Morgan Sierra safety

I can assure you that they were common place in early ultralights and still being used. If you doubt their effectiveness get a piece of hose worm drive clip on one end and cable tie on the other and pressure test until one leaks, you will be surprised. Then replace the worm drive which failed with a cable tie and increase the pressure until the something breaks you will be surprised. Then throw away the piece of broken fuel hose.

 

RAA should issue an immediate requirement to remove these items from fuel line assemblies.

These are actually cable ties, designed for the realively low tension job of bundle electrical wiring into a "harness"
Sure we've adapted them for many other uses, usually associated with tidying things up.

However, their achilles heel is that the plastic or nylon deteriorates in a relatievly short time; I've had them fail in agricultural use where there was sunlight in less than one summer period.

The secondary problem around fuel lines is that in the case of a fire they usually perform at around Z-2 standard which says:

• They may not burn for more than 30 seconds (in tension, as in being used as a hose clamp, elasticity will begin immediately, and a hose under pressure can be pushed off, providing a major fire fuel source.
• Specimens are allowed to drip flaming particles, so if you are using them in the engine bay, instead of a small fire burning out, they can ignite other areas.

Forget about the clowns who have been using them; DON'T EVEN THINK ABOUT IT!

 

30 seconds in a fuel fire, hmmm, don't think cable ties come into the equation.

 

Afuel fire can be caused by a cable tie perishing and cracking and in that case its fire properties are secondary, but most fires are electrical or due to oil being spilled or an oil line failing. The fire may only be smouldering. Im those cases you will have been trained in how to manage the aircraft down to the ground, including assymetrical flight to keep flames to one side. If a cable tie softens or elasticises THEN you have the big fuel fire.

 

A fuel fire can be caused by an a engine failure, an electrical failure, a hose clamp failure, a fuel pump failure, a crash landing failure, a fuel hose failure. And?

 

....and a steel clamp cannot catch fire and doesn't perish due to oil, heat or sunlight.
I've been through the steel clamp issue that Facthunter mentioned, and went over to the thin stainless steel type, and the overlap issue doesn't occur there.
The stainless steel hose clamps are petty cash.
However, and someone mentioned earlier there are even better ones.

 

Yep sure is, and? I really do wonder if you fly cause it seems a bit to dangerous for you.

 

IF you are serious about engine fires we would pay more attention to isolating fuel and oil and a better firewall. We have a lot of pressured oil lines on a lot of motors and oil coolers which can fail. ALL this stuff needs inspection and maintenance. Your oil and fuel lines should be replaced regularly, long before they show evidence of deterioration , and use quality components. Nev

 

Yes I do, and no it doesn't; and any thinking person will understand the safety advantage of a steel clamp.

 

Sometimes these things are not as obvious as they seem. The main thing with hoses is the hose quality, and the raised bit you push it over. A plain pipe is not safe , no matter what the clamp unless a strip goes to a fixed point to anchor the clamp and prevent it coming adrift. Nev

 

I think that the issue is that a small fire melts the cable tie and it then becomes a big fuel fire.....

 

Your carburetter is a source of possible fuel leakage. All you need is a faulty float or grunge under the needle or overpressure from the auxiliary fuel pump. Pressurised fuel lines should consider upgraded fittings rather than push on and clamp. Horses for courses. Nev

 

The fuel didnt leak from a hose that came off, cable ties are one of the best ties just look at a out board motor tank. The fuel filter was NOT forward of the fire wall as stated. The fuel tank split open. The 747 has wires inside the fuel tank, there is no safety issue with tiring a wire to a fuel proof line to stop it vibiriting, this was removed ,but it will brake with vibrating. there was no shafing of the trim bungee this was made up.the stick yes some one in the work shop has not done a good job here . Have a good look at a piper of such and you can find fault with anything. The reason it never passed the second time we did all the paper work by our tech guy the first thing he said my plane hit a ferris wheel. and then condemned ever thing we had done, no through of how much time and money a small business has put in. Also the guys did walk away and not taken away . I get abusive calls and mail that it flew into a hole, but i can tell you that is not the case ,it took out the two main outer supports and two gondoliers. A 22G main fuse stayed together.So if you think it a crap aircraft you had better take a closer look at the imported craft. Your aussie designed aircraft are going to come out better in a crash.

 

You are in "wheel" trouble with CASA if you hit a Ferris wheel. It's something you don't get over easily.. Many others don't get the opportunity to hit one and become famous. Mostly Ferris wheels aren't put in stupid places, near where planes fly.. Nev

 

It is interesting to note that the damaged Sierra was repaired and lived to fly again....I bet my Cessna 150 wouldn't have.
Alan.

 

A Cessna 150 is pretty tough. They have proven themselves over the years. Nev

 

Here fishy fishy fishy.

 

Going back to the actual Morgan design....what do others (including builders) think of pop rivets going into FRP ribs? Is the fibreglass strong enough to hold a rivet over time...especially with the uneven temperature expansion/contraction of the metal skin over the plastic ribs?

Also, the stabilator appears to have all the FRP ribs epoxied to a single metal torque tube (is that the right term?). Again, it seems to me in the long term that epoxy might lose adhesion to the metal due to uneven expansion/contraction. Of all the joints in a plane they are the ones I would most hate to fail. Comments?

 

As long as you use a washer behind the rivet and epoxy the rib to the skin it should ok

 

Epoxy shrinks as it cures and also shrinks a small amount over time so the grip on the roughened tube is very good. I did a test piece on a tube and could not get it to separate.