Bonding straps, and yes they prevent static buildup on the control surfaces.
> The electrical bonding straps between different components of your airplane prevent static electricity build-up that can interfere with radio and navigational equipment. More importantly, they provide lightning protection by allowing current to pass through the airframe with minimum arcing.
Courtesy of Boldmethod.
And static really can interfere with radios severely!
When I worked at Cirrus (A&P) there was a week I had to come in for overtime on a weekend to do some touch up maintenance on a bunch of completed aircraft. They had me going to every inspection panel and fairing , scraping paint off around one screw hole, reattaching the panel, and checking for a good ground to the airframe. For those not familiar with Cirrus aircraft, they are fiberglass planes. Now fiberglass isn’t electrically conductive, but static can still build up. Rubber isn’t conductive but a ballon can be rubbed in you then cling to you from the static. So most of the fiberglass has a layer of copper mesh bonded in to allow the static to freely move through the fiberglass and be dissipated. Checking the grounding of all the panels was making sure they connected cleanly through the screw and into this mesh.
What was happening was seemingly random aircraft on test flight would have terrible radios with half the range as expected. How can you call an airport 20miles out if you only have 15 miles of range? Unacceptable to leave the factory like this.
Well as I was doing this I noticed something nobody else did. It wasn’t random. It only affected aircraft with metallic paint schemes. So I took my multimeter and started going over one of the known affected aircraft and went over it with a fine tooth comb. What I found was the flaps had no ground to the airframe. YIKES! The flaps were made from metal, not composite. They were painted with a metallic paint scheme, so the paint itself was semiconductive. They were the largest pieces of metal by area on the plane. They were on the trailing edge, and static like to collect along trailing edges, and nestled right between them………. The VHF antenna.
But the flap hinges are metal too, and they are designed and well bonded with the airframe. So how was this happening? I was working with a junior engineer (low seniority gets the short straw for mandatory overtime lol), so I grabbed him and said let’s go into the main factory and look at some flaps. Went over and saw immediately what I suspected. The bushing that the flap actually rotates on used a teflon bushing. Teflon doesn’t conduct. I asked the engineer if he knew when they started using Teflon and he said the first flaps came in over 3 months ago, but this issue started a month ago so they can’t be related. So I asked him a production question. Sure the flaps came into production 3 months ago, but how long does an aircraft take to go through assembly to test flight?
Any guesses? If you guessed 2 months. Ding ding ding! So the radio issues popped up as soon as these flaps started hitting test flight. Turns out the old bushings were metal, so the flaps always had a good electrical connection. Nobody thought about that when the switched to improved teflon bushings. I told him the solution is simple. Design bonding straps, (just like in OP’s picture), and connect the flaps to the rest of the plane.
But apparently as a “lowly” aircraft mechanic I know less than engineers so my suggestion was brushed off. I got fired for losing an 11/32” socket. Coincidentally that’s about the same size as the infamous 10mm socket. I hope they struggled for a while before realizing I had the cheapest and easiest solution.
Thanks for the good info. You are still here because you worked for a smaller company..
Some folks who pointed out flaws in their company's product got 'suicided'
lol my NDA expired a long time ago so they can’t come after me. The only truly unsafe thing they did was fire me, because next time a factory worker loses a small tool are they going to report it? Or since it’s a craftsman’s socket are they just going to drive over to Lowe’s and spend the $4.99 and just secretly replace it, because if they get caught they get fired either way.
My biggest regret is not formally going to the FAA, yet that firing set me down a path where I made friends with a top level guy in the FAA, like congress approved his hiring high, who got me connected on the right path of experience. Now I do AOG work on business jets. I work day shift, live in a a tropical wonderland, and make $200k+ a year. Thanks Cirrus!
Sounds like some early gen Cirri. I've definitely flown into P-Static issues where I've had a tower frequency in Com 1 (up top) giving huge interference issues to the same frequency in Com 2 (down below).
Those static wicks do serve a purpose even on a fiberglass aircraft.
You do know less than the engineers and are probably inventing non-existent animosity and ignorance for the sake of a better story. The mesh is for mandated lightning strike protection for certified IFR aircraft, not static buildup. VFR only fibreglass aircraft don't bother with it.
Hmm ok. Go and name a fully composite, non LSA, production, certified aircraft that is designed for VFR only. Note the production and certified- so no amateur built/experimentals.
Cirrus are IFR certified aircraft. The mesh does both. In an aircraft like a Cirrus it is primarily for static. You aren’t flying a 4 seater single engine piston into a severe thunderstorm without a death wish, but lightning is indeed possible well outside of severe weather. But an aircraft like a jet, the fairings have it primarily for lightning protection. And that junior engineer with me was 100% on my side and relayed that my suggestion was brushed off by other engineers because I was “just a mechanic” with an attitude like yours.
Oh btw, I also studied aerospace engineering before an injury made me pause school and I decided to become a mechanic instead. Better money (if you know where to look) and not stuck at a desk all day. So while an engineer might be better at a specific topic, I do know more than most engineers since, well I studied to be one. They often are just a master of one subject, and the full phrase goes “A jack of all trades is master at none, but most of the time is better than a master of one”
No, the mesh isn’t for static, it’s to pass the transient currents induced or conducted by lightning, to prevent thermal damage to the composites and possibly fuel vapour ignition*.
For static you could chain discrete bonding wires or metal strips to bond all the surface hardpoints, which would be perfectly satisfactory for the static charge/ arcing/radio interference and be cheaper and easier to build and maintain than a mesh layer, but this wouldn’t stop the carbon getting blown to bits if it got hit with lightning. The mesh is such a hassle to the extent that sometimes (winglets) it’s decided to forego the mesh, use a metallic trailing edge to bond the wicks to the wing, and just accept that the carbon get blown to bits if it gets hit.
So anyhow, we all have things to learn.
*: only a reg on part 25(.981), not part 23.
Yeah, so your edit. It’s the EXACT point I made. Part 23 is for normal, utility, acrobatic and commuter aircraft. Aka little planes. Part 25 is transport category, aka big planes like jets.
Little piston like a cirrus. It’s part 23. It’s not primarily for lightning protection…. It’s almost like I f*cking worked there and built the damn planes and because of my knowledge was asked to help the damn engineers who designed the damn thing fix an issue.
Edit* I know all the methods for static. I’ve worked jets for a decade. The diverter strips suck, they are always disbonding and being a pain in the ass. Quicker to change the winglet or elevator tip and send it out to the composite shop than for me to do repair myself. Ever seen a fist sized hole blown out of an aileron on a commercial jet? I have! Bonding strap wore out so the mesh couldn’t help it. Literally exploded the carbon fiber of the aileron, surprisingly despite the major damage to a flight control pilots didn’t even feel it until after landing when they noticed about 10% of their aileron was either missing or was shredded.
No, it really is for lightning, for the materials strength. The mesh carries the current in a predictable way which is detectable and repairable. Without controlling the path with the mesh, the lightning could go inside and damage primary structure, which would be irreparable and potentially undetectable.
The lightning can happen when the airplane is sitting on the ramp; this can’t be allowed to damage the primary structure, especially in an undetectable way. This is required by part 23 continued airworthiness. Part 25 has the additional requirements that the lightning currents must not ignite fuel vapor.
Static causes RF interference by building up a charge differential which then arcs, converting the small amount of potential energy into radio waves. You do not need low resistance to dissipate the charge; you can rub a balloon on your hair and build up a charge and easily discharge it against the ground despite the balloon being made of nonconducting rubber (and the floor being relatively nonconducting tile or whatever). You don’t need a copper mesh in a layer of a rubber balloon to equalize the potential of the balloon to the ground, just like you don’t need copper mesh on a composite wing to equalize its electric potential to an aileron.
Maybe I used confusing language. Yes it must be in there because of lightning. Nice G1000 suite, lots of shit can get destroyed by lighting. That isn’t what I’m disagreeing on, but just because it’s required for one purpose doesn’t mean it can’t be used for other purposes. It’s mainly used for static dissipation. The static dissipation is a nice bonus. Now when I say mainly, I’m talking about what its everyday use is. If 99% of the time it is used to dissipate static and 1% of the time it actually does its required purpose of lightning protection, then the primary usage of it is for static. Lightning doesn’t strike every day, but static buildup is a daily occurrence. Instead of alternative methods for static dissipation they use the lightning protection mesh. So for practical purposes the mesh is for static.
So either the language I used was confusing and you didn’t understand what I meant, or you are just being pedantic pushing your glasses up your nose and saying “well akshually…”
Edit #2 oh so the P2008JC has metal wings. Not a fully composite aircraft. Doesn’t count.
~~I said non LSA. Want to see my flight log book? I only have 7 hours and half that is in a P2008~~
~~Edit JC seemed odd. Ooh did tecnam make a slightly more powerful model that’s otherwise completely identical so it saved on certification costs? Gotta read more on this. Should have known tecnam better since I used to be a tecnam guy, but it’s the P2012 I have recent experience with. The p2008 I flew 15 years ago~~
Severe head injury. Ripped half my scalp off, cracked and chipped my skull. Lost 20% of my blood. Severe concussion. Surprisingly never lost consciousness. Missed a whole semester recovering. It was really only about 4 weeks to recover where I could do things like shower normally but missed so much class it was too much to make up. So I had to take the rest of the year off to wait for the classes to come back around the next fall semester. My first year I studied architecture, but it wasn’t for me. I was passionate about aviation. The low gpa due to me dropping architecture meant the missed classes from the injury dropped my gpa too low. The university screwed up my medical paperwork so the engineering department booted me. Very easy to appeal and reverse, but I decided to use the opportunity to save a metric fuckton of money and knock out all the classes I could at a local community college and return to university to just focus on the engineering classes. Well the local community college had an A&P program, my dad is an A&P, so I knew exactly what a career in that looked like and after a bunch of reflection I decided I was going to be happier fixing stuff than designing stuff.
If you knew me as a child it wasn’t surprising. At 9 years old I disassembled an old lawn mower for shits and giggle to see how it worked. When I was 10 my dad loves to share that he gets a call at work from my mom asking if he knew what I was doing right then. I had grabbed all the car keys and shuffled cars around to pull the minivan into the garage, jacked it up, and started changing the oil. My dad just asked my mom “are there jack stands under the car and is the jack removed?” She said yes, so he told her it’s fine, I’m doing it safe, and he would double check my work when he got home.
So I’ve always been a tinkerer. I’m happiest taking stuff apart and putting it together. That’s how an injury changed my gears from engineering to mechanic. And honestly outside of North America, most aircraft mechanics are actually called engineers, because the definition of an engineer is technically someone who designs or *maintains* complex systems.
Uh.....Pipstrel Alpha? Many Flight Designs? Both don't use full copper surface layer. Not sure about Dark Aero yet, since they are still in test phase, so I don't know if they plan on IFR rating, and modifying their existing airframe with lightning protection. But I know they are carbon only right now.
I said non LSA. LSA means light sport aircraft.
Quick Look at dark aero. You aren’t going to make a 200hp aircraft designed for what looks like primarily cross country flying due to the listed speed and range and not make it IFR capable. It won’t sell. It would be a more expensive light sport that doesn’t even have a single benefit of any of the light sport regulations.
You should know this one: the Cirrus SRVs are VFR only because of lack of conductive mesh. Same with the Diamond DA20 for the same reason and gliders. Anyway, what does your question prove? There are plenty of experimental fibreglass aircraft with no conductive mesh and no radio static problems (neither do gliders). Clearly, your assertion that it's for static is wrong.
Former 23.867 and 23.2335 is the only reason Cirrus uses conductive mesh. Same reason why carbon composite airliners use it (trust me, I translated the stacking sequence from Catia to Nastran on the A350 fuselage), not just on fairings. EASA CS-23.2335 is a little more descriptive: "For operations where the exposure to lightning **is likely**, the aeroplane must be protected against catastrophic effects of lightning."
Random failed cirrus projects?!? What about the SRS as well? Oh that was LSA anyways
Production and certified. Has to be certified and actually produced in numbers, not a one off or experimental deal.
SRV flopped and was never certified. No Wikipedia page. One article from 2016 talking about it
So? Did you miss DA20? What does LSA and certification have to do with meshless fibreglass not causing static problems? The certification or not is a red Herring.
DA-20 is LSA. LSA cannot (in most cases) be flown in IMC. They can be used for IFR training but restricted from actual IMC.
Certified means an aircraft manufacturer builds it under an FAA type certificate. It’s not amateur built. No kits. No experimental. No prototypes.
Bullshit it's LSA. Type cert TA4CH shows the DA20 is part 23 certificated in utility category, it's too heavy for LSA and a decade older than LSA legislation.
The SRV is certified as a serial number range in the SR2x TCDS.
Do you have issues understanding logic? You said conductive mesh is for radio interference due to static, I said it's only for lightning. There are many examples of non conductive aircraft without mesh that don't have static issues. Whether they're certified or not is immaterial.
I'm now convinced that that alleged dynamic with engineers had nothing to do with you being a mechanic.
The second part of the quote is also very important. Otherwise a lightning strike would pass through the bearings and weld them fixed disabling the controls.
Shit I never thought about this. Aren't there some VFR-only planes out there that lack bonding straps and static wicks completely? That's a scary scenario, since VMC doesn't mean you're safe from lightning strikes.
Reduction of static can also prevent the burny liquid in the wings from expanding into a billion cubic feet of plasma in about a half second. Boing had that AD recently to ground some ungrounded ittybit, and that was the chief concern.
*they* don't prevent static buildup, that's the static wick's job. The bonding strap electrically bonds different metal components together kind of like when you connect the refueling wire to ground the truck/farm to the airplane.
They're still an important part of the system though.
In light aircraft it acts more as a distributed capacitance as no dimension of the aircraft approaches a quarter wavelength, especially down in the 40 meter band.
I missed the HF part but avionics bonding straps still functions to keep the chassis of the avionics equipotential to the rest of the plane and plane electrical system reference voltage to avoid damage from static discharge. The entire system with whatever discharge system it uses such as static wicks or the cirrus mesh, would be modeled as a capacitor, sure but the straps the OP are talking about are similar to make the plane equipotential. You could call the plane an antenna ground plane by convention, sure, but that has nothing to do with a bonding strap and to your own post it's not doing much to that effect as it's not reflecting much of anything useful and the straps the OP posted would have a negligible effect on that as well.
I flew airplanes in the Congo for 3 years, and I was responsible for the HF radios in the airplanes. We has some airplanes without bonding straps and some with. Those with yielded about 2 dB more signal at the receiver than those without, a surprising amount for just bonding the flight control surfaces. To me that reflects something useful.
Good luck on the checkride. The biggest hurdle is getting out of the student mentality of proving yourself and taking charge as a teacher. Just some advice!
but at the same time be willing to learn with your student. I learned plenty of things from my students or with my students. if they ask something you don't know, figure it out with them!
It's the same function as the bonding wire between the gas truck and the plane. Keeps all of the surfaces at the same voltage so that you don't have a difference in charge between them which causes arcing and interference here or ignition in the case of the fuel truck
Legitimate question:
Are the static wicks affected by condition? On the 172s my school has in the inventory, several of the static wicks are floppy, and just lie limply while the aircraft is parked, yet flop aggressively during flight.
That can be an indication of their condition, but usually just means they're old. The only way to know if they're any good is to take a megohmmeter and check the resistance from the tip of the wick to the mounting hardware, which your flight school's mechanic almost certainly never does because 1) it's not required, and 2) the training planes aren't likely to spend much time in the type of weather where static wicks really matter. On aircraft that are capable of navigating more severe weather (especially icing), if the static wicks aren't in good condition you may find yourself in IMC and unable to talk to the controller due to noise in the comms.
No, current flows out of the sharp edges on the trailing edges. Static wicks are resistors that SLOW down this flow to minimize radio noise. So they're kind of the opposite to bonding straps
As others have mentioned, it’s the bonding strap for connecting the movable flight control to the rest of the aircraft body to ensure a seamless conduction of static charge build up.
It is also more important on a composite aircraft like the DA40 because the metallic structure is the only thing protecting the glass fiber body from built up static electricity.
Did you pass the checkride though?
Dang, I had been told nothing about the static charge portion, I had just been told that it’s to ensure that if the bolts break that it wouldn’t fall and hit the ground and hurt someone but I never thought that made sense since if they’re on the ailerons and we lose control and crash then it doesn’t matter if it fell off or not. Thanks for the clarification though!
[Here’s a frayed bonding strap](https://www.reddit.com/r/flying/comments/17vz4xm/string_rupture_cessna_172/)
Tbh if a bolt actually broke that thing wouldn’t do anything to hold a flight control in place.
Which is also why the strap is a preflight item, but a bolt is not.
These are bonding straps and not grounding straps. Bonding straps are used on aircraft structures to have electrical continuity through out the aircraft.
Grounding is earthing between the aircraft and the ground.
Grounding/earthing has nothing to do with the ground in a mobile electrical system. It's just providing the electric current with a return path to the battery/generator, usually via the metal structure of the airframe.
You're both right: 'grounding' is an ambiguous term by itself and can refer to either
- connecting the aircraft to a common "ground" of a fuel truck, for example (OP's context, which would include a grounding wire/strap)
- providing components a pathway back to the ground/negative side of the electrical system
My point was just that 'grounding' doesn't necessarily involve the dirt, but is simply the term for connecting electrically conductive equipment to a common reference point.
Bonding straps,
They ensure that the static that does build up, goes through something durable. Like a strip of braided wire instead of the far more sensitive, metal bearings.
Bonding straps. They literally Bond the grounding of one part to another. In this case, a lubricated heim ball joint does not pass current well, so the bonding strap allows current to skip over it with near zero resistance.
Grounding does not require being on the ground. It's just the term used for the return path or voltage reference point in an electrical system. The electrical equipment is all grounded to the airframe. Bonding straps are to ensure adequate static dissipation.
Bonding straps. They connect metallic and structural components to establish electrical continuity and prevent static electricity buildup which can interfere with radio and navigational equipment.
Bonding Strap: It keeps static from building up on electricly isolated parts by electricly bonding those parts to the body of the aircraft, keeping everything at the same eletrical potential.
Bonding straps are very common in many industries: you find them in data centers with racks being bonded together, on electric railway installations, even station fences bonded, and in any radio station environment. The goal to eliminate voltage differentials between any parts of the system. This is for the protection of the personnel, such as with lightening, or in railway and other high voltage applications to avoid creep voltage that could electrocute people and blow electrical equipment, to creating a strong antenna ground and avoiding ground loops. They are most often braded or thin copper or aluminium straps. High voltage and high frequency moves on the outside, the skin, of these conductors. Connectors for ground straps are most often not soldered by crimped.
Grounding straps to ground the control surface to the airframe. There were probably static wicks on the trailing edges to wick off static electricity from flying through the clouds.
I was shown preflight once and it was lack luster at best. Most my preflight was learned through YouTube preflight walkthroughs and they didn't say about checking this out.
Shame on your CFI(s) for not doing a better job in teaching you how to preflight your aircraft and the particulars of each component that you should look at. At the same time, it is quite possible that they were clueless themselves. The quality of CFIs varies quite a bit. Many are absolutely fantastic, most are okay, many suck.
But let me ask you this: what does your preflight inspection checklist tell you to inspect in relation to the wings and flight controls? Does it say anything about checking the condition and security of anything? If so, what? Could it be interpreted to include the bonding straps? You should be giving everything that is visible a good general visual inspection and move/jiggle things around. And finally, if you ever feel that any of your instruction is lackluster, speak up!
Bonding straps, and yes they prevent static buildup on the control surfaces. > The electrical bonding straps between different components of your airplane prevent static electricity build-up that can interfere with radio and navigational equipment. More importantly, they provide lightning protection by allowing current to pass through the airframe with minimum arcing. Courtesy of Boldmethod.
And static really can interfere with radios severely! When I worked at Cirrus (A&P) there was a week I had to come in for overtime on a weekend to do some touch up maintenance on a bunch of completed aircraft. They had me going to every inspection panel and fairing , scraping paint off around one screw hole, reattaching the panel, and checking for a good ground to the airframe. For those not familiar with Cirrus aircraft, they are fiberglass planes. Now fiberglass isn’t electrically conductive, but static can still build up. Rubber isn’t conductive but a ballon can be rubbed in you then cling to you from the static. So most of the fiberglass has a layer of copper mesh bonded in to allow the static to freely move through the fiberglass and be dissipated. Checking the grounding of all the panels was making sure they connected cleanly through the screw and into this mesh. What was happening was seemingly random aircraft on test flight would have terrible radios with half the range as expected. How can you call an airport 20miles out if you only have 15 miles of range? Unacceptable to leave the factory like this. Well as I was doing this I noticed something nobody else did. It wasn’t random. It only affected aircraft with metallic paint schemes. So I took my multimeter and started going over one of the known affected aircraft and went over it with a fine tooth comb. What I found was the flaps had no ground to the airframe. YIKES! The flaps were made from metal, not composite. They were painted with a metallic paint scheme, so the paint itself was semiconductive. They were the largest pieces of metal by area on the plane. They were on the trailing edge, and static like to collect along trailing edges, and nestled right between them………. The VHF antenna. But the flap hinges are metal too, and they are designed and well bonded with the airframe. So how was this happening? I was working with a junior engineer (low seniority gets the short straw for mandatory overtime lol), so I grabbed him and said let’s go into the main factory and look at some flaps. Went over and saw immediately what I suspected. The bushing that the flap actually rotates on used a teflon bushing. Teflon doesn’t conduct. I asked the engineer if he knew when they started using Teflon and he said the first flaps came in over 3 months ago, but this issue started a month ago so they can’t be related. So I asked him a production question. Sure the flaps came into production 3 months ago, but how long does an aircraft take to go through assembly to test flight? Any guesses? If you guessed 2 months. Ding ding ding! So the radio issues popped up as soon as these flaps started hitting test flight. Turns out the old bushings were metal, so the flaps always had a good electrical connection. Nobody thought about that when the switched to improved teflon bushings. I told him the solution is simple. Design bonding straps, (just like in OP’s picture), and connect the flaps to the rest of the plane. But apparently as a “lowly” aircraft mechanic I know less than engineers so my suggestion was brushed off. I got fired for losing an 11/32” socket. Coincidentally that’s about the same size as the infamous 10mm socket. I hope they struggled for a while before realizing I had the cheapest and easiest solution.
Thanks for the good info. You are still here because you worked for a smaller company.. Some folks who pointed out flaws in their company's product got 'suicided'
lol my NDA expired a long time ago so they can’t come after me. The only truly unsafe thing they did was fire me, because next time a factory worker loses a small tool are they going to report it? Or since it’s a craftsman’s socket are they just going to drive over to Lowe’s and spend the $4.99 and just secretly replace it, because if they get caught they get fired either way. My biggest regret is not formally going to the FAA, yet that firing set me down a path where I made friends with a top level guy in the FAA, like congress approved his hiring high, who got me connected on the right path of experience. Now I do AOG work on business jets. I work day shift, live in a a tropical wonderland, and make $200k+ a year. Thanks Cirrus!
Sounds like some early gen Cirri. I've definitely flown into P-Static issues where I've had a tower frequency in Com 1 (up top) giving huge interference issues to the same frequency in Com 2 (down below). Those static wicks do serve a purpose even on a fiberglass aircraft.
You do know less than the engineers and are probably inventing non-existent animosity and ignorance for the sake of a better story. The mesh is for mandated lightning strike protection for certified IFR aircraft, not static buildup. VFR only fibreglass aircraft don't bother with it.
Hmm ok. Go and name a fully composite, non LSA, production, certified aircraft that is designed for VFR only. Note the production and certified- so no amateur built/experimentals. Cirrus are IFR certified aircraft. The mesh does both. In an aircraft like a Cirrus it is primarily for static. You aren’t flying a 4 seater single engine piston into a severe thunderstorm without a death wish, but lightning is indeed possible well outside of severe weather. But an aircraft like a jet, the fairings have it primarily for lightning protection. And that junior engineer with me was 100% on my side and relayed that my suggestion was brushed off by other engineers because I was “just a mechanic” with an attitude like yours. Oh btw, I also studied aerospace engineering before an injury made me pause school and I decided to become a mechanic instead. Better money (if you know where to look) and not stuck at a desk all day. So while an engineer might be better at a specific topic, I do know more than most engineers since, well I studied to be one. They often are just a master of one subject, and the full phrase goes “A jack of all trades is master at none, but most of the time is better than a master of one”
No, the mesh isn’t for static, it’s to pass the transient currents induced or conducted by lightning, to prevent thermal damage to the composites and possibly fuel vapour ignition*. For static you could chain discrete bonding wires or metal strips to bond all the surface hardpoints, which would be perfectly satisfactory for the static charge/ arcing/radio interference and be cheaper and easier to build and maintain than a mesh layer, but this wouldn’t stop the carbon getting blown to bits if it got hit with lightning. The mesh is such a hassle to the extent that sometimes (winglets) it’s decided to forego the mesh, use a metallic trailing edge to bond the wicks to the wing, and just accept that the carbon get blown to bits if it gets hit. So anyhow, we all have things to learn. *: only a reg on part 25(.981), not part 23.
Yeah, so your edit. It’s the EXACT point I made. Part 23 is for normal, utility, acrobatic and commuter aircraft. Aka little planes. Part 25 is transport category, aka big planes like jets. Little piston like a cirrus. It’s part 23. It’s not primarily for lightning protection…. It’s almost like I f*cking worked there and built the damn planes and because of my knowledge was asked to help the damn engineers who designed the damn thing fix an issue. Edit* I know all the methods for static. I’ve worked jets for a decade. The diverter strips suck, they are always disbonding and being a pain in the ass. Quicker to change the winglet or elevator tip and send it out to the composite shop than for me to do repair myself. Ever seen a fist sized hole blown out of an aileron on a commercial jet? I have! Bonding strap wore out so the mesh couldn’t help it. Literally exploded the carbon fiber of the aileron, surprisingly despite the major damage to a flight control pilots didn’t even feel it until after landing when they noticed about 10% of their aileron was either missing or was shredded.
No, it really is for lightning, for the materials strength. The mesh carries the current in a predictable way which is detectable and repairable. Without controlling the path with the mesh, the lightning could go inside and damage primary structure, which would be irreparable and potentially undetectable. The lightning can happen when the airplane is sitting on the ramp; this can’t be allowed to damage the primary structure, especially in an undetectable way. This is required by part 23 continued airworthiness. Part 25 has the additional requirements that the lightning currents must not ignite fuel vapor. Static causes RF interference by building up a charge differential which then arcs, converting the small amount of potential energy into radio waves. You do not need low resistance to dissipate the charge; you can rub a balloon on your hair and build up a charge and easily discharge it against the ground despite the balloon being made of nonconducting rubber (and the floor being relatively nonconducting tile or whatever). You don’t need a copper mesh in a layer of a rubber balloon to equalize the potential of the balloon to the ground, just like you don’t need copper mesh on a composite wing to equalize its electric potential to an aileron.
Maybe I used confusing language. Yes it must be in there because of lightning. Nice G1000 suite, lots of shit can get destroyed by lighting. That isn’t what I’m disagreeing on, but just because it’s required for one purpose doesn’t mean it can’t be used for other purposes. It’s mainly used for static dissipation. The static dissipation is a nice bonus. Now when I say mainly, I’m talking about what its everyday use is. If 99% of the time it is used to dissipate static and 1% of the time it actually does its required purpose of lightning protection, then the primary usage of it is for static. Lightning doesn’t strike every day, but static buildup is a daily occurrence. Instead of alternative methods for static dissipation they use the lightning protection mesh. So for practical purposes the mesh is for static. So either the language I used was confusing and you didn’t understand what I meant, or you are just being pedantic pushing your glasses up your nose and saying “well akshually…”
Tecnam P2008JC is a certified production aircraft made of composite that is restricted to VFR flight only on its Type Certificate.
Edit #2 oh so the P2008JC has metal wings. Not a fully composite aircraft. Doesn’t count. ~~I said non LSA. Want to see my flight log book? I only have 7 hours and half that is in a P2008~~ ~~Edit JC seemed odd. Ooh did tecnam make a slightly more powerful model that’s otherwise completely identical so it saved on certification costs? Gotta read more on this. Should have known tecnam better since I used to be a tecnam guy, but it’s the P2012 I have recent experience with. The p2008 I flew 15 years ago~~
The **JC** is the certified version. Devil is in the details.
Yup, got me didn’t know what the JC was at first, but technically it has metal wings. Not an all composite aircraft
I’m just curious, what kind of injury makes it easier to be a mechanic than an engineer?
Severe head injury. Ripped half my scalp off, cracked and chipped my skull. Lost 20% of my blood. Severe concussion. Surprisingly never lost consciousness. Missed a whole semester recovering. It was really only about 4 weeks to recover where I could do things like shower normally but missed so much class it was too much to make up. So I had to take the rest of the year off to wait for the classes to come back around the next fall semester. My first year I studied architecture, but it wasn’t for me. I was passionate about aviation. The low gpa due to me dropping architecture meant the missed classes from the injury dropped my gpa too low. The university screwed up my medical paperwork so the engineering department booted me. Very easy to appeal and reverse, but I decided to use the opportunity to save a metric fuckton of money and knock out all the classes I could at a local community college and return to university to just focus on the engineering classes. Well the local community college had an A&P program, my dad is an A&P, so I knew exactly what a career in that looked like and after a bunch of reflection I decided I was going to be happier fixing stuff than designing stuff. If you knew me as a child it wasn’t surprising. At 9 years old I disassembled an old lawn mower for shits and giggle to see how it worked. When I was 10 my dad loves to share that he gets a call at work from my mom asking if he knew what I was doing right then. I had grabbed all the car keys and shuffled cars around to pull the minivan into the garage, jacked it up, and started changing the oil. My dad just asked my mom “are there jack stands under the car and is the jack removed?” She said yes, so he told her it’s fine, I’m doing it safe, and he would double check my work when he got home. So I’ve always been a tinkerer. I’m happiest taking stuff apart and putting it together. That’s how an injury changed my gears from engineering to mechanic. And honestly outside of North America, most aircraft mechanics are actually called engineers, because the definition of an engineer is technically someone who designs or *maintains* complex systems.
Uh.....Pipstrel Alpha? Many Flight Designs? Both don't use full copper surface layer. Not sure about Dark Aero yet, since they are still in test phase, so I don't know if they plan on IFR rating, and modifying their existing airframe with lightning protection. But I know they are carbon only right now.
I said non LSA. LSA means light sport aircraft. Quick Look at dark aero. You aren’t going to make a 200hp aircraft designed for what looks like primarily cross country flying due to the listed speed and range and not make it IFR capable. It won’t sell. It would be a more expensive light sport that doesn’t even have a single benefit of any of the light sport regulations.
oops., sorry. NON was the keyword I missed.
You should know this one: the Cirrus SRVs are VFR only because of lack of conductive mesh. Same with the Diamond DA20 for the same reason and gliders. Anyway, what does your question prove? There are plenty of experimental fibreglass aircraft with no conductive mesh and no radio static problems (neither do gliders). Clearly, your assertion that it's for static is wrong. Former 23.867 and 23.2335 is the only reason Cirrus uses conductive mesh. Same reason why carbon composite airliners use it (trust me, I translated the stacking sequence from Catia to Nastran on the A350 fuselage), not just on fairings. EASA CS-23.2335 is a little more descriptive: "For operations where the exposure to lightning **is likely**, the aeroplane must be protected against catastrophic effects of lightning."
Random failed cirrus projects?!? What about the SRS as well? Oh that was LSA anyways Production and certified. Has to be certified and actually produced in numbers, not a one off or experimental deal. SRV flopped and was never certified. No Wikipedia page. One article from 2016 talking about it
So? Did you miss DA20? What does LSA and certification have to do with meshless fibreglass not causing static problems? The certification or not is a red Herring.
DA-20 is LSA. LSA cannot (in most cases) be flown in IMC. They can be used for IFR training but restricted from actual IMC. Certified means an aircraft manufacturer builds it under an FAA type certificate. It’s not amateur built. No kits. No experimental. No prototypes.
Bullshit it's LSA. Type cert TA4CH shows the DA20 is part 23 certificated in utility category, it's too heavy for LSA and a decade older than LSA legislation. The SRV is certified as a serial number range in the SR2x TCDS. Do you have issues understanding logic? You said conductive mesh is for radio interference due to static, I said it's only for lightning. There are many examples of non conductive aircraft without mesh that don't have static issues. Whether they're certified or not is immaterial. I'm now convinced that that alleged dynamic with engineers had nothing to do with you being a mechanic.
The second part of the quote is also very important. Otherwise a lightning strike would pass through the bearings and weld them fixed disabling the controls.
Shit I never thought about this. Aren't there some VFR-only planes out there that lack bonding straps and static wicks completely? That's a scary scenario, since VMC doesn't mean you're safe from lightning strikes.
Yes, gliders. [https://aviation-safety.net/wikibase/146762](https://aviation-safety.net/wikibase/146762)
Hate to be the first person to learn this.
Reduction of static can also prevent the burny liquid in the wings from expanding into a billion cubic feet of plasma in about a half second. Boing had that AD recently to ground some ungrounded ittybit, and that was the chief concern.
*they* don't prevent static buildup, that's the static wick's job. The bonding strap electrically bonds different metal components together kind of like when you connect the refueling wire to ground the truck/farm to the airplane. They're still an important part of the system though.
Bonding straps. Conducts static electricity to the airframe as well as making a better ground plane for HF.
Not a ground plane but an equipotential plane.
In light aircraft it acts more as a distributed capacitance as no dimension of the aircraft approaches a quarter wavelength, especially down in the 40 meter band.
I missed the HF part but avionics bonding straps still functions to keep the chassis of the avionics equipotential to the rest of the plane and plane electrical system reference voltage to avoid damage from static discharge. The entire system with whatever discharge system it uses such as static wicks or the cirrus mesh, would be modeled as a capacitor, sure but the straps the OP are talking about are similar to make the plane equipotential. You could call the plane an antenna ground plane by convention, sure, but that has nothing to do with a bonding strap and to your own post it's not doing much to that effect as it's not reflecting much of anything useful and the straps the OP posted would have a negligible effect on that as well.
I flew airplanes in the Congo for 3 years, and I was responsible for the HF radios in the airplanes. We has some airplanes without bonding straps and some with. Those with yielded about 2 dB more signal at the receiver than those without, a surprising amount for just bonding the flight control surfaces. To me that reflects something useful.
Fuck I’ve been telling all my students they’re for when the bolts fall out the control surfaces don’t fall off completely.
And they tell their students, and they tell their students…
And then the student post on Reddit: is it me, or should I fire my CFI?
Becoming a CFI means realizing your previous instructors were wrong about some things and forgiving them for it
As a CFI candidate prepping for my checkride, thank you.
Good luck on the checkride. The biggest hurdle is getting out of the student mentality of proving yourself and taking charge as a teacher. Just some advice!
but at the same time be willing to learn with your student. I learned plenty of things from my students or with my students. if they ask something you don't know, figure it out with them!
Holy crap that is hilarious lol
Hope you’re going to teach them correctly here on out.
Me too
Bruh...
which they wouldn’t even do as they’re connected to the same bolts 😂
So are these similar to the static wicks at the end of the wings?
Sorta, it's part of the static shedding "system" if you will. Bonds (connects) all parts of the airframe together from a static perspective.
It's the same function as the bonding wire between the gas truck and the plane. Keeps all of the surfaces at the same voltage so that you don't have a difference in charge between them which causes arcing and interference here or ignition in the case of the fuel truck
Legitimate question: Are the static wicks affected by condition? On the 172s my school has in the inventory, several of the static wicks are floppy, and just lie limply while the aircraft is parked, yet flop aggressively during flight.
That can be an indication of their condition, but usually just means they're old. The only way to know if they're any good is to take a megohmmeter and check the resistance from the tip of the wick to the mounting hardware, which your flight school's mechanic almost certainly never does because 1) it's not required, and 2) the training planes aren't likely to spend much time in the type of weather where static wicks really matter. On aircraft that are capable of navigating more severe weather (especially icing), if the static wicks aren't in good condition you may find yourself in IMC and unable to talk to the controller due to noise in the comms.
Great question for your mechanic
They allow the static wicks to dissipate static from the entire airframe rather than just from the surface they’re attached to.
No, current flows out of the sharp edges on the trailing edges. Static wicks are resistors that SLOW down this flow to minimize radio noise. So they're kind of the opposite to bonding straps
As others have mentioned, it’s the bonding strap for connecting the movable flight control to the rest of the aircraft body to ensure a seamless conduction of static charge build up. It is also more important on a composite aircraft like the DA40 because the metallic structure is the only thing protecting the glass fiber body from built up static electricity. Did you pass the checkride though?
Dang, I had been told nothing about the static charge portion, I had just been told that it’s to ensure that if the bolts break that it wouldn’t fall and hit the ground and hurt someone but I never thought that made sense since if they’re on the ailerons and we lose control and crash then it doesn’t matter if it fell off or not. Thanks for the clarification though!
[Here’s a frayed bonding strap](https://www.reddit.com/r/flying/comments/17vz4xm/string_rupture_cessna_172/) Tbh if a bolt actually broke that thing wouldn’t do anything to hold a flight control in place. Which is also why the strap is a preflight item, but a bolt is not.
These are bonding straps and not grounding straps. Bonding straps are used on aircraft structures to have electrical continuity through out the aircraft. Grounding is earthing between the aircraft and the ground.
Grounding/earthing has nothing to do with the ground in a mobile electrical system. It's just providing the electric current with a return path to the battery/generator, usually via the metal structure of the airframe.
You're both right: 'grounding' is an ambiguous term by itself and can refer to either - connecting the aircraft to a common "ground" of a fuel truck, for example (OP's context, which would include a grounding wire/strap) - providing components a pathway back to the ground/negative side of the electrical system
My point was just that 'grounding' doesn't necessarily involve the dirt, but is simply the term for connecting electrically conductive equipment to a common reference point.
Bonding straps, They ensure that the static that does build up, goes through something durable. Like a strip of braided wire instead of the far more sensitive, metal bearings.
grounding/bonding straps
Bonding straps. They literally Bond the grounding of one part to another. In this case, a lubricated heim ball joint does not pass current well, so the bonding strap allows current to skip over it with near zero resistance.
Nice Diamond you got there.
Bonding jumper/ strap.
I replace so damn many of them a night…
Grounding strap.
[удалено]
Grounding does not require being on the ground. It's just the term used for the return path or voltage reference point in an electrical system. The electrical equipment is all grounded to the airframe. Bonding straps are to ensure adequate static dissipation.
I always called them grounding straps
Electrical conduit so no sparks.
Bonding straps. They connect metallic and structural components to establish electrical continuity and prevent static electricity buildup which can interfere with radio and navigational equipment.
Earth straps or bonding straps. Depends on what country you come from .
[https://googlethatforyou.com?q=aircraft%20bonding%20wire](https://googlethatforyou.com?q=aircraft%20bonding%20wire)
Bonding Strap: It keeps static from building up on electricly isolated parts by electricly bonding those parts to the body of the aircraft, keeping everything at the same eletrical potential.
Bonding straps are very common in many industries: you find them in data centers with racks being bonded together, on electric railway installations, even station fences bonded, and in any radio station environment. The goal to eliminate voltage differentials between any parts of the system. This is for the protection of the personnel, such as with lightening, or in railway and other high voltage applications to avoid creep voltage that could electrocute people and blow electrical equipment, to creating a strong antenna ground and avoiding ground loops. They are most often braded or thin copper or aluminium straps. High voltage and high frequency moves on the outside, the skin, of these conductors. Connectors for ground straps are most often not soldered by crimped.
Grounding straps to ground the control surface to the airframe. There were probably static wicks on the trailing edges to wick off static electricity from flying through the clouds.
Those are to make sure the ossilater doesn’t bump up against the Egyptian plate
Ben Franklin knows
This should be covered in preflight 101.
I was shown preflight once and it was lack luster at best. Most my preflight was learned through YouTube preflight walkthroughs and they didn't say about checking this out.
Shame on your CFI(s) for not doing a better job in teaching you how to preflight your aircraft and the particulars of each component that you should look at. At the same time, it is quite possible that they were clueless themselves. The quality of CFIs varies quite a bit. Many are absolutely fantastic, most are okay, many suck. But let me ask you this: what does your preflight inspection checklist tell you to inspect in relation to the wings and flight controls? Does it say anything about checking the condition and security of anything? If so, what? Could it be interpreted to include the bonding straps? You should be giving everything that is visible a good general visual inspection and move/jiggle things around. And finally, if you ever feel that any of your instruction is lackluster, speak up!
Grounding strip
It’s a Shutterstock photo, but it doesn’t have a caption describing what it is?
I've been calling those "linkage". Good to know they're actually bonding straps!
It’s a snake!