Oil & fuel hoses - rotax 912

[johnm]

Howdy

 

With a 24 registered aircraft and with a 5 year Rotax 912 installed it seems a good idea to at least think about replacing them hoses

 

The catch is that the manufacturer of the plane (does not really matter which one) installed them (engine oil and fuel hoses) so you need to do it their way ?

 

I personally don't reckon that the plane maufacturer gives 2 hoots what you do - after all its a Rotax operating system (s)

 

The question is - I believe the hoses should be ripped off - new hoses installed and a suitable clamping system used - is this what we do in the end ............ ? (the hose has n't got a brain so it does not what clamp is being used - same goes for the clamp)

 

As far as I am concerned its an inert bit of hose - so hoses and hose clamps - as per say a 'Sportsstar' installation should do ( ....... and yes I know - 24 registered - you must do what the plane maufucaturer did)

 

Any thoughts please - thanks

 

JM

 

 

[HEON]

Rotax say change at 5 years.

 

Interesting question! Like how far from the engine?

 

Some would be Rotax parts (fuel hose near carby's; on 914 turbo to air box)...what of let us say fuel hose from tanks to engine?

 

What is the answer?

 

Just a note however...24 rego you MUST DO as the maker did ONLY if LSA...if 24 UL different rules.

 

 

[Guest Maj Millard]

As Heon stated, Rotax hoses (rubber) are to be renewed every five years. This includes the rubber carb sockets, however after inspection these may need more frequent replacement.

 

The paricular oil-tank positioning and hose routing needs to be maintained as laid out by the aircraft manufacturer.

 

You should however adhere to Rotaxs recommendations as to the type of hose, in particular the oil hose which needs to have an inside diam no less than 10mm.

 

Rotax does suggest double clamping if required, and in particular the out lines from the oil pump.

 

Clamps are cheap, total loss of oil in flight is not !!..................................................................Maj...

 

 

[Guest JeffC]

I have recently finished the 5 yr rubber replacement on my Foxbat (912ULS). Wal (Bert Floods) has a "kit" including the engine specific hoses (oil, coolant from header tank to heads), the carb sockets and carb diaphrams.

 

The line maintenance manual states what has to be replaced and the installation manual gives you the specifications. The kit was over $700 but the sockets and diaphrams are the expensive items. Fuel hose and the 25mm coolant hose can be sourced from automotive shops. You should be able to find suitable bends to suit the radiater installation by fossicking through the hose bins at Autocheap or similar and cutting back to size.

 

I bit the bullet and replaced all hoses including fuel from the tanks. They weren't in bad condition but there was evidence of cracking at the cut ends so probably worthwhile.

 

It turned out to be a big job (for me). The Foxbat is pretty open so most hoses were easily accessed. The exception was the short hoses from the fuel cocks to the tanks through the wing roots. The manufacturer probably laid these before the wing skins were riveted on and it was a swine of a job to get the replacement hose in. The point is it can be easy to pull things out but a real bugger to put them back! All the connections are important but Wal was particularly keen to ensure I connected the large diameter coolant pipe to the water pump securely and to check it after every flight. The pipe fitting lacks a significant flange or lip so the clamp does all the work. If it blows off in flight your engine turns from a finely machined work of art into a lump of junk.

 

The manuals and Wal (or your L2) are your friends.

 

Cheers,

 

Jeff

 

 

[facthunter]

Not having a flange is really a no-no. Can you place a strap under the clamp and anchor it to the pipe upstream? Nev

 

 

[Guest JeffC]

Not having a flange is really a no-no. Can you place a strap under the clamp and anchor it to the pipe upstream? Nev

That's a good thought Nev. I'll have a closer look. Jeff

 

 

[johnm]

Good general advice ................. once again !

 

HEON - who is the 'maker' - the aircraft manufacturer or Rotax - I'm going to put my money on Rotax

 

I'll replace diligently per Rotax - oil tank and hoses - same position

 

Thanks

 

JM

 

 

[HEON]

My understanding regarding an aircraft is the maker is the person or firm that makes the aircraft HOWEVER they CANNOT change the maintenance requirements listed for the components they use. ie if a Rotax engine is used THEN ROTAX REQUIREMENTS MUST BE MET

 

Is this what you ment johnm? My comment regarding LSA and UL do not change this. This referes to who can/must approve changes...NOT MAINTENANCE

 

 

[johnm]

Thanks Heon

 

Its a bit of an ambiguous conversation - probably I'm causing it. Regarding the plane I refer to - the aircraft manufacture fitted the hoses - I presume. I suspect the aircraft manufacturer will not comment re replacement of hoses. Therefore the conclusion is - we must be talking about a 'Rotax system' and I'll replace them per Rotax

 

Assuming that fits with a '24' registered LSA aircraft ? If it doesn't - well then there's no sensible answer - so they WILL be replaced anyway ???????????????????

 

thanks

 

JM

 

 

[facthunter]

Destiny, that view has been around for a long time. Personally I would take it with a pinch of salt. Most installations (912), don't pay much attention to the airflow over the cylinders. It seems that it is taken for granted that it is adequate. Also, the radiator size/airflow is fairly critical to get the liquid cooling system to operate at the correct temperature. recommended max head temps are quoted but the big problem is that overheating causes the coolant to go overboard by venting, Anytime this has happened I get the plane on the ground as quickly as reasonably possible. Till I see concrete evidence of the rotax being bench/ air tested without coolant, I would not like to rely on the statement, that it will keep going. Most of the heat goes out through the coolant, it doesn't make sense to think that after all the engine doesn't really need it. Nev

 

 

[HEON]

LSA's are a can of worms regarding replacement of "parts". We know that a LSA requires the manufacturer to approve modifications.

 

Steve Bell when up for L2 course at Clifton last year in conversation said one (European) manufacturer would not approve the replacement of rivits with a different sort!

 

I personally would replace like with like if no manufacturer repair part available and fight the fight later if required. In my view better to be got for using LIKE replacement than crash due to the failure of aged manufactures part...to me that is a no brainer!

 

 

[johnm]

Yep .... thanks Heon

 

Fight any fight later

 

Actually a 'no brainer' is probably good fertile ground for the justice and legal professions (including an insurance company) - still I suppose I could argue a potential complete plane is better than a trying to prevent the creation of a twisted aluminium ball

 

thanks

 

JM

 

 

[facthunter]

Dex, I don't disagree with most of your points.( Iam sure YOU would do the right thing), but I wouldn't want the general view out there to be that 912's will keep running with no coolant. People might act on it and continue to a destination and lose an engine over unsuitable country, having flown over better opportunities to put the plane down with some engine power available. An engine out landing, gives you little ability to choose your landing field, and no second chance. Pilots with malfunctioning engines, (noises, vibrations, oil , fuel, oil or coolant leaks), should investigate them on the ground, as soon as they can find a SUITABLE place to land. Nev

 

 

[Guest JeffC]

"It would be good to hear from anyone that has experienced coolant loss on a 912 as to their experiences. I'm sure they're out there...."

 

It seems my overly colourful mention of the engine turning into junk has prompted this. I agree a failure is unlikely to be instantaneous or complete but you still wouldn't want it to happen for want of a loose connection not discovered during pre-fight.

 

RA Aus issued AN270810-1 in Sep 10 requiring checking of liquid cooled engine hose fittings and this may have followed a complete loss of coolant by a Foxbat A22LS that was reported in the November 2010 magazine. Luckily this happened and was detected by the pilot during taxi so no major consequences as far as I know. I don't think it is a Foxbat thing - it's the 912 fitting and loose connections that are at issue. There may have been other events giving rise to the AN but one is probably enough. It coincided with my hose replacement project and probably encouraged Wal to emphasise the importance of getting it right. He left not much doubt in my mind as to the likely consequences for the engine. At the least, considerable dollars could be expended investigating the engine for any signs of damage.

 

I imagine a sudden loss of coolant would be hard to miss and could be quite spectacular. In my case the muffler is immediately behind and below the water pump connection so all the coolant would dump on the hot exhaust and cause a cloud of steam. You could miss it I guess as the cloud might all go out the bottom and into the slipstream. A pusher arrangement may leave you blissfully unaware for a few short minutes. The Flydat would soon be beeping and flashing and things would start to get busy. Murphy's Law would also ensure the hose would blow under maximum load during the takeoff or climb-out. In that case there is a reasonable chance, if high enough, that you would have enough power left to get back into the circuit for a glide approach. In any event, as Nev says, we need to get safely back on the ground as soon as possible.

 

At the risk of repeating myself, the likelihood of a sudden loss of coolant can be significantly reduced by ensuring the connections are secure and by including them in the pre-flight (and post-flight) inspection.

 

I'll moderate my descriptions in future....

 

Cheers,

 

Jeff

 

 

[Guest Crezzi]

An interesting accident from a few years ago involving sudden loss of 912 coolant - http://www.aaib.gov.uk/cms_resources.cfm?file=/dft_avsafety_pdf_500043.pdf

 

IIRC SB-912-039 was issued as a result of this event.

 

Cheers

 

John

 

 

[Guest davidh10]

An interesting report. Thaks for the link John.

 

 

[Guest JeffC]

Yes, thanks John. It seems the operators worked hard to bring the failure about what with oversize hose, loose clamps, extended ground run, etc. I hadn't considered the immediate loss of power due to ingestion of steam and cooling fluid through the carbs but it makes sense. The fact that the boiling point of the coolant is below the engine heat limits and wont trigger an alarm by itself is also interesting. Gives a better understanding of the waterless vs mixed coolant options.

 

Regards,

 

Jeff

 

 

[facthunter]

Might be worth mentionong at this point that GLYCOL does not move as much heat as water does. Glycol does elevate the boiling point of the coolant, which is helpful as the engine should run above the boiling point of water. The other way to raise the boiling point is to pressurise the system but I would NEVER advocate going above 13 lbs/sq inch as the system becomes less reliable. (Likely to blow hoses.) Nev

 

 

[jetboy]

Is there a quality brand rubber hose for fuel available? My 5 yrs Jabiru is almost outlasting the fuel lines installation, but they are cracking around the end flares as they go over the fittings. Yes I'm aware that 2 or 5 years is the 'life' especially in FAR23 aircraft but my Cessna was near 40 yrs old and unlikely to have had any replaced, I asked about doing it and it wasn't considered a good idea.

 

The most common 'quality' hose available here is Gates, however this is the hose I'm having the cracks appear, they go straight into the inner. It is fuel & PCV hose SAE 30R7. Repco can offer some gates SAE 30R9 'fuel injection hose' and while it looks OK new the same can be said for the stuff i'm replacing. Supercheap carry some other brand, which I'll look at tomorrow.

 

I'm really a bit annoyed the Gates, which doesnt like JetA that much either, just doesn't work well with er... fuels. The hose ends out of the fuel tanks came from Europe and is still as flexible and intact as new.

 

Ralph

 

 

[jetboy]

Checked today - cost of Gates USA FI hose $45 per metre

 

BNT supply DAYCO brand USA the regular 30R7 type $ 5 per Foot or 30R9 FI $23 per Foot

 

Supercheap is $10 per meter for 30R6 spec

 

 

[Guest Maj Millard]

Jetboy, You mention both your Jab and Cessna. Two differnt situations really. With the Jab, the factory should spell out in their maintenance manual what minimum quality hoses they recommend for their engine, and you would be wise to adhere to that.

 

With the Cessna (unless it is RAAus registered of course) you also need to stick to the manufactures' recommendations. Generally you remove and send your old hoses to a recognized aviation hose shop for new ones. Standard rubber type hose must be replaced with the recognized aviation 5000 series type, and not with any old brand that you source locally at your local auto store.

 

With an RAAus type your should also refer to manufactures specs for good reason, but in some cases auto-style hoses can be acceptable, and are in common use. A local Level 2 would be able to advise you on this. I personally won't fit any rubber fuel line unless it has 'Made in the US' written on it. This comes from much experience over the years experiencing bad non-US line.

 

Gates rubber came out many years ago and said they did not want their hoses or belts to be fitted to any UL aircraft under any circumstances. I do not know if this is still the case...............................................................Maj...

 

 

[Guest Maj Millard]

Facthunter, Glycol on it's own is not a coolant fluid, and is not intended to be used as such. Glycol is a substance that when mixed with water, enhances the water molicules' ability to absorb, and carry heat.

 

Simply put, no water, no enhanced heat carrying ability, which in turn significently raises the boiling point above that of standard water, which on it's own is really quite limited.

 

The recommed mix of Glycol/water (as listed on the back of most coolant bottles) is from 30-50 percent with demineralized water. Not bore water, or common tap water under any circumstances !!.

 

Additionally, not all coolants containing glycol available at your local auto store are created equal. The only two brands that I would even consider putting in an alum based engine are Castrol Anti-freeze Anti-boil, or a very similiar product produced by the parent US company that owns the patent to this particular coolant. There is a patented rubber seal lubricant in this brand, that lubricates water seals and water pump bushes. No other coolant brands has this particular capability, and some are simple basic water with a colour dye to make them 'coolant' ?. The above coolant/coolant mix that I use is the first recommende for all the Rotax engines in their Service Bulletin: 'Selection of suitable lubricating fluids'..Castrol Anti-freeze Anti-boil was good for two years service, but when I last fitted some I see that it has now gone out to three years of service............................................................................Maj...

 

 

[jetboy]

Thanks Maj,

 

Yesterday I replaced all the Gates fuel hose with Dayco made in USA SAE30R7 hose which the local supplier had to get in for me.

 

Whilst none of the Gates hoses have ever leaked, all were cracked and hardened, although this was never obvious except at the ends. When flexed, there are both radial and lengthwise cracks of the outer exposing the weave. At the ends the cracks go right to the centre in straight lines.

 

The kit is a Zenair 701 supplied from CZAW and as far as I can tell the small amount of hose that came with it was same spec.

 

I will do some more research but Aeroquip and ACS do not appear to supply this type of hose.

 

As for the Cessna which I operated for 12 years, I never did any work on it that was the domain of the LAMEs, just that I noticed from the logbooks that none of the wing root hoses nor the one to the carb had been looked at and I asked about this (knowing full well I'd be up for at least $500 too) .... but the response was .... they are fine, nothing should be changed. But what i'm quoting was 10 years ago and anyone that still has a small fortune to run a Cessna round here must have started their aviation exploits with a large fortune because everything now must be replaced by the mntce manual dates so I think its seatbelts, hoses every 5 years (and landing light switches) I sold the Cessna so I could build the 701.

 

I'd really like to hear what people are using or not using for their replacements on microlights. Gates does not cut it anymore for me, whether it be cars, JetA or Avgas, its cracked everywhere, and hardens in as little as 6 months

 

Ralph