Petrol is not used in aircraft primarily because it has a higher freezing point compared to aviation gasoline (AVGAS), making it unsuitable for the extreme cold temperatures encountered at high altitudes.
The Issue with Petrol at High Altitude
Aircraft frequently operate at high altitudes where temperatures can drop significantly. Using regular petrol under these conditions presents a severe risk due to its relatively high freezing point. Here's why:
- Freezing Point: Petrol freezes at a higher temperature than AVGAS. This means that at the extreme cold temperatures encountered at high altitudes, petrol could solidify or form ice crystals within the fuel lines and engine components, causing engine issues.
- Engine Complications: The formation of ice or solid petrol in the fuel system can lead to:
- Fuel starvation of the engine.
- Poor combustion.
- Engine failure.
- Safety Risks: Engine failure in an aircraft is a significant safety hazard that can have catastrophic consequences.
Comparison of Petrol and AVGAS
To illustrate the differences, let’s compare petrol and AVGAS:
| Feature | Petrol | AVGAS |
|---|---|---|
| Freezing Point | Higher | Lower |
| Suitability for High Altitude | Unsuitable | Suitable |
As indicated in the reference, petrol’s higher freezing point makes it a dangerous choice for aircraft, especially in the low temperatures encountered at high altitudes.
Because of the freezing risks and resultant safety concerns, AVGAS with its much lower freezing point is the only suitable choice for aircraft engines.
