DJ Todd B Posted July 4, 2020 Report Share Posted July 4, 2020 Hello folks. I just developed an aerodynamic harmonic type noise which increases with airspeed. The noise starts at around 70 knots but does not follow the engine RPM. I have included a link to the camera footage which was not hooked up to the audio panel so the audio you hear is from inside the cockpit and not through the audio system. Has anyone experienced this before? My Oil Access door doesn't seem to shut flush to the cowl and I am thinking that this may be the problem. I am going to tape it shut and fly it tomorrow to see if the noise goes away. Does anyone know how to fix these fasteners or get new ones so that the door stays flush with the cowl while in flight? I also have quite a bit of Stabilator play (up and down) but Roger said that this particular model doesn't have the replaceable bearings but I am still worried about the SLOP and possible flutter. Quote Link to comment Share on other sites More sharing options...
Roger Lee Posted July 4, 2020 Report Share Posted July 4, 2020 I doubt that it's the oil inspection door. You could still get a new fastener and get it shut farther though. Here's where I would start and then move on from here. Look real close at the wing gap tape if you have any. I mean close on top of the wing, but really close under it. Several hear have had high pitch or whine type noises that change with speed. Most times it was a slit or crack in the wing gap tape. Quote Link to comment Share on other sites More sharing options...
Warmi Posted July 4, 2020 Report Share Posted July 4, 2020 Different plane and different problem but I had a very similar noise with a cracked BRS canopy opening which was structurally similar to what Roger suggests - the opening was taped and I ended up with some fluttering tape. Quote Link to comment Share on other sites More sharing options...
KentWien Posted July 4, 2020 Report Share Posted July 4, 2020 I had this exact sound with a crack in the wing root tape. I removed the tape, cleaned the residue with goo gone and never put the tape back on. Quote Link to comment Share on other sites More sharing options...
Skunkworks85 Posted July 4, 2020 Report Share Posted July 4, 2020 11 hours ago, KentWien said: I had this exact sound with a crack in the wing root tape. I removed the tape, cleaned the residue with goo gone and never put the tape back on. I had he same noise too, It was the root tape at the leading edge of the wind. Replaced and sound went away. Quote Link to comment Share on other sites More sharing options...
DJ Todd B Posted July 5, 2020 Author Report Share Posted July 5, 2020 SO... is it OK to remove ALL the WHITE tape from the Aircraft to see if the noise goes-away or will it create OTHER noises where the voids are exposed? Quote Link to comment Share on other sites More sharing options...
Roger Lee Posted July 5, 2020 Report Share Posted July 5, 2020 Just re-tape the wing root. When you apply the 1" Bolus tape do not stretch it. Just lay it down. Stretching will cause cracks. Quote Link to comment Share on other sites More sharing options...
DJ Todd B Posted July 5, 2020 Author Report Share Posted July 5, 2020 Where do I get the 1" Bolus Tape? I can't seem to find it online. Quote Link to comment Share on other sites More sharing options...
GrassStripFlyBoy Posted July 6, 2020 Report Share Posted July 6, 2020 https://www.cumulus-soaring.com/bowlus.htm Quote Link to comment Share on other sites More sharing options...
AGLyme Posted July 6, 2020 Report Share Posted July 6, 2020 I need some white tape... I tried to buy it in a West marine store but they were out... (the tape is used to wrap rigging, etc it is rugged as hell) Quote Link to comment Share on other sites More sharing options...
DJ Todd B Posted July 6, 2020 Author Report Share Posted July 6, 2020 I went to the Cumulus Soaring website and tried to order the tape but it said... The page you requested cannot be found! Then I went to The Wings and Wheels Website and it says they are out of stock. What a way to run an airline! Quote Link to comment Share on other sites More sharing options...
George in San Diego Posted July 6, 2020 Report Share Posted July 6, 2020 Wing tape is usually the prime suspect but I believe I have a new buzz spot. My tape is tight so I had to look for something else. In my case (2008 CTLS) the heater duct and its attached rubber pieces behind the cowl are suspect. Noise starts about 80. After one flight I pulled the upper flap outside and it didn't buzz until 100 kts..but then was REALLY loud. Put it back inside and it changed back. There are four pieces. The small section on the right has a chunk broke out of it. Also, the rivets holding the chute are loose which may be contributing. It's out of Annual now and my mechanic of seven years moved out of state so, due to that and "other stuff", we are just sitting...again. A couple of you know what I'm talking about sigh. Quote Link to comment Share on other sites More sharing options...
DJ Todd B Posted July 6, 2020 Author Report Share Posted July 6, 2020 Do you have any Photos of this area George? Quote Link to comment Share on other sites More sharing options...
George in San Diego Posted July 6, 2020 Report Share Posted July 6, 2020 2 hours ago, DJ Todd B said: Do you have any Photos of this area George? I’ll post a video. IMG_7857.MOV Quote Link to comment Share on other sites More sharing options...
FlyingMonkey Posted July 6, 2020 Report Share Posted July 6, 2020 If you can't find the bowlus tape, Spruce has this: https://www.aircraftspruce.com/catalog/cspages/3mvinyltape.php?clickkey=29747 It's very similar but somewhat thicker IIRC. I have used it on the stab/tab line before. They also have this, which I have not used but looks potentially suitable, but super pricey at $48 for six yards (because Teflon!) : https://www.aircraftspruce.com/catalog/cspages/teflonantichafetape.php?clickkey=29747 Quote Link to comment Share on other sites More sharing options...
DJ Todd B Posted July 6, 2020 Author Report Share Posted July 6, 2020 Thanks George, I will remove the cowl and investigate. Quote Link to comment Share on other sites More sharing options...
FlyingMonkey Posted July 6, 2020 Report Share Posted July 6, 2020 11 hours ago, George in San Diego said: Wing tape is usually the prime suspect but I believe I have a new buzz spot. My tape is tight so I had to look for something else. In my case (2008 CTLS) the heater duct and its attached rubber pieces behind the cowl are suspect. Noise starts about 80. After one flight I pulled the upper flap outside and it didn't buzz until 100 kts..but then was REALLY loud. Put it back inside and it changed back. There are four pieces. The small section on the right has a chunk broke out of it. Also, the rivets holding the chute are loose which may be contributing. It's out of Annual now and my mechanic of seven years moved out of state so, due to that and "other stuff", we are just sitting...again. A couple of you know what I'm talking about sigh. Hmm...I'm skeptical of this explanation. I have a hard time believing you'd hear any noise from that inlet duct, being under the cowl and right next to all the engine/prop noise. That said, those rubber pieces are looking pretty beat up and it's probably time for replacements. I think you can just get some suitable pieces of rubber, drill out the attach rivets, and rivet the new pieces into the same holes. Or drill new holes if the old ones get too wallowed out in the process. Quote Link to comment Share on other sites More sharing options...
Roger Lee Posted July 6, 2020 Report Share Posted July 6, 2020 I'd be surprised if it is the rubber. Seen many with rubber broken or missing. Never a sound. It has almost always been the wing tape. Not to mention it is always best to go after the most common cheapest and easy known issues first then progess outward to other less common causes if it didn't work. Quote Link to comment Share on other sites More sharing options...
DJ Todd B Posted July 6, 2020 Author Report Share Posted July 6, 2020 My wing tape and other tape around the fairings look good but I will replace any of them that are frayed then take it up again to sear/hear. Quote Link to comment Share on other sites More sharing options...
Roger Lee Posted July 6, 2020 Report Share Posted July 6, 2020 DJ, Many times the tape slit is very hard to see and it acts like a an instrument reed. It will also make noise many times if the tape on the underside doesn't go all the way back to the flap bracket. When someone comes into the shop and complains about a high pitched noise that changes at speed then the first thing I do is replace the wing gap tape. That will take care of it 99 times out of a hundred. There have been several here that swore it couldn't be that or their tape was fine only to discover it was the tape. It's quick cheap and easy to replace. Wipe the old tape residue off before applying the new tape and remember to not stretch the tape. Just lay it down because it will flex while flying and if it's been stretched tight it will split. Double tape the leading edge about 8-10 inches back on the top and bottom. You can lay the second layer exactly right on top of the first and won't even see. This protects the tape from the wind forces on the edge. Quote Link to comment Share on other sites More sharing options...
George in San Diego Posted July 6, 2020 Report Share Posted July 6, 2020 55 minutes ago, Roger Lee said: I'd be surprised if it is the rubber. Seen many with rubber broken or missing. Never a sound. It has almost always been the wing tape. Not to mention it is always best to go after the most common cheapest and easy known issues first then progess outward to other less common causes if it didn't work. I searched for a photo somewhere of what the chute rubber is supposed to look like but had no luck. I agree from past experience it would be tape flapping like a reed and I found a loose spot and re-taped it. Unfortunately this did not change anything which is why I went looking elsewhere. It's interesting that this sound is not cancelled by the headsets. Wrong frequency I guess. It's hard to believe the sheer power of that sound considering how loud the mechanical noises are. Quote Link to comment Share on other sites More sharing options...
AGLyme Posted July 6, 2020 Report Share Posted July 6, 2020 To Roger's point about the slit "reed effect"... I went on a two hours trip yesterday and for the very first time, I had a slight hum... and sure enough one of the tapes had a slight slit to it... so, I will replace the wing tapes... which takes almost no time at all. I will experiment with the Marine rigging tape if I can find it and report back... It should have the characteristics we seek... withstands heat, flexible and should be able to be removed easily. Quote Link to comment Share on other sites More sharing options...
George in San Diego Posted July 6, 2020 Report Share Posted July 6, 2020 If anyone has not yet experienced this effect, in my case it sounds just like the stall warning horn in a Cessna. Instinctively, one lowers the nose but that makes this problem louder. Likewise, if you pull up and slow down, it goes away. It's a strange quirk indeed. Quote Link to comment Share on other sites More sharing options...
CTSWguy Posted July 22, 2020 Report Share Posted July 22, 2020 Did you have a Garmin GPS antennae installed on the top of the fuselage near the trailing edge of the left wing? I’ve got the same problem and I think that is the cause. Quote Link to comment Share on other sites More sharing options...
DJ Todd B Posted July 22, 2020 Author Report Share Posted July 22, 2020 Nope. This sound is new and I installed my ADSB over 150 hours ago. Quote Link to comment Share on other sites More sharing options...
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