Clive,
I haven=92t had much of a problem with the stall warner switch itself, but
now days, I put the switch in the wing and run wires to the panel and place
the light near the airspeed indicator and the buzzer, if wanted, on the un
derside of the panel top so it will resonate. The switch is adjustable fro
m the aileron belcrank access door with a Phillips head.
I had problems in some installations running a long tube from the wing to t
he cockpit as the Europa Mod installation states, and getting the accuracy
I expected even with tight connections. I moved the sensor to the wing and
it was fine. Go figure. The tubing is quite firm and doesn=92t expand so
I couldn=92t figure it out and it wasn=92t worth the time.
At 7.5 mbar or 3 inches of water(about 45 Knots IAS) pressure it is pretty
easy to check on the ground. Check your wiring first. Bypass the switch a
nd check the light/buzzer. Push 3 inches of water pressure to the inlet tu
be and or the sensor in the fuselage (using a manometer) and check the swit
ch operation. If it checks on the ground it should work in the air. Your
Ops check for your periodic inspections is: Light should be on when stoppe
d, stay on until about 50-55 on takeoff. Come on about 3 Gs at Vman or man
euvering speed or 5-10 knots above the straight ahead stall of course... S
ince the wing stalls near 17 degrees, and the inlet tube is pretty close to
that, you should be getting full pressure in the tube and if the switch gr
ound checks, it all should work.
RS 317-443 and Herga 6753 are identical switches. Honeywell has switches b
ut are not adjustable so are worthless.
China has a manufacturer: Antunes controls. Their SMD series is in th
e range. Big and heavy and is plus or minus .5 inches water, so not terr
ibly accurate.
8021203090
0.17" to 6" W.C.
Yes
I find that it is important to check all pressure and temp sensors for accu
racy. Sensors are not always out of the box accurate. Test it and be in t
he know for sure. If it works on the bench, try installing the sensor clos
er in the wing near the spar connection. That=92s why we call it experiment
al, we get just enough info to learn what really works for us.
Of course you can spend much more money and time and research AOA systems a
nd put one of those in.
To be honest, I prefer the stall strips. Nice rumble just prior to the sta
ll. See POH chapter 9. No bells or whistles. A straight wing plane needs
little more normally. But electronics are nice=85.Sort of=85
Regards,
Bud Yerly
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s 10
From: clivesutton<mailto:clive.maf@googlemail.com>
Sent: Friday, June 16, 2017 5:23 PM
Subject: Europa-List: Stall Warner - switch problems
I have the 0.072 PSI/5mBar/500Pascal Vacuum stall warner switch supplied by
Europa fitted in G-YETI (RS Components part No 317-443) but I'm struggling
to get it to work correctly - despite changing the switch for a new one to
day.
The first switch would not reliably make contact at the stall warn speed (l
ight/intermittent squeaks at varying speeds) and whilst the other does work
more reliably it is closed/the horn sounds once the a/c is back on the gro
und/at zero to low forward speed.
Has anyone else had this problem and can share how they fixed it or can any
one recommend another more reliable switch (based on personal experience in
use) please? The pipe between switch and the hole just below the wing lea
ding edge is correctly connected to the NO port A btw.
All inputs appreciated
Clive S
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