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Webinar 1 Q&A

Q1How can we avoid water accumulation in transformer housing/pits as it affects overall IR values and deteriorates the male female connectors?

Muhammad Asjad
The AGL pit and duct system becomes the drainage but these electrical infrastructure systems should be connected to a proper airfield drainage / outlet system. Where this is not possible, transformers and the primary joints should be kept as high as possible within the pit – hopefully above the water level. Additional protection using amalgamating tapes over the joints (including the back of the joint over the cable) should be used to protect against moisture ingress into the joint.Derek
Q2How to decrease the sludge formed in t/f pits?

Vijay Barrey
Pits and ducts should be cleaned before any cables are installed. If this refers to ongoing maintenance then pits can be cleaned using vacuum suction (the same as would be used on a road drainage system). Greasing of existing pits is also useful to prevent soil/sand particles entering through the pit lid.Derek
Q3Hi Keith. Kindly comment on ducting of cables in high water table environments.

Jonah Kinyua
Again – referring to Q1 – try to ensure that the duct system is connected at regular intervals to an airfield drainage system.Derek
Q4Hi Wendell here, What is best a resin filled primary connector or the other plug in quick one?

Wendell Villacencio
The resin connector kits are very good if made well and can be rested in position whilst setting. If making off in a workshop this can be achieved easily but on site the part formed joint may get knocked or water ingress. The quicker primary plug and socket kits have less to go wrong with them and do not need any time to set. Derek
Q5When sealing connectors remember to tape the cable entry end also.

Tony Coates
Correct – many times we see that self-amalgamating tape has been applied to the join between the plug and socket rubber components but it is equally, if not more important to apply a good few layers of the tape where the cable or transformer primary lead enters the rubber joint.Derek
Q6What is best technique of laying out Underground AGL Cables to ensure longer circuit life and easy fault tracing/trouble shooting?

Muhammad Asjad
Separation of cables and circuits if possible so that if any damage is caused to one (ie. Burn out or vermin damage) the adjacent cables are not affected. For fault finding it is good practice to take the feed and return legs of the series circuit within the same duct/pit route. This will allow the technician to split the circuit and short-circuit into loops that can be individually tested. This will reduce the time spent locating earth or open circuit faults.Derek
Q7Question for Derek. What is the main cause of poor IR values at commissioning of the airfield lighting?

Anonymous Attendee
The main causes would be a badly made joint, faulty transformer or damaged primary cable – either on installation or by vermin attack. We have had experiences of isolating transformers failing after a short term of service despite all being tested prior to installation. Cable is sometimes damaged on transit/shipment, if installed over rough ground or if not using pit wheels/covers to protect the cable when installing. We have also had experiences of primary cables having manufacturing defects that are not easily transparent on installation and only appear once the circuit is energised. Derek
Q8What is the safest way to discharge the built up voltage once the AGL circuit is isolated?Very simply with a short length of insulated electrical cable. WHEN the CCR is off and isolated. You first check the output is at zero with a suitable RMS Multimeter, you then touch one cable end to one side of the Output Terminal in the CCR and the other end to a known earth. The residual electrical charge will dissipate.Derek
Q9Hi Keith, I think we could have condition base maintenance (CBM) Instead of preventive type.

Mohammad Ghashghaei
ICAO Aerodrome Design Manual Part 4 Chapter 17 gives guidance on CBM under the name Differential Maintenance. YES … I fully support a combination of preventive maintenance & condition based maintenance. The Preventive Maintenance strategy alone could mean that we are undertaking task ( eg under a calender based frequency) whereby any specific preventive maintenance function may NOT actually need to be performed. CBM targets deteriorating equipment & systems hence is more cost effective, better use of engineering time and less effect of operations.Keith
Q10What are best maintenance practices for Thyristor based CCRs and LED Lights along with associated circuitry?

Muhammad Asjad
Planned maintenance must include CCR functionality checks – Lamps out detection, earth leakage fault, brilliancy settings, overcurrent trip settings and open circuit trip operation.
Other tasks which seem to be missed is the general cleaning within the CCR itself …. Dust etc can build up on “electronic boards” which may enable tracking across components creating defect operation. Essential to ensure that the CCR is regularly cleaned internally.
You specifically mention Thyristor CCR’s feeding LED based circuits. Remember, that when circuits migrate for Tungsten Halogen to LED the actual “electrical load “ on the CCR is dramatically reduced. Consequently, the CCR “output tappings” need adjusting accordingly. Failure to do so means that the CCR will operate inefficiently, the power factor is compromised and there will be “heat loss & noise” from the CCR. This will reduce its operational effectiveness and lower its lifex.
Q11How we differentiate among CAT III A, B and C in AGL/AFL? As far as i know AGL/AFL only describes CAT III.

Muhammad Asjad
ICAO are very clear in the operation category definitions. There is both an RVR (Runway Visual Range) and a DH (Decision height) consideration for each category.
However, for AGL we are concerned about RVR !
• CAT I : RVR @ 550 metres and above
• CAT II : RVR between 550m and 300 metres
• CAT IIIA : RVR between 300 metres and 175 metres
• CAT IIIB : RVR between 175 metres and 50 metres
• CAT IIIC : RVR below 50 metres ( in practise for a travelling aircraft at speed … this is “no can see” hence inappropriate for AGL
Q12Dear Robert, I think we should create such AMO (Aerodrome maintenance organisation). As like as Aircraft's AMO. So AGL maintenance could have special training and expert logbooks.

Mohammad Ghashghaei
All Aerodrome Authorities should have their own Aerodrome Manual or Airport Operating Manual which defines operational procedure etc etc
Airfield maintenance comes under this umbrella and should be defined accordingly.
For AGL there should be :
1. Airport Maintenance Manual
2. AGL Safe Working Procedures
3. Technical Guidance Document (TGM) for runway & taxiway lighting
For AGL personnel …. A competency & proficiency scheme + supporting registration & documentation (eg. Log book similar to ATSEP’s) is being investigated.
Q13You talked about short circuit, so that the light fixtures between the short circuits line will be gone, is there any control/monitor system (similar to CCMS Scada for MV network) to move the short circuit open point automatically??

Khaled ElOrr
Many options for identifying the exact location of an earth have been investigated, tried out etc. However, none have proved effective or reliable. The traditional way of “halving” the circuit and then progressively halving each section is still the most effective way to locate an earth fault SAFELY !
However, please note that :
• The EFD system within the CCR, when set-up correctly, provides an alarm when the “first earth” occurs. Failure to act at this time will mean multiple earths may arise meaning identification become more difficult.
• When ILCMS is included (Individual light Control & Monitoring System) is installed, the monitoring side of ILCMS may provide early indication that the full current is NOT being received at the light fixture. This can assist in earth fault location diagnosis.
Q14When we operate our LED lights at full brilliancy/ step 5/ full step associated with Thyristor based CCRs, T/F Wining of CCRs start heating up at very temperatures. What could be the possible reasons?

Muhammad Asjad
Without visiting site and observing your actual problem, it is highly likely that the field load value (because of the introduction of LED light fixtures) is dramatically LOWER that the actual size of the CCR.
ie. Un-matched load.
Check this out by re-adjusting the CCR output “tap settings” so that the capacity of the CCR more closely matches the load in the field.
It is probable that when you migrated from Tungsten Halogen to LED light fixtures, the CCR remained at its original settings. Efficiency was compromised, hence heat or noise loss !
The CCR will still continue to work for you without this adjustment BUT it will reduce its life expectancy and possibly result in other internal CCR component failures.
Q15Can you Please list down Name of top leading Manufacturer of high quality LED Airfield Lights ?

Muhammad Asjad
TMS is an Independent company, free from external influence and has a long established reputation for integrity. We work with Airports, Regulators, Designers, Consultants, Installers and AGL Manufacturers equally to ensure their visual aids are the best they can possibly be.Robert
Q16What 3rd party verification work do you do with airfield lighting companies to verify the accuracy of the field photometric testing ?

Anonymous Attendee
The performance of MALMS Photometric Equipment is safety critical with the result that it has been tested for accuracy many times over the years to ensure its fitness for purpose. TMS spends approximately 10% of turnover on research and development. Much of this is invested on an integrity program to ensure our photometric testing solutions are the best they can possibly be. This is conducted in our purpose built laboratories and in the field with regulators, test houses, lighting manufacturers and airports e.g.

• Test Houses
- Intertek
- TÜV Rheinland Lichttechnik GmbH
- British Standards Institution (BSI)
• Regulators
- Many other national civil aviation authorities
• Airfield Lighting Companies several of which use MALMS to test all
their production fittings

I hope you can see that TMS take photometric testing VERY seriously. As a result MALMS is widely recognized as the best photometric measurement system available.
Q17While ICAO states 50% output results in a failed lamp, I believe IES states 70% output is a failed lamp....which takes precedent? Sorry... for LEDs......

Bob Chernish
The calculation of the ICAO and IES (FAA) 70% are different so cannot be compared and the question of precedence does not arise. We will prepare a paper explaining the differences and publish on our Website. Furthermore the FAA calculation method is currently under review and may be brought in line with ICAO.Robert
Q18Is photo metric test mandatory for any airport size and operation type?

Oswaldo Acosta
It is mandatory for your lighting to meet the relevant serviceability requirement set out for your particular aerodrome – the only way you can determine if you meet those requirements is by measurement. This effectively means you must perform regular photometric tests in order to confirm your serviceability levels.

ICAO Design manual part IV section 17.5 specifically advises that Regulatory authorities publish guidance on this matter and even includes a photograph of the MALMS Mobile system. (Figure 17-4)

There are plenty of other references to the use of photometric test equipment in Maintenance and Monitoring of visual aids worldwide. (e.g. EASA GM2 ADR.OPS.B.015: “Photometric testing of runway lighting and approach lighting that is accessible with the equipment to be used, should be carried out in a targeted manner aimed at maintaining high levels of serviceability.”, or FAA: AC 150/5340-26 section 4.1.2 is a complete section on the use of mobile photometric equipment. )

We at TMS would recommend the use of photometric test equipment in order to assist efficient maintenance practices (by maintaining only the fixtures that require maintenance) and demonstrating compliance.

With automated record keeping of the data collected by a mobile photometric system, there are many reports that can be generated in order to show current and past performance of individual services or fixtures. In the UK, this data for example can be used to obtain “RVR Credits” for good maintenance practices. This can only be achieved by providing measured photometric data.
Q19What is the techniques for measuring photometric values of Elevated Light fixtures, like runway edge lights/elevated approach lights?

Muhammad Asjad
With the MALMS Trailer based photometric inspection system services can be measured rapidly and accurately without the use of specially adapted vehicles or equipment. The MALMS system requires only a vehicle with a towing hitch and a cigarette lighter socket for provision of power.
Lengthwise Inset services (centreline, TDZ, approach centreline inset edge etc) are generally measured by driving over the fixtures to be measured at a speed of up to 80kmh/50mph.
Elevated lengthwise services (elevated edge) are driven alongside the fixtures to be tested, with the sensors mounted on an “arm” that is held above the fixtures. Fittings up to a height of 0.75m (30 inches) can be measured in this way.
Widthways services (approach crossbars, threshold, ends) up to a maximum height of 1m from ground level are generally driven in a line parallel to the fixtures, 4.4m away, using a sensor array mounted on the side of the trailer. Note that this may be on surfaces other than asphalt/concrete and may require the use of a four wheel drive vehicle.
Q20Should airports measure less frequently with LED lights?

Anonymous Attendee
A lot of people ask us this question. The simple answer is that the frequency of measurement should not depend upon the lighting technology used.
The purpose behind measuring the lighting is to ensure serviceability levels are kept within the limits defined by the local regulations at all times. Even LED light fixtures get covered by rubber and suffer from damaged lenses, water ingress or get coated with deicing fluids. A “perfect” LED fitting in laboratory conditions may not degrade its light output over time in the same way a halogen would (for example by lamp blackening), but on the runway it will suffer the same level of punishment. The only way to ensure that each and every fixture is performing as it should is by regularly measuring them.
Factors that may affect the frequency of measurement would include local environmental conditions and traffic density. Nearly all of our customers have a different frequency of testing but somewhere between weekly and monthly is usually the frequency used. Don’t just measure your lights once a year to demonstrate compliance – they should be compliant year round and the regular use of photometric test equipment should be considered as a tool to help you with your maintenance planning and scheduling.
Q21How harmonization of PAPI can be achieved with ILS and what are the consideration we need to account during PAPI siting.

Rubul Kalita
This question will be answered during Webinar 7 (July 7th).
Q22What is an acceptable tolerance when calibrating PAPI and APAPI Lights? This question refers to both instrument and non-instrument RWYs.

Hugh Radebe
This question will be answered during Webinar 7 (July 7th).
Q23One question regarding the PAPI light, is there any regulatory requirements to have these lights on both side of the runways and if its required only on one side than on which side is preferred i.e on right or left of the runway ?

Sohail Akram
This question will be answered during Webinar 7 (July 7th).

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