The certification requirement for G with flaps is usually +2/0, but remember this is part of certification flight testing so normal POH limits are not necessarily applied. I would expect the calculated safe limits to be on the test card for the serial.
“It was interesting to see the stalls [spins] being done flaps down. Extra points. I usually whip the flaps up when it breaks, "
Exactly my reaction to the video. Also g-limits are low flaps-down in the typical piston singles I fly. Does the PC-12 have high g-load limits flaps down?
Excellent demonstration.
Consider a stick pusher as a stall barrier, it does not prevent a stall, it introduces a barrier to getting there – but a pilot can still get there with effort/super carelessness. More importantly, the stick pusher can fail. The design requirements state that it must not be possible to cause an unrecoverable spin with any use [misuse] of the controls. But this is not one of the design requirements which says that it must be done without unusual pilot skill. Recovering an abused stall might require unusual pilot skill, but it can be done. The pilot might very suddenly achieve unusual skill, if he spins it. So the stick pusher, assuming normal operation, helps the careless pilot not get the plane fully stalled, and in a spin. It was interesting to see the stalls [spins] being done flaps down. Extra points. I usually whip the flaps up when it breaks, as passing through Vfe is likely in a spin recovery.
I’ve never flown a PC-12, but during my spin testing of a modified Caravan, the recovery was as required – it did, but it was exciting! Similar to what you see with the PC-12, the Caravan would easily roll upside down. Bear in mind that the design requirement states “normal use of the controls” during entry and recovery – nothing prohibits the use of ailerons. The Caravan Flight Manual does say that using ailerons during recovery might prolong the recovery, simply because the up going aileron also operates a spoiler.
The recovery at forward C of G consistently resulted in a rate of descent momentarily exceeding 9000 FPM, accelerating to Vne, and 2.8G to prevent exceeding Vne. But perfectly repeatable. Aft C of G spins were very different.
Forward C of G spin video:
This looks exciting, but let me tell you it’s heart stopping when you’re inside the plane. I did some of those with a Pilatus test pilot many years ago and it was scary. That was before i did my aerobatic rating but still, when such a heavy plane rolls inverted like that … no fun!
The dramatic stalls you see are without the pusher. Those with the pusher active are benign and straight ahead.
But that’s because with the stick pusher there is no Stall in the first place. It simply pushes the nose down long before the wing stalls.
Thank you for posting. Given that it is a T-Tail it was good to see that after the un-commanded roll, recovery without a stick pusher was predictable.
this would be a perfect snap roll entry
…MH you would normally be applying some acceleration (typically 2G at basic/intermediate) for a snap roll entry; in the video they appear to be applying ‘normal’ stall entry, gently increasing back pressure close to 1G, reducing speed by a knot per second – which somewhat makes a lot of stall practice somewhat artificial.
Remember that the aircraft is certificated with a pusher because it’s normal stall behaviour is “undesirable”. The dramatic stalls you see are without the pusher. Those with the pusher active are benign and straight ahead.
@Silvaire, this may be the most obvious case, I think.
@Nestor, it depends on the control input. I have experienced power on stalls in a C150, resulting in a bad executed snap roll because of unexpected pilot inputs. In the video the pilot applies right aileron all the way at one point and then the plane reacts by rolling over the stalled wing. If he had applied right rudder, too, and neutralised it when he was overcorrecting with the aileron, this would be a perfect snap roll entry. In any case the left wing stalled completely and the right doesn’t. This means the plane keeps on rolling until either the right wing stalls, too, or both wings get unstalled. So it does, what it’s expected to do :-)
“normal” is not what was stated. The statement was “as it should be”.
And could it be the issue was rather with pilot behaviour than with aircraft behaviour, anyway?
Not an expert, either, though.
