Menu Sign In Contact FAQ
Banner
Welcome to our forums

Mythbusters

5 - "You have to pass the Air Law exam before your first solo"

One shouldn't use flaps in a turn? Mmm, not sure about that one.... A myth? Or good advice?

Personally I think that the risk of asymmetry makes this good advice.

EGTK Oxford

Personally I think that the risk of asymmetry makes this good advice.

Yes but if you have the flaps out for a reason (usually it would be slow flight) and you have to make a turn, then you have to make a turn with the flaps out.

If you are making a turn then, unless the turn involves a continued vertical acceleration downwards, the wing loading will increase as a result of the bank angle, and if you retract the flaps at that point, your Vs will rise and you could stall, purely as a result of retracting the flaps.

Flap retraction in slow flight has caused many fatal accidents in airliners. I think this is the classic UK one.

If you get full flap assymetry then you are having a seriously bad day I think, on most certified GA types, it is hugely unlikely, due to interconnection via the hull.

You have to pass the Air Law exam before your first solo

That one may be country dependent. In the UK, this appears to be a universal practice. I haven't got a clue what the actual regs are, and they are changing so fast nowadays...

Administrator
Shoreham EGKA, United Kingdom

Let me be clear, I don't think extending flaps during a turn is a good idea. I am fine with turning while they are out. I equally do not think retracting them in a turn is a good idea.

EGTK Oxford

I once had asymmetric flap extension, in a TB10 in fact. It was due to faulty maintenance, the torque tube was not fastened to the airframe in one wing. It was moderately alarming, obviously increasing with more flap selected.

I think the original point was not supposed to mean that you shouldn't turn with flaps extended, but was meant to say don't alter flaps in the turn.

I still don't think it's a likely cause of problems, and I alter flap whenever I want to.

Darley Moor, Gamston (UK)

One shouldn't use flaps in a turn? Mmm, not sure about that one.... A myth? Or good advice?

Sorry, yes, to be absolutely clear, I do mean one shouldn't actually extend them while in a turn. Well, that's what I've always been taught, but Jean Zilio - guru of French GA with over 16,000 hours of instruction (!) - states quite categorically in his "Guide Pratique du Pilotage" that there is 'no particular reason why one shouldn't extend flaps in a turn'....

Bordeaux

One shouldn't use flaps in a turn? Mmm, not sure about that one.... A myth? Or good advice?

Total urban myth

Wine, Women, and Airplanes = Happy
Canada

One shouldn't use flaps in a turn? Mmm, not sure about that one.... A myth? Or good advice?

Total urban myth

Well I have seen asymmetric deployment of flaps and (separately) speed brakes. It is obviously manageable but I don't want to learn about it in a bank at low level. Maybe this can be put in the bucket of opinion rather than myth?

EGTK Oxford

Regarding the flaps. The underlying reason, I think, for not making configuration changes in general in a turn, is that it makes aircraft control harder on the student/early PPL.

In a turn, especially when it's relatively steep, you have to increase the backpressure to maintain altitude. This leads to induced drag, which requires a tad of extra power (or even full power) to compensate. That's why steep turns are taught and practiced. In a descending turn (like base or final) you can't even use the altimeter to see if you're doing things right, and you have to fly by look and feel. (That's also one reason that base and final turns are normally taught and done with relatively shallow bank angles - it takes more skill to get them right at higher bank angles. Plus of course the increased G loading increases the stall speed.)

Now combine this with flap extension. Which adds drag and typically causes a pitch change as well. Keeping the aircraft under control and on the right flight path all of a sudden becomes a lot more complicated.

Sure, if you are experienced on type and are able to fly the aircraft by feel even through turns and configuration changes, it's no problem at all to combine both. But for a student, early PPL or when transiting to a different type, I guess it's a good idea not to combine those.

Regarding Air Law. It's a widespread practice but there is no basis in any regulation for it. The only regulation with regards to the order of things in the PPL syllabus is that you have to have passed all the theory exams, and done the QXC, before you may attempt the skills test.

I have no problem with extending flaps in the turn. I've flown with instructors who have said it's not good practice, but really.... it's not something I'll worry about in an aeroplane I know very well (including various flap failure mode experiences), though I can see why students and low hour PPLs might be disuaded from doing it.

Barton is my spiritual home.
Sign in to add your message

Back to Top