KCC's Quizzes: AQQ 236 about strange marking on airplane engines

OK, let's publish the official answer: The mark is a security sign: when the comma sign is static; it indicates the motor is not in rotation and therefore it is safe for the ground personnel to circulate around the plane. There were some feedback mentioning it could be to scare birds. And indeed there were studies made in that way, but the conclusion is there is absolutely no influence: birds were not impressed at all by that mark!

Congratulations to all having proposed the right answer and big applause to our 4 first winners:

* MTF_Walker , rkg ,TReinhardt RobB 

Be ready for the next coming quiz!

Regards

I guess the role is to hypnotize the passengers who are afraid to fly.

Is it to find out the direction of rotation (clockwise/anti-clockwise) of the blades?

Similar to the cycle wheel spokes phenomenon, once the rotation speed exceeds the refresh rate of the human eye, the wheels appear to rotate backwards.

Thnaks rahulnoolu18 , but no. It is really for security reason when the plane is on the ground. When flying, the rotation speed is such that one will not be able to see the sign anymore, hence the direction of the rotation

In the past, it is used to know the direction of rotation of engine propeller. In older aircrafts, the propeller needs to spin before the fuel is supplied. This helps the ground crew in spinning the propeller in the correct direction. Now, it is used to indicate if the propeller has started to spin. It is dangerous to work near powerful aircraft engines as one can be sucked inside when running. This marking will indicate if the engine is now running for the safety of ground crew.

to see its running

Yes, mainly for the ground maintenance people circulating around the airplane

Oh, thta's amazing, I didn't know that one! Interesting. Thanks!

To indicate/measure turbine rotation