Interview
with Henk Dumont by webmaster Leo, after a flight to Spa that ended
up a little bit different than planned. Maybe this article also could
have been called "Shaken, not stirred", but after all, ask
a pilot to pronounce W and he will answer "Whiskey" and not
"Wodka Martini, shaken not stirred". But, as you will read,
"shaken" is the right word for Henk's feelings after ending
this flight.
Also a word of warning for other Taifun 17EII pilots!
February
15th, 2007
Henk Dumont:
"Today I planned to make a flight from Geilenkirchen (ETNG, my
homebase) to Spa / Belgium (EBSP), a distance somewhere about 30 NM
in a straight line. The reason for this short flight is that I wanted
to make a test flight after I made some check ups on the oil and brakes
system earlier this week. After a period of 4 years every Taifun must
at least have changed the oil in the brakes system one time. That's
why I dissassembled the brake claws, cleaned them, blew out the brake
cylinder with some air-pressure, cleaned that one too, mounted new O-rings
(meant for sealing the cylinder), rubbed them in with petroleum jelly,
replaced the old (Bosch DOT-4 brake fluid) oil with the new one (same
kind of course), put new brake claws on, assembled the whole system
again and checked everything to be sure the brakes would function as
they were supposed to.
Image 1:
Wheel brakes as seen from the outside
Image 2: For the tech freaks; brake system as seen from
the inside (behind the seats)
Since everything worked perfectly after this revision, I filed a flight
plan at Frisbee Tower, to make a short test flight to Spa-La Sauveniere,
a small private-plane-friendly airfield just across the German-Belgian
border.
Weather was very inviting this morning with skies all clear and the
winter sun shining brightly from above when at 10.47 a.m. I was taxying
to the runway. Damian, a friend of mine and also member of LSV Geilenkirchen,
joined in as a co pilot. Frisbee tower opened the flight plan minutes
before and so we were free to take off at 10.50 . After a little less
than half an hour we contact Spa-info and are allowed to go for final
right away.
Unpleasant surprise
Flying on final I suddenly notice that the airspeed brakes (pulled half
the way) seem to be stuck. Something is holding the brake lever from
being pulled back! There's only limited space for the lever to move
back and forward! Within seconds I realize that Spa's asphalt landing
strip (800 x 30 m.) is much too short to land for a Taifun with no brakes.
I've got no possibility to use the ground brakes, I can't slow down
as much as I want to because of failing airbrakes and on both sides
of the Spa landing strip trees and hills are preventing a low approach.
I decide to contact Spa info again and tell them I'm having brake problems.
I discontinue my descent and try to gain safer altitudes. Im very lucky
to find it's possible to push the brake lever back (in "zero"
position), so the airbrakes are not constantly slowing down my speed.
There's no time to wonder what my have caused this failure, first priority
is to contact Geilenkirchen Frisbee Tower that I'm returning home for
an emergency landing. No need for worries that the landing strip over
there might be too short; ETNG´s 3051 meters of concrete runway
are more than enough for a safe rolling out with no brakes. 20 Nm Southwest
of Geilenkirchen I contact Frisbee tower to let them now of my problems
and that I didn't land at Spa. Frisbee tower immediately responds: "Roger
sir, please contact when entering CTR. We will be taking necessary precautionary
measures." I reply that making an extra 360 at the base was no
problem since my tanks are almost full, but immediately they let me
know that I am number one to land !
Number one to land
From the
air both my copilot and I see they didn´t make a joke at Frisbee
Tower when they said we were number one to land. A complete esquadron
of firefighters, police and a rescue team are ready in case something
might go wrong during our emergency landing. Because of the presence
of these rescue teams, we are ordered to make a full roll until the
end of the runway. After a slow approach we are able to land with neglible
problems (other than having no brake system of course) and at the end
of the runway we turn the Taifun to taxi very carefully towards the
hangar. There we have to fill out a lot of paper work (which actually
is quite understandable) to attend to all required formalities.
My compliments and respect goes out to all Tower Crew and Controllers
of the E3/A compound at Frisbee Tower, who (as always in this kind of
situation) kept their heads very cool and have been very helpful in
this critical situation.
At the hangar I pull D-KFDI on to its undercarriage and start looking
around for the cause of this unexpected surprise. This takes a while,
because much of the brake system can only partly be seen from above,
but after half an hour of bending and stretching my neck into all kinds
of curves finally the problem reveals itsself.
A broken rod !
When examining the rod behind the seats that connects the air
brakes with the wheel brakes I discover that it´s broken. It seems
that what once must have been a minor crack or a weak spot near the
weld turned into a real break which caused my problems earlier this
day. At first I´m quite shocked. Imagine that during the flight
I hadn´t put the brakes in overlock, then a vacuum force could
have easily sucked out the air brakes which could have led to my Taifun
ending up in the trees during take off!
In fact you could say the two of us have been very lucky today.
In my humble opinion the crack must have been caused by a faulty construction
error. As some of you might now I have been a high pressure welder during
a large part of my professional life and while examining the line of
the crack I found out that it´s not the weld itself where the
T-shaped part of the rod has broken off, but right next to the weld!
|
Image 3: At first glance it appears that the crack has occured
right on the welding line |
|
Image 4: Closer examination learns it has broken off right next
to the weld |
|
Image 5: In fact, there's quite a large part on the other side
of the weld still intact |
I
took some pictures of the T-shaped part (three of these pictures you
can see above) and sent them to Korff Company, together with the part
itself. Korff confirmed they too thought this break was not caused by
a bad welding, but by a construction failure. At the moment the part
has been sent elsewhere for further examination.
Attention please
Without knowing the outcome of this examination I would like
to warn every Taifun owner at forehand to check his or her Taifun (be
it 17E or 17EII) to check this part of the brake system for minor cracks.
This is not an easy job though! The best is to put a mirror underneath
the system, cause from above the part where the crack has occured is
not visible. You really have to put a mirror underneath to make an inspection.
To help you a little bit with your search, please have a look at the
following picture.
|
Image
6: Where to look for the crack |
The
cylinder-shaped part which forms the head of the T-shape can be found
within the yellow dashed rectangle. The green arrow actually points
to a part that is above this cylinder, but the part where you should
look for minor cracks is situated on the same spot, but underneath
the cylinder, not on top of it! Just because it's underneath you will
need the mirror.
After contacting Cornelia Korff several times we have found out that
only a Taifun 17EII is equiped with a part that's akind the one that
broke off in Henk's plane. Therefore: if you own a Taifun 17E there's
no need to worry, if you own a 17EII, then you should surely check
your brake system for minor defects.
If your Taifun is suffering the same problem you should immediately
quit flying and contact Cornelia Korff at Korff
Company in Germany!
During the weeks I faced this problem myself my Taifun has been grounded
and I have been waiting for a spare part. At the moment (March 19th)
I'm lucky to say that after a full day's work I have re-assembled
the brakes system and I'm happy that I'm able to fly again.
But as said before: all Taifun owners should really check this part
!!!"
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