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mr.crocodile
30th Jul 2015, 14:12
Hi, I hope some experts could answer to a couple of questions about flaps on 737-800.
How much time does it take the system to fully extend the flaps from 0 to 40? In this video https://www.youtube.com/watch?v=cld62K4ntbk seems that for complete extension it takes about 1 minute.
Is the speed constant during all the range?
Does the flaps gauge indicate in every instant the exact position of the flaps during the extention or its movement is independent from the exact flaps position except for the final position (for example flaps 15)?

Thanks

Yeelep
1st Aug 2015, 02:23
The video shows flap ext./ret. with "B" system electric pump. The electric pump output 5.7 GPM, whereas the engine driven pump outputs 36GPM. Because of this the flaps are much slower on the electric pump. With engines running the time for 0-40, 40-0 is around 25 seconds.
The speed is generally constant, though on electric only they slow way down when the leading edge devices are moving.
There is a flap transmitter at the left and right outboard flap transmissions which sends the position signal through the FSEU to a dual pointer gauge in the flight deck. The gauge indicates the actual position of the left and right wing flaps whether they are moving or not.

mr.crocodile
1st Aug 2015, 06:41
Excellent reply. Thanks a lot