What is sign maintenance?
Keeping every airfield guidance sign readable, evenly lit, sealed and correctly mounted, so a pilot or driver can read it at a glance, day and night.
A guidance sign is only useful if it can be read. Sign maintenance keeps the face and legend clean and undamaged, the illumination bright and even across every segment, and the enclosure sealed against water and dust. It also checks that the sign is still mounted on its frangible supports, at the right height and facing the right way, with nothing blocking the view.
Behind the sign, the same visit checks the electrical side: the connector, the isolation transformer or supply feeding the sign, and the earth bond. A sign on a series circuit is live while the circuit is on, so the circuit is isolated, locked out and proved dead before the enclosure is opened.
- Look first. Check the face, legend colours and legibility from the pilot’s and driver’s viewpoint, day and night.
- Isolate. Circuit off, locked out and proved dead before opening the sign.
- Inspect. Face, enclosure seals, LED modules or lamps, wiring and connectors.
- Check the mount. Frangible couplings, height, orientation and clear surroundings.
- Clean & repair. Clean the panel, replace failed modules or lamps, reseal and tighten.
- Test & record. Restore, confirm even illumination, then log the defect and action.
Frequently Asked Questions
Q1What is sign maintenance in airfield lighting?
The routine inspection, cleaning and repair of airfield guidance signs, covering the face and legend, illumination, enclosure seals, mounting and the electrical connections behind the sign.
Q2Why must the circuit be isolated before opening a sign?
A sign fed from a series lighting circuit carries live current while the circuit is on. The circuit is switched off, locked out and proved dead under the site permit-to-work procedure before the enclosure is opened.
Q3What are the most common sign defects?
A dirty, faded or cracked face, a failed lamp or LED module that leaves part of the legend dark, water getting past damaged seals, and signs knocked out of position or damaged mounts.
Q4Why do signs sit on frangible supports?
So that an aircraft that strikes a sign breaks it away rather than being damaged. Maintenance checks the frangible joints are intact and that nothing has been added that would stop them breaking.
Q5How is illumination checked?
By looking at the lit sign from the viewing position at night or in low light, confirming that every part of the legend is lit evenly with no dark patches, then investigating any failed lamp or LED module.
Q6How often should signs be maintained?
The interval is set by the airport’s maintenance programme, the manufacturer’s instructions and the national authority’s guidance, and may be shorter where dirt, jet blast or snow clearance affect the sign.
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