Ever wondered why aircraft engines have Swirls painted on the tip of their spinners?
The use of these spirals can be traced back to World War 2 and is still being used by many jet engine
manufacturing companies like Rolls Royce, CFM, Pratt and Whitney, and General Electric.
The main idea of these swirls or spirals is to warn ground staff. Aircraft engines do generate deafening noises, however, on the ground, many jet engines are roaring at the same time.
Ground staff also use hearing protection to protect their ears from this deafening noise, making it difficult to tell which engine is running and which engine is not.
Also, at night ground staff may not be able to notice the engine rotating. These white spirals or swirls rotate as the engine rotates helping the ground personnel to identify a running engine.
This small little paint job can save lives as it’ll avoid humans from getting sucked in by the engine. A Boeing 737 engine at idle power has a hazard zone of 9ft to the front and side of the engine, increasing engine power will increase the area to up to 14ft.
No doubt, bigger the engine, greater the hazard area and higher the risk of being sucked into the running engine. But, is saving human lives the only reason? Birds have always been a threat to flying airplanes.
There are over 13,000 bird hit cases annually in the US alone and the Federal Aviation Administration (FAA) estimates that costs associated with bird strikes could be as high as $957million a year in the US.
This is because birds usually tend to move towards dark holes. A rotating spiral on an engine tip will thus help to scare away the birds moving towards it.
Many jet engine manufacturers believe that there has been a significant drop in bird hits
ever since they started painting these spirals. A small paint job could thus not only save a lot of money but most importantly save lives.
Different manufacturing companies use different paint jobs, the majority use Spirals, however, you may have
come across different shapes like a rectangle, comma, horseshoe spiral, hurricane, wobbly ball, etc.