Ulmo133 Posted September 16 Report Share Posted September 16 Hello CTfliers, I'm encountering a problem with my anemometer since I replace the 2-blades Neuform by the E-Props Glorieuse. When I carry out the engine test at 4000 rpm, the anemometer is alive and indicating around 40 km/h. I'm afraid this is also the case in flight, and particularly on take-off and landing, giving an erroneous IAS value. During the test, the variometer and altimeter didn't move, so I don't think the static is to blame. Pitot is far away from the propeller wind and also on the right side so theoretically not influenced by the the propeller wind. Has anyone encountered this or could help me solve the problem? I'm already going to perform these tests: - Try an engine test put with the pitot protection - Check that I don't have a damaged or disconnected tube on the pitot line (or the static line) but I don't think it has any influence when the engine is running, as the lines don't pass through the propeller flow. Thank you and good flights. Quote Link to comment Share on other sites More sharing options...
Madhatter Posted September 16 Report Share Posted September 16 Just run a pitot static test with a test box if you know a shop that has one. There are other options but I don't want to describe them as they are easily done incorrectly . Best to use a pitot/static test setup. Prop should not have anything to do with it. Quote Link to comment Share on other sites More sharing options...
Skunkworks85 Posted September 16 Report Share Posted September 16 My Dynon airspeed will some speed at higher power levels. ( i have noticed this with a short field take off, Brakes applied and full power) Like you stated, Put the cover on it at try at the same power setting. Quote Link to comment Share on other sites More sharing options...
Ulmo133 Posted September 16 Author Report Share Posted September 16 Thanks. It’s planned but first I will try to check if the static and pitot lines are clean. But anyway, I test and the speed I saw on the anemometer is clearly linked with the RPM (on ground + brakes). And the anemometer start moving around 2500 RPM and clearly more after 4000. I will let you know as soon as I perform some test Quote Link to comment Share on other sites More sharing options...
Ulmo133 Posted September 23 Author Report Share Posted September 23 After checking, there is what I discovered : lines static and pitot are ok (no damage) with pitot plugged or not, same result at 4000 RPM : 45 km/h on the two anemometer and +200ft/min on the variometer. with pitot unplugged and static plugged at 4000 RPM : no problem. So first I will clean the static line blowing from the inside to the outside in it. And will recheck. Quote Link to comment Share on other sites More sharing options...
Madhatter Posted September 23 Report Share Posted September 23 You can not check pitot/static integrity by how they look, ever. You can have leaks that occur within the instruments themselves. I have found many, including in my CT after I bought it. My leak was in the airspeed indicator and it made a significant difference in approach speed. Quote Link to comment Share on other sites More sharing options...
Ulmo133 Posted September 24 Author Report Share Posted September 24 Thanks for information. But it was a first look if I saw cracks or something else on the tube. Anyway the problem comes from the Static and clearly from the entry point as I have no problem when I plug it. Quote Link to comment Share on other sites More sharing options...
Anticept Posted September 24 Report Share Posted September 24 On mine it was the hosing near the fittings that was leaking. Quote Link to comment Share on other sites More sharing options...
Ulmo133 Posted September 24 Author Report Share Posted September 24 As I install an EFIS I will change the hoses anyway but the problem doesn't appear if I plug the static inlet and run my engine test at 4000 RPM, so I think it's either dirt at the inlet or the flow, which would be very different from that of the old propeller (but I don't know how to solve that...). Quote Link to comment Share on other sites More sharing options...
Tom Baker Posted September 24 Report Share Posted September 24 I have seen the indicated airspeed before while doing a run up. It happens because the airflow around the aircraft during the run up creates a low pressure on the static port. These airplanes are FLIGHT tested to determine where to place the static port for neutral pressure during flight. They are not tested to see if there is a low pressure during run up. The airflow around the airplane is much different in flight compared to doing a run up on the ground. In my experience the indication during run up does not relate to there being an issue in flight. Quote Link to comment Share on other sites More sharing options...
Ulmo133 Posted September 24 Author Report Share Posted September 24 I understand but this is new and not happened before. I also have 20km/h more indicated than GPS speed with no wind in final and stall at 85 with 30 degrees flaps and IAD falls in the last 10m when I cut the power. And it’s was also not the case before. So I’m pretty sure I have a IAS problem. Quote Link to comment Share on other sites More sharing options...
Madhatter Posted September 24 Report Share Posted September 24 You have an indicator or static leak or both most likely. Should be easy to determine. Again get a test box, should only take 10 min. Quote Link to comment Share on other sites More sharing options...
Ulmo133 Posted September 25 Author Report Share Posted September 25 I will try to find one. Thanks. Quote Link to comment Share on other sites More sharing options...
Madhatter Posted September 25 Report Share Posted September 25 6 hours ago, Ulmo133 said: I will try to find one. Thanks. An avionics shop is where you will have to go. Most people don't have one. It's also very easy to damage instruments if someone doesn't know how to use it. Quote Link to comment Share on other sites More sharing options...
Ulmo133 Posted September 25 Author Report Share Posted September 25 I have an avionics shop close to my airfield (20 minutes flight including take off and landing) I will ask him. Quote Link to comment Share on other sites More sharing options...
Madhatter Posted September 25 Report Share Posted September 25 When I had my avionics repair station I found that about 50 to 75 percent of VFR aircraft failed. VFR aircraft aren't required to have a 2yr pitot/static check but when I installed new equipment tied into it I had to. Quote Link to comment Share on other sites More sharing options...
Ulmo133 Posted Sunday at 03:24 PM Author Report Share Posted Sunday at 03:24 PM Hello I go to the avionics shop and everything is okay with the pitot/statics. Before this, I blew out the lines and after all this, problem remains. I tried to plug the static port, no more issue. I tried measuring the static inside the cabin, and no more problem. Next step, I will made in flight measurement of the speed and altitude, with normal static and static taken from the cabin to check if there's a difference in the different flight phases. As I said, I've had this problem since installing the variable pitch propeller, but I'm not sure if it's related. Could pilot show me the different position of static ports ? My are under the pilot seat. Thank you. Quote Link to comment Share on other sites More sharing options...
Ulmo133 Posted Sunday at 03:48 PM Author Report Share Posted Sunday at 03:48 PM I found a topic. I will ask my question on this one. Quote Link to comment Share on other sites More sharing options...
Madhatter Posted Sunday at 04:04 PM Report Share Posted Sunday at 04:04 PM An interesting issue and I'm sure there is a simple reason. Some issues are so small they are overlooked. Maybe there is a distortion in airflow over the static port, it could be anything. Maybe put the old prop back on to verify, maybe one blade is off on pitch causing an airflow distortion, could be anything. You will have to methodically look everything and eliminate variables each time. I have run into these type of issues before and have always found the problem. Sometimes they required a lot of time and analysis. One point on prop pitch settings, I noticed that digital protractors have terrible repeatability. I set the first blade with a digital protractor and match the rest of the blades to it with a machinist bubble protractor. Bubbles don't lie. I can't tell what the problem is but you eventually find it. Quote Link to comment Share on other sites More sharing options...
Ulmo133 Posted Monday at 09:02 AM Author Report Share Posted Monday at 09:02 AM Thank you Madhatter. In this case it's a variable Pitch propeller from E-Props. So the angle of the blade is not the question. And a disassembly / Reassembly of the old one will be a pain in the a... I have to check all of this. I will let you know. Quote Link to comment Share on other sites More sharing options...
Madhatter Posted Monday at 01:19 PM Report Share Posted Monday at 01:19 PM Like Tom said, it may not be an issue in flight. You have the ground just under the static opening which probably changes the pressure gradient. Go fly and note the A/S during a power off stall, I'm betting it's normal. Quote Link to comment Share on other sites More sharing options...
Skunkworks85 Posted Monday at 01:28 PM Report Share Posted Monday at 01:28 PM My AC did the same thing with the neuform and the eprop. Quote Link to comment Share on other sites More sharing options...
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