Accelerated spin in unexpected direction at low altitude

At 05:33 05 July 2018, Bruce Hoult wrote:
On Wednesday, July 4, 2018 at 9:38:27 PM UTC-7, Charlie Quebec wrote:
Because of the large number that have spun to the ground and killed the
occupants perhaps?
The Puch is overepresented in these kinds of accidents.

And generally with an instructor on board. And not spinning accidentally
in
the circuit, but spins deliberately initiated at altitude.

They recover just fine 99.99% of the time. But it seems that every so
often
.. no.

All the Puchacz spin ins I know of had a most likely reason that no
recovery action was initiated.

One because a couple of instructors kept it spinning until too low to
recover. There was a voice recording and no indication of a problem
recovering, or any attempt to do so.
One because it had a low cable break and the instructor did a low circuit,
got too slow round the final turn.
One because the pupil froze on the controls so the instructor couldn't get
the stick forwards. I saw that one.
And one where the instructor seems to have had a heart attack and the pupil
didn't cope.

The Puchacz recovery process is normal and what matters is to move the
stick forwards to pitch the nose down to reduce the angle of attack and so
unstall the wing. It takes more movement than a Ka13 but not more than a
lot of single seaters.

Chris

At 06:44 05 July 2018, Chris Rowland wrote:
At 05:33 05 July 2018, Bruce Hoult wrote:
On Wednesday, July 4, 2018 at 9:38:27 PM UTC-7, Charlie
Quebec wrote:
Because of the large number that have spun to the ground
and killed the
occupants perhaps?
The Puch is overepresented in these kinds of accidents.

And generally with an instructor on board. And not spinning
accidentall
in
the circuit, but spins deliberately initiated at altitude.

They recover just fine 99.99% of the time. But it seems that
every s
often
.. no.

All the Puchacz spin ins I know of had a most likely reason that n
recovery action was initiated.

One because a couple of instructors kept it spinning until too low
t
recover. There was a voice recording and no indication of a
proble
recovering, or any attempt to do so.
One because it had a low cable break and the instructor did a
low circuit
got too slow round the final turn.
One because the pupil froze on the controls so the instructor
couldn't ge
the stick forwards. I saw that one.
And one where the instructor seems to have had a heart attack
and the pupi
didn't cope.

The Puchacz recovery process is normal and what matters is to
move th
stick forwards to pitch the nose down to reduce the angle of
attack and s
unstall the wing. It takes more movement than a Ka13 but not
more than
lot of single seaters.

Chris



Well said Chris! The Puchacz is a superb training machine . It
comes out of the spin as well as it goes in! Anything will hurt if
you don’t use the correct recovery procedure of spin too close to
Mother Earth.

Mark

At 19:31 05 July 2018, Mark Wright wrote:
At 06:44 05 July 2018, Chris Rowland wrote:
At 05:33 05 July 2018, Bruce Hoult wrote:
On Wednesday, July 4, 2018 at 9:38:27 PM UTC-7, Charlie
Quebec wrote:
Because of the large number that have spun to the ground
and killed the
occupants perhaps?
The Puch is overepresented in these kinds of accidents.

And generally with an instructor on board. And not spinning
accidentall
in
the circuit, but spins deliberately initiated at altitude.

They recover just fine 99.99% of the time. But it seems that
every s
often
.. no.

All the Puchacz spin ins I know of had a most likely reason that
n
recovery action was initiated.

One because a couple of instructors kept it spinning until too
low
t
recover. There was a voice recording and no indication of a
proble
recovering, or any attempt to do so.
One because it had a low cable break and the instructor did a
low circuit
got too slow round the final turn.
One because the pupil froze on the controls so the instructor
couldn't ge
the stick forwards. I saw that one.
And one where the instructor seems to have had a heart attack
and the pupi
didn't cope.

The Puchacz recovery process is normal and what matters is to
move th
stick forwards to pitch the nose down to reduce the angle of
attack and s
unstall the wing. It takes more movement than a Ka13 but not
more than
lot of single seaters.

Chris



Well said Chris! The Puchacz is a superb training machine . It
comes out of the spin as well as it goes in! Anything will hurt if
you don’t use the correct recovery procedure of spin too close to
Mother Earth.

Mark


P.S. I think the accelerated spin to which you refer is called a high
speed stall with yaw in the U.K..

At 06:36 04 July 2018, CindyB wrote:

Don't spin a Puch without chutes and a hard deck(1000m agl). Ever.

Best wishes,

Cindy B

Setting a hard deck of 1000ft agl is not really of much use. It is very
unlikely that you would be able to make a successful abandonment if in
a spin at 1000ft. You should really double that if you are serious about
having a hard deck which leaves you with another option if the spin
cannot be stopped. I rejected an abandonment with a control restriction
in level flight at 1000ft as I was not sure that I had the time. My
parachute was reputed to open and decelerate in time at 750ft when it
was new.

The reasons why Puchs have spun in is speculative in most cases. In
most cases the only witnesses worth anything at all, who could tell you
what happened, couldn't. It is very easy to blame pilots who are unable
to speak for themselves. As far as I can make out in most cases the
cause should have been recorded as undetermined. Probably is just not
good enough.

On Thursday, July 5, 2018 at 3:00:06 PM UTC-7, Don Johnstone wrote:
At 06:36 04 July 2018, CindyB wrote:

Don't spin a Puch without chutes and a hard deck(1000m agl). Ever.

Best wishes,

Cindy B

Setting a hard deck of 1000ft agl is not really of much use. It is very
unlikely that you would be able to make a successful abandonment if in
a spin at 1000ft. You should really double that if you are serious about
having a hard deck which leaves you with another option if the spin
cannot be stopped. I rejected an abandonment with a control restriction
in level flight at 1000ft as I was not sure that I had the time. My
parachute was reputed to open and decelerate in time at 750ft when it
was new.

The reasons why Puchs have spun in is speculative in most cases. In
most cases the only witnesses worth anything at all, who could tell you
what happened, couldn't. It is very easy to blame pilots who are unable
to speak for themselves. As far as I can make out in most cases the
cause should have been recorded as undetermined. Probably is just not
good enough.


Don: Cindy said meters not feet.

I have also been instructing & regularly spinning the Puchacz in many different configurations for 17 years now. In Australia our "hard deck" has always been 1000ft agl.

At 22:35 05 July 2018, Steve Koerner wrote:
On Thursday, July 5, 2018 at 3:00:06 PM UTC-7, Don Johnstone
wrote:
At 06:36 04 July 2018, CindyB wrote:

Don't spin a Puch without chutes and a hard deck(1000m
agl). Ever.

Best wishes,

Cindy B

Setting a hard deck of 1000ft agl is not really of much use. It is
very
unlikely that you would be able to make a successful
abandonment if in
a spin at 1000ft. You should really double that if you are serious
about
having a hard deck which leaves you with another option if the
spin
cannot be stopped. I rejected an abandonment with a control
restriction
in level flight at 1000ft as I was not sure that I had the time. My
parachute was reputed to open and decelerate in time at 750ft
when it
was new.

The reasons why Puchs have spun in is speculative in most
cases. In
most cases the only witnesses worth anything at all, who could
tell you
what happened, couldn't. It is very easy to blame pilots who are
unable
to speak for themselves. As far as I can make out in most cases
the
cause should have been recorded as undetermined. Probably is
just not
good enough.


Don: Cindy said meters not feet.

Sorry I missed that, 1000 metres is a sensible number.

At 03:03 25 June 2018, wrote:
I witnessed Jantar Std3 doing 180 from downwind to short final in 60
degree of bank at an altitude about 150 feet. In the middle of RIGHT 180
turn the glider flipped LEFT and made ONE full turn of accelerated spin in
about 2-3 seconds before hitting ground.

Does anyone know the date and location of this accident. I haven't heard
back from the original poster in this regard.

Normally you think of a spin associated with turning flight where there is an inside wing that is going slower than the outside wing and thus already at a higher AOA than the outside wing. The discussion about flipping into a spin to the outside seems very weird until you start thinking about a turn at very high bank angle.

Consider a turn at 90 deg bank angle. In that case there no longer is an inside wing going slower than the other. Both wings are on equal footing with respect to their vulnerability to stall. In a very steep turn, it's easy to see that the top wing could well stall first if there was a bit of yawing action introduced or if the air had the right sort of irregularity to it. Near the ground, horizontal wind shear is the commonplace and could easily provide the irregularity that would be the impetus for a "backwards" spin. Clearly, depending on the degree of shear that's going on, the bank angle could be well less than 90 degrees and still get the backwards spin induced.

n Friday, July 6, 2018 at 3:14:51 PM UTC-4, Steve Koerner wrote:
It is confusing when the top wing is coming down instead of the bottom wing, for sure, but the airplane is spinning to the direction of the rudder. To recover, opposite rudder and forward stick is needed, just like the "normal" spin.
Dan
Normally you think of a spin associated with turning flight where there is an inside wing that is going slower than the outside wing and thus already at a higher AOA than the outside wing. The discussion about flipping into a spin to the outside seems very weird until you start thinking about a turn at very high bank angle.

Consider a turn at 90 deg bank angle. In that case there no longer is an inside wing going slower than the other. Both wings are on equal footing with respect to their vulnerability to stall. In a very steep turn, it's easy to see that the top wing could well stall first if there was a bit of yawing action introduced or if the air had the right sort of irregularity to it. Near the ground, horizontal wind shear is the commonplace and could easily provide the irregularity that would be the impetus for a "backwards" spin. Clearly, depending on the degree of shear that's going on, the bank angle could be well less than 90 degrees and still get the backwards spin induced.