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test flew my new 170B today

PostPosted: Thu Apr 29, 2021 2:47 am
by Fandango8691
Hello all, I joined a few months back, and have just been reading up and lurking here for the most part. I bought a 1952 170B here in the Austin area. We finished up the annual last week, and then it took me a few days to button everything up, clean, etc. Today I flew it, and it flew VERY nice. It was a bit gusty, but over all a good short shakedown. The only issue really today was the airspeed indicator. It read very low. On the order of 15-20 mph low. First approach/landing, it felt like i had a bit too much energy, but continued... bounced a bit, still wanted more, finally it settled down a bit, got it airborne again, and went up to 3000ish to check it out. The initial buffet and horn werent until like low 30s indicated! did several, got an idea of a new adjusted values for approach and landing. Next was a bit better, but still need lots of practice. Got a bit blustery and called it a day.. Now begins the process of trying to fix this. Where should I start? My son is low time, and will be starting to fly the plane soon after we get it sorted. He has his private single and multi, getting ready to start commercial instrument. We also have a piper apache and he will be splitting time between the two. Thanks in advance. I look forward to getting to know y'all here.

Re: test flew my new 170B today

PostPosted: Thu Apr 29, 2021 1:27 pm
by brianm
My first instinct is always to reproduce the problem on the ground if possible. So I'd start with a pitot-static check to verify and quantify the error. An avionics shop can do it easily enough, or if you ask around somebody might have to equipment to DIY. If the error is still there, start dividing and conquering. Disconnect the instrument from the pitot system. Test the instrument directly and if necessary replace or overhaul. Check the pitot plumbing for leaks or blockages and fix what you find.

Re: test flew my new 170B today

PostPosted: Thu Apr 29, 2021 2:13 pm
by c170b53
Welcome to the association. Good lurking, I didn’t realize you were a new member :D . Texas is well represented in the association, hopefully you can meet up with Ken, Richard and George just to name a few, at one of their fly get togethers.
Brian has a good response to isolate the issue, hopefully its just a connection in the Pitot. Good luck with the machine

Re: test flew my new 170B today

PostPosted: Thu Apr 29, 2021 4:20 pm
by Fandango8691
brianm wrote:My first instinct is always to reproduce the problem on the ground if possible. So I'd start with a pitot-static check to verify and quantify the error. An avionics shop can do it easily enough, or if you ask around somebody might have to equipment to DIY. If the error is still there, start dividing and conquering. Disconnect the instrument from the pitot system. Test the instrument directly and if necessary replace or overhaul. Check the pitot plumbing for leaks or blockages and fix what you find.


Thanks. Yep, ground would have been better, it seemed reasonably normal on initial take off roll, but it was pretty windy so it didn’t seem out of sorts really until airborne. I am on the list with a few others in the near future for fir check/cert by mobile guy, but of course want it close before it’s checked. I had to go back on the road for 4-5 days, so I will begin tracing it when I get back. Much appreciated, look forward to flying when schedule works out.

Re: test flew my new 170B today

PostPosted: Fri Apr 30, 2021 9:58 am
by Bruce Fenstermacher
Look in the Cessna Maintenance Manual '62 and prior for the pitot tube template to compare your pitot angle to what it should be. This template is for the original metal tube pitot. If you have a L pitot, you have to use the template to swag the correct angle for you L pitot.

It is not that hard to build a manometer which you can use for testing. https://www.google.com/search?q=manomet ... e&ie=UTF-8

Search EAA for the conversion from inches of water to airspeed.

Look for a blockage in your pitot line or a leak. A typical blockage is a drop of water or a bug carcass. After that, and it likely is, your indicator.

But it is fun and somewhat satisfying building a manometer and running tests, specially running your indicator to 150 mph and dreaming your airplane is GREEN. :mrgreen:

Re: test flew my new 170B today

PostPosted: Sun May 02, 2021 9:14 pm
by mmcmillan2
Welcome, I live near Bryan, and currently hangar CLL. We have a 170 fly in this Saturday May 8th 11am at Gate 12 on the field CLL.