Everytime I fly and approach, i hear a rumbling and I think there goes the gear. After a few minutes (final) there is again the same rumbling. What are these noises?
Another question, when I aprroached Charleroi in a ryanair 738, the thrust was decreased every 50 feet or so. I recognised the soynd and I think they started at 60N1. the noise decreased five times untill going to idle at 10 feet (around 25N1). I flew a return trip on a 737-300 and the sound the flaps made wanted me to spray some oil in the systems. In otehr aircraft the flaps make practically no noise at all.
Mysterious noises in aircraft; who can explain?
By: Spotty M Driver - 4th February 2004 at 22:02
Yeah lots of flap settings with Boings. I remember the 737’s Flaps 0,1,2,5,10,15,25,30,40, frickin 9 flaps settings, mad.
Gotta love the Airbus FBW, flaps like a Cessna 150 😀 😀
People often ask me what the noise is in the centre cabin after start, that’ll be the PTU doing its auto test and the clunking is the brake valves :p
Spotty M Driver.
By: wysiwyg - 4th February 2004 at 20:33
As Matthew says I’d imagine you are talking about the gradual deployment of further stages of flap in the latter stages of the approach (there are 7 different flap positions for the 757 while the 737 has even more). With both engines operational we would normally land a 757 with Flap 25 or 30 so there is a lot of deployment to do. Each time we put flap out it usually coincides with a need to slow down. On the 757 approximately 1.2 EPR (on RB211-535E4 engines) will give a suitable speed for just about all flap settings, so for example if you are coming down a 3 degree glideslope with the gear down and Flap 20 and 1.2 EPR at 160 knots, selection of landing flap while maintaining the thrust at 1.2 will drift the speed back to almost exactly Vref+5 which is our non-wind factored threshold speed. This is the only reson I can find for explaining a noise (flap movement) without thrust change.
By: Jeanske_SN - 4th February 2004 at 18:51
Maybe it’s moving to a specific flap setting that creates rumbling? But the noise is the same than on takeoff when the gear retracts. Wysiwyg, can you explain the different thrust settings on approach?
By: andrewm - 4th February 2004 at 13:25
Unless our me in flight sim 😀
By: wysiwyg - 4th February 2004 at 09:32
On most types spoilers would only be used in the earlier stages of the approach and almost certainly not with landing flap selected.
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February 3, 2004 at 7:43 pm