Arwel,
Pressure senders differ. When a rapid change occurs, they tend to lag or even
fluctuate for a moment. Bench test is the only way to assure yourself of what
is going on. Normally a momentary change in flow or pressure causes lights to
flash and all kinds of exciting things. Every manufacturer has a smoothing
method to prevent rapid needle or digit fluctuation. They are all annoying.
Most gauges and senders have their own idiosyncrasies. Normally a direct reading
fuel pressure has a very small orifice to dampen the gauge. If the gauge hookup
is teed into a line, the change in flow/pressure rapidly changes the direct
reading gauge. It is that damned Italian Bernoulli to blame. We forget that
pressure and flow are related. Change either and the other is quickly affected.
Put in a bleed orifice like the FS02 and that too affects the momentary
pressure/flow.
Sounds like you tested it out on the ground and all's well.
Gauges moving up and down after any change don't excite me unless I hear, see,
feel other changes. Sudden quiet does bother me though.
Best Regards,
Bud Yerly
-----Original Message-----
From: owner-europa-list-server@matronics.com
<owner-europa-list-server@matronics.com>
On Behalf Of arwel pritchard
Sent: Wednesday, April 21, 2021 6:47 PM
Subject: Europa-List: Rotax 912ULS Low Fuel Pressure
Good Evening
I noticed something strange this evening asI was climbing out at full
power, when I got to about 1000ft, I switched the electric fuel pump off
and the fuel pressure dropped quite alarmingly from about 0.32bar to
below 0.2bar. When I noticed it, I immediately switched the electric
pump back on to restore the pressure. I then leveled off, reduced power
and flew a tight circuit back to land.
After landing, I monitored the pressure at various power levels (with
mechanical pump only) and saw the pressure was at around 0.3bar
continuously.
I have seen it posted on various forums that its 'one of those things'
and its nothing to worry about, but I do!!
I should also mention that Im seeing the pressure on a mechanical gauge
as opposed to an electrical display readout.
Has anybody else come accross this before and is it a real problem?
Thanks
Arwel
G-BYPM
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