Installation & Commissioning Faults

Equipment / System

In-pavement or elevated AGL fixture and its mounting interface to the base can, stake, or frangible coupling, as installed.

Possible Causes

Required Tools

Safety Precautions

• Coordinate airside access through ATC/apron control before approaching the fixture.
• LOTO the circuit before disturbing the mounting or fixture.

Diagnostic Procedure

1. ObservationCompare the as-installed mounting method against the installation drawing for that fixture type and location.
2. MeasurementWith the circuit isolated, remove the fixture and inspect the mounting interface, coupling, and any packing/shims used.
3. MeasurementConfirm the frangibility rating of the coupling or stake matches the specification for that area.
4. DecisionMounting method matches the drawing after inspection → close out as correct. Mounting deviates from the drawing → correct to the specified method before commissioning proceeds.
5. Fault LocationIsolate whether the deviation is at the fixture-to-coupling interface or the coupling-to-base-can interface.
6. Root CauseConfirm the corrected mounting is stable, correctly torqued, and matches the drawing before final sign-off.

Test Points

Root Cause Verification

Re-inspect the corrected mounting, confirm fixture height/angle against the drawing, and verify frangible coupling function before final commissioning sign-off.

Corrective Action

• Remove and remount the fixture using the correct coupling, bracket, or hardware specified in the installation drawing.
• Replace any incorrectly rated frangible coupling or stake.
• Remove unauthorised packing/shims and re-set to the specified height/angle.

Preventive Action

• Verify mounting method against the installation drawing during the commissioning walk-down, not only at final flight check.
• Provide contractors with fixture-specific mounting kits pre-matched to each location to prevent substitution.
• Include a frangibility rating check in the commissioning checklist for all elevated fixtures.

Related References

SOP: SOP-INST-01 (Fixture Mounting Verification Procedure)

Standards: FAA AC 150/5340-30, ICAO Annex 14 Vol I (frangibility requirements)

Diagram: Fixture Mounting Detail Drawing

Case Study: Division 25 — Field Case Study Troubleshooting

Equipment / System

AGL fixture height as installed, measured from the surrounding pavement or ground reference to the top of the fixture lens or housing.

Possible Causes

Required Tools

Safety Precautions

• LOTO the circuit before adjusting fixture height.
• Coordinate airside access through ATC/apron control before approaching the fixture.

Diagnostic Procedure

1. ObservationMeasure the as-installed fixture height against the specified tolerance in the design drawing.
2. MeasurementWith the circuit isolated, check the base-can elevation itself against the civil design, distinct from the fixture-to-base-can shimming.
3. MeasurementIf pavement has been overlaid, confirm the current surface elevation used for the reference measurement.
4. DecisionHeight deviation traced to shimming → adjust shims to bring the fixture within tolerance. Height deviation traced to base-can elevation or a pavement overlay → escalate to a civil/base-can correction rather than a fixture-level fix.
5. Fault LocationConfirm whether the deviation is fixture-level (shimming) or base-can/pavement-level before deciding the scope of correction.
6. Root CauseVerify the corrected height meets tolerance and remains stable under normal traffic loading.

Test Points

Root Cause Verification

Re-measure fixture height after correction and confirm it is within the specified tolerance before commissioning sign-off.

Corrective Action

• Adjust shims/spacers to bring the fixture to the specified height.
• Escalate a base-can elevation error to civil works for correction.
• Replace the fixture if the wrong model/height variant was installed.

Preventive Action

• Include a height check with a calibrated gauge in the commissioning checklist for every fixture, not a sample.
• Verify base-can elevation against civil design before fixture installation begins.
• Re-verify fixture heights after any pavement overlay or resurfacing project.

Related References

SOP: SOP-INST-02 (Fixture Height Verification Procedure)

Standards: FAA AC 150/5340-30, ICAO Annex 14 Vol I

Diagram: Fixture Height Tolerance Table

Case Study: Division 26 — Photometric & Intensity Compliance

Equipment / System

AGL fixture body and lens assembly as rotationally installed in its base can or mount, relative to the specified beam direction.

Possible Causes

Required Tools

Safety Precautions

• LOTO the circuit before adjusting fixture orientation.
• Coordinate airside access and any required runway/taxiway closure through ATC before working on an active surface.

Diagnostic Procedure

1. ObservationConfirm the reported orientation issue via a night visual check or photometric reading from the specified viewing direction.
2. MeasurementWith the circuit isolated, check the fixture's orientation mark against the specified beam direction on the drawing.
3. MeasurementIf the base can itself appears rotated, verify its installed orientation against the civil/electrical design.
4. DecisionOrientation error is at the fixture level → rotate and re-secure the fixture correctly within the base can. Orientation error is at the base-can level → escalate for base-can correction.
5. Fault LocationIsolate whether the fixture, the base can, or both are misoriented.
6. Root CauseConfirm the corrected orientation with a night visual or photometric check from the specified approach/viewing direction.

Test Points

Root Cause Verification

Conduct a night visual check (or photometric measurement) from the specified direction after correction and confirm the beam is correctly oriented before sign-off.

Corrective Action

• Rotate and re-secure the fixture to the correct orientation.
• Escalate a misoriented base can for civil correction.
• Re-mark or replace a fixture with an illegible orientation indicator.

Preventive Action

• Verify fixture orientation against the drawing during the commissioning walk-down using a directional reference, not visual estimation alone.
• Confirm base-can orientation before fixture installation begins.
• Include an orientation check whenever a fixture is removed for maintenance and reinstalled.

Related References

SOP: SOP-INST-03 (Fixture Orientation Verification Procedure)

Standards: ICAO Annex 14 Vol I, FAA AC 150/5340-30

Diagram: Fixture Orientation and Beam Direction Drawing

Case Study: Division 26 — Photometric & Intensity Compliance

Equipment / System

AGL fixture aiming mechanism (vertical elevation angle and/or horizontal azimuth) as set relative to the runway/taxiway centreline or approach path.

Possible Causes

Required Tools

Safety Precautions

• LOTO the circuit before adjusting fixture aiming.
• Coordinate airside access through ATC/apron control before approaching the fixture.

Diagnostic Procedure

1. ObservationIdentify whether the misalignment is a single fixture or a pattern across multiple fixtures on the same run.
2. MeasurementWith the circuit isolated, measure the current vertical and horizontal aiming angle using a calibrated aiming tool.
3. MeasurementCompare the measured angle against the specified aiming angle for that fixture's position on the run.
4. DecisionSingle fixture out of tolerance → re-aim to specification. Pattern across multiple fixtures → investigate a systemic cause such as a reference-point or survey error.
5. Fault LocationConfirm the specific angle (vertical, horizontal, or both) that is out of tolerance before adjusting.
6. Root CauseRe-verify aiming with the calibrated tool after adjustment and, where practical, confirm with a photometric or visual check.

Test Points

Root Cause Verification

Re-measure the aiming angle with the calibrated tool after adjustment, and where practical confirm visually or photometrically before sign-off.

Corrective Action

• Re-aim the fixture to the specified vertical and horizontal angle.
• Re-survey and correct the reference baseline if a systemic pattern error is found.
• Secure the aiming mechanism to prevent drift after adjustment.

Preventive Action

• Include an aiming angle spot-check in the periodic PM cycle for fixtures on critical approach or centreline runs.
• Verify aiming tool/jig calibration before each commissioning campaign.
• Re-verify aiming after any pavement resurfacing or settlement event.

Related References

SOP: SOP-INST-04 (Fixture Aiming and Alignment Verification Procedure)

Standards: ICAO Annex 14 Vol I, FAA AC 150/5340-30

Diagram: Fixture Aiming Angle Specification Table

Case Study: Division 26 — Photometric & Intensity Compliance

Equipment / System

Mounting bolts, connector gland fittings, and terminal lugs across fixtures, base cans, and transformer housings, assessed against manufacturer torque specifications.

Possible Causes

Required Tools

Safety Precautions

• LOTO the circuit before adjusting torque on any live-circuit component.
• Inspect for cracking or thread damage before applying further torque to a component found over-tightened.

Diagnostic Procedure

1. ObservationIdentify which hardware/fittings are suspected of incorrect torque and gather the manufacturer's specified torque value for each.
2. MeasurementWith the circuit isolated, check current torque using a calibrated torque wrench without first loosening the fitting.
3. MeasurementInspect over-torqued items for cracking, thread deformation, or crushed gaskets/seals before deciding whether they can simply be backed off to spec.
4. DecisionUnder-torqued and hardware undamaged → re-torque to specification. Over-torqued with visible damage → replace the damaged component rather than merely adjusting torque.
5. Fault LocationConfirm which specific fitting is out of tolerance rather than re-torquing every fastener in the area speculatively.
6. Root CauseConfirm the tool used for correction is calibrated and set to the correct specification for that hardware.

Test Points

Root Cause Verification

Re-check torque with a calibrated wrench after correction and inspect for any resulting damage before closing out.

Corrective Action

• Re-torque under-tightened hardware to the specified value.
• Replace hardware, gaskets, or fittings damaged by over-torquing.
• Replace incorrect-grade hardware with the specified type.

Preventive Action

• Issue torque specification tables alongside calibrated torque wrenches as standard field kit.
• Verify torque wrench calibration on a defined schedule.
• Include a spot-check torque verification in the commissioning checklist.

Related References

SOP: SOP-INST-05 (Torque Verification and Correction Procedure)

Standards: Manufacturer torque specification tables, FAA AC 150/5340-30

Diagram: Hardware Torque Specification Table

Case Study: Division 14 — L-823 / Connector Troubleshooting

Equipment / System

Fixture mounting bolts, base-can lid fasteners, and bracket hardware securing AGL components in place.

Possible Causes

Required Tools

Safety Precautions

• LOTO the circuit before working on mounting hardware.
• Coordinate airside access through ATC/apron control, and secure any loose hardware immediately as FOD risk on an active surface.

Diagnostic Procedure

1. ObservationNote which specific fasteners are loose or missing and whether the fixture itself has visible play.
2. MeasurementWith the circuit isolated, check remaining hardware for correct torque and confirm whether the specified lock washer or thread-locker is present.
3. MeasurementInspect fastener condition for corrosion, thread damage, or wrong size/type.
4. DecisionHardware intact but simply under-torqued or missing a locking feature → re-torque and add the specified locking feature. Hardware damaged, corroded, or wrong type → replace with correct specification.
5. Fault LocationConfirm all fasteners at that mounting point are checked, not only the one initially reported loose.
6. Root CauseDetermine whether the looseness is an isolated installation gap or a pattern across multiple locations pointing to a missing locking-feature specification in the original install.

Test Points

Root Cause Verification

Re-check torque and confirm no play remains in the fixture or lid after correction, and re-inspect at the next scheduled PM cycle to confirm the fix has held.

Corrective Action

• Re-torque loose hardware to specification.
• Replace missing, damaged, or corroded fasteners with the correct type.
• Add the specified lock washer or thread-locking compound where missing.

Preventive Action

• Include a hardware torque and completeness check in the routine PM cycle for fixtures and base cans in high-traffic areas.
• Specify and enforce use of locking hardware/thread-locker on all vibration-exposed mounting points.
• Track fastener replacement history to identify locations with a recurring hardware-loosening pattern.

Related References

SOP: SOP-INST-05 (Torque Verification and Correction Procedure)

Standards: FAA AC 150/5340-30

Diagram: Mounting Hardware Specification Table

Case Study: Division 07 — Taxiway Light Troubleshooting

Equipment / System

L-867/base can assembly as installed in the pavement, including its depth, orientation, bedding material, and connection to conduit/duct.

Possible Causes

Required Tools

Safety Precautions

• LOTO the circuit and coordinate excavation/pavement work through the appropriate airside safety process.
• Treat any excavation around an energised base can as a live-circuit hazard until isolation is confirmed.

Diagnostic Procedure

1. ObservationCompare the as-installed base-can depth, orientation, and model against the civil/installation drawing.
2. MeasurementWith the circuit isolated, excavate as needed to inspect bedding material, frost protection, and conduit connection.
3. MeasurementConfirm the base-can model matches the fixture type specified for that location.
4. DecisionDeviation is minor and correctable without full replacement (e.g. re-bedding, re-sealing conduit) → correct in place. Deviation is fundamental (wrong depth, wrong model) → replace/reset the base can.
5. Fault LocationIsolate the specific aspect of the installation that deviates from the drawing before determining the scope of correction.
6. Root CauseConfirm the corrected installation meets specification before backfilling and reinstating the pavement surface.

Test Points

Root Cause Verification

After correction, confirm base-can depth, bedding, and conduit sealing meet specification before backfilling, and re-verify fixture height once the fixture is remounted.

Corrective Action

• Reset the base can to the correct depth and orientation.
• Replace inadequate bedding material with the specified type.
• Replace the base can if the wrong model was installed.
• Properly seal the conduit entry to the base can.

Preventive Action

• Verify base-can depth and bedding against the civil drawing during installation inspection, before pavement is placed over it.
• Confirm base-can model against the fixture schedule prior to installation.
• Include frost/heave protection verification in cold-climate installation checklists.

Related References

SOP: SOP-INST-06 (Base Can Installation Verification Procedure)

Standards: FAA AC 150/5340-30, civil/electrical installation drawings

Diagram: Base Can Installation Detail Drawing

Case Study: Division 08 — Taxiway Centreline / Guidance Lighting Troubleshooting

Equipment / System

L-867/base can assembly, its drainage provisions, and lid seal, as installed at a specific pavement location.

Possible Causes

Required Tools

Safety Precautions

• LOTO the circuit before pumping out or working in a flooded base can.
• Treat a flooded base can as a serious shock hazard until the circuit is confirmed isolated and the connector/fixture wiring inspected.

Diagnostic Procedure

1. ObservationNote the water level and whether it recurs after pump-out, indicating an active source versus a one-off event.
2. MeasurementWith the circuit isolated, pump out the base can and inspect the drainage weep hole/sump, lid gasket, and conduit seal.
3. MeasurementCheck the surrounding pavement grade and water table conditions for that location.
4. DecisionDrainage/seal defect identified and correctable → clear or repair and monitor. Location is chronically below water table with inadequate sump design → escalate for a civil design correction.
5. Fault LocationIdentify the specific entry/retention mechanism — blocked drainage, failed lid seal, or high water table — responsible for the flooding.
6. Root CauseConfirm the base can drains properly after the next rainfall or irrigation cycle before considering the issue resolved.

Test Points

Root Cause Verification

Megger the affected circuit after pump-out and drying to confirm no lasting insulation damage, and re-inspect the base can after the next significant rainfall to confirm drainage is restored.

Corrective Action

• Clear the drainage weep hole/sump of debris.
• Replace a failed or missing lid gasket.
• Reseal the conduit entry to the base can.
• Escalate to civil works for a sump/drainage redesign where the water table is the underlying cause.

Preventive Action

• Include base-can drainage condition in the routine PM checklist, particularly in low-lying or high-water-table areas.
• Verify surrounding pavement grading directs surface water away from base cans.
• Specify sump/drainage design appropriate to local water-table conditions during future installations.

Related References

SOP: SOP-CON-05 (Water Ingress Inspection and Remediation Procedure), SOP-INST-06 (Base Can Installation Verification Procedure)

Standards: FAA AC 150/5340-30

Diagram: Base-Can Drainage Detail Drawing

Case Study: Division 14 — L-823 / Connector Troubleshooting (water ingress)

Equipment / System

Subsurface drainage system serving a section of the AGL installation — base-can sumps, drainage pipe/trench runs, and surrounding pavement grading, considered collectively rather than at a single location.

Possible Causes

Required Tools

Safety Precautions

• LOTO all affected circuits before any base-can access during the survey.
• Coordinate airside access and any required excavation through the appropriate safety process for that section.

Diagnostic Procedure

1. ObservationMap which base cans in the section are affected and look for a pattern (e.g. all cans along one low-lying stretch).
2. MeasurementWith circuits isolated, inspect the drainage trench/pipe run for blockage, undersizing, or damage along its length.
3. MeasurementSurvey the surrounding pavement grade across the affected section to confirm whether it directs water toward or away from the lighting corridor.
4. DecisionBlockage or damage found in the drainage run → clear/repair and re-monitor. Grading or design capacity is inadequate → escalate for a civil drainage redesign of the section.
5. Fault LocationDetermine whether the issue is isolated to a single drainage run or reflects a section-wide grading/design problem.
6. Root CauseConfirm the correction resolves the pattern across the whole affected section, not just the base can that first prompted investigation.

Test Points

Root Cause Verification

Re-survey the affected section after the next significant rainfall to confirm the drainage pattern has improved across all previously affected base cans.

Corrective Action

• Clear or repair the blocked/damaged drainage run.
• Correct pavement grading directing water toward the lighting corridor where practical.
• Escalate to civil engineering for a drainage capacity/design review if the issue is systemic.

Preventive Action

• Include a section-wide drainage walk-down after any significant rainfall event as part of storm-response PM.
• Track base-can flooding incidents by location to detect emerging section-wide patterns early.
• Review drainage design capacity against updated local rainfall/water-table data periodically.

Related References

SOP: SOP-INST-07 (Section Drainage Survey Procedure)

Standards: FAA AC 150/5340-30, local civil drainage design standards

Diagram: Section Drainage As-Built Drawing

Case Study: Division 14 — L-823 / Connector Troubleshooting (water ingress)

Equipment / System

Primary or secondary cable routing between base cans, pull boxes, and the CCR/equipment vault, as installed relative to the design drawing.

Possible Causes

Required Tools

Safety Precautions

• LOTO all affected circuits before excavation or duct access.
• Coordinate with other utility owners before any excavation near cable routes to avoid third-party strikes.

Diagnostic Procedure

1. ObservationCompare the as-built (or as-found) routing against the design drawing to identify the specific deviation.
2. MeasurementWith circuits isolated, trace the actual cable route using a cable/duct tracer where the drawing and field condition disagree.
3. MeasurementConfirm separation distances from other utilities and other lighting circuits at the points of concern.
4. DecisionRouting deviates but meets separation and protection requirements → update the as-built drawing and close out. Routing violates separation, protection, or duct-sharing requirements → re-route or add protection to bring it into compliance.
5. Fault LocationIdentify the specific segment where the deviation occurs rather than assuming the entire run is affected.
6. Root CauseConfirm the corrected or documented routing is reflected accurately in the as-built record before closing out.

Test Points

Root Cause Verification

After correction (physical re-route or drawing update), confirm the as-built record matches the field condition and that separation requirements are met before sign-off.

Corrective Action

• Re-route the cable to meet the design/separation requirements where a physical correction is warranted.
• Add protection (conduit, marker tape, additional depth) where separation cannot be practically corrected.
• Update the as-built drawing to accurately reflect the field-verified route.

Preventive Action

• Verify actual cable routing against the design drawing during commissioning rather than relying on the design drawing alone.
• Maintain accurate as-built records for every excavation/routing change made during construction.
• Coordinate with other utility owners early in design to avoid routing conflicts before installation.

Related References

SOP: SOP-INST-08 (Cable Routing Verification Procedure)

Standards: FAA AC 150/5340-30, local utility separation standards

Diagram: Cable Routing As-Built Drawing

Case Study: Division 08 — Taxiway Centreline / Guidance Lighting Troubleshooting (cable faults)

Equipment / System

Direct-buried or duct-enclosed cable as installed below grade, assessed for depth, bedding, and marker/warning tape compliance.

Possible Causes

Required Tools

Safety Precautions

• LOTO the circuit before any excavation near the cable.
• Coordinate with all utility owners and use safe digging practices (hand excavation near known cable routes) to avoid a strike during verification.

Diagnostic Procedure

1. ObservationIdentify the specific run or section where burial depth or protection is in question.
2. MeasurementWith the circuit isolated, expose the cable at representative points along the run to measure actual depth, bedding material, and presence of marker tape.
3. MeasurementCompare findings against the specified burial standard for that circuit type and location (e.g. under pavement vs. open ground).
4. DecisionDepth and bedding meet specification, only marker tape missing → add marker tape without re-burial. Depth or bedding does not meet specification → re-bury the affected section to standard.
5. Fault LocationDetermine the extent of the affected run — an isolated section or the full length — before deciding the scope of correction.
6. Root CauseConfirm the corrected section meets specification and update as-built depth records accordingly.

Test Points

Root Cause Verification

After correction, confirm depth and protection meet specification at the corrected section and update the as-built record before closing out.

Corrective Action

• Re-bury the affected section to the specified depth and bedding.
• Add marker/warning tape where missing.
• Add duct/conduit protection through vehicle-loaded areas where specified but absent.
• Update as-built depth records for the corrected section.

Preventive Action

• Verify burial depth and marker tape presence during construction inspection before backfilling, rather than relying on after-the-fact spot checks.
• Maintain accurate as-built depth records for all buried cable runs.
• Coordinate excavation permits with accurate cable location records to prevent future strikes.

Related References

SOP: SOP-INST-09 (Cable Burial Verification Procedure)

Standards: FAA AC 150/5340-30, local electrical code burial depth requirements

Diagram: Cable Burial Depth and Marker Tape Detail

Case Study: Division 08 — Taxiway Centreline / Guidance Lighting Troubleshooting (cable faults)

Equipment / System

Cable protective measures (conduit, sleeving, armour, or duct) at road/taxiway crossings, pavement penetrations, and other locations specified as requiring additional mechanical protection.

Possible Causes

Required Tools

Safety Precautions

• LOTO the circuit before excavation or protection work.
• Coordinate with ATC/apron control and other utility owners before excavating at a crossing point.

Diagnostic Procedure

1. ObservationIdentify the specific crossing or location where protection is suspected to be missing or inadequate.
2. MeasurementWith the circuit isolated, expose the cable at the location in question and confirm whether protection is present, and if so its type and condition.
3. MeasurementCompare against the design specification for protection type/rating at that location.
4. DecisionProtection present but damaged or degraded → repair or replace in place. Protection missing entirely or undersized for the loading → install the correctly specified protection.
5. Fault LocationConfirm the full extent of the unprotected or under-protected section before closing the excavation.
6. Root CauseVerify the corrected protection extends fully across the loaded area with no gaps at the transition points.

Test Points

Root Cause Verification

After installing or repairing protection, confirm full coverage across the loaded area and inspect the cable jacket beneath it for any pre-existing damage before backfilling.

Corrective Action

• Install the specified conduit/sleeving/armour where missing.
• Repair or replace damaged protective sleeving.
• Extend protection to eliminate gaps at transition points.
• Replace any cable segment found damaged beneath inadequate protection.

Preventive Action

• Verify protection installation against the design specification during construction inspection, before backfilling.
• Update design records promptly for any field change affecting protection requirements.
• Include a periodic condition check of accessible protective sleeving/conduit in the PM cycle.

Related References

SOP: SOP-INST-08 (Cable Routing Verification Procedure)

Standards: FAA AC 150/5340-30, local electrical code mechanical protection requirements

Diagram: Cable Crossing Protection Detail Drawing

Case Study: Division 14 — L-823 / Connector Troubleshooting (mechanical damage)

Equipment / System

Earthing/grounding conductors and connections at AGL fixtures, base cans, transformer housings, and the equipment vault/CCR earthing system.

Possible Causes

Required Tools

Safety Precautions

• LOTO the circuit before working on earthing connections.
• Treat a confirmed earthing deficiency as a touch-voltage hazard and prioritise correction, restricting access to the affected component in the meantime if necessary.

Diagnostic Procedure

1. ObservationIdentify the specific fixture, base can, or equipment location where earthing is suspected to be deficient.
2. MeasurementWith the circuit isolated, test earth resistance at the location and continuity of the bonding path back to the main earthing grid.
3. MeasurementInspect the physical earthing connection for correct conductor size, termination method, and corrosion.
4. DecisionResistance and continuity within specification → no fault, log and close out. Resistance or continuity outside specification → correct the conductor, termination, or electrode as needed.
5. Fault LocationDetermine whether the deficiency is a local termination issue or a break in the bonding path back to the main grid.
6. Root CauseRe-test earth resistance and continuity after correction to confirm it meets specification.

Test Points

Root Cause Verification

Re-test earth resistance and bonding continuity after correction and confirm both meet the specified threshold before sign-off.

Corrective Action

• Install or replace the missing/undersized earthing conductor.
• Re-terminate with a correctly sized and rated lug/clamp.
• Restore bonding continuity to the main earthing grid where broken.
• Improve or replace the earth electrode where resistance exceeds specification.

Preventive Action

• Include earth resistance and bonding continuity testing in the commissioning checklist for every fixture and equipment location, not a sample.
• Verify earthing continuity is restored after any excavation or cable repair in the vicinity.
• Use corrosion-resistant, correctly rated earthing hardware in all new installations.

Related References

SOP: SOP-INST-10 (Earthing/Grounding Verification Procedure)

Standards: IEC 60364, FAA AC 150/5340-30, local electrical code earthing requirements

Diagram: Site Earthing/Grounding System Drawing

Case Study: Division 01 — CCR Troubleshooting (earth-fault protection)

Equipment / System

Field connector installation practice as applied at a specific location, assessed against the standard connector installation procedure rather than the connector hardware itself.

Possible Causes

Required Tools

Safety Precautions

• LOTO the circuit before correcting connector installation practice.
• Coordinate airside access through ATC/apron control before approaching the location.

Diagnostic Procedure

1. ObservationCompare the as-installed connector placement, support, and sealing practice against the standard installation procedure.
2. MeasurementWith the circuit isolated, open the base can and inspect grease/sealing application, cable slack, and support hardware.
3. MeasurementCheck insulation resistance to confirm the deviation has not already resulted in moisture ingress or another fault.
4. DecisionDeviation identified with no resulting fault yet → correct the installation practice proactively. Deviation has already caused a related fault (moisture, mechanical stress) → correct both the practice and the resulting fault.
5. Fault LocationIdentify which specific step of the standard procedure was not followed.
6. Root CauseConfirm the corrected installation follows the standard procedure and note whether the deviation reflects a training gap for that crew.

Test Points

Root Cause Verification

After correcting the installation, verify insulation resistance is within tolerance and confirm the connector is supported and sealed per the standard procedure before closing the base can.

Corrective Action

• Correct the connector's support, dressing, and sealing to match the standard installation procedure.
• Apply the specified dielectric grease/sealing compound where missing.
• Add the specified service loop/slack to relieve cable tension.

Preventive Action

• Provide the standard connector installation procedure/checklist to all field crews as part of every base-can work order.
• Include an installation-practice spot check in the commissioning checklist, not just an electrical pass/fail test.
• Refresh crew training whenever a new connector type or sealing compound is introduced.

Related References

SOP: SOP-CON-01 (L-823 Connector Inspection and Reseating Procedure), SOP-INST-11 (Standard Connector Installation Procedure)

Standards: FAA AC 150/5345-26, manufacturer installation instructions

Diagram: Standard Connector Installation Checklist

Case Study: Division 14 — L-823 / Connector Troubleshooting

Equipment / System

Isolation transformer as physically and electrically installed in the base can, including its support, orientation, and lead routing/sealing.

Possible Causes

Required Tools

Safety Precautions

• LOTO the circuit before correcting transformer installation.
• Coordinate airside access through ATC/apron control before approaching the location.

Diagnostic Procedure

1. ObservationCompare the as-installed transformer support, orientation, and lead routing against the standard installation procedure.
2. MeasurementWith the circuit isolated, megger the transformer primary and secondary to confirm no insulation damage has resulted from the incorrect installation.
3. MeasurementConfirm the transformer VA rating matches the fixture specification for that location.
4. DecisionInstallation deviates but transformer tests sound → correct the physical installation and re-verify. Installation deviation has caused measurable insulation degradation → replace the transformer and correct the installation.
5. Fault LocationIdentify the specific installation step — support, routing, sealing, or rating — that deviates from the standard procedure.
6. Root CauseConfirm the corrected installation follows the standard procedure and re-test insulation resistance before closing out.

Test Points

Root Cause Verification

After correction, re-megger the transformer and confirm the fixture operates correctly at all intensity steps before closing the base can.

Corrective Action

• Correct the transformer's support, orientation, and lead routing to match the standard installation procedure.
• Replace the transformer if insulation testing shows damage from the incorrect installation.
• Complete potting/sealing per the manufacturer's procedure where it was missing.

Preventive Action

• Provide the standard transformer installation procedure/checklist to all field crews.
• Include transformer installation-practice verification in the commissioning checklist alongside electrical testing.
• Verify VA rating against the fixture schedule before installation, not after a fault is reported.

Related References

SOP: SOP-INST-12 (Transformer Installation Verification Procedure)

Standards: FAA AC 150/5345-46, manufacturer transformer installation instructions

Diagram: Transformer Installation and Support Detail Drawing

Case Study: Division 01 — CCR Troubleshooting

Equipment / System

Lighted airfield guidance sign (mandatory instruction, location, or direction sign) and its mounting/frangible base as installed.

Possible Causes

Required Tools

Safety Precautions

• LOTO the circuit before adjusting or relocating a sign.
• Coordinate airside access and any required runway/taxiway closure through ATC before working on or near an active surface.

Diagnostic Procedure

1. ObservationCompare the as-installed sign location, message, height, and mounting against the site specification drawing.
2. MeasurementWith the circuit isolated, measure height and setback distance, and confirm the message panel matches the specification for that location.
3. MeasurementInspect the frangible mount for correct type and installation.
4. DecisionDeviation is minor and correctable in place (height/angle adjustment) → correct and re-verify. Deviation is fundamental (wrong location or message) → relocate or replace the sign and notify airfield operations.
5. Fault LocationIsolate the specific aspect — location, message, height, or mount — that deviates from specification.
6. Root CauseConfirm the corrected sign meets specification and, where the discrepancy could have affected published guidance information, coordinate with airfield operations on any required NOTAM action.

Test Points

Root Cause Verification

After correction, re-verify location, height, and message against the specification, and conduct a night visual check to confirm correct readability and illumination before sign-off.

Corrective Action

• Relocate the sign to the correct chainage/position where required.
• Replace the message panel with the correct designator/arrow/type.
• Adjust height/setback to within specification.
• Replace an incorrect or missing frangible mount.
• Notify airfield operations/NOTAM if the discrepancy affected published guidance information.

Preventive Action

• Verify sign location and message against the specification drawing during the commissioning walk-down, not only a functional light-on check.
• Confirm frangible mount type against the specification before installation.
• Include sign message/location verification in the periodic night inspection cycle.

Related References

SOP: SOP-INST-13 (Sign Installation Verification Procedure)

Standards: ICAO Annex 14 Vol I (sign specifications), FAA AC 150/5340-18

Diagram: Airfield Sign Location and Message Schedule

Case Study: Division 26 — Photometric & Intensity Compliance

Equipment / System

PAPI unit array (typically four units) including its elevation angle setting, lateral offset, longitudinal position, and unit sequence relative to the runway.

Possible Causes

Required Tools

Safety Precautions

• LOTO the circuit before adjusting any PAPI unit.
• Coordinate any PAPI adjustment work with ATC given its direct role in approach guidance, and treat the system as out of service for approach guidance purposes until verification is complete.

Diagnostic Procedure

1. ObservationReview flight inspection results or pilot reports to identify whether the discrepancy is a single unit or the whole array.
2. MeasurementWith the circuit isolated, verify each unit's elevation angle setting using the specified tool against the design angle for that runway.
3. MeasurementSurvey the array's lateral offset, longitudinal position, and unit sequence against the design drawing.
4. DecisionA single unit's angle is out of tolerance → re-set that unit and re-verify. Spacing, offset, or sequence is wrong across the array → escalate for a full re-installation/re-survey of the array.
5. Fault LocationIsolate whether the discrepancy is at the individual-unit level (angle) or the array level (position, spacing, sequence).
6. Root CauseConfirm correction with a follow-up flight inspection before returning the system to full approach-guidance service.

Test Points

Root Cause Verification

Schedule a follow-up flight inspection after correction and confirm the glide path indication meets specification before returning the PAPI to full service.

Corrective Action

• Re-set the elevation angle on the affected unit(s) to the design specification.
• Re-survey and reposition the array if spacing, offset, or longitudinal position is out of tolerance.
• Correct unit sequence if installed out of order.

Preventive Action

• Verify PAPI elevation angle, spacing, and offset against the design specification and an independent survey before the commissioning flight inspection is scheduled.
• Use a calibrated, unit-specific angle-setting tool for every PAPI installation or adjustment.
• Schedule periodic flight inspection re-verification per the applicable regulatory interval.

Related References

SOP: SOP-INST-14 (PAPI Installation and Angle-Setting Procedure)

Standards: ICAO Annex 14 Vol I (visual approach slope indicator systems), FAA AC 150/5345-28

Diagram: PAPI Array Geometry and Elevation Angle Drawing

Case Study: Division 26 — Photometric & Intensity Compliance

Equipment / System

Approach Lighting System structure and fixtures — centreline light bars, crossbars, and sequenced flashing lights on their supporting towers/frangible structures — as installed relative to the design layout.

Possible Causes

Required Tools

Safety Precautions

• LOTO the circuit before adjusting any ALS structure or fixture.
• Coordinate any ALS work with ATC given its role in approach guidance, and treat affected elements as out of service until verification is complete.

Diagnostic Procedure

1. ObservationReview flight inspection or survey results to identify which specific bar, crossbar, or flasher deviates from the design layout.
2. MeasurementWith the circuit isolated, survey the affected structure's distance from threshold, height, and lateral offset against the design drawing.
3. MeasurementConfirm the frangible structure rating and, for sequenced flashers, the firing position within the array.
4. DecisionDeviation is within a correctable range (height/offset adjustment) → correct in place. Deviation is fundamental (wrong distance from threshold, wrong frangible rating) → escalate for structural relocation/replacement.
5. Fault LocationIsolate the specific structure/fixture affected before assuming a wider array-level issue.
6. Root CauseConfirm correction with a follow-up survey and, where relevant, flight inspection before returning the element to full service.

Test Points

Root Cause Verification

Re-survey the corrected structure and, where the deviation could affect approach guidance, coordinate a follow-up flight inspection before returning it to full service.

Corrective Action

• Adjust height/offset in place where correctable.
• Relocate or replace the structure where the deviation is fundamental (distance from threshold, frangible rating).
• Correct the firing sequence position for an affected sequenced flasher.

Preventive Action

• Verify ALS structure position, height, and frangible rating against the design layout during the commissioning survey, before final flight inspection is scheduled.
• Maintain accurate as-built records for the full ALS layout.
• Include periodic structural/positional spot-checks in the PM cycle for ALS elements.

Related References

SOP: SOP-INST-15 (Approach Lighting System Installation Verification Procedure)

Standards: ICAO Annex 14 Vol I, FAA AC 150/5340-30, FAA AC 150/5345-56 (sequenced flashers)

Diagram: ALS Layout and Structure Detail Drawing

Case Study: Division 26 — Photometric & Intensity Compliance

Equipment / System

Circuit identification labelling and documentation — CCR panel labels, cable tags, base-can markings, and as-built circuit drawings — as compared against the actual physical circuit function.

Possible Causes

Required Tools

Safety Precautions

• LOTO the circuit being verified, but be aware the physical circuit may not match its label — confirm isolation electrically (zero-energy check) rather than relying on the label alone.
• Treat any circuit with a known or suspected identification discrepancy as unconfirmed/energised until physically verified.

Diagnostic Procedure

1. ObservationNote the discrepancy between the expected result of a labelled action and what was actually observed in the field.
2. MeasurementWith appropriate precautions, trace the actual physical circuit from the CCR output or pull box to confirm which fixtures/areas it truly serves.
3. MeasurementCompare the traced result against the existing label, tag, and as-built drawing.
4. DecisionDiscrepancy confirmed → correct the labels, tags, and as-built drawing to match the verified physical circuit. Apparent discrepancy resolves to an operator/reading error → close out with no documentation change.
5. Fault LocationConfirm the discrepancy is isolated to labelling/documentation rather than an actual wiring cross-connection that itself needs correction.
6. Root CauseVerify all downstream labels (base cans, pull boxes, as-built drawings) are consistently updated, not just the CCR panel label.

Test Points

Root Cause Verification

After correcting labels and documentation, perform an independent verification (e.g. a second technician isolating by the corrected label) to confirm the fix is accurate before closing out.

Corrective Action

• Correct the CCR panel label, cable tags, and base-can markings to match the verified physical circuit.
• Update the as-built circuit drawing to reflect the verified configuration.
• Replace illegible or damaged labels/tags.

Preventive Action

• Require physical circuit tracing verification, not just label review, whenever a circuit identification discrepancy is suspected.
• Update as-built drawings and all physical labels immediately after any circuit modification, as a closeout requirement rather than a follow-up task.
• Periodically audit a sample of circuit labels against physical tracing to catch drift before it causes a maintenance incident.

Related References

SOP: SOP-INST-16 (Circuit Identification Verification Procedure)

Standards: FAA AC 150/5340-30, internal documentation control procedure

Diagram: Master Circuit Identification and As-Built Drawing Set

Case Study: Division 01 — CCR Troubleshooting

Equipment / System

Equipment identification labelling and asset records for transformers, CCRs, fixtures, and base cans, as compared against the physical equipment installed.

Possible Causes

Required Tools

Safety Precautions

• LOTO the circuit before physically verifying or re-labelling equipment.
• Do not rely on an existing label to determine equipment rating or type before working on it — verify the physical nameplate directly.

Diagnostic Procedure

1. ObservationIdentify the specific discrepancy between the physical equipment's nameplate/rating and its recorded identification.
2. MeasurementWith the circuit isolated, read the actual nameplate/rating plate on the physical equipment and compare it against the asset record.
3. MeasurementCheck for a pattern — whether other equipment from the same installation or delivery batch shows a similar mislabelling.
4. DecisionDiscrepancy is a labelling/record error only → correct the label and record. Discrepancy indicates the wrong equipment type was actually installed → treat as a wrong-component-installed fault and correct the equipment itself.
5. Fault LocationConfirm whether the error is documentation-only or reflects an actual wrong-equipment installation.
6. Root CauseUpdate both the physical label and the asset/inventory record consistently, and check for the same error at related equipment from the same batch.

Test Points

Root Cause Verification

After correcting labels and records, cross-check the updated record against the physical nameplate a second time to confirm consistency before closing out.

Corrective Action

• Correct the physical label to match the verified nameplate/rating.
• Update the asset/inventory management record to match the physical equipment.
• Investigate and correct related equipment from the same batch if a pattern is found.

Preventive Action

• Verify physical nameplate against the asset record during commissioning for every new or replaced piece of equipment.
• Update the asset/inventory record as a mandatory closeout step for any equipment replacement, including emergency repairs.
• Periodically audit a sample of equipment labels against the asset record to catch drift early.

Related References

SOP: SOP-INST-17 (Equipment Identification Verification Procedure)

Standards: FAA AC 150/5340-30, internal asset management procedure

Diagram: Equipment Asset Register

Case Study: Division 24 — Complete Runway Lighting Failure

Equipment / System

Any AGL system component (fixture, transformer, connector, control card, or ancillary part) as physically installed, compared against the specification for its installed location.

Possible Causes

Required Tools

Safety Precautions

• LOTO the circuit before removing or replacing a component.
• Verify the replacement component's rating/specification before energising, to avoid introducing a new mismatch while correcting the old one.

Diagnostic Procedure

1. ObservationIdentify the specific component and compare its nameplate/rating against the current component schedule for that location.
2. MeasurementWith the circuit isolated, confirm there is no resulting electrical fault (overcurrent, undercurrent, incompatible rating) from the substitution before deciding on urgency.
3. MeasurementCheck whether other locations from the same installation or delivery batch show the same substitution.
4. DecisionSubstituted component is functionally compatible and rated adequately → schedule replacement at next convenient access. Substituted component is a genuine mismatch risking a fault → replace immediately.
5. Fault LocationConfirm the specific component and location affected before ordering replacement stock.
6. Root CauseDetermine how the wrong component entered service — emergency substitution, outdated schedule, or unapproved contractor change — to prevent recurrence.

Test Points

Root Cause Verification

After replacing with the correctly specified component, verify function and rating against the schedule before closing out.

Corrective Action

• Replace the incorrect component with the one specified in the current schedule.
• Correct the schedule/documentation if it was found to be outdated rather than the installation being at fault.
• Investigate and correct related locations from the same batch if a pattern is found.

Preventive Action

• Maintain a current, version-controlled component schedule accessible to all field crews.
• Require formal change-control approval for any contractor-proposed component substitution.
• Control emergency repair stock to prevent ad-hoc substitution without specification verification.

Related References

SOP: SOP-INST-18 (Component Verification Against Specification Procedure)

Standards: FAA AC 150/5340-30, internal change-control procedure

Diagram: Site Component/Equipment Schedule

Case Study: Division 14 — L-823 / Connector Troubleshooting (incorrect connector type)

Equipment / System

Isolation transformer VA/wattage rating as installed, compared against the rating specified for the fixture it feeds.

Possible Causes

Required Tools

Safety Precautions

• LOTO the circuit before replacing the transformer.
• Treat an under-rated transformer under load as a potential overheating hazard and prioritise correction.

Diagnostic Procedure

1. ObservationCompare the installed transformer's nameplate VA rating against the specification for that fixture type.
2. MeasurementWith the circuit isolated, confirm the fixture's actual current/wattage draw and the transformer's rated capacity.
3. MeasurementInspect the transformer for any signs of thermal stress consistent with sustained under-rating.
4. DecisionTransformer rating is inadequate for the fixture load → replace with the correctly rated transformer. Transformer rating is adequate despite a labelling discrepancy → correct documentation only.
5. Fault LocationConfirm the specific fixture/transformer pair affected before ordering replacement stock.
6. Root CauseDetermine whether the mismatch originated at installation, a later fixture upgrade, or an original schedule error, to prevent recurrence.

Test Points

Root Cause Verification

After replacing with the correctly rated transformer, verify fixture output at all intensity steps and confirm no thermal stress under normal load before closing out.

Corrective Action

• Replace the transformer with the correctly rated unit for that fixture type.
• Update the fixture/transformer schedule if a fixture upgrade was not previously reflected.
• Correct the original design schedule if it specified the wrong rating from the outset.

Preventive Action

• Review and update the transformer rating whenever a fixture is upgraded or replaced with a different load characteristic.
• Maintain clear, legible nameplate ratings and verify them against the schedule before installation.
• Include a transformer rating spot-check in the commissioning checklist.

Related References

SOP: SOP-INST-12 (Transformer Installation Verification Procedure)

Standards: FAA AC 150/5345-46

Diagram: Fixture and Transformer Rating Schedule

Case Study: Division 08 — Taxiway Centreline / Guidance Lighting Troubleshooting (photometric)

Equipment / System

AGL fixture part number/model as physically installed, compared against the fixture schedule specification for that location.

Possible Causes

Required Tools

Safety Precautions

• LOTO the circuit before replacing the fixture.
• Coordinate airside access through ATC/apron control before approaching the fixture.

Diagnostic Procedure

1. ObservationCompare the installed fixture's part number/nameplate against the fixture schedule for that location.
2. MeasurementWith the circuit isolated, confirm any resulting photometric, colour, or classification discrepancy caused by the wrong fixture.
3. MeasurementCheck whether other locations from the same installation or delivery batch show the same substitution.
4. DecisionSubstituted fixture meets all functional/photometric requirements despite a part-number mismatch → correct documentation and monitor. Substituted fixture does not meet specification → replace with the correct fixture.
5. Fault LocationConfirm the specific location and fixture affected before ordering replacement stock.
6. Root CauseDetermine how the wrong fixture entered service to prevent recurrence, and correct related locations from the same batch if a pattern is found.

Test Points

Root Cause Verification

After replacing with the correctly specified fixture, verify photometric/colour output and confirm it matches neighbouring fixtures in the same run before closing out.

Corrective Action

• Replace the incorrect fixture with the one specified in the fixture schedule.
• Notify airfield operations/NOTAM if the discrepancy affected published guidance information (e.g. colour or classification).
• Investigate and correct related locations from the same batch if a pattern is found.

Preventive Action

• Maintain a current fixture schedule with clear part-number references accessible to all field crews.
• Verify fixture part number against the schedule during receiving/inspection before installation, not only after a fault is reported.
• Require formal change-control approval for any contractor-proposed fixture substitution.

Related References

SOP: SOP-INST-18 (Component Verification Against Specification Procedure)

Standards: FAA AC 150/5340-30, ICAO Annex 14 Vol I

Diagram: Site Fixture Schedule

Case Study: Division 08 — Taxiway Centreline / Guidance Lighting Troubleshooting (wrong colour)

Equipment / System

Field connector part number/rating as physically installed at a specific location, verified against the connector schedule at the point of commissioning.

Possible Causes

Required Tools

Safety Precautions

• LOTO the circuit before replacing the connector.
• Coordinate airside access through ATC/apron control before approaching the location.

Diagnostic Procedure

1. ObservationCompare the installed connector's part number/rating against the connector schedule for that location.
2. MeasurementWith the circuit isolated, confirm the circuit's actual design current and required connector rating.
3. MeasurementCheck whether other locations from the same installation or delivery batch show the same substitution.
4. DecisionSubstituted connector meets or exceeds the required rating and configuration → correct documentation and monitor. Substituted connector is under-rated or missing a required function (e.g. multi-pin) → replace with the correct connector.
5. Fault LocationConfirm the specific location and connector affected before ordering replacement stock.
6. Root CauseDetermine how the wrong connector entered service during installation to prevent recurrence, and correct related locations from the same batch if a pattern is found.

Test Points

Root Cause Verification

After replacing with the correctly specified connector, verify continuity, insulation resistance, and fixture operation before closing out.

Corrective Action

• Replace the incorrect connector with the one specified in the connector schedule.
• Quarantine any mislabelled or legacy stock found to be the source of the substitution.
• Investigate and correct related locations from the same batch if a pattern is found.

Preventive Action

• Maintain a current connector schedule with clear part-number references accessible to all field crews.
• Verify connector part number against the schedule during receiving/inspection before installation.
• Control legacy connector stock to prevent unintended use on new installations.

Related References

SOP: SOP-CON-13 (Connector Type Verification Procedure), SOP-INST-18 (Component Verification Against Specification Procedure)

Standards: FAA AC 150/5345-26

Diagram: Site Connector Schedule

Case Study: Division 14 — L-823 / Connector Troubleshooting (incorrect connector type)

Equipment / System

The full commissioning test suite for a new or modified AGL circuit or installation, covering electrical, mechanical, and photometric acceptance criteria.

Possible Causes

Required Tools

Safety Precautions

• LOTO the circuit before conducting or repeating any commissioning test.
• Coordinate airside access through ATC/apron control for any fieldwork required to investigate a failed test.

Diagnostic Procedure

1. ObservationIdentify exactly which test(s) failed and by how much, distinguishing a marginal near-pass from a clear failure.
2. MeasurementWith the circuit isolated, repeat the failed test using verified, calibrated equipment and the correct procedure to rule out a test-execution error.
3. MeasurementIf the failure is confirmed, trace it to the specific installation or component fault using the relevant division of this troubleshooting atlas (e.g. earthing, connector, cable, transformer).
4. DecisionRepeat test passes → original result was a test-execution error; log and close out. Repeat test confirms failure → investigate and correct the underlying installation or component fault before re-testing.
5. Fault LocationIsolate the specific segment, component, or connection responsible for the failed reading.
6. Root CauseConfirm the corrected installation passes the full commissioning test suite, not just the single test that originally failed, before final acceptance.

Test Points

Root Cause Verification

Repeat the full relevant commissioning test suite after correction and confirm all results meet acceptance criteria before issuing final commissioning sign-off.

Corrective Action

• Correct the underlying installation or component fault identified as the cause of the test failure.
• Repeat the test with verified, calibrated equipment if the original failure was a test-execution error.
• Update commissioning records to reflect the corrected result and the root cause identified.

Preventive Action

• Verify test equipment calibration before every commissioning campaign.
• Build in a settling period where appropriate (e.g. for cable insulation) before final acceptance testing.
• Cross-reference the correct acceptance threshold for each test against the applicable standard before testing begins.

Related References

SOP: SOP-INST-19 (Commissioning Test Procedure and Acceptance Criteria)

Standards: FAA AC 150/5340-30, ICAO Annex 14 Vol I, IEC 60364

Diagram: Commissioning Test Record Template

Case Study: Division 25 — Field Case Study Troubleshooting