Yet another head scratcher from an "extensive" annual.

[N201MKTurbo]

4 hours ago, Skates97 said:

"We now return to your regularly scheduled programming..."

If someone has a pic of how/where the mixture cable is mounted I would love to see it. The parts catalog that I have doesn't show anything there.

I looked it up too and came to the same conclusion. I haven’t worked on that many Cs so I can’t tell you exactly how it is supposed to be.

 

OK Mooneyspace, we need a picture here!

[ragedracer1977]

2 hours ago, N201MKTurbo said:

I looked it up too and came to the same conclusion. I haven’t worked on that many Cs so I can’t tell you exactly how it is supposed to be.

 

OK Mooneyspace, we need a picture here!

I pulled the cheek off and looked all over.  I can't see a way you could mount it to the engine, short of a bracket off the oil screen plug.  There just doesn't seem to be anything there.  

@M20Doc You are correct there is no nut.  The throttle cable was replaced about a year or so ago, I looked at pictures from the original cable and there was no nut either.  

@N201MKTurbo You once mentioned changing out the ball and socket connection for something more substantial. Can you remind me? Might as well do that if the cable needs to be disconnected anyway

[jetdriven]

4 hours ago, EricJ said:

From what I can gather firesleeve is good to 500F continuous, and SCAT is similar.   Even the lowest temp aluminum alloys don't melt until about 900F, and some alloys and pure aluminum are as high as ~1220F.  Given that there's some decent mass to that part (i.e., it's not foil or thin material) and it's plugged into a stainless heatsink, I'm having difficulty seeing why the part in question would be an issue, given the general number of other holes in the firewall and the stuff that's usually connected to them.   As others have mentioned, I think if you get to the point where that thing melts and creates an issue it's unlikely to add significantly to your problems at hand.

But if you really don't like the aluminum one, you can use a plain Bowden clamp:

https://www.aircraftspruce.com/catalog/appages/bowdenclamp.php

Or put some red rtv on it, supposedly good to 600F, better than firesleeve!

Just my dos centavos, ymmv. 

There is a remarkable about of downplaying the seriousness of a firewall and the penetrations through it. For starters, check your sources, a TSO C53a hose, the kind that carries fuel, must withstand a 5 minute direct application of a 2000F flame 5 inches away for 5 minutes.  The firewall and all fittings are rated for 20 minutes of something similar.  Now, like I said, older airplanes are what they are, copper tubing or TSO hoses behind the panel for fuel and oil, no shoulder harnesses, single vacuum pump with a lazy turn and bank indicator for the backup.  You upograde them to newer standards when you can.

But the justification for adding an uncertified fitting in a safety-related function becuause its "easy" or "looks spiff" is inexcusable. The rules are there for safety, and once you know about it, you know. A grommet with some Permatex red silicone will burn through in less than a minute.  This fitting is good for a couple minutes longer. Usually you are more than one minute away from a suitable landing site.  Its your plane, but your passengers donrt get to make the same deliberate decision to, or not to, compromise their airplane.

from: https://www.aopa.org/news-and-media/all-news/2006/january/01/airframe-and-powerplant

What's the difference between fire-resistant and non-fire-resistant hoses? A fire sleeve. There are two types of fire sleeves — the slip-on and the molded-on, or integral. The minute a woven fiberglass slip-on fire sleeve is properly installed over a rubber tube or Teflon tube hose, that assembly becomes fire resistant. Slip-on fire sleeving has a bright-orange exterior while the integral sleeving is colored a rust brown. TSO C53a requires that fire-resistant hose assemblies be able to withstand a 2,000-degree Fahrenheit flame applied from one-quarter inch away for 5 minutes.

[N201MKTurbo]

2 hours ago, ragedracer1977 said:

I pulled the cheek off and looked all over.  I can't see a way you could mount it to the engine, short of a bracket off the oil screen plug.  There just doesn't seem to be anything there.  

@M20Doc You are correct there is no nut.  The throttle cable was replaced about a year or so ago, I looked at pictures from the original cable and there was no nut either.  

@N201MKTurbo You once mentioned changing out the ball and socket connection for something more substantial. Can you remind me? Might as well do that if the cable needs to be disconnected anyway

https://www.aircraftspruce.com/catalog/appages/hmbrng.php

something like this.

Make sure it is the right size for the cable and arm. Rig it with a fender type washer on one side to keep it from cocking and binding. And add a jam nut.

[Jerry 5TJ]

If an Exocet hits your Mooney I doubt the Stainless Steel firewall will be of much help. 

[EricJ]

19 hours ago, jetdriven said:

There is a remarkable about of downplaying the seriousness of a firewall and the penetrations through it. For starters, check your sources, a TSO C53a hose, the kind that carries fuel, must withstand a 5 minute direct application of a 2000F flame 5 inches away for 5 minutes.  The firewall and all fittings are rated for 20 minutes of something similar.  Now, like I said, older airplanes are what they are, copper tubing or TSO hoses behind the panel for fuel and oil, no shoulder harnesses, single vacuum pump with a lazy turn and bank indicator for the backup.  You upograde them to newer standards when you can.

But the justification for adding an uncertified fitting in a safety-related function becuause its "easy" or "looks spiff" is inexcusable. The rules are there for safety, and once you know about it, you know. A grommet with some Permatex red silicone will burn through in less than a minute.  This fitting is good for a couple minutes longer. Usually you are more than one minute away from a suitable landing site.  Its your plane, but your passengers donrt get to make the same deliberate decision to, or not to, compromise their airplane.

from: https://www.aopa.org/news-and-media/all-news/2006/january/01/airframe-and-powerplant

What's the difference between fire-resistant and non-fire-resistant hoses? A fire sleeve. There are two types of fire sleeves — the slip-on and the molded-on, or integral. The minute a woven fiberglass slip-on fire sleeve is properly installed over a rubber tube or Teflon tube hose, that assembly becomes fire resistant. Slip-on fire sleeving has a bright-orange exterior while the integral sleeving is colored a rust brown. TSO C53a requires that fire-resistant hose assemblies be able to withstand a 2,000-degree Fahrenheit flame applied from one-quarter inch away for 5 minutes.

I don't think anybody has been downplaying anything, nor have I noticed anybody suggest use of something because it's "easy" or "looks spiff".    Maybe I missed it, but I don't think that's been part of the dialogue.    The part that appears to be in question was brought up as having been recommended and used by somebody's IA, so maybe your issue is with them?   I think other comments have been more in context of the realities of typical Mooney firewalls.

Bowden cables don't carry flammable liquid, so TSO C53a doesn't apply to them.  My previous comment compared continuous temps because they're more comparable for materials, since the time-specific requirements may differ for different things.   For certification firewall fittings require exposure to 2000F for 15 minutes, in a fixture with 10"x10" (or so, whatever the docs actually say) of the firewall materials, or maybe there are other appropriate tests as well.  As usual, there's a whole test criterion, and the firewall and the cable and the fitting will make a system with it's own thermal conductivity  characteristics that I think would be tough to fully evaluate without actually doing a test.    As previously mentioned, cannon plugs with plastic cores seem to pass these, so I wouldn't make assumptions without actually doing a test.   AC 20-135 and AC 33-17 are useful here if one wants to actually do a test.

It is true that aluminum fittings aren't recommended for firewalls in the certification process, especially if 3/4" or larger, and I previously linked the non-aluminum Bowden clamp page at aircraft spruce for those so inclined.    If the firewall is actually the place where the cable gets attached, that's certainly an option.

Edited October 15, 2019 by EricJ