Jump to content
Al Downs

Air speed gauge

Recommended Posts

The round air speed gauge shows 40kt when on the ground and builds from there when flying? Is there an adjustment or what can I replace it with. Digital air speed is fine and if we are at 100Kts the round one shows 140 kt

Share this post


Link to post
Share on other sites

Is this an UMA instrument? If so all I can suggest is to check the lines to be sure they are not kinked or have water in them (long shot I know). Otherwise I think it will have to be sent back to them for repair. I would guess $50-75.

Share this post


Link to post
Share on other sites

I have seen many airspeeds like that. This happens when someone blows air into the pitot system and it bends the diaphragm linkage. The other way is when performing the altimeter/encoder correlation the static and pitot pressures were not balanced causing the airspeed to go to far causing the same results. The only solution is to send it in for overhaul.

Share this post


Link to post
Share on other sites

Happened to mine several years ago when I took it to an avionics shop for the biennial transponder and pitot/static check. They ruined the round airspeed indicator but not the one in the D100. They got to buy me a new one which was just less than $300 at the time.

When I got in the plane to take it home I noticed the indicator showing something like 60K. Glad I caught it before leaving or it may have been on me. It was weird returning to homeplate. According to the indicator we were really moving out but it was the 100K indicated on short final that stood out!! Fortunately the D100 was working properly. Even if it hadn't been, not a problem in these aircraft, especially the CTSW where flaps 30 with the drooped wingtip level with the horizon and throttle closed you will be on speed.

Share this post


Link to post
Share on other sites
1 hour ago, sandpiper said:

CTSW where flaps 30 with the drooped wingtip level

I use this reference a few times a week.  Mostly on approach.

Share this post


Link to post
Share on other sites

I sent mine in right after I bought my CT for the same reason. It is a cheap instrument and does not have an internal adjustable snubber like TSO intruments. This causes the needle to shake. A VERY small hole in a rivet ( aircraft rivet) installed in the pitot line at the airspeed fitting connection solves the problem.

Share this post


Link to post
Share on other sites
16 hours ago, Madhatter said:

You do not need a pitot static check for VFR. Only transponder tests. 

I know. Haven't done it since then. I think I was just doing what I always did with my previous planes which did go IFR. Old habits, etc.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×