So What’s With The Aircraft Engine Spirals Symbol?

If you’ve ever boarded an airplane from outside the terminal via a ladder, you might have been close enough to see the engines of the plane. Upon closer inspection, you might notice that at the center of the engine point is a depiction of a spiral, which spins and eventually turns into a white spinning symbol once the engines start spinning at full speed. Sometimes the symbol doesn’t resemble a spiral, rather it looks like a comma, or a typhoon symbol, or even a wobbly crescent. Sometimes you’ll see that there is no symbol at the center of the spiral. But what significance do these symbols, if present, have?

The practice of drawing symbols at the aircraft engine’s center has been present since World War II. The main reason for implementing these designs is for the safety of ground personnel. Standing near an engine, even when it’s running at idle power, is extremely dangerous. At idle power, the engine has a hazard zone of 9 ft, meaning that anyone stepping within 9 ft around the engine risks being consumed by its sheer strength. At full power, that zone extends to 14 ft. With designs at the center of the spiral as well as around it, ground personnel can take note when an engine is running. When running the spiral (or whatever symbol has been depicted) will be spinning, letting others know not to venture close.

There are some theories prevalent that suggest that the symbols can scare oncoming birds. Bird impact can cause extensive damage to the engines and to prevent any more harm to the animals, aircraft engine spirals, as the theory says, can startle birds away during taxi, takeoff or landing. Multiple studies have been done by Japan’s All Nippon Airways (ANA), the University of Ohio, as well as many others. While ANA found a small reduction of bird impacts on airplanes with “engine eyes, many others concluded inconclusive results. In the modern era, most major manufacturers, such as Boeing AIrcraft and Rolls Royce, seem to take the stance that aircraft engine swirls do not significantly reduce bird impacts. For inquiries on engines with or without symbols, contact the folks now at ASAP Buying.

At ASAP Buying, owned and operated by ASAP Semiconductor, we can help you find all the NSN parts for the aerospace, civil aviation, and defense industries. We’re always available and ready to help you find all the parts and equipment you need, 24/7-365. For a quick and competitive quote, email us at or call us at  +1-714-705-4780.


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