"Aaron Coolidge" wrote in message
...
Mike Rapoport wrote:

: The airspeed indicator seems to read correctly at cruise but it reads at
: least 8kts high around 55kts.

I can't speak for the Helio, but many Cessna airplanes have a conversion
table in the POH that describes the CAS - IAS differentials. It's quite
large at lower airspeeds, as I recall. I presume that its due to
pitot/static
errors that are not cancelled out (as they could be with an air data
computer). Do you suppose this may be the reason for the discrepancy?
The Cessna tables also noted that despite the error between CAS and IAS,
the range markings on the airspeed indicator were accurate. In other
words,
Vs0 was at, say, 44kts IAS and that was marked on the airspeed indicator,
while the calibrated Vs0 was a different number. I can't remember the
exact
wording, and I gave away my Cessna stuff years ago.

I'm not sure of the cause of the descrepancy. It could be water in the
pitot line or an error in the instrument. I am aware that most airplanes
have increasing IAS errors at lower speeds. My issue is that the IAS points
for my airplane seem to be quite a bit higher than in the skimpy flight
manual and higher than other people are getting. The Helio was certified in
the bronze age and only has minimal documentation. There are no detailed
charts for anything.

Anyway, have fun with the new toy.

I am!


Aaron Coolidge