Richard,
Further to Brian's advice, the Europa electrical system design included
a separate circuit with a switch and fuse or CB to feed the trim. Ivan
Shaw insisted that the pilot should still be able to operate the trim
even if the master switch was off, e.g. because of smoke in the cockpit,
so that it would be possible to conduct a forced landing without the
distraction of an out-of-trim force.
Of course, where you site the switch so that you could turn the trim off
quickly in the event of a runaway is a matter of cockpit layout.
Although heavy, I believe the forces on the Europa control column as a
result of a full trim runaway are not so large that the average pilot
could not cope, but there may well be airspeed or flight situations
where such a runaway would cause difficulties.
When there were in-service problems with trim runaway on the Hawker
Hunter, which had an all moving tail that could definitely provide
forces beyond the control of the pilot, the ability of a stray positive
to cause an commanded trim movement was virtually eliminated by
"back-contact earthing". This involved grounding the contacts of the
trim control when movement was not required. This is probably not
justified for a Europa, where it is less likely that a stray positive
would cause a runaway that was uncontrollable.
It is important to understand the actual circuit installed on your
aircraft, which may of course differ from the basic Europa diagram. Some
people have switches on one or both control columns, possibly operating
a relay. The greater the complexity, the more chance there is of a
contact getting stuck on or failing to operate.
I am sure others will respond with advice as to their experience of
exercising the trim at a safe height, airspeed and location (e.g. over
the home airfield) and saying whether this was reassuring or worrying.
Best regards,
Mike
Dr Mike Gregory
Europa Club safety officer
01480 451655
07885 355765
-----Original Message-----
From: owner-europa-list-server@matronics.com
<owner-europa-list-server@matronics.com> On Behalf Of Brian Davies
Sent: 08 April 2019 09:53
Subject: RE: Europa-List: Anyone experienced trim runaway?
--> < <mailto:brian.davies44@gmail.com> brian.davies44@gmail.com>
The LAA acceptance initial test flight requires an examination of the
effect of an electric trim runaway in both directions and at various
aircraft speeds in order to confirm that the aircraft remains
controllable after leaving the trim in a simulated runaway for 4 seconds
before taking any action, which would be to trip the CB to isolate the
system. I have not tried to simulate a runaway that takes the trim to
the full extent of its travel.
Regards
Brian
-----Original Message-----
From: <mailto:owner-europa-list-server@matronics.com>
owner-europa-list-server@matronics.com [
<mailto:owner-europa-list-server@matronics.com>
mailto:owner-europa-list-server@matronics.com] On Behalf Of Richard
Lamprey
Sent: 08 April 2019 08:24
Subject: Europa-List: Anyone experienced trim runaway?
--> < <mailto:lamprey.richard@gmail.com> lamprey.richard@gmail.com>
Having taken the Ethiopian Airlines flight from Addis to Nairobi
recently, the recent B737 tragedy made me think about aircraft systems
turning rogue=C3=A2=82=AC=C2 If there=C3=A2=82=AC=84=A2s an
electric trim runaway on the Europa (either nose up, nose down), is
there enough pitch movement in the column at normal C of G to contain
it? Has anyone had such experience? I seem to remember someone talking
about it some years ago, but can=C3=A2=82=AC=84=A2t find it in the
thread.
Richard
Europa Classic 912UL, 5Y-LRY
Read this topic online here:
<http://forums.matronics.com/viewtopic.php?p=488606#488606>
http://forums.matronics.com/viewtopic.php?p=488606#488606
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