Mark89114 Posted September 23, 2019 Report Share Posted September 23, 2019 (edited) The airspeed indicator in my 2000 Ovation is reading “funny”, 90 to 130 kias, it seems to jump around a bit, up and down 3-4 knots, doesn’t appear to be an issue faster or slower. Again this is just approximate. Just curious if airspeed indicators wear out? I am assuming some type of gears connected to a bellows internally? Or is it the lines feeding the system? I do check the pitot and static drains, and pulling the alternate static air doesn’t seem to make any difference. Just looking for thoughts on where to start troubleshooting. Edited September 23, 2019 by Mark89114 Spelling Quote Link to comment Share on other sites More sharing options...
carusoam Posted September 23, 2019 Report Share Posted September 23, 2019 Mark, Check Both drains... Static and pitot. Static is below the N, Pitot is under the pilot wing near the pilot’s position... Alt air... under the instrument panel... Then pitot static system check... is the ship IFR current? Been in any rain lately, heavy winds in rain while parked outdoors can be challenging... Some drains have been shown to leak with age... or dirt. Few ASIs seem to show wear... at least in Ovations around here... Could be a good reason to consider the next step though... TXI, Aspen, G5.... PP thoughts only, not an instrument mechanic... Best regards, -a- Quote Link to comment Share on other sites More sharing options...
Mark89114 Posted September 23, 2019 Author Report Share Posted September 23, 2019 Everything is current, airplane is hangered, doesn't fly in much moisture. I check the pitot static drains and alternate static. Question is how do you test the drains for leakage? That pitot one is riveted in there, I think and I don't recall any access. Will look next time. Pushing into yellow, it doesn't vary, 90-130 it jumps quickly up and down in landing/final approach it is pretty steady. Right now just throwing it out there to see if there is any collective wisdom. I will try to get some video. Thanks. Mark Quote Link to comment Share on other sites More sharing options...
Guitarmaster Posted September 24, 2019 Report Share Posted September 24, 2019 Does the altimeter jump at the same time?Sent from my Pixel 2 XL using Tapatalk 1 Quote Link to comment Share on other sites More sharing options...
Mark89114 Posted September 24, 2019 Author Report Share Posted September 24, 2019 No. Quote Link to comment Share on other sites More sharing options...
takair Posted September 24, 2019 Report Share Posted September 24, 2019 14 hours ago, Mark89114 said: Everything is current, airplane is hangered, doesn't fly in much moisture. I check the pitot static drains and alternate static. Question is how do you test the drains for leakage? That pitot one is riveted in there, I think and I don't recall any access. Will look next time. Pushing into yellow, it doesn't vary, 90-130 it jumps quickly up and down in landing/final approach it is pretty steady. Right now just throwing it out there to see if there is any collective wisdom. I will try to get some video. Thanks. Mark Is this in light turbulence? As they age they do lose some damping. 3-4 knots in bumps does not seem terrible. My 50+ year old ASI jumps a little more than that. Even some EFIS aircraft bounce if the software filtering is not optimized. The drains are tested with a pitot/static test set as part of the leak check. Usually an avionics shop thing. Leaky static more likely to cause bouncing, leaky pitot can cause calibration issues. One way to test is plumbers clay over drain, but you risk getting it in the mechanism, causing more expense....so the avionics shop is the preferred way. Quote Link to comment Share on other sites More sharing options...
Rjfanjet Posted September 24, 2019 Report Share Posted September 24, 2019 Had a GTX335 installed for ADSB out. When they did the pitot static test, found the airspeed indicator line had a hole rubbed in the line. Replaced the line. Ran test again and found all pitot static instruments were leaking around the case. 3AMU's to overhaul instruments, including labor to install. Should be flying again Friday. It's been a long 4 weeks. Quote Link to comment Share on other sites More sharing options...
0TreeLemur Posted September 24, 2019 Report Share Posted September 24, 2019 AI probably needs overhauled. I've seen that kind of jumpy behavior in a MP gauge before back when I had one. Quote Link to comment Share on other sites More sharing options...
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