The following instructions are typical procedures suggested by many gas turbine manufacturers. These instructions are applicable to the engine ignition components. Always consult the applicable manufacturer’s instructions before performing any ignition system maintenance.
Ignition System Leads
- Remove clamps securing ignition leads to engine.
- Remove safety wire and disconnect electrical connectors from exciter units.
- Remove safety wire and disconnect lead from igniter plug.
- Discharge any electrical charge stored in the system by grounding and remove ignition leads from engine.
- Clean leads with approved dry cleaning solvent.
- Inspect connectors for damaged threads, corrosion, cracked insulators, and bent or broken connector pins.
- Inspect leads for worn or burned areas, deep cuts, fraying, and general deterioration.
- Perform continuity check of ignition leads.
- Reinstall leads, reversing the removal procedure.
Igniter Plugs
1. Disconnect ignition leads from igniter plugs. A good procedure to perform before disconnecting the ignition lead is to disconnect the low-voltage primary lead from the ignition exciter unit and wait at least one minute to permit the stored energy to dissipate before disconnecting the high-voltage cable from the igniter.
2. Remove igniter plugs from mounts.
3. Inspect igniter plug gap surface material. Before inspection, remove residue from the shell exterior using a dry cloth. Do not remove any deposits or residue from the firing end of the low-voltage igniters. High-voltage igniters can have the firing end cleaned to aid in inspection. [Figure 1]
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| Figure 1. Firing end cleaning |
4. Inspect for fretting of igniter plug shank.
5. Replace an igniter plug whose surface is granular, chipped, or otherwise damaged.
6. Replace dirty or carbonized igniter plugs.
7. Install igniter plugs in mounting pads.
8. Check for proper clearance between chamber liner and igniter plug.
9. Tighten igniter plugs to manufacturer’s specified torque.
10. Safety wire igniter plugs.
Troubleshooting
Apply logical troubleshooting procedures when you investigate an ignition system problem. To aid in
this process, many engine manufacturers provide troubleshooting charts for diagnosing and repairing
commonly encountered problems. [Figure 2]
this process, many engine manufacturers provide troubleshooting charts for diagnosing and repairing
commonly encountered problems. [Figure 2]
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| Figure 2. Gas Turbine Engine Ignition System Troubleshooting Procedures |
As a safety precaution, never energize a turbine engine ignition system for troubleshooting with the
igniter plugs removed. Doing so can cause serious overheating or damage to the exciter box.