Post Go back to editing

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

Most of us, when boarding airplanes have seen all the motors marked with a kind of "comma" sign in their centers as shown

in the above picture.

Question: what is its role?

Hide replies until user replies
[edited by: emassa at 8:53 PM (GMT -4) on 1 Jun 2023]
Please share your answer to view other submitted answers
  • Hi Kuo-Chang,

    My guess is that it is there to show the ground crew whether or not the blades are rotating or not, for safety reasons.  It could be oriented in that particular way (chirality) to also show the direction of rotation of the turbine blade.  I guess it could also be used to measure the speed of rotation with a stroboscope.  My last wild theory is that it is there to mesmerise oncoming birds!

  • Bingo Martin, you get it! The mark is really a security item for the people operating around the plane; it indicates if the engine is still rotating.

    I am not sure if it is really used to measure the rotation velocity.... If so there must be an optical sensor somewhere...

  • Thanks Kuo-Chang,

    I put in the comment about preventing bird strikes as a joke but apparently they have done studies on this, although the results are inconclusive.

Reply Children