Today's Message Index:
----------------------
1. 04:29 AM - Safety wire? (Grant Corriveau)
2. 05:32 AM - Re: Safety wire? (Harvey Rule)
3. 06:38 AM - Re: Safety wire? (Gary Casey)
4. 03:50 PM - Re: Engines-List Digest: 9 Msgs - 10/22/05 (gena perevedentsev)
Message 1
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--> Engines-List message posted by: Grant Corriveau <grantc@ca.inter.net>
> In what respect do we use auto engines differently than in automotive use, I
> wonder?
I've been appreciating the various comments: In response to the above
question:
1/ I think it's mainly heat and vibration... to illustrate, my engine came
with an automotive grade 2" tube that connected the exhaust heat shroud to
the carb heat air inlet. My inspector recommended changing that for an
(expensive!) aviation grade Scat Tube. But I reasoned that the engine
manufacturer must know what he's doing -- right?
Well, within the first 3 hours, that auto grade tube began to disintegrate
and send small shards of crap into my air filter. I was unhappy to say the
least. I think the engine room in an airplane gets a lot hotter than in a
car. The bottom and most of the frontal area of a car's engine is exposed
to airflow.
Also, the propellor-induced air pulses in the air that does flow through the
airplane cowling and the low frequency vibes caused by the forces on a
propellor swinging round and round (no matter how well balanced) add up to
constant stress and fatigue.
2/ The consequences of minor failures can have dire consequences in an
airplane compared to a car. In an airplane, losing all the coolant when
flying over northern Canada in winter is a life-threatening situation no
matter how good the emergency landing is. And the likelihood of being
within operating range of any airport is minimal. It's for this reason that
when operating over lake and bush country or in the mountains (and I suppose
this applies to desert flying too) IFR (I Follow Roads) is the only way to
go in a single-engine airplane unless you are feeling particularly
adventuresome.
Regards,
--
Grant Corriveau
C-GHTF / HDS / CAM100
Message 2
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| Subject: | Re: Safety wire? |
--> Engines-List message posted by: Harvey Rule <harvey.rule@sympatico.ca>
AMEN to that brother;I mean in a car if something goes wrong you just
pull over if you can.Add in the third
element ,hight and you have a whole new ball game.Mike is right;do it
right and save yourself a whole pile
of grief!
>--> Engines-List message posted by: "Mike" <mlas@cox.net>
>
>
>I only have a few things to say on the subject of safety wire, first it
>is your airplane and it is your experiment. Therefore you can do it
>what ever way you want. You can do like the factory airplanes and
>safety wire almost everything, or like a road car nothing at all. But
>keep this in mind, some night you may be flying over eastern AZ or NM
>and your oil filter or the likes may loosen up and cause and engine
>failure. Was the extra headache, the $10, or the pin prick to the
>finger worth it? I'll let you decide.
>
>As far as cars and safety wire, in every form of regulated racing safety
>wire is required.
>
>Mike Larkin
>
>TS-11 Iskra
>A-320
>Lancair Legacy
>Kitfox 4
>25 year pilot
>22 year aircraft mechanic
>
>
>
>
Message 3
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| Subject: | Re: Safety wire? |
--> Engines-List message posted by: Gary Casey <glcasey@adelphia.net>
Some observations from a non-professional outside observer:
Some aircraft bolts (not all by any means) have some sort of
retention device and others don't. Same is true in the automotive
world. Typically, if the bolt torque is a higher percentage of the
strength of the bolt and the things bolted together are stiff (like
the crankcase halves) then no locking method is required. If the
bolt is short - meaning it has little elasticity, or stretch -
locking methods are usually used. an example here are bolts that
hold throttle cable mounting brackets to the engine block. Also,
when the things bolted together are soft, like the exhaust flanges
with a thick gasket, a locking method is used. Metal (not plastic in
the engine compartment) self-locking nuts can be used if the other
half is a bolt. If it is a stud these cannot be used as the stud
could end up backing out with the nut. With a stud the nut has to be
retained by the flange, usually by an internal star washer. A lock-
nut applied on top of a standard nut works if the required torque for
the original nut is very low, preventing it from being tightened
enough to prevent torque loss. There are a number of locking devices
that work. Loctite is okay, but the metal should be clean, not too
hot (like a cylinder head) and the loctite needs to be renewed with
every removal. Star washers are okay, but they are supposed to be
renewed with every removal (although I admit I've never seen this
done or done it myself). Metal locking nuts can be used with a
bolt. And finally, safety wire. When should safety wire be used?
In my opinion, when the other methods don't work or are inconvenient
and when you're not sure that the retainer will stay put without it.
How do you be sure? You can analyze each bolted joint (time
consuming), rely on the experience of others, or safety everything.
The last is impractical, so some reasonable balance is appropriate.
For instance, why safety an oil filter? I've never heard of one
backing off in a car and I've seen several airplanes where the
service guy forgot to do it and nothing happened. It's usually not
difficult, the alternative could prove catastrophic, so I do it. On
the other hand, I've never seen a hose clamp in a plane safetied.
but if it held coolant in then I'd be tempted. I usually double-
safety throttle cables because of all the vibration. If it's hard to
inspect - like maybe the bolts inside the engine that hold the oil
baffles in place on a Chevy V-8 - I'd be tempted to add safety wire.
And does an engine vibrate more in an aircraft than in a car? The
vibration amplitudes and frequencies are probably different, if not
higher, and that would be reason enough to add safety wire in a few
places at least simply because there is no large body of experience
upon which to draw.
In other words, no absolute solution is good for everything.
Gary Casey
Message 4
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| Subject: | Re: Engines-List Digest: 9 Msgs - 10/22/05 |
--> Engines-List message posted by: gena perevedentsev <genaperevedent@yahoo.co.uk>
With all respect,if there is any chance, I would put
safety wiring.Another reason for it,is that it is
easier to asses the joint for tightness with locking
wire.
Aero engine could be
overheated/overcooled,overrevved,frozen,fouled/overoiled
at low RPM,overprimed etc etc. So, I mean they are
working in much tougher conditions than car engines.
Could anybody explain, why there is no wirelocking on
any oil, fuel, hydraulic line. Is it because of thread
profile or any coating.Thank you.
--- Engines-List Digest Server
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> Engines-List Digest
> Archive
> ---
> Total Messages Posted Sat
> 10/22/05: 9
>
>
>
>
> Today's Message Index:
> ----------------------
>
> 1. 04:27 AM - Safety wire? (Grant Corriveau)
> 2. 05:35 AM - Re: Safety wire? (Ken)
> 3. 05:45 AM - Re: Safety wire? (Hans
> Teijgeler)
> 4. 06:30 AM - Re: Safety wire?( Kiss principle)
> (Daniel Tappan)
> 5. 06:59 AM - Re: Safety wire?( Kiss principle)
> (Hans Teijgeler)
> 6. 07:15 AM - Re: Safety wire?( Kiss principle)
> (Joe Healy)
> 7. 07:45 AM - Re: Safety wire?( Kiss principle)
> (Hans Teijgeler)
> 8. 09:02 AM - Re: Safety wire? (AI Nut)
> 9. 08:49 PM - Re: Safety wire? (Mike)
>
>
>
> ________________________________ Message 1
> _____________________________________
>
>
> Time: 04:27:11 AM PST US
> Subject: Engines-List: Safety wire?
> From: Grant Corriveau <grantc@ca.inter.net>
>
> --> Engines-List message posted by: Grant Corriveau
> <grantc@ca.inter.net>
>
> > There seems to be two schools of thought about
> safety wire. One says lay one
> > strand
> > of the wire over the bolt head, the other says
> warp both strands (twisted)
> > around the bolt head (obviously in the direction
> to prevent backing out.)
>
> Thanks for raising this and to the person who
> supplied the .pdf on the
> topic. For those of us with auto-conversions,
> here's a couple of other
> ideas for safety-wiring that my inspector
> recommended:
>
> 1/ Radiator cap
>
> 2/ hose clamps - a strand of safety wire across the
> slot of the screw to
> prevent any backing off from vibes.
>
> 3/ On any taps or drains in the water jacket on the
> engine block
>
> 4/ Also, he strongly recommended safety wires on the
> oil filter and oil pan
> drain plug. I have a temp sensor installed in the
> oil pan plug, so I
> accomplished these two by putting hose clamps on
> them, then safetying these
> clamps together so neither should be able to spin
> out.
>
> 5/ He strongly recommended some sort of spring or
> clamp to prevent the
> dipstick from popping out.
>
> 6/ Any other particularly critical bolts -- i.e.
> someone else with a CAM100
> had a bolt from the camshaft cover come loose and
> fall into the PSRU drive
> belt -- much noise, adrenalin and 'damaged shorts'
> in flight and an
> expensive drive belt to replace... So I took the
> hint and drilled these bolt
> heads and safetied them too.
>
> fwiw
> --
> Grant Corriveau
> C-GHTF / HDS / CAM100
>
>
>
>
>
>
> ________________________________ Message 2
> _____________________________________
>
>
> Time: 05:35:22 AM PST US
> From: Ken <klehman@albedo.net>
> Subject: Re: Engines-List: Safety wire?
>
> --> Engines-List message posted by: Ken
> <klehman@albedo.net>
>
> Thanks for the comments Grant.
> I'll take another look but there are hundreds of
> bolts that have never
> come loose on a car engine. Some have loc-tite. The
> bigger risk with
> many is that they will break off when you want to
> remove them IMO. I've
> always wondered where to draw the line on safety
> wire especially since
> in most cases all it really does is prevent a bolt
> from falling out. If
> it is going to loosen, safety wire is unlikely to
> stop the underlying
> problem on a car engine. The inspectors are used to
> Lyc's that vibrate
> hugely compared to our engines and that use gaskets
> instead of RTV...
> I've seen some intallations that had serious design
> weakness's but were
> well safety wired - presumably to cover the
> inspectors conscience (and
> other things)...
> Ken
>
>
>
>
>
>
> ________________________________ Message 3
> _____________________________________
>
>
> Time: 05:45:48 AM PST US
> From: "Hans Teijgeler" <hans@jodel.com>
> Subject: RE: Engines-List: Safety wire?
>
> --> Engines-List message posted by: "Hans Teijgeler"
> <hans@jodel.com>
>
> In what respect do we use auto engines differently
> than in automotive use, I
> wonder? They work a bit harder than US/Canada
> everyday use, but I can assure
> you that the Subaru in my Jodel has an easier life
> than the engine in my car
> (you've got the love the German Autobahns).
>
> Billions of hours annually of automotive hours have
> taught us that certain
> things simply do not happen. Why then modify them
> for use in aircraft?
>
> > 1/ Radiator cap
>
> Result: You don't open the cap quite as often as you
> could. Counter
>
=== message truncated ===
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