ROTAX 912is Fuel Assembly

[Gazunda61]

Anybody operating a 912is?
 

I am curious to establish why on my Bristell there is a flexible hose running between the fuel rails. The parts manual has a solid fuel line.  
 

See attached photo. The reason I’m asking is because during start up yesterday one of the couplings at the banjo fitting burst and started spraying fuel. Fortunately I was still on the ground.

[Blueadventures]

Don't know why; could you list hours and age of engine for information.  Glad it worked out ok being on ground.  Look forward to the answer about the IAW Rotax hookup (looks like a non-compliant part) and details of your connecting hose and its time in service and pressure rating etc.  I'm not sure I like the hose clamps if the blue hose is oil lines. Thanks for sharing the question.

Edited March 11 by Blueadventures

[Gazunda61]

The aircraft is a 2014 model - one previous owner. Total hours 370.  Rubber hose replacement (as per logbook entry) was March 2020, just prior to transfer of ownership.  Those blue oil lines are as a result of the oil return line splitting in flight about two years ago. This resulted in a declining oil quantity, smoke/fumes in the cockpit and messy engine, but aircraft was able to land safely. Oil lines were then replaced by our L2.  (Makes me think aforementioned rubber replacement may not have actually happened?.?). Trying to establish why that fuel line between the fuel rails is a flexible type,  as according to the maintenance manual and parts manual it is a solid line. Would like to hear from any other 912is owners to see if theirs is also a flexible line. Hard to imagine ROTAX issuing a SB replacing a solid line with a flex one. I’m yet to ascertain if that is in fact the case -  no entry in logbook to support that.

 

Edited March 11 by Gazunda61

[Blueadventures]

12 minutes ago, Gazunda61 said:

The aircraft is a 2014 model - one previous owner. Total hours 370.  Rubber hose replacement (as per logbook entry) was March 2020, just prior to transfer of ownership.  Those blue oil lines are as a result of the oil return line splitting in flight about two years ago. This resulted in a declining oil quantity, smoke/fumes in the cockpit and messy engine, but aircraft was able to land safely. Oil lines were then replaced by our L2.  (Makes me think aforementioned rubber replacement may not have actually happened?.?). Trying to establish why that fuel line between the fuel rails is a flexible type,  as according to the maintenance manual and parts manual it is a solid line. Would like to hear from any other 912is owners to see if theirs is also a flexible line. Hard to imagine ROTAX issuing a SB replacing a solid line with a flex one. I’m yet to ascertain if that is in fact the case -  no entry in logbook to support that.

 

I have no experience with the iS engine.  Maybe call Rotax (Floods) or Wal  (AVTEK)for their comment.  Re the pressure bands on the oil line I have only seen them used for the 17mm coolant hose and only seen screw tightening clamps on the oil hoses.  The 912 iS parts manual shows band clamps tightened with metal thread and nuts.  Recommend checking about their suitability as well.  Even source some images of 912 iS installs in the mean time.

Edited March 11 by Blueadventures

[Thruster88]

I have done rubber replacement on a 912iS engine at work. They definitely have a rigid steel line between the left and right side injection. Not sure why anyone would replace it with a flexible line.

 

Agree with Blue, those clamps on the blue lines don't look right.

Edited March 12 by Thruster88

[Gazunda61]

Thanks Thruster.  

[Gazunda61]

Thruster, 

 

what do you think about this line running from the pump to the 1/3 Fuel rail?  Is it standard? And should it be fire sleeved? I would say that it would need to be a flexible line. 
 

[Area-51]

Its possible the flex line was fitted when the blue oil hose mod was installed due to components clashing. If your engine is a certified red label version, without required mod cert approval, it is no longer certified.

 

Unless there is a log entry the high pressure fuel flex line should be regarded as  an unknown, and unless it can be identified as a high pressure fuel line then it would be prudent to replace it with a verified known spec component.

 

Just because it looks right does not always mean it is. The last aircraft I purchased, after having a bit of a poke around, I realised the previous owner should not ever been allowed near any tools; which motivated giving the aircraft an entire and thorough scrutiny and expunging of all remaining badness.

 

If the aircraft is 24 registered then return it to factory spec and maintain your insurance cover.

[Gazunda61]

Now it’s starting to make sense. The oil lines have been run forward over the engine to the cooler which has been moved so it can be accommodated in the Bristell cowl. Accordingly they have replaced the solid fuel line with a flexible one where it may have clashed. .  Zero entries in the logbook to show when/where this modification was made. No indication of flex fuel line rating or date of installation. Or indeed if it has ever been replaced. All I know was that it was pissing fuel when I was starting it. 👍 good one.

Edited March 12 by Gazunda61

[Thruster88]

3 hours ago, Gazunda61 said:

Thruster, 

 

what do you think about this line running from the pump to the 1/3 Fuel rail?  Is it standard? And should it be fire sleeved? I would say that it would need to be a flexible line. 
 

Impossible to say without knowing if the hose is compatible with the end fittings. Aircraft AN fittings and hose can be trusted because they are manufactured to spec. Automotive "AN" stuff can be manufactured by anyone, could be very good, could be junk. 

 

This accident comes to mind.

https://www.atsb.gov.au/publications/investigation_reports/2020/aair/ao-2020-028

[facthunter]

ANY piping around a reciprocating motor is subject to vibration and harmonics. I can't see flexible hose being a problem in principle. Like everything it must be done properly. Copper pipe is notorious for work hardening. Look at the pressures in some brake lines and how much movement they have to cope with but mineral oil will wreck them. Nev

[skippydiesel]

The blue oil lines interest me - never seen blue oil lines before. I wonder if they meet the Rotax specifications?  A clue might be in who supplied them - if Rotax dealership/agent probably OK.

 

As for the 360 degree spring hose clamps -  should be okay if correctly sized.  In fact probably better than any worm drive as they deliver an even pressure all round and a will not loosed as spring takes up any shrinkage in hose. Rotax oil pressure & temps are not so different to  coolant pressure/temp.

 

FYI: Wal  (of Flood & Rotax association) is recuperating from an operation - unlikly to be back at work for at least 12 months.

[facthunter]

I knew Ol Bert way back to when his kids DID Motorcross. He was a noted  Bultaco tuning Man and he was at Lethbridge often and I learned a few extra things then about Rotax..   Nev

[walrus]

Sorry to hear about Wal - the Rotax Whisperer. I run a 912 iS and I don't like that flexible line at all. If I had to use one at all, it would be a reputable make of AN6 teflon and braided stainless with fire sleeve.

 

The oil lines also need fire sleeves but they are not under much pressure and they also have to be able to take vacuum which can be considerable with a cold engine - which is why you can't apply full power until the oil is at or above 50C.

 

I run Goodridge convoluted teflon and braided SS forward of the firewall because it is very flexible although expensive. NB if using Teflon and SS hose, be very careful not to overtorque the securng nut because it can split, leaving you with a difficult to trace fuel weep.

[Area-51]

The blue oil hose could be a Parker aviation grade product line; google the reference numbers on the hose.

 

You might want to check the Bristell parts catalogue to see what is factory under the hood. Anything 'on' the motor including fuel pumps is required to be Rotax factory spec. Anything running 'to' the motor needs to be Bristell factory spec. So check first before assuming things have been mod changed without a log book entry. Its quite possible the fuel supply line is Bristell factory installed.

[danny_galaga]

A couple of us here have blue oil line on our 912ULS. mine was supplied by my mechanic and it is fitted to other 912 he services. Can't remember brand or anything.