airspeed indicator

[moriches1]

having troubles with the airspeed. it is accurate at slower speeds but when you go faster it reads low. any idea where to start looking?

thanks
danny

[aadamson]

Originally Posted by moriches1

having troubles with the airspeed. it is accurate at slower speeds but when you go faster it reads low. any idea where to start looking?

thanks
danny

The obvious areas to check would be Pitot/static plumbing for leaks (the whole system)

Is pitot in a "standard' location, using standard hardware? Same for static?

If not then all bets might be off. if so, then I'd suspect the gauge. Are we talking *lots* or *little* as the definition of "off" and how did you determine *off*?

[Vern]

I went thru similar travails with my 6A a/s .

Getting the A&P to do a pitot static check on my system gave absolute direction to solving my issues.The equipment used is more useful than I thought at solving pitot-static issues. For $100 I solved many hours of small issues. I strongly recommend it.

1>A small leak at the pitot wing-to-fuselage junction.
2>New behind the panel push-on tubing onto barbed fittings as opposed to original leaky Nylok style fittings/tubes eliminated a few suspect areas
3>The A/S indicator was replaced because the original one leaked excessively. It was an imported mph TAS style where you can set temp on a scale to get TAS. It seemed to indicate low as if it were a knots mechanism with a mph face. Anyway, I tossed it and the new one works great.

[Kevin Horton]

Things to check:

1. Pitot system leaks,
2. Static system leaks,
3. ASI instrument error, and
4. the accuracy of the method used to determine airspeed system error (some methods are very accurate, but some home-brew methods are mathematically incorrect).

There is lots more info on my web site:
Determing static system error
Pitot-static system links

[joeboisselle]

Just fealing smart, but the airspeed reads low when you're going fast? Sure it does! l tell all my friends that too...