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masaki

Dial-a-flap in flight

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Hi all,I have a question regarding takeoff flaps, hopefully someone can explain. A few days ago, I was taking off from FAJS to HECA. It was hot and high and had a lot of fuel and payload onboard. I entered 22 takeoff flaps in FMS and selected via dial-a-flap. Obviously, due to takeoff weight, the V2 was rather high (175 kts or similar). I took of normally, maintaining V2 and engaged auto flight at 500ft AGL. Now, once I get into the acceleration phase, I notice the FR green mark on the speed tape is rather close to the flaps overspeed yellow band, so, at FR+5kts, I raise the flap. Normally, I would wait a little more but this time, as soon as I do that, I got into low speed protection, which in a way was expected, going from flap 22 to 0 at heavy weight, the stall speed increased. AP did it

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The FR is not a max flap speed, you could delay retraction up to max flap speed if you wanted to. The normal thing to do in your case would be to ensure acceleration during flap retraction to avoid a journey into speed protection. You could let the speed start accelerating before starting the flap retraction. An intermediate stop such as 15 on flap retraction doesn't help you accelerate, which is one of your key goals at this phase of flight.

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Hi Dan,I understand FR is not a maximum, rather a minimum recommended, I actually retracted 5kts above FR. I could have waited to accelerate 5 more knots and would have been fine, but I was close to flap overspeed. It just seems such an abrupt change in stall speed when going from 25 flaps and 0, especially since during descent, a 15 degree setting is available. I understand it would not help with acceleration, but would give a smoother transition to clean config. I wonder what the procedure in the MD11 is. I guess I'll have to watch the Martinair DVD again :)

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