Mailing List lml@lancaironline.net Message #32780
From: Art Jensen <flycassutts@yahoo.com>
Sender: <marv@lancaironline.net>
Subject: OAT probe location
Date: Thu, 10 Nov 2005 07:36:08 -0500
To: <lml@lancaironline.net>
Does any one have any ideas on the best location for
the OAT probe?

In my Legacy it is installed inside the NACA duct on
the pilot side of the plane.  The problem is that
while on the ground it reads exactly the same as the
oil temp probe and exactly the same as the thermometer
on the wall of the hanger.  However, in flight it
always reads much higher than actual outside
temperature.

For example, yesterday I took the temp reported on
ASOS which was 20C, I converted that to 68F.  I
subtracted the lapse rate of 3C or 5.4F degrees for
each thousand feet in the air where it should have
been 14F degrees.  If I used 2C as the lapse rate it
would have been 34F degrees.  On my Chelton it read
71F at 10,500'.  This happens on every flight so it is
not a temp inversion.  There must be something wrong
with the location.  I cannot believe it is getting
alot of heat from the engine with all the cold air
blasting across the probe through this fresh air vent
which is always open.  What else could it be?????  Any
ideas?  Is there a better location for the probe?

Art Jensen
Legacy 927J




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