.

(b)The maintenance programme should, as a minimum, include the following:

(1)power cables and distributors in field;

(2)transformers and regulators;

(3)transformer stations for electric power supply;

(4)relay and switch cabinets;

(5)control cables, monitoring units and control desk;

(6)secondary power supply; and

(7)fixed ground power supply for aircraft, and should contain the frequency of the scheduled maintenance activities and the elements that should be checked during each inspection.

(c)Checklists to be used during the scheduled maintenance activities should be developed by the aerodrome operator.

(d)The relevant procedures should cover the maintenance activities for each area, including the way such activities should be implemented.

ELECTRICAL SYSTEMS The serviceability and reliability of air navigation equipment and installations are prerequisites for the safe operation of aircraft in the aerodrome area, but also for the regularity and efficiency of the air transportation system. The required serviceability of installations and equipment can only be achieved if constant power supply is ensured. To this end, regular maintenance work is required for aerodrome equipment and installations distributing primary power and equipment supplying the secondary power when there is such a need. Special attention needs to be given to cases where there is interconnection between the electrical systems of the various components of the aerodrome (e.g. terminal building with lighting systems etc.). Further guidance on the issue may be found in Chapter 3 of Part 9 ‘Airport Maintenance Practices’ of ICAO Doc 9137 ‘Airport Services Manual’.

ELECTRICAL SYSTEMS Electrical systems, and parts thereof, may also be subject to certain requirements (e.g. national) which address elements or aspects that do not fall within the scope of the requirements contained in Regulation (EU) No 139/2014. Such requirements should not be neglected when determining the maintenance programme.

LIGHTING SYSTEMS — ALLOWABLE PERCENTAGES OF SERVICEABLE LIGHTS The allowable percentages of serviceable lights are shown in Table 1 below.

Table 1: Allowable percentages of serviceable lights

LED LIGHTS — MAINTENANCE PROGRAMME — ICING AND SNOWING CONDITIONS

(a)The energy savings of light emitting diodes (LEDs) are due in large part to the fact that they do not produce the infrared heat signature of incandescent lamps. Thus, operators of aerodromes with presence of ice or snow, who have come to expect their melting by this heat signature, need to evaluate whether or not a modified maintenance schedule is required during such conditions, or evaluate the possible operational value of installing LED fixtures with heating elements. Manufacturers can provide a heater, sometimes referred to as an ‘arctic kit’, for their LED light units. Whether a heater is needed is dependent upon the site location and the weather conditions to which it is exposed. In some instances, the low-operating temperature is an advantage in that drifting snow does not melt and attach itself to the fixture lens. It is likely that LED PAPI will require some form of lens heater regardless of site location to ensure that condensation/icing does not occur.

(b)While LEDs could last for many thousands of hours under certain conditions, the life of the LED itself, and more importantly, that of the complete luminaire including the electronics, still depends on the system integration and the actual conditions in which the luminaire is used. Application conditions that could have an impact on the expected life of the luminaire include, primarily, the temperature of operation, on-off cycling patterns and humidity. Because LEDs do not have filaments that break or deteriorate, when operated under normal conditions, they tend to last for a long time. However, their light output decreases and the colour of their light shifts over time, with the rate of depreciation increasing at higher-operating temperatures. The implication for practice is that at some point in time the loss of light output or the colour shift may render the LED source outside the specifications for a given application or purpose; while the LEDs may technically still be operating, they would no longer be considered useful. Therefore, the long life of the LED in comparison to that of an incandescent lamp may not be taken as a reason for ‘install and forget’. A system of preventive maintenance is necessary as the LED light does eventually fail. In addition, there are other factors that can reduce performance, such as contamination on the lens of in-pavement fixtures.

LIGHTING SYSTEMS — SERVICEABILITY LEVELS Serviceability levels are intended to define the maintenance performance level objectives. With respect to barrettes, crossbars and runway edge lights, lights are considered adjacent if located consecutively and:

(a)laterally: in the same barrette or crossbar; or

(b)longitudinally: in the same row of edge lights or barrettes. In barrettes and crossbars, guidance is not lost by having two adjacent unserviceable lights. Further guidance on the development of preventive maintenance programme of lights is given in Chapter 2 of Part 9 ‘Airport Maintenance Practices’ of ICAO Doc 9137 ‘Airport Services Manual’.

UNSERVICEABLE LIGHTS CS ADR-DSN.U.940 ‘Aeronautical ground light characteristics’ contains the figures for determining the unserviceability of individual lights. The aerodrome operator needs, however, to consider defining, as part of its maintenance programme, two levels of intensity for individual lights, i.e. a maintenance level and the unserviceability level. The higher level gives aerodrome maintenance personnel advance warning that a light unit is beginning to produce an output significantly below the required value. This level is always above 50 per cent of the specified intensity, which is the level at which the light is classified as being outside specification tolerance and therefore to have failed from an operational perspective. Once the light output reaches the maintenance level, corrective action can be scheduled. This prevents lights from losing performance to the level where immediate maintenance action must be taken.

LIGHTING SYSTEMS

GROUND CHECKS

(a)As part of the maintenance programme, the lighting system maintenance activities should include ground checks. During the daily checks, the lighting systems should be checked at least for light failures, breakage or gross misalignment and correct operation of the intensity control system. The maintenance programme should identify the frequency of other checks that need to be performed throughout the year, as well as their content. Moreover, irrespective of the runway type, the aerodrome operator should ensure the serviceability of the lights by conducting photometric measurements, at appropriate intervals, as part of the maintenance programme.

(b)Ground checks of visual approach slope indicator systems (VASIS) should determine their alignment and serviceability. The alignment of VASIS should be checked at defined intervals, taking into account environmental conditions (e.g. rain, drought, etc.) that may affect the stability of the system, using an appropriate intensity setting. Additional checks should be conducted following an aircraft occurrence. Errors in excess of one minute of arc should be corrected. The maintenance programme should also cover the obstacle protection surface of the VASIS to ensure that it is clear of all obstacles. The serviceability of VASIS should be checked on each runway inspection. With regard to serviceability of the precision approach path indicator (PAPI) and abbreviated precision approach path indicator (APAPI), a unit should be considered to be unserviceable if more than one light is unserviceable and the unit consists of three or more lights; or at least one light is unserviceable and the unit consists of less than three lights. In addition, whenever a red filter does not produce the correct colour light beam, is missing, or is damaged, all the lights associated with that filter should be extinguished until the red filter is rectified.

(c)For a precision approach runway category II or III:

(1)The system of preventive maintenance employed should include at least the following checks:

(i)visual inspection and in-field measurement of the intensity, beam spread and orientation of lights included in the approach and runway lighting systems;

(ii)control and measurement of the electrical characteristics of each circuitry included in the approach and runway lighting systems; and

(iii)control of the correct functioning of light intensity settings used by air traffic control.

(2)In-field measurement of intensity, beam spread and orientation of lights included in approach and runway lighting systems should be undertaken by measuring all lights, as far as practicable, to ensure conformance with the appropriate figure in CS ADRDSN.U.940.

(3)Measurement of intensity, beam spread and orientation of lights included in approach and runway lighting systems should be undertaken using an appropriate measuring unit of sufficient accuracy to analyse the characteristics of the individual lights.

(4)The frequency of measurement should be based on traffic density, the local pollution level, the reliability of the installed lighting equipment and the continuous assessment of the results of the in-field measurements but, in any event, should not be less than twice a year for in-pavement lights and not less than once a year for other lights.

FLIGHT CHECKS

(d)As part of the maintenance programme of the lighting systems, flight check of the approach, runway and taxiway lighting systems, VASIS, aerodrome beacon, and the light intensity control system should be carried out at regular intervals, at least on a yearly basis, to ensure that the pattern is correct and that lights are operating properly. Special flight checks should be arranged in case of major maintenance of, or changes to, such systems, as well as before the commissioning of new systems, both at day and night.

LIGHTING SYSTEMS GROUND CHECKS — GENERAL The ground checks of the lighting system includes a set of different actions that would need to be undertaken at different intervals. These checks include but are not limited to the following:

(a)broken lights or parts of the unit;

(b)condition of filters;

(c)corrosion;

(d)cleanness;

(e)tightening of fasteners of units;

(f)alignment of lights;

(g)presence of moisture/water;

(h)electrical connections of lights; and

(i)condition of structure and the foundation of each unit. GROUND CHECKS —VASIS VASIS are used in order to provide correct visual glide slope indication to the flight crews in all variable weather conditions, by day and by night. It is therefore imperative that the maintenance programme ensures the correct alignment of the system, as well as its serviceability at all times. In order to achieve this, a suitable maintenance programme, including the correct frequency of ground checks, needs to be developed and implemented. During daily checks, the general condition of each unit is checked to determine the following:

(a)all lights are lighted and illuminated evenly;

(b)there is no evidence of apparent damages;

(c)the change from red to white is coincident for all elements in a unit; and

(d)the lenses are not contaminated. Regarding the alignment of VASIS, the individual unit setting angles are checked by means of angular measurement, in accordance with the manufacturer’s instructions. A visual comparison between all the units in the system set at the same angle may be used to identify a unit in which there is a misalignment between the optical system and the datum plate. The cause of any misalignment of this nature needs to be ascertained and corrected before any adjustment is made to the setting angles. Where the ground where the VASIS are installed is less stable, or intense weather phenomena such as frost, heavy rain or drought take place, or variations in weather occur, the aerodrome operator needs to adjust the ground checks of the VASIS, as such phenomena may lead to misalignment of the VASIS. In this way, gross alignment errors may be prevented.

FLIGHT CHECKS Flight checks for precision approach runways aremore frequent and detailed than other runway types. Lights are checked for failures and alignment, while the VASIS are also be checked for correct approach slope, and compatibility with the non-visual aids, if available. Moreover, the balance of light intensity, at all intensity settings, needs to be checked. During daylight flight checks, an assessment of the markings needs also to take place. Flight checks may be arranged to be conducted with the planned calibration flights of the no-visual aids. The opportunity is also be taken to identify any confusing or misleading lights in the aerodrome surroundings. Further guidance on how to conduct a flight check and the items that need to be checked during the flight check may be found in Chapter 5 of Part 8 ‘Airport Operational Services’ of ICAO Doc 9137 ‘Airport Services Manual’, and in Chapter 8 of Part 4 ‘Visual Aids’ of ICAO Doc 9157 ‘Aerodrome Design Manual’.

REMOVAL OF MARKINGS Whenever, for maintenance or other purposes (e.g. relocation of markings, redesign of pavements), a marking on the movement area is not needed any longer, the marking should be physically removed. In no case should a non-needed marking be painted over. The removal of the marking may be accomplished by using various techniques, but irrespectively of the technique used, it should not cause damage to the pavement or parts of the lighting systems. In order to eliminate the visual appearance of the removed marking(s) on the pavement, the physical removal of any old marking(s) should include a predetermined larger size and shape of the area occupied by the marking(s), that encompasses the old marking(s), and by grouping adjacent markings together into a larger rectangular removal area.

REMOVAL OF MARKINGS A marking may need to be removed for various reasons (marking patterns are changed, physical areas or operating procedures are modified, or the thickness of the layers of paint becomes excessive, etc.) It has been found that covering markings that need to be removed, with a darker colour (e.g. black or dark grey) in order to make them resemble the colour of the adjacent pavement (e.g. runway, apron, taxiway) is likely to mislead the flight crews, as well as drivers operating in this area because of the reflection of the sun or other sources of light upon the new surface. Moreover, the surface layer of paint will wear away or erode and the lower layers will become visible and this may cause confusion. Methods used for removing unnecessary markings include but are not limited to water blasting, sand blasting, chemical removal, burning, etc. If the sand blasting method is used, arrangements are necessary to remove the sand deposited on the pavement as the work progresses, in order to prevent accumulation. Grinding is not recommended because of the damage to the pavement surface and probable reduction of the friction characteristics. When chemicals are used for marking removal, a large and continuous source of water is usually needed to reduce potential damage to pavement surfaces and to dilute the chemicals washed into drains or channels. Prior to the use of chemicals, consideration is necessary to the applicable environmental protection requirements. If burning is used to remove a marking, care is necessary not to damage the pavement surface, as a result of the extended periods of exposure to the heat source. Examples of predetermined areas that should cover the area of the old marking(s), as well as adjacent markings, appear in Figure 1. [Figure or form omitted from this preview — available in the Avioverse workspace library.] Figure 1

MARKINGS AND SIGNS

(a)Markings A system of preventive maintenance of visual aids should be employed to ensure marking system reliability, both day and night. All markings should be inspected thoroughly at least semiannually, depending on local weather conditions, and corrective action should be taken in case of need, such as peeling, discolourment, fading, or accumulation of deposits.

(b)Signs Maintenance should ensure integrity and perfect legibility of the information provided by the signs. Checks for each sign should be both scheduled (daily, annual) and unscheduled, and should take into account the instructions of the manufacturer.

MARKINGS AND SIGNS

(a)An assessment of the condition of the signs and markings performed during the night when compared with an assessment performed during the daylight, allows determining the reflectivity of the marking. Therefore, the maintenance programme takes due account of this.

(b)Daily checks of signs need to focus on the functioning of the lamps, the legibility of inscriptions, damage to the sign panels, fading of the colours, and the removal of possible obstructions. During night inspections, the proper illumination of the signs is also checked.

(c)Annual checks of signs include:

(1)the mounting of both the sign and its lighting; and

(2)the sign’s structure.

(d)Unscheduled checks are necessary after weather phenomena that may affect the functioning of a sign, such as snowfalls to remove snow accumulation, storms that may have damaged the signs, etc.