Fuelling bonding, grounding & static charge
Terms (TC AIM AIR 1.3.2):
- Bonding: links aircraft and fuelling equipment electrically. Static charge equalizes, no spark.
- Grounding: drains charge to earth.
Bonding and grounding:
| Setup | Item | Action | Timing | Ref |
|---|---|---|---|---|
| Over-wing | Nozzle | Bond to aircraft; stay bonded throughout | Before tank cap comes off | TC AIM AIR 1.3.2 |
| Over-wing | Funnel or filter | Bond to aircraft | - | TC AIM AIR 1.3.2 |
| Over-wing | Fuel truck | Ground | Before nozzle touches aircraft | TC AIM AIR 1.3.4.1 |
| Drums or cans | Pump | Bond to drum | Before bungs come off | TC AIM AIR 1.3.2 |
Drums or cans equipment:
| Item | Requirement | Ref |
|---|---|---|
| Filter and water separator | Use | TC AIM AIR 1.3.2 |
| Chamois strainer | Use | TP 1102 |
| Pump suction tube | At least 1 inch clear of drum bottom: rust and condensation settle there | TP 1102 |
Drum bonding order (TP 1102):
- Drum to ground (anchor post)
- Drum to pump
- Pump to aircraft
- Nozzle to aircraft
- Open fuel cap
- Finish: reverse order. Drum-to-ground broken last.
Jet fuel vs AVGAS (TC AIM AIR 1.3.4.1):
- Generates more static charge than AVGAS.
- Poor conductor: needs time at rest to dissipate charge.
Charge controls (TC AIM AIR 1.3.4.1):
| Control | Does | Does not |
|---|---|---|
| Anti-static additive | Raises conductivity: charge drains faster | Reduce charge generated |
| Bonding/grounding | Equalizes potential | Eliminate accumulated charge |
Hazards (TC AIM AIR 1.3.4.1):
- Plastic jerry cans cannot be properly grounded or bonded.
- "Empty" tank can still hold flammable vapour.
- Fuelling in enclosed space or with inadequate bonding: has caused death and injury.
- Cold, dry air: blower heater can charge dust, which combines with fuel vapour.
Precautions (TC AIM AIR 1.3.4.1):
- Control every other ignition source nearby, smoking and portable electronics included.
- Never refuel with thunderstorm in vicinity.
Trap: opening fuel cap before nozzle is bonded to aircraft; or assuming anti-static additives and bonding stop jet fuel static outright: they only speed dissipation or equalize potential, never eliminate the charge.
References
- TC AIM AIR 1.3.2
- TC AIM AIR 1.3.4.1
- TP 1102 (Engine Handling, Prior to Starting)