[NSRCA-discussion] Trim Change

[J N Hiller]

OH I never thought about it being a TX problem. I hope not, I'm using a 9C
and it's the only TX I have suitable for pattern.
I have with two identical servos in the same environment acting the same
with no effect to the ailerons. I use the TX for several airplanes and will
probably fly my backup today. If it's the TX it should offset the rudder and
elevator as soon as the RX is turned on.
I don't think it was leaking for three years but it was sever, I could have
pulled the stopper out without further loosening of the screw. The threads
don't hold very well in the plastic disks and as a designer I would NEVER do
this.
Thanks for the heads up on the TX.
Jim

-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org]On Behalf Of Ed White
Sent: Thursday, August 06, 2009 9:42 AM
To: General pattern discussion
Subject: Re: [NSRCA-discussion] Trim Change

What Tx are you using?  I had a similar problem earlier this summer with my
Futaba 9Z.  Every flight required a few clicks of down trim, rudder and
throttle seemed to be drifting slowly also.  But otherwise the radio seemed
to be working.  I sent it in to Futaba where they replaced some gimbal parts
and some ribbon cables, but I think the only thing they did that could have
really solved this problem is replace the small Lithium battery that
maintains the memory.  It is rock solid now.

If your transmitter has such a battery (9Z and I think the 14MZ also has a
battery?), I would get that replaced.  If it doesn't have a battery, I would
definitely send it in for repair.  I would think you would need a lot of
exhaust on the servos for oil to get into the pots, but maybe after 3
seasons.

Ed

  _____

From: J N Hiller <jnhiller at earthlink.net>
To: NSRCA Mailing List <nsrca-discussion at lists.nsrca.org>
Sent: Thursday, August 6, 2009 11:26:40 AM
Subject: [NSRCA-discussion] Trim Change

Yesterday I was trying to get a few flights between thunder storms and
experienced abnormal elevator trim change.
I hadn't flown this airplane for about a month but it has been totally
reliable and predictable. My first flight was cut short due to repeated
fly-overs by a full size helicopter. I got an uninterrupted second flight
with only a beep or two of up elevator trim, which isn't excessive in
changing weather conditions. The third flight I had to add about three more
beeps of up trim and I thought the air was really getting thin. The fourth
flight needed about six more beeps of up trim but the airplane acted normal
so I continued. After landing I noticed the rudder was offset about 1/4", no
wonder the flight was a little screwy.
This airplane has a tight, full pull-pull cable system that never changes
mechanically. I had a centering offset of about ten beeps on both the
elevator and rudder servos and was changing the idle trim more than normal.
You electric guys can laugh now. The fuel tank stopped had loosened and
everything in the fuselage was wet probably all the way to the tail post.
The inside of the airplane is a mess and I will be flying the other airplane
in Redmond OR this weekend.
The receiver had a little oil on one corner of the case but appears to be
dry inside and doesn't even smell like fuel. I suspect the centering change
resulted from fuel getting into the servo pots. I'm reluctant to get into
them that deep and will probably just scrap them. After three seasons they
were due for replacement anyway.
Jim Hiller

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