Jason;

A couple of months ago I had the same problem. I called and talked to
Cambridge and they suggested I look at the altitude readings on screen
#6. There are 3 alt readings on this screen: Flight Level, GPS, and
Pressure. Mine read FL=590 ft, GPS=600 Ft, and PR=6000 ft. The needle
and audio would make large up/down movements at random times. I
returned the 302 to the factory for repair.

Rich

Jason Armistead wrote:

My club has a Cambridge 302 DDV (purchased in February/March 2003)
which oscillates wildly even when sitting on the ground. The needle
and audio are going haywire.

We have the latest firmware, V2.63, installed.

Audio and pointer responses on screens #4 anbd #5 are set at the
factory recommended 2.3 seconds value.

Going to screen #10 (sensor readings) showed the Indicated Airspeed
(IAS) as
13 (knots / km ?) with the glider parked on the ground. See page 11
of the 302 DDV manual (February 2003, Firmware V2.6 edition

This is definitely WRONG !!!

Section 2.2.1 on page 4 of that same document says

"Proper DDV function depends CRITICALLY on correct airspeed
measurement. It
is REALLY important that pitot and static pressure connections are
correct." and so on.

So my take on this all is that while the vario thinks the glider is
moving when stationary (and the GPS input to it indicating contrary to
this) , it will NEVER give accurate readings.

The "ASI" value shown on screen 10 is supposed to be a "Airspeed
Indicator
zero offset (should be less than 1000)"

What the manual doesn't say is how to CHANGE that offset to fix up
problems such as the one we're seeing.

I had a quick look at the IAS shown while flying, and at around 55 kts
on the mechanical ASI, the 302 screen #10 IAS was showing around 50
kts (somehow the accuracy seemed to improve when aloft). Because I
had a passenger in the back I really didn't spend much time fiddling.

I want to know how to change the zero offset value (screen #10 ASI
reading), which is wrong. Can it be done without opening the 302 -
opening it will break the security seal and prevent it being used for
badge claims !!!

As we're in Australia, the idea of shipping the unit back to the USA
for repairs is not encouraging.

Can someone help me PLEASE !!!

Cheers

Jason A.
Southern Cross Gliding Club
Camden NSW