Fuel Hoses

Gentlemen,

# This Forum is about Rotax engines that, for the most part, are fitted to non certified aircraft.

I don't have an issue with using fire sleeve and other insulating materials/systems, I use them, in a targeted way, myself.

I do have an issue with; 

"...........don’t forget fuel and oil hose belong in protective fire sleeve". "It is simply best practice, do what you can to mitigate risk ..."

This sort of statement, coming from influential members of the Forum, might suggest that the fitting of fire sleeves will have some significant safety benefit. This would be great, if tue & supported by evidence. I suggest that the evidence is not there or at best, limited to a small safety  enhancement, when installed as per certified aircraft standards and with complimentary fire resistant systems/materials (not often the case).

The debate following, has focused on custom (always done it), an Advisory document aimed at Certified aircraft (hardly pertinent as many complementary safety factors are likly absent), a video (from a commercial/vested interest promoter) and social norm (fashion - adopted/conformity by many).

"............a large number did catch fire.  Could this have ended better if they had followed the best practice is the question and without hesitation?  I would say yes."

This is emotive "scaremongering" - what other factors were involved? Was the installation of the engine/ancillary systems, maintenance & build standard  "up to scratch "?

The safety benefits of fitting fire sleeve, to reduce the risk of inflight/post crash fire, seems to be conjecture. 

Could there be a negative outcome to fitting fire sleeve?; Speculation - elevated safety expectations, leading to reduced standard of maintenance eg extending  5 year rubber replacement. Insufficient care in the routing of fuel/oil hose, as far away from extreme heat source, as practical.  Failure to adequately support/restrain hose against movement.

Arguably the main benefit in using fire sleeve (& other insulators) is minimise fuel heating and damage to "rubber" hose, (which could be extended to having a safety benefit).

Sean

At risk of increasing your blood pressure here is a small study done by Kitplanes on this very subject.  It is USA based only as that is what the NTSB database covers.  It is likely a similar ratio in other regions.  

https://www.kitplanes.com/homebuilt-accidents-fire/

no Cheers on this one, obviously you are not happy with my opinion. 

RW, 

Thank you for the thought provoking article.

I was pleased to be be shown to be incorrect in my assumption, that inflight fires are almost always fatal. Seems that in most cases, the aircraft makes it to the ground and the crew manage to get out & survive.

It was also reassuring in its assurance of this being a relativly uncommon incident. This in itself is quite remarkable, given the lack of conformity in small aircraft construction standards (both factory & homebuilt)

Unfortunatly the article does not address my repeated assertion, that many, possibly most, small Rorax powered, recreation level aircraft do not have firesleeve installed to certified standards. Further, complimentary fire resistant systems eg firewall built to certified standard, may be absent.

If I am correct, the Kitplanes article might suggest not much difference between certified and non certified firesleeve installation ie where is the benefit?

So the question is:

If firesleeve is not installed to the certified standard, is it providing a fire resistant safety function?

All I am asking for is evidence to support the policy of comprehensive (all engine bay oil/fuel hose) installation of firesleeve below certified standard - so far 0.

".......obviously you are not happy with my opinion. "

Opinion is great, without it what would we debate. I respect both you & Roger - that does not mean that I won't question what seems to me to be a policy, full of good intent but seemingly lacking in empirical foundation.

Hi Sean,

Here in the USA most SLSA have fire sleeve. (Not all)  Here it’s close to an industry standard. All the light sport I work on have fire sleeve except a couple and when I get them for a five year rubber change it gets installed and the ends get secured with Band-It clamps. Another industry standard.

Retiring from the medical field after 30 years always taught me to error on the better side. 

Hi Roger,

"...most SLSA have fire sleeve." 

I would suggest "most" here (Australia) also. However many will not have all the oil/fuel lines sleeved and many more will not have "Band-It clamps" or similar securing the ends of the sleeve.

".....it’s close to an industry standard"

This does not make it an effective system. There can be other motives for making something an industry standard eg fashion (always a big driver). Not so many years ago most cars had a  metal "mascot" on the front of the bonnet/hood, an industry standard? No more, why? because the unfortunate pedestrian hit by a car had his/her injuries magnified by being sliced by the mascot.

Time sometimes radically changes what previously was an accepted norm/truism. This is especially so when the truism has been adopted using "common sense" rather than scientific study (empirical evidence).

Few would argue with the idea that the fitting of fire sleeve is a safety enhancement  - just common sense, yes? I would not be surprised that a scientific study could back this but has it actually been done??? I suggest not. 

Example: In my limited experince (a bit of European, mostly Australian) people with "colour blindness" were barred from obtaining a pilots licence/ train drivers ticket/etc. Common sense says this is a reasonable safety ruling, because they cant see (blind) colours, used in aviation/rail industry, for a host of communication systems.

Times change and it has become apparent that colour blindness (an emotive & incorrect term) is as variable as other visual ability/limitations and as far as I know its extraordinarily rare to be colour blind (no colour perception ).

For a quite a few years now, the original absolut barrier ruling has been relaxed and pilots with colour vision issues, have been able to fly, with restriction to Day VFR Only. More recently, even obtain a CPL

I just read today that a pilot, with colour perception issues,  aspiring to become an unrestricted commercial pilot, can now do so, subject to a satisfactory visual assessment (empirical evidence). 

The process of moving from a common sense ruling, to an empirical assessment, has probably taken 80 years or more.

Back to fire sleeves;

The application of  risk mitigating features, must have a diminishing return ie when a hierarchy of risks is done, the most risky item(s) addressed,  all subsequent risks are reduced. At some point, it ceases to be worth while applying further safety features. Could it be that fire sleeve has very little impact on the survivability of any small aircraft. I would suggest that good maintenance/installation technique(s) would have a far greater effect, in reducing the chance of fire in the first instance (Prevention/Elimination being fist on the list of Hierarchy of Control)