Compare the reading son the airspeed, altimeter and VS while
pressurized and with the cabin vented at ambient. You could
have a static leak inside the pressure cabin that is letting
pressurized cabin air into the pilot's static line.


--
James H. Macklin
ATP,CFI,A&P

--
The people think the Constitution protects their rights;
But government sees it as an obstacle to be overcome.
some support
http://www.usdoj.gov/olc/secondamendment2.htm
See http://www.fija.org/ more about your rights and duties.


"Bob Gardner" wrote in message
...
| And my point is that absolute accuracy is not important.
|
| Bob
|
| "O. Sami Saydjari" wrote
in message
| ...
| Bob Gardner wrote:
|
| If there is no means of adjustment, the question
answers itself. Keep in
| mind that the blue line is not sacrosanct...actual Vyse
will vary with
| weight and density altitude. The vertical speed
indicator is a much more
| accurate means of determining best rate of climb.
|
| Well, not really. My question is whether their is a
good way to measure
| the absolute accuracy of a ASI. And my concern is that
6 nts is too far
| off when it could make a significant difference in
performance in critical
| situations, like single engine operation.
|
|
| Bob Gardner
|
| "O. Sami Saydjari"
wrote in message
| ...
|
| In my Cessna 421C, the pilot-side airspeed indicator
reads 6 nts below
| the co-pilot-side airspeed indicator. When I pointed
this out to a
| mechanic, he said that it was "within toleraance." He
said it was
| possible that one was 3 nts high and the other 3 nts
low and so both
| could be within tolerance. He added that there is no
real internal
| adjustment, so there is not much he could do about it
anyway.
|
| Seems to me that when you are talking about a possible
6nt difference and
| given the need for accurately maintain blue-line speed
in case of a
| single-engine failure, it is important to know that
one's airpseed
| indicator is accurate. Isn't there a way to judge true
accuracy of speed
| indicators (just as there is for altimeters)? Should I
be satisfied with
| my mechanic's answer and move on?
|
| -Sami
| N5554G, Cessna 421C
|
|
|