Puchacz reviews

On Thu, 27 Sep 2012 05:36:30 -0700 (PDT), cuflyer
wrote:

Hello All,

I am looking for real world reviews of the Puchacz (or the newer Perkoz)
in the club / instructional environment.
How do they hold up to daily use/abuse?
Maintenance issues?
How are they for ab-initio?
Truth to the spin-eager rep?
Any bad habits?

Just a small addition since the same topic is just being discussed in
the German gliding board segelflug.de.


Since August of 2009, five letal accidents of Puchacz gliders with
nine people being killed an one injured badly.

Each time an instructor was on board.

http://aviation-safety.net/wikibase/wiki.php?id=137025
http://www.abc.net.au/news/2012-04-0...cident/3925952
http://aviation-safety.net/wikibase/wiki.php?id=144869
http://aviation-safety.net/wikibase/wiki.php?id=146849
http://aviation-safety.net/wikibase/wiki.php?id=137365
http://aviation-safety.net/wikibase/wiki.php?id=68075

Note that nearly all accident reports contain the word "spin" or
"stall".

Google "puchacz accident" - there's hardly a year where there was not
a Puchacz accident that killed both student and instructor.

Draw your own conclusions.


Andreas

On Thursday, September 27, 2012 8:36:31 AM UTC-4, cuflyer wrote:
Hello All,



I am looking for real world reviews of the Puchacz (or the newer Perkoz)

in the club / instructional environment.

How do they hold up to daily use/abuse?

Maintenance issues?

How are they for ab-initio?

Truth to the spin-eager rep?

Any bad habits?



Thanks,

Tim

Thanks for all your comments, folks. Very helpful.

Cheers,
Tim
1FL

Andreas's list is probably mainly stalls/spins (though 2 of the 6 are during the climb out on aerotow, which seems to me the least likely phase of flight for such an occurrence). But I wouldn't automatically say the Puchacz is unsafe, even though it has proportionately more stall/spin accidents than most other trainers.

My experience is in being trained as a UK Basic Instructor, a large proportion of which included stalls and spins. I find that it stalls or spins only when expected, normally with lots of warning, and recovers immediately with the correct control inputs more crisply and reliably than other trainers I've flown.

However, the Puchacz loses lots of height in these manoeuvres - for a one-turn spin around 800 ft compared to 350 ft or so in a K13. This gives a lower margin for errors. As an example, one of the accidents:

http://aviation-safety.net/wikibase/wiki.php?id=137365

is a spin off a practice aerotow rope break at 150m/500 ft. At that height, if the instructor doesn't prevent spin entry then the departure is almost certainly irrecoverable.

For that reason I wouldn't want to use a Puchacz for all aspects of basic training, at least unless the instructors were able to take special care in these no-margin situations and were prepared to take over control early. For upper air work, however, it's excellent .

The biggest concern I'd have is winch launching. The BGA recommendation is that minimum launch speed should be 1.5 x Vs, or 55kt. Max winch speed is 59kt, and a previous poster has written of damage from overspeed on winch launching. That 4kt window is very narrow!

As an advanced trainer, launching mainly by aerotow, I reckon the Puchacz is very good indeed.

The Puchacz handles very well on a winch launch, I have done
hundreds.

The biggest problem with the Puchaz is the a lack of orders, its
old technology (1970's) replacement the Perkoz is around the
£100,000 ready to go with trailer etc. The ASK 21 £110,000 for
the similar option.

Other than second hand there are no cheap gliders around.

Dave



At 18:21 07 October 2012,
wrote:
Andreas's list is probably mainly stalls/spins (though 2 of the 6
are
durin=
g the climb out on aerotow, which seems to me the least likely
phase of
fli=
ght for such an occurrence). But I wouldn't automatically say
the Puchacz
i=
s unsafe, even though it has proportionately more stall/spin
accidents
than=
most other trainers.

My experience is in being trained as a UK Basic Instructor, a
large
proport=
ion of which included stalls and spins. I find that it stalls or
spins
only=
when expected, normally with lots of warning, and recovers
immediately
wit=
h the correct control inputs more crisply and reliably than other
trainers
=
I've flown.

However, the Puchacz loses lots of height in these manoeuvres
- for a
one-t=
urn spin around 800 ft compared to 350 ft or so in a K13. This
gives a
lowe=
r margin for errors. As an example, one of the accidents:

http://aviation-safety.net/wikibase/...hp?id=3D137365

is a spin off a practice aerotow rope break at 150m/500 ft. At
that
height,=
if the instructor doesn't prevent spin entry then the departure
is almost
=
certainly irrecoverable.

For that reason I wouldn't want to use a Puchacz for all aspects
of basic
t=
raining, at least unless the instructors were able to take special
care in
=
these no-margin situations and were prepared to take over
control early.
Fo=
r upper air work, however, it's excellent .

The biggest concern I'd have is winch launching. The BGA
recommendation is
=
that minimum launch speed should be 1.5 x Vs, or 55kt. Max
winch speed is
5=
9kt, and a previous poster has written of damage from
overspeed on winch
la=
unching. That 4kt window is very narrow!

As an advanced trainer, launching mainly by aerotow, I reckon
the Puchacz
i=
s very good indeed.

The biggest concern I'd have is winch launching. The BGA recommendation is
that minimum launch speed should be 1.5 x Vs, or 55kt. Max winch speed is
59kt, and a previous poster has written of damage from overspeed on winch
launching. That 4kt window is very narrow!

Like posted here, winch launching is usually uneventful. I did wonder why
BGA promote 55 Kt (100 kmh). Manufacturer says 90kmh min, which is fine.
Still only gives you 20 kmh margin, not too much. Structural damage
occurred to a glider that routinely did 110-140 kmh, on a black weaklink.
Asking for trouble, but yes, it can happen.

On Oct 8, 6:15*am, Eric Munk wrote:
Like posted here, winch launching is usually uneventful. I did wonder why
BGA promote 55 Kt (100 kmh). Manufacturer says 90kmh min, which is fine.
Still only gives you 20 kmh margin, not too much. Structural damage
occurred to a glider that routinely did 110-140 kmh, on a black weaklink.
Asking for trouble, but yes, it can happen.

Not all of us have heard of this incident. Conventional (including
BGA) wisdom is that as long as the glider is structurally sound, and
the correct weak link is in use, exceeding max winch speed should not
result in structural damage, as the weak link should break well before
structural limits are reached. The specified weak link strength for
the Puchacz is 750 daN (red), it should be obvious that using a 1000
daN weak link (black) is an accident waiting to happen. What did
happen?

Marc

Not all of us have heard of this incident. Conventional (including
BGA) wisdom is that as long as the glider is structurally sound, and
the correct weak link is in use, exceeding max winch speed should not
result in structural damage, as the weak link should break well before
structural limits are reached. The specified weak link strength for
the Puchacz is 750 daN (red), it should be obvious that using a 1000
daN weak link (black) is an accident waiting to happen. What did
happen?

Like I said: glider was routinely flown above max winch speed on too-high
strength weak links. Mainly human factors involved ('but we've been doing
this for some years now and it's still allright isn't it?'), some national
regulations getting in each others' way (Dutch glider flying only on
off-home airfield on a German airfield where they only use red and black
weaklinks versus the usual Dutch blue/brown which are lower max strength),
and a winch drivers' mentality (and training) that overemphasized the risk
of stalls on winchlaunch (under underestimating the danger over overloading
gliders), leading to excessive winch launch speeds. Combined with
instructor experience (complacency) and some other factors (peer pressure,
pressure to fly the airplane, lack of understanding of the risk of
overstress) this eventually (after some months) led to structural damage
that became visible as spanwise cracks along the leading edge of the wing
which I noticed when the aircraft came in for an annual. The underlying
structure was compromised, leading to extensive GRP repairs to the D-nose
of both wings (at the factory).

In reply to the list of accidents with spinning:

Recently there was spin training (on a Fox) in The Netherlands. Out
of 20 instructors, only one got the Fox out of a spin without any
unintended maneuvers. Many instructors pulled to early after
stopping the rotation (and recovering the stall), causing a
spin/flick maneuver.
The one instructor that did it right the first time had extensive
aerobatic experience.

All I'm trying to say is: while it might appear from the statistics
that the Puchacz is at fault, other factors can also play a role.

Roel

What did happen?

Marc

- Lack of awareness of operational restrictions with the pilots (Vwinch
max)
- Local customs different than at homefield (black is standard in Germany.
In The Netherlands borwn is. As you state black is not within
manufacturer's specs)
- Complacency (on the instructors' part)
- Poor local winch driver training (highlighting the danger of slow
launches, but omitting dangers of overload during launch)
- Poor winch lay-out (small gas handle which made distributing the power
input difficult)
- And another couple of minor things, all combined make for a good
combination of overstressing a glider.

It was operated (very) regularly outside limits, and this came to light
during the next annual when I found significant spanwise cracking in the
wing nose structure. Went back to the factory for extensive GRP repairs to
both leadings edges before it was cleared for flight again.

1. As another (late) subscriber wrote, you will only find spin accidents in gliders that spin, and more frequently in those that spin easily when the inputs cause departure. Hence lots more spin fatalities in Puchacz than in K7/K13/K21. It does not mean that the Puchacz is in itself dangerous, but if abused, if not correct recovery, and if too low, yes it can kill. So can anything in one way or another if stupidly flown.


2. My understanding of the BGA guidance/advice about winch launch limitation speed is that IN THE LOWER AND MIDDLE PART of a winch launch, when the cabale is far from in line with the glider's weight and so adding only partly to the bending load on the wings, it is not dangerous to exceed the winch launch speed limit by a modest margin. IN THE TOP PART OF THE CLIMB however, when the cable is close to in line with the gravitational load and its vector is substantially additive, the winch launch speed should be respected. If too fast, at least lower the nose and reduce the load, or pull off. (Open to correction by current instructors etc., if the guidance is now pull off regardless.)

Chris N