I'm working on tidying up the firewall forward portion of my 9a, and I'm wondering what is an acceptable way to restrain wires and harnesses under the cowl. In particular an easy way to run wires along the motor mount without damaging the powdercoat by chafing. I have used adel clamps for the starter wire, but I'm looking for an easier way for the various other wires. Thanks Bob
Van's Air Force
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Restraining wires firewall forward
- Thread starter rvator9a
- Start date
Rick6a
Well Known Member
Bob,
I am going to assume you do not mean to start a flame war. Some people rather forcefully purport that tie wraps can over time cut through a steel motor mount. I've heard the horror stories, yet have never seen ANY evidence first hand, not even a photograph. Maybe someone here can produce an incriminating photo for us to consider. My longtime and highly seasoned IA friend and mentor wholeheartedly concurs. Although I have no idea who installed them in the first place, my Cessna 150 had tie wraps still firmly intact after 18-1/2 years of my personnal ownership and I saw NO hint of chaffing when I snipped a number of them off the motor mount. The paint wasn't even worn through. So, with that in mind, I offer you my potentially controversial technique for securing wires to the motor mount.
Interestingly, that is a Lycoming installed tie wrap shown in the upper right hand corner of the photo and several more tie wraps were included in the hardware bag that came with the new engine.
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Jeff Vaughan
Well Known Member
Bob I used red silicone tape that only sticks to itself and wrapped it around the mount and then you can wire tie on top of it with out rubbing the painted surface of the mount. You can get the tape at Aircraft Spruce.
Jim P
Well Known Member
Bob, this pic isn't as current as my progress (this does show my general routing), but I've become pretty adept at adel clamps, which is really the way to go. DG12s seem to be the right size for most of the engine mount tubing and shold really secure anything forward of the firewall. I suppose this falls within the practice of not using fiber lock nuts as well.
I suppose there's folks using zip ties, but I'll stick with the adel clamps. They're a pain in the rear to install, but are not going to come loose.
I suppose there's folks using zip ties, but I'll stick with the adel clamps. They're a pain in the rear to install, but are not going to come loose.
Jeff Vaughan
Well Known Member
securing wires
Maybe this thime I can get the photo to show!
Maybe this thime I can get the photo to show!
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I use a combination of adel clamps and tie wraps - whatever seems to work best. I'm glad that Rick posted the tie-wrap photos first - that way, I know I am not alone!
I generally secure hoses with Adel clamps if I can, and wires with tie wraps, but there are exceptions.
I generally secure hoses with Adel clamps if I can, and wires with tie wraps, but there are exceptions.
kevinh
Well Known Member
I used some adel clamps but mostly zip ties. However, rather than using a pair of ties for each loop, I used a single tie with a 1/4" length of fuel hose scrap as a spacer. This allows you to create a figure-8 out of the zip tie, with one side around the mount and the other side around the bundle. The hose provides a nice stand-off to keep the bundle away from the mount.
I didn't think of this idea, but I'm very glad I copied it from a local builder.
After 200 hrs I cut a few off to inspect the mount - no signs of rubbing, so I'm still quite happy with this approach.
I didn't think of this idea, but I'm very glad I copied it from a local builder.
After 200 hrs I cut a few off to inspect the mount - no signs of rubbing, so I'm still quite happy with this approach.
fstringham7a
Well Known Member
RE:Tie Wrap ... TEMP.....
Rick
Are your tie wraps on the 150 high temp or......................
Frank @ SGU RV7A NDY..............
Rick
Are your tie wraps on the 150 high temp or......................
Frank @ SGU RV7A NDY..............
Rick6a
Well Known Member
Frank,
It depends on where I'm installing a particular tie wrap. For instance, I used all the ones Lycoming sent me for FWF purposes and for other areas, Stein has a good selection of tie wraps designed for a variety of uses. That said, GE distributes tie wraps thru the big box stores rated at 167 degrees. I use those too.
http://www.steinair.com/cableties.htm#STANDARD
Walt
Well Known Member
I use string tie whenever possible...
I use silicone tape around the mount and then string tie the bundle to the mount in many cases. I have not seen wire ties cut through steel but I have personally seen them cut through T6 aluminum. Just FYI, Boeing a few years back let a bunch of 757's go out of the factory with the "tempory" plastic tie wraps in place, they put out a SB and recommended removing and replacing with string ties which we did. My personal standard is I only use plastic tie wraps when I absolutely cannot get access to string tie.
I use silicone tape around the mount and then string tie the bundle to the mount in many cases. I have not seen wire ties cut through steel but I have personally seen them cut through T6 aluminum. Just FYI, Boeing a few years back let a bunch of 757's go out of the factory with the "tempory" plastic tie wraps in place, they put out a SB and recommended removing and replacing with string ties which we did. My personal standard is I only use plastic tie wraps when I absolutely cannot get access to string tie.
RV7Guy
Well Known Member
Coupla hints
Very timely. I was just helping my neighbor on his 7A. He has had to make a couple of wiring changes because of conflicts with other components.
So, my suggestion is to install everything on the engine that you do not have a choice where it goes. As an example, starter, alternator, exhaust system, carb or FI system, and mags. Don't forget to think about the oil cooler as well but it won't be mounted till later. Now, a place that got my friend in trouble, the mixture throttle and prop cables. There is very little flexibility in where these get mounted to work properly and should not be an after thought.
Okay, so everything is mounted, now start running wires. I used a combination of double adels and linked zip ties. I used the hi temp mini zip ties anywhere close to the engine. I am slowly phasing out all of the non hi temp ties. Another invaluable tool is the silicone wrap as described by others.
Always try to work smarter not harder. I hate doing stuff over. I only got caught a couple of times thanks to the guidance of those who had building experience.
Very timely. I was just helping my neighbor on his 7A. He has had to make a couple of wiring changes because of conflicts with other components.
So, my suggestion is to install everything on the engine that you do not have a choice where it goes. As an example, starter, alternator, exhaust system, carb or FI system, and mags. Don't forget to think about the oil cooler as well but it won't be mounted till later. Now, a place that got my friend in trouble, the mixture throttle and prop cables. There is very little flexibility in where these get mounted to work properly and should not be an after thought.
Okay, so everything is mounted, now start running wires. I used a combination of double adels and linked zip ties. I used the hi temp mini zip ties anywhere close to the engine. I am slowly phasing out all of the non hi temp ties. Another invaluable tool is the silicone wrap as described by others.
Always try to work smarter not harder. I hate doing stuff over. I only got caught a couple of times thanks to the guidance of those who had building experience.
Tie Wraps
I used tie wraps for wire routes away from the engine. One of the judges at OSH this year looking at my plane, walked over to another judge and commented that I had tie wraps in the engine bay. There reaction appeared that that would knock my judging score down as if that was considered a bad thing.
I used tie wraps for wire routes away from the engine. One of the judges at OSH this year looking at my plane, walked over to another judge and commented that I had tie wraps in the engine bay. There reaction appeared that that would knock my judging score down as if that was considered a bad thing.
Rick6a
Well Known Member
Well THAT settles it. I guess Lycoming had better start consulting with those OSH judges before they ship any more engines with tie wraps installed!
I built my airplane to please myself, not a group of judges....I've won a few trophies for the Val at fly-ins, and each time, I either had to be goaded into registering, or simply recieved the trophy without registering....
Of course, none of those were at OSH, "the big show"...
David-aviator
Well Known Member
The only thing I add to this thread is you may want to consider high temp tie wraps under the cowl. They are available at
http://www.terminaltown.com/Pages/Page206.html
They won't melt quite as easy as conventional wraps.
I've used tie wraps since 1982 and have found they do get brittle in a high temp environment. The high temp ones may not. I've never heard of a tie wrap destroying an engine mount, that seems ridiculous. The OSH judges probably don't like tie wraps because they are not adel clamps but they sure work well for our purposes. (I've heard the judges also like to see all screw head slots aimed in the same direction - that's really important stuff - especially in time of war and the enemy is coming over the horizon.)
If you want to get fancy, I've learned to use corrugated loom under the cowl to contain all the wires with the Subaru. It too comes in high temp plastic. It is a split flexible tubing that comes in various sizes and can be used for single wires or up to starter cable. It's black color gives a nice uniform appearance and does protect wire from general wear and tear. It is available at
http://order.waytekwire.com/CGI-BIN/LANSAWEB?WEBEVENT+L0E8C124F5F8801006683021+M37+ENG
http://www.terminaltown.com/Pages/Page206.html
They won't melt quite as easy as conventional wraps.
I've used tie wraps since 1982 and have found they do get brittle in a high temp environment. The high temp ones may not. I've never heard of a tie wrap destroying an engine mount, that seems ridiculous. The OSH judges probably don't like tie wraps because they are not adel clamps but they sure work well for our purposes. (I've heard the judges also like to see all screw head slots aimed in the same direction - that's really important stuff - especially in time of war and the enemy is coming over the horizon.)
If you want to get fancy, I've learned to use corrugated loom under the cowl to contain all the wires with the Subaru. It too comes in high temp plastic. It is a split flexible tubing that comes in various sizes and can be used for single wires or up to starter cable. It's black color gives a nice uniform appearance and does protect wire from general wear and tear. It is available at
http://order.waytekwire.com/CGI-BIN/LANSAWEB?WEBEVENT+L0E8C124F5F8801006683021+M37+ENG
Walt
Well Known Member
Hmmm...
http://www.amtonline.com/publication/article.jsp?pubId=1&id=2050
Believe it or not, tie wraps cause damage... I'm sure Boeing, Rolls Royce, GE and most other manufactures have done their homework and still choose to use string tie in place of plastic tie wraps for good reason
PLASTIC ?TY-WRAPS? AGAIN!!... SDR # 20020122003
SDR # 20020122004
Upon descent, the pilot of the Beech 1900D noticed that he had no aural warnings for decision height, altitude, alert,
overspeed, gear warning, or stall warning. Maintenance personnel inspected plugs for aural amplifiers, and nothing
appeared to be wrong. Wiring was inspected and one wire (Code 24A22) for 28VDC input of the aural annunciator
amplifier (P/N 207), and another wire at plug W314P8 for co-pilot speakers, had been chafed by large plastic ty-wraps.
The wires in question were ?ty-wrapped? at a point where the bundle was bending. If the ty-wraps were 1 cm on
either side of the bend, this would not have happened.
In another incident, an ELT remote switch indicator light was on in the hangar with no aural signal being received on
comm frequency 121-5. The ELT and the wiring were inspected at Zone 312, and the wires 3150-12, 3150-13,
3150-15 were found chafed and were grounding out. Plastic ty-wraps, and plastic clamps cutting into the wiring
were the cause of the problem.
Transport Canada continues to receive SDRs on plastic wire ties that, due to incorrect installation, have damaged
adjacent wiring, structure, or components. Plastic wire retention devices, although more convenient that the lacing
method for certain installations, often are installed quickly and as a result, not in the optimum position, leading to
the chafing of adjacent wires or structures.
Manufacturers? Instructions for Continuing Airworthiness and/or AC 43.13 2B, Chapter 11, Aircraft Electrical
Systems, covers wire installation and inspection, and includes information on the use of wire ties.
http://www.amtonline.com/publication/article.jsp?pubId=1&id=2050
Believe it or not, tie wraps cause damage... I'm sure Boeing, Rolls Royce, GE and most other manufactures have done their homework and still choose to use string tie in place of plastic tie wraps for good reason
PLASTIC ?TY-WRAPS? AGAIN!!... SDR # 20020122003
SDR # 20020122004
Upon descent, the pilot of the Beech 1900D noticed that he had no aural warnings for decision height, altitude, alert,
overspeed, gear warning, or stall warning. Maintenance personnel inspected plugs for aural amplifiers, and nothing
appeared to be wrong. Wiring was inspected and one wire (Code 24A22) for 28VDC input of the aural annunciator
amplifier (P/N 207), and another wire at plug W314P8 for co-pilot speakers, had been chafed by large plastic ty-wraps.
The wires in question were ?ty-wrapped? at a point where the bundle was bending. If the ty-wraps were 1 cm on
either side of the bend, this would not have happened.
In another incident, an ELT remote switch indicator light was on in the hangar with no aural signal being received on
comm frequency 121-5. The ELT and the wiring were inspected at Zone 312, and the wires 3150-12, 3150-13,
3150-15 were found chafed and were grounding out. Plastic ty-wraps, and plastic clamps cutting into the wiring
were the cause of the problem.
Transport Canada continues to receive SDRs on plastic wire ties that, due to incorrect installation, have damaged
adjacent wiring, structure, or components. Plastic wire retention devices, although more convenient that the lacing
method for certain installations, often are installed quickly and as a result, not in the optimum position, leading to
the chafing of adjacent wires or structures.
Manufacturers? Instructions for Continuing Airworthiness and/or AC 43.13 2B, Chapter 11, Aircraft Electrical
Systems, covers wire installation and inspection, and includes information on the use of wire ties.
Thanks for all the posts and info, by chance I had another rv builder over yesterday to look my project over, he showed me the way to use tie wraps and tubing to space wires apart. I think with proper attention to detail and regular inspections I can use tie wraps to clean up the FWF, no it might not be aerospace standards, but I think it will be fine. Thanks to all
Vibration matters ?
This thread got me thinking about what I see as the "when is it ok to tie-wrap" something. This is my train of thought for an "if I was designing something for an RV engine compartment" exercise. My first thought was; How much of this is about vibration ? If the item being secured can move on one or both sides of the tie wrap, and is in a high vibration environment then I think there is definite possibility of abrasion between the nylon (tie-wrap) and whatever is being secured. Nylon has a particularly abrasive nature. It is a good choice for securing things, particularly in the engine compartment, because it is tough, doesn't creep (stress relieve), and is very high temperature and chemical resistant). For instance, plastic molds for nylon, glass filed nylons in particular, have to be made from the best tool steels because the surfaces of the mold are eroded much sooner than with other plastics.
I know that a long length of unsecured wire or cable has more mass than a shorter length and will be capable of more relative motion. More mass means more displacement if vibration is induced into the wire or cable, and this means more abrasion between the tie wrap and the wire or cable.
Intuitively I know that a light wire secured very with closely spaced tie wraps is not going to vibrate with much motion, and a heavy wire secured widely spaced is going to move a lot in a high vibration environment. Can't forget that the frequency of the vibration matters also. High frequencies move the short light wires and low freq's move the long heavy wires. In a plane the engine is the vibration source and it is isolated from the plane at the engine mount.
The vibrations will be most intense, and have the widest frequency range, on the engine side of the rubber vibration dampers and less have less intense, lower frequency, vibrations on the engine mount side of the dampers.
Stiff, light structures transmit vibration very efficiently (nylon is stiff !). So, rigidly attach an aluminum sheet to the rigid engine case and you have a recipe for fatigue failure: cracking, particularly at stress concentrations (sharp corners etc...) The engine mount is rubber isolated from the engine but it is a very stiff structure so it will transmit whatever vibration is induced into it (the dampers don't stop vibration, they just reduce it). The firewall should be the lowest vibration mounting location in the engine compartment (away from the exhaust anyway). The wing tips and the tail are the farthest from the engine and will see the most attenuated vibrations.
How I interpret all this is that anything that is mounted directly to the engine, I want to keep it from moving (closely spaced mounts) and/or try to isolate or "damp" the mounting as much as possible (rubber cushioned adel clamp or silicone wrap etc...). If I mount it to the engine mount and it is high value (fuel line etc...) and heavy I will isolation mount it (adel clamp). If I mount it to the engine mount and it is light, and won't cause catastrophic system failure if it is broken, then I would not worry at all about using a tie-wrap to secure it. Your mileage may vary.
This helped me, I hope it is correct and also helps others.
Regards
Kerry Stevens
This thread got me thinking about what I see as the "when is it ok to tie-wrap" something. This is my train of thought for an "if I was designing something for an RV engine compartment" exercise. My first thought was; How much of this is about vibration ? If the item being secured can move on one or both sides of the tie wrap, and is in a high vibration environment then I think there is definite possibility of abrasion between the nylon (tie-wrap) and whatever is being secured. Nylon has a particularly abrasive nature. It is a good choice for securing things, particularly in the engine compartment, because it is tough, doesn't creep (stress relieve), and is very high temperature and chemical resistant). For instance, plastic molds for nylon, glass filed nylons in particular, have to be made from the best tool steels because the surfaces of the mold are eroded much sooner than with other plastics.
I know that a long length of unsecured wire or cable has more mass than a shorter length and will be capable of more relative motion. More mass means more displacement if vibration is induced into the wire or cable, and this means more abrasion between the tie wrap and the wire or cable.
Intuitively I know that a light wire secured very with closely spaced tie wraps is not going to vibrate with much motion, and a heavy wire secured widely spaced is going to move a lot in a high vibration environment. Can't forget that the frequency of the vibration matters also. High frequencies move the short light wires and low freq's move the long heavy wires. In a plane the engine is the vibration source and it is isolated from the plane at the engine mount.
The vibrations will be most intense, and have the widest frequency range, on the engine side of the rubber vibration dampers and less have less intense, lower frequency, vibrations on the engine mount side of the dampers.
Stiff, light structures transmit vibration very efficiently (nylon is stiff !). So, rigidly attach an aluminum sheet to the rigid engine case and you have a recipe for fatigue failure: cracking, particularly at stress concentrations (sharp corners etc...) The engine mount is rubber isolated from the engine but it is a very stiff structure so it will transmit whatever vibration is induced into it (the dampers don't stop vibration, they just reduce it). The firewall should be the lowest vibration mounting location in the engine compartment (away from the exhaust anyway). The wing tips and the tail are the farthest from the engine and will see the most attenuated vibrations.
How I interpret all this is that anything that is mounted directly to the engine, I want to keep it from moving (closely spaced mounts) and/or try to isolate or "damp" the mounting as much as possible (rubber cushioned adel clamp or silicone wrap etc...). If I mount it to the engine mount and it is high value (fuel line etc...) and heavy I will isolation mount it (adel clamp). If I mount it to the engine mount and it is light, and won't cause catastrophic system failure if it is broken, then I would not worry at all about using a tie-wrap to secure it. Your mileage may vary.
This helped me, I hope it is correct and also helps others.
Regards
Kerry Stevens
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high temp split loom tubing
I'm working on the FWF wiring, and using adel clamps where possible. One item mentioned by David earlier is the high temp split loom tubing - this stuff looks really good, is easy to install, and seems to behave when I blast it with a heat gun and it finally melts - no sign of flame.
Anyone know why there does not seem to be any love for high temp split loom tubing? Seems a bit better than just tie wrapped wires. Perhaps this is a "non-issue", and I should just get on with using tie wraps.
I'm working on the FWF wiring, and using adel clamps where possible. One item mentioned by David earlier is the high temp split loom tubing - this stuff looks really good, is easy to install, and seems to behave when I blast it with a heat gun and it finally melts - no sign of flame.
Anyone know why there does not seem to be any love for high temp split loom tubing? Seems a bit better than just tie wrapped wires. Perhaps this is a "non-issue", and I should just get on with using tie wraps.
Plastic wire ties (panduits)
Fyi, Boeing decided plastic wire ties are ok now. They surprised us when the started showing up in main wheel wells a bit ahead of the certifying documentation but they are heat and solvent resistant...the blue ones. They are not used on jet motors.
Back to the question, I've seen tiewraps wear through paint to the point where you can feel a trough starting to form. It just has to be loose enough to barely move. I use adels as much as possible and have no problems.
Fyi, Boeing decided plastic wire ties are ok now. They surprised us when the started showing up in main wheel wells a bit ahead of the certifying documentation but they are heat and solvent resistant...the blue ones. They are not used on jet motors.
Back to the question, I've seen tiewraps wear through paint to the point where you can feel a trough starting to form. It just has to be loose enough to barely move. I use adels as much as possible and have no problems.
I don?t like it because no matter how careful you are, eventually, you?ll have oil and oil residue firewall forward, and you?ll also be using solvent on the engine to wash it down. Corrugated tubing will catch oil and solvent, and you?ll never get it out. It just tends to end up being messy.
One thing to watch out for with ty-wraps (zip-ties) is a tendency a lot of people have to over-tighten them. If overly tightened, the insulation on the wire can creep out from underneath the ty-wrap, and may lead to abrasion or shorting of the wires to each other.
I prefer lacing cord whenever possible.
I prefer lacing cord whenever possible.
Lacing cord! Cheaper, just as easy to install/remove, just as easy for inspection and access, AND looks much more professional
(when done right).First Flight Aug 1998 to Condition Inspection Feb 2018 RV-6
Just completed the annual condition inspection on Feb 25, 2018.
After almost 20-years of flying, I have some 1-year owner comments about the purchase of my already flying RV-6.
The zip ties have removed paint on every place they have been used to secure something to the engine mount. A rust ring is under every one. My mechanic suggested using adel clamps, which is what was done.
Some of the zip ties moved and the new issue was a stainless steel oil line rubbing on aluminum brake line. They also wore the paint off of the new spot they ended up at.
Ended up using several clamps to fix many things including wire bundles.
After seeing the engine mount and how it looks, if I ever build, will not be using zip ties!
Best regards,
Mike Bauer
Just completed the annual condition inspection on Feb 25, 2018.
After almost 20-years of flying, I have some 1-year owner comments about the purchase of my already flying RV-6.
The zip ties have removed paint on every place they have been used to secure something to the engine mount. A rust ring is under every one. My mechanic suggested using adel clamps, which is what was done.
Some of the zip ties moved and the new issue was a stainless steel oil line rubbing on aluminum brake line. They also wore the paint off of the new spot they ended up at.
Ended up using several clamps to fix many things including wire bundles.
After seeing the engine mount and how it looks, if I ever build, will not be using zip ties!
Best regards,
Mike Bauer
Very interesting thread, I used as well mostly adel clamps for my firewall forward installation. But at several spots I used lacing tape.. Unfortunately I don`t know if this is acceptable FF or not...
For my spark plug wires I will use the blue zip ties as well as I want a clean installation.
I also covered all wire bundels with braided sleeving out of Nomex (meta-aramid) which is rated at 240?C and passes the flammability tests UL94 V0 (Raw material), UL224 VW-1.
For my spark plug wires I will use the blue zip ties as well as I want a clean installation.
I also covered all wire bundels with braided sleeving out of Nomex (meta-aramid) which is rated at 240?C and passes the flammability tests UL94 V0 (Raw material), UL224 VW-1.
A couple of years ago Christer at Stein air won a Lindy with his RV8. He had the cowl off to show his beautiful wire work forward of the cowl. He use a Lacing tape that was white with black threads running thru it on much of the wiring. It is Nomex lacing tape. Not easy to find but it is available and I was lucky and found a roll on Ebay. It is rated for a much higher temp than zip ties. It is used in many turbo prop planes forward of the fire wall.
