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Tighten Your Tie-Wraps!

RVTrumpet

Active Member
Last Saturday we were out at the hangar to inspect the 12 for a small coolant leak. After pulling both the top and bottom cowls off, the following was noticed:



The black tie-wrap had apparently been installed at the last annual to hold the oil line in position that passes under the crankcase and over the muffler. It had been installed around the oil line and the rubber coolant hose that joins the elbow coming from the cylinder to the elbow coming from the coolant pump. Apparently the tie-wrap was not installed quite tight enough. Sometime in the last ~40 hours of operation the tie-wrap slipped forward off the rubber coolant tube and came to rest on the aluminum elbow coming from the cylinder head. Because the OD of the aluminum tube is much less than the OD of the rubber tube, the tie-wrap was very loose and freely vibrated against the elbow. (The tie-wrap was moved aft for the picture).

As shown in the picture, the result of the tie-wrap vibrating against the elbow was a chafed groove in the aluminum approximately .020 deep. The decision was made to ground the aircraft until the elbow could be replaced. Thankfully the elbow is fairly inexpensive and the repair will not be too extensive. However it is scary to think what could have happened if the tie-wrap had ground its way through the entire tube wall.

The lesson here is that the plastic components we use in our aircraft are harder than the aluminum ones. Plastic wiring connectors, tie-wraps, and even wire insulation will slowly chafe aluminum components if not properly restrained, resulting in possible electrical systems failure and compromising the strength of the aluminum component it chafes against.
 
Zip ties don't really belong in the engine compartment.

The only place they're used on big airplanes is in the pressurized areas. The hot/cold cycles make them brittle and never in a high vibration area.

Glad it's an easy fix.
 
Don't use tie wraps. I am shocked your DAR signed off on that plan. Mine told me long before he ever saw my plane, a single tie wrap firewall forward and you fail the inspection.
 
Don't use tie wraps. I am shocked your DAR signed off on that plan. Mine told me long before he ever saw my plane, a single tie wrap firewall forward and you fail the inspection.

Oh lord - another guy making up his own rules! I have seen more certified airplanes with tie-wraps forward of the firewall than I can count. Let's not start folks off with old wives tails and false doctrine. Tie wraps come in many different types and temperature ranges, and I have seen them in some pretty awful environments. You just have to use the right ones, and use them appropriately.
 
And there are some stainless zip ties as well, although those might cause chafing or other issues if not installed properly. As Paul said, depends on the job whether they can be utilized safely.
 
Interesting to me how many tie wraps Lycoming sent with a brand new engine as part of the hardware kit to secure the spark plug cables. You'd think they know...
 
A friends $3,500,000 TBM 850 came from the factory with tie wraps all over the engine compartment. I think Paul said it best.
 
The inspectors at Oshkosh said the same thing while inspecting my engine compartment. No tie wraps. They said they will do the same thing to your engine mount as the photo above did to the aluminum pipe. I dunno if it's true or not of course, as I followed my DAR's directive and everything is done with adel clamps. Considering how easy it is to clamp everything and use sparkplug wire separators on the sparkplug wires, I can't say I was ever tempted to argue it out with the DAR, unlike the ridiculous wet compass requirement.

I can't think of any good reason to use zip ties firewall forward. I used a few hundred of them for initial wire bundling in the fuselage but once complete used the tie methods called out in the bible (Ac43). The great thing about these planes though is we get to do what we want (as long as your DAR isn't the pain in the butt mine was). Obviously there are tie wraps out there that will work firewall forward. There are far more that will do what the photo above did. We each spend our money and make our own decisions. How many of those 3.5M TBM's came with Lycoming vibration generators?
 
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Obviously there are tie wraps out there that will work firewall forward. There are far more that will do what the photo above did.

Just for clarification, the damage done in the photo above was not a result of the type of tie-wrap used but was because it slipped forward off a larger tube and onto a smaller tube causing the tie-wrap to be very loose and vibrate against the aluminum tube. If the tie-wrap would have been tight to where it couldn't vibrate, even against that aluminum tube (not recommended at all), it would not have caused that much damage and possibly no damage at all.
 
Use them properly. If you are wrapping them around something, put Rescue Tape on the something first. Two ties can make an excellent standoff to hold things in place with no chafing. Sheesh!
 
Tie wraps

Strong opinions have been expressed in this thread, and do not always agree with real world experience - at least mine. We have a 1981 Pitts S-2A which was purchased new with many tie wraps in the FWF area. In about 1300 hours we have added many new tie wraps and replaced some that looked or felt marginal. Not a single one has broken. That's 33 years. Many are the common hardware store variety. If they tie around a motor mount tube or other metal structure they are placed over a layer of rubber tape. We've had no chafing or damage to metal or to wire bundles. My RV-8 is just finished and the Chief inspector from the FAA loves tie-wraps FWF and favors using them extensively. I used Adel clamps in some areas but also a lot of tie wraps. Hopefully they'll last as well on the -8 as they have on the Pitts. After some flying time has accumulated I'll try to give a follow up. Anybody else have some long term real experience to share?
 
Same experience Bill, just shorter term. During my first Condition Inspection following my purchase, the A&P/IA had me remove all the tie wraps that were directly on the engine mount, and reinstall new ones with rescue tape or fuel hose segments protecting the mount. Showed me how to make standoffs with them as well, and to use adels, when that is a good solution. I take a good look at installed ties and clamps to look for breakage and slippage when the cowl is off as well. Knowing what tie wraps can do to unprotected metal is a good lesson from the OP.

Cheers,
Bob
 
My 2008 G36 Bonanza has them FWF in many places... If you get the blue tefzel tie wraps, they'll survive that environment just fine, but they are expensive. As in all things, it depends!
 
Don't use tie wraps. I am shocked your DAR signed off on that plan. Mine told me long before he ever saw my plane, a single tie wrap firewall forward and you fail the inspection.
Interesting. I had an FAA inspector sign off on my plane and I had plenty in the engine compartment. Guess I've cheated death now 14+ years with them there. (Not the same ones, of course.)
 
I am shocked your DAR signed off on that plan. Mine told me long before he ever saw my plane, a single tie wrap firewall forward and you fail the inspection.

Why? Is there some regulation that says you can't have tie wraps FWF?

Interesting. I had an FAA inspector sign off on my plane and I had plenty in the engine compartment. Guess I've cheated death now 14+ years with them there. (Not the same ones, of course.)

In another thread it was pointed out quite forcefully that "it is not an FAA inspectors (or DAR for that matter) responsibility to inspect a builders airplane on the premise of making a judgement on whether it is in a condition for safe operation or not. His only official duty is to make a judgement on whether the airplane meets all of the certification requirements as spelled out in FAA Order 8130.2G" (I'm not picking on the original poster with this quote, just using it to make a point).

Then along comes a DAR who makes up a new rule about tie wraps and threatens failure if there's even *one* FWF. Not "don't use them directly on X parts, because they'll wear through the part and that's unsafe" or anything like that. Nope...can't have 'em. Period.

What gives with inspectors or DARs making up their own rules? Some examples I recall:

No nylock nuts FWF (despite the fact that Lycoming ships their engines with nylock nuts in certain places)
Refusal to accept nylocks on props (as shipped from Hartzell)
"Requirement" for red fuel caps
Insisting on .040 lockwire on props, despite Hartzell service instructions specifying .032
Requiring "wet compasses" in EFIS-equipped aircraft
Requiring A&P "sign-offs" prior to the DAR doing the inspection
*Numerous* "challenges" to Van's plans (forcing builders to change a design in some small or large way which deviates from the kit plans...changing rudder stop locations, using a single pin in the seat back hinge and safetying it,
How about the guy in this thread?

The list goes on and on...wildly varying standards of inspection, huge discrepancies between the regulations and what some require of builders (essentially holding their A/W certificate hostage unless/until the builder complies), fabricated rules, regulations or best practices, etc.

And on the other hand, there are highly competent, skilled, knowledgeable DARs and inspectors out there who do a great job (both at the formal paperwork and at helping ensure the aircraft is safe).

Nearly 9,000 RVs flying now, you'd think that EAB inspections would be getting significantly more consistent FSDO-to-FSDO, inspector-to-inspector, but I don't see it...
 
Ty-wraps

When using Ty-wraps, I first run a piece of heat shrink over it on the section that tightens on the tube. kinda protects the tubing and have not noticed any chaffing in many many hours.
 
Why? Is there some regulation that says you can't have tie wraps FWF?



In another thread it was pointed out quite forcefully that "it is not an FAA inspectors (or DAR for that matter) responsibility to inspect a builders airplane on the premise of making a judgement on whether it is in a condition for safe operation or not. His only official duty is to make a judgement on whether the airplane meets all of the certification requirements as spelled out in FAA Order 8130.2G" (I'm not picking on the original poster with this quote, just using it to make a point).

Then along comes a DAR who makes up a new rule about tie wraps and threatens failure if there's even *one* FWF. Not "don't use them directly on X parts, because they'll wear through the part and that's unsafe" or anything like that. Nope...can't have 'em. Period.

What gives with inspectors or DARs making up their own rules? Some examples I recall:

No nylock nuts FWF (despite the fact that Lycoming ships their engines with nylock nuts in certain places)
Refusal to accept nylocks on props (as shipped from Hartzell)
"Requirement" for red fuel caps
Insisting on .040 lockwire on props, despite Hartzell service instructions specifying .032
Requiring "wet compasses" in EFIS-equipped aircraft
Requiring A&P "sign-offs" prior to the DAR doing the inspection
*Numerous* "challenges" to Van's plans (forcing builders to change a design in some small or large way which deviates from the kit plans...changing rudder stop locations, using a single pin in the seat back hinge and safetying it,
How about the guy in this thread?

The list goes on and on...wildly varying standards of inspection, huge discrepancies between the regulations and what some require of builders (essentially holding their A/W certificate hostage unless/until the builder complies), fabricated rules, regulations or best practices, etc.

And on the other hand, there are highly competent, skilled, knowledgeable DARs and inspectors out there who do a great job (both at the formal paperwork and at helping ensure the aircraft is safe).

Nearly 9,000 RVs flying now, you'd think that EAB inspections would be getting significantly more consistent FSDO-to-FSDO, inspector-to-inspector, but I don't see it...

Very well stated
 
I use them sparingly FWF. Silicon tape works well for a backing and will not degrade like vinyl or others types of tape.
 
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