Rotax Fuel Pump

[bilby54]

I have just fitted a new 912A engine into my Gazelle and the new engine has a different mechanical fuel pump to the one that it was certified with.

 

The new pump has a drain port that must be vented to outside of the engine bay so does this require a sign off by a Reg 35 (or whatever number these days) engineer for it to be legal as a factory built? The original pump is no longer available now from Rotax and could potentially affect many certified aircraft.

 

The aircraft was originally certified with a transponder that was removed by an L2 some years ago so does this make it now 'not certified?

 

If I were to remove the airbox and very complicated (read high maintenance and prone to failure) Scat hoses and carby heat system and replace it with a water heated ring system, does this make the aircraft non compliant? It still has a carburettor heat system but not one where the pilot has to pull a little knob to get it to work.

 

Just asking of course

 

 

[rankamateur]

Just asking of course

Hy-pathetically?

 

 

[Guest Maj Millard]

Bilby. , the Gazelle is a CASA certified trainer so few changes are permitted from the original factory produced form. If major changes or modifications were made, then the aircraft would not comply to its certification standard, and would then be illegal.

 

In respect to the fuel pump upgrade. This is a required maintenance item issued by the engine manufacturer, as a replacement for fuel pumps that are required to be removed from service via a Rotav Service instruction. Additionally there is also a maintenance requirement to renew the mechanical pump as part of the 5 year rubber replacement. As most Gazelles are well over 5 years old , none should be running the original fuel pump anyway.

 

It is a requirement to maintain the aircraft and Powerplant to the 'manufacturers instructions'...so by fitting the newer style fuel pump you are complying with the manufacturers instructions, as long as you install the new pump per their instruction.................Maj.....

 

 

[Dafydd Llewellyn]

And DO NOT muck about with the carbie hot-air system - that's a significant certification item and caused a lot of trouble in development. I do not doubt it's troublesome - it was never well engineered by Skyfox - but at least it meets the certification requirement. The manual control of it is mandatory.

 

 

[bilby54]

Thanks fella's.

 

Maj, I know that the aircraft is certified as I use it a trainer and I know about servicing the fuel pump. My concern is that the fuel drain on the new pump now protrudes into the airstream between the two exhaust pipes and was not on the aircraft when certified. I also realise that this outlet only flows fuel in the event of a diaphragm rupture. I want to know exactly how I document that this is a modification from original and does it require an engineering sign off.

 

Daffyd, could you clarify where it is a requirement for the carby heat system to be manually operated so as I can understand the certification system please? I have spoken to a lot of people who were involved in the original development of the Gazelle and the concept of making more like a GA trainer with carby heat. The Gazelle is a great little aircraft but the engine installation and set up is applling compared to the european set ups.

 

Essentially, the 912A certified engine has to be modified to fit the Gazelle installation so isn't this already a contradicition?

 

 

[Guest Maj Millard]

Bilby, being as you stated, that the aircraft is used as a trainer, it therefore has to be maintained by a Level 2, as you should be aware.

 

If I were doing the jobs and the sign off I would make the following entry, or something similar, in the aircraft's maintenance logbook.

 

Installed new fuel pump Pt No xxxxxx on engine SNo xxxxxxxx in accordance with the instruction of Rotax Service Bulletin SB 912-xxxxxx. Engine performance run carried out, engine found serviceable. Signed...Joe Blow L2 No xxxxxxxxx

 

 

[Dafydd Llewellyn]

Thanks fella's.Daffyd, could you clarify where it is a requirement for the carby heat system to be manually operated so as I can understand the certification system please? I have spoken to a lot of people who were involved in the original development of the Gazelle and the concept of making more like a GA trainer with carby heat. The Gazelle is a great little aircraft but the engine installation and set up is applling compared to the european set ups.

 

Here's the FAR 23 version; the Gazelle was certificated to a lesser standard, but they all say much the same on this point. I've deleted the irrelevant bits:

 

§ 23.1091 Air induction system.

 

(a) The air induction system for each engine must supply the air required by that engine under the operating conditions for which certification is requested.

 

(b) Each reciprocating engine installation must have at least two separate air intake sources and must meet the following:

 

(1) Primary air intakes may open within the cowling if that part of the cowling is isolated from the engine accessory section by a fire-resistant diaphragm or if there are means to prevent the emergence of backfire flames.

 

(2) Each alternate air intake must be located in a sheltered position and may not open within the cowling if the emergence of backfire flames will result in a hazard.

 

(3) The supplying of air to the engine through the alternate air intake system may not result in a loss of excessive power in addition to the power loss due to the rise in air temperature.

 

§ 23.1093 Induction system icing protection.

 

(a) Reciprocating engines. Each reciprocating engine air induction system must have means to prevent and eliminate icing. Unless this is done by other means, it must be shown that, in air free of visible moisture at a temperature of 30 °F.—

 

(1) Each airplane with sea level engines using conventional venturi carburetors has a preheater that can provide a heat rise of 90 °F. with the engines at 75 percent of maximum continuous power.

 

This has to be tested in flight in the manner described in FAA Advisory Circular 23.8 para 256 (now at amendment C, I think; the Gazelle was tested at amendment A); that's too big to include here, but you can download it from the FAA website, www.faa.gov

 

The necessity for manual operation comes from the method of testing; you cannot do the tests without being able to select full hot or full cold. "Manual" does not necessitate a knob & a bowden cable; you could do it via some servomechanism, but you'd bring down on your head the task of proving the reliability of the servomechanism.

 

There's also:

 

§ 23.1157 Carburetor air temperature controls.

 

There must be a separate carburetor air temperature control for each engine.

 

and

 

§ 23.777 Cockpit controls.

 

(a) Each cockpit control must be located and (except where its function is obvious) identified to provide convenient operation and to prevent confusion and inadvertent operation.

 

(b) The controls must be located and arranged so that the pilot, when seated, has full and unrestricted movement of each control without interference from either his clothing or the cockpit structure.

 

© Powerplant controls must be located—

 

(1) For multiengine airplanes, on the pedestal or overhead at or near the center of the cockpit;

 

(2) For single and tandem seated single-engine airplanes, on the left side console or instrument panel;

 

(3) For other single-engine airplanes at or near the center of the cockpit, on the pedestal, instrument panel, or overhead; and

 

(4) For airplanes, with side-by-side pilot seats and with two sets of powerplant controls, on left and right consoles.

 

(d) The control location order from left to right must be power (thrust) lever, propeller (rpm control), and mixture control (condition lever and fuel cutoff for turbine-powered airplanes). Power (thrust) levers must be at least one inch higher or longer to make them more prominent than propeller (rpm control) or mixture controls. Carburetor heat or alternate air control must be to the left of the throttle or at least eight inches from the mixture control when located other than on a pedestal. Carburetor heat or alternate air control, when located on a pedestal must be aft or below the power (thrust) lever.

[bilby54]

If I were doing the jobs and the sign off I would make the following entry, or something similar, in the aircraft's maintenance logbook.

Installed new fuel pump Pt No xxxxxx on engine SNo xxxxxxxx in accordance with the instruction of Rotax Service Bulletin SB 912-xxxxxx. Engine performance run carried out, engine found serviceable. Signed...Joe Blow L2 No xxxxxxxxx

I don't agree with you here Maj as this is a change to the original aircraft certification and should have a document from the aircraft manufacturer stating exactly how and where to install. The engine manufacturer does not care about how a change in their product will affect the certification on the aircraft.

 

This change to the fuel system has a direct safety issue that could ground this and possibly other aircraft as engines or fuel pumps are changed. This not the 'it does not comply because there is not a liability sticker on the panel', this is a change where there is a real possibility of dumping fuel in vapour form directly into the hot exhaust gasses and causing an inflight fire.

 

I am not comfortable as an L2 in signing off mine or anyone else aircraft with such a modification. As an L2 I believe that I am not legally allowed to do it which is why I have asked Daffyd to clarify the certification process.

 

 

[Guest Maj Millard]

Bilby, Read the Rotax service bulletin...have you ?....they clearly state that the location of the drain tube should be located in a safe area, and they even give you the option of using a drain bottle if you wish. It would not be hard to do so safely and well away from the exhaust pipes or exhaust outlets. Additionally go to Rotaxowner .com and view their instructional video on the subject.

 

The way you are looking at the whole thing is if for instance you changed a tyre and the brand was different to that certified , then you would have to go crying to Daffyd to have the aircraft re certified !.............Maj.....

 

 

[bilby54]

Thanks Daffyd, it makes you wonder how the Gazelle got through certification especially the part refering to controls being easily identified. It is very easy for students to miss identify the carb heat knob and pull on the choke or cockpit heater. I will read the rest in depth.

 

I don't want to take up all of your time here but I am curious as to how the european aircraft can be certified - be it GA or RAA - in Australia without having a carburettor heat system? If the carb heat system is replaced does it have to be exactly as the original or substantially the same? As parts are dropped by manufacturers or improvements made or redesigned but that is what is available to use now, how does that change the certification? If the cabin heater is removed from the Gazelle because the airbox is no longer made as an example, does that make it non compliant with certification?

 

 

[bilby54]

Bilby, Read the Rotax service bulletin...have you ?....they clearly state that the location of the drain tube should be located in a safe area, and they even give you the option of using a drain bottle if you wish. It would not be hard to do so safely and well away from the exhaust pipes or exhaust outlets. Additionally go to Rotaxowner .com and view their instructional video on the subject.The way you are looking at the whole thing is if for instance you changed a tyre and the brand was different to that certified , then you would have to go crying to Daffyd to have the aircraft re certified !.............Maj.....

I have a lot of respect for your views and knowledge Maj but I full on object to you saying that I am crying because I am trying to get a better understanding of the subject!!!

 

Where do I put this bottle that now changes the cerification of the aircraft?? Where is the "safe" area? How big is the bottle to catch the fuel? Where is the engineering order to change this?

 

 

[Guest Maj Millard]

Bilby, it is obvious to me that you have not read the Rotax Service Bulletin pertaining to the new pump refit. First of all the tube is not a fuel drain, it is for air compensation on the back side of the diaphragm. The only time fuel would ever pass through the tube is on the rare occurrence that the diaphragm might rupture of fail.

 

They do state that there may be some 'lubrication oil' that may weep from the tube after it has been installed, and that if you were concerned about the quantity, you my install a catch bottle...that's all. You are probabily are also in the group who mistakenly thinks the clear tubes running out of the carbs are fuel drains also....they are not, but are 'air compensation tubes' which allow ambient air pressure on top of the fuel, and therefore act as vents for the carb bowls..........answer me this...have you read the Rotax Service Bulletin yet ?................Maj.....

 

 

[Guest Maj Millard]

Further if you leave the old pump installed after Rotax has indicated you have to replace it, then you are clearly not maintaining the aircraft correctly by the engine manufacturers instructions, as you are required to do. All Rotax fuel pumps, even the latest new ones are now required to be replaced every five years, per Rotaxs latest instructions.

 

When your old pump fails and hurts someone, I'd like to be present in court the day you try and justify your reason for not changing it......Maj.....

 

 

[Dafydd Llewellyn]

Thanks Daffyd, it makes you wonder how the Gazelle got through certification especially the part refering to controls being easily identified. It is very easy for students to miss identify the carb heat knob and pull on the choke or cockpit heater. I will read the rest in depth.I don't want to take up all of your time here but I am curious as to how the european aircraft can be certified - be it GA or RAA - in Australia without having a carburettor heat system? If the carb heat system is replaced does it have to be exactly as the original or substantially the same? As parts are dropped by manufacturers or improvements made or redesigned but that is what is available to use now, how does that change the certification? If the cabin heater is removed from the Gazelle because the airbox is no longer made as an example, does that make it non compliant with certification?

You'd have to look up the TCDS for the Gazelle - it will be on the CASA website - and find what its certification basis was - quite likely JAR-VLA; then go look at that and see how it differs from FAR 23 in this area. Re its cockpit labelling, look up the Flight Manual - it should be specified there. If what is shown in the FM isn't there, it's probably fallen off. However I would not bet the Gazelle FM was as comprehensive as that.

 

Re the European aircraft, same story; if it's an LSA aircraft, the ASTM design standard simply says:

 

"7.5 Induction System—The engine air induction system shall be designed to minimize the potential of carburetor icing."

 

Just HOW it minimises the potential, is anybody's guess. With FAR 23, you are told exactly how, and how to prove it. I'm somewhat underwhelmed with the certification standards for LSA aircraft, as you will readily understand. Faced with something like the ASTM requirement, we'd inevitably apply the FAR 23 methodology, if we were doing this in Australia - if only to minimise the product liability. I have a feeling it's a lot looser in Europe. I tend to see the LSA class as junk, candidly, because this sort of thing is all through them.

 

If you replace the fuel pump with a later part number from the 912 parts catalog, that happens to have a double diaphragm with a drain tube (the Jabiru had this from day one, by the way), then you are not making an unapproved modification to the design, so long as you do it IAW the factory instructions. Look at any Cessna or Lycoming parts catalog, and see how they have handled up-dating of components from external suppliers; if it's in the parts book, it's legal.

 

Removing the cabin heater from a Gazelle would be a modification, and unless it's covered in the manufacturer's data, you need an approval for it; see CAR Part 2A.

 

 

[seb7701]

[quote="

 

The way you are looking at the whole thing is if for instance you changed a tyre and the brand was different to that certified , then you would have to go crying to Daffyd to have the aircraft re certified !.............Maj.....

 

I would have to disagree with this statement, as a different fuel pump now incorporating another feature is not just a different brand of the same type of pump, as there is clearly a difference in construction of the pump. So while I agree with the options for the new pump to solve the fuel drain issue and the rotax bulletin, I don't think that was a fair statement to make. Clearly not apples with apples... And no, not even going to begin to suggest that I have the technical knowledge re this one, just don't see where the angst came in for reasonable questions.

 

 

[Guest Maj Millard]

[quote="The way you are looking at the whole thing is if for instance you changed a tyre and the brand was different to that certified , then you would have to go crying to Daffyd to have the aircraft re certified !.............Maj.....

I would have to disagree with this statement, as a different fuel pump now incorporating another feature is not just a different brand of the same type of pump, as there is clearly a difference in construction of the pump. So while I agree with the options for the new pump to solve the fuel drain issue and the rotax bulletin, I don't think that was a fair statement to make. Clearly not apples with apples... And no, not even going to begin to suggest that I have the technical knowledge re this one, just don't see where the angst came in for reasonable questions.

 

Sebb, As Bilby is an L2 I would expect him to understand the basics requirement to maintain things per the manufacturers instructions.

 

CASA itself has in recent years been converting over to that requirement, in lue of setting the rules themselves about things they know nothing about, and certainly not more than the original manufacturer.

 

As a matter of safety it is obvious the pumps need to be changed, and no L2 should be prepared to sign out training aircraft without the five year required upgrade, of the fuel pumps.

 

The instructions for installing the tube and overflow container (if required) are very clear, and quite flexible. It really should not in any way effect the certificated status of the aircraft, as per the service bulletin it would have no effect on performance, GC location or aircraft total weight.........these type of engine upgrades occur all the time (valve collets, ign moduals, ign stators, radiators etc etc) ..surely your not suggesting we get all aircraft recertified every time one occurs ?!.............Maj....

 

 

[seb7701]

Yep, it's obvious the pumps needed to be changed which is why Bilby did it! Already said I dont dispute your technical explanation, it was the tyre analogy that I believe was incorrect along with the terse nature of the reply.

 

We are all on the same team here, so all the technical explanations in the world wont hide that sort of lingo, just as the technical explanation in the last post didnt make an ounce of difference. I already indicated that I have no challenge for your solution Maj, just the delivery.

 

 

[bilby54]

Bilby, it is obvious to me that you have not read the Rotax Service Bulletin pertaining to the new pump refit. First of all the tube is not a fuel drain, it is for air compensation on the back side of the diaphragm. The only time fuel would ever pass through the tube is on the rare occurrence that the diaphragm might rupture of fail...........answer me this...have you read the Rotax Service Bulletin yet ?................Maj.....

I have no idea what got under your bonnet but let me reassure you that I have read SI-912-022R7 issued 15th May 2013 and it says inter alia-

 

4.4 In case of an engine replacement or retrofitting.......... Proof of certification to the latest requirements such as FAR has to be supplied by the aircraft manufacturer. For more information and related instruction contact the aircraft and/or airframe manufacturer

 

Option 2

 

CAUTION Drainage line have to routed into ram air and vacuum free zone according to the requirements and release of BRP-Powertrain. The drainage line must not be routed into the slipstream.

 

The drainage line has to installed in such a way that excessive fuel/oil flows off

 

Fig 5 clearly illustrates this and is part number 12 if you care to look

 

The reason for the drainage is not as you have suggested to put static pressure onto the diaphragm but to vent the fuel outside of the crankcase to prevent a crankcase explosion in the event of a ruptured diaphragm.

 

Your second post about watching me go to court was completely un-called for and childish as if you visited my first it states a NEW engine in my Gazelle which was the reason that I asked.

 

I will accept an appology in this instance but a donation to the RFDS would be more preferable. Why does everyone get so worked up on these forums ffs?

 

 

[bilby54]

If you replace the fuel pump with a later part number from the 912 parts catalog, that happens to have a double diaphragm with a drain tube (the Jabiru had this from day one, by the way), then you are not making an unapproved modification to the design, so long as you do it IAW the factory instructions. Look at any Cessna or Lycoming parts catalog, and see how they have handled up-dating of components from external suppliers; if it's in the parts book, it's legal.

Removing the cabin heater from a Gazelle would be a modification, and unless it's covered in the manufacturer's data, you need an approval for it; see CAR Part 2A.

Thanks for that information Daffyd and that was the reason for me asking questions regarding this

 

 

[Guest Maj Millard]

bilby, In reference to your post #18 there is no current SI 912-022 R7 listed . You may have ment SI 912-020 R7 ?....dated 2013-05-01 'Running modifications' , which is current and lists with many others, the fuel pump upgrade.

 

Rotax Service Bulletin SB 912-063 UL or SB 912-063 deals with the replacement also, listing specific superceded pump Part numbers as applicable, with applicable engine S/nos, plus the requirement to replace all pumps after five years.

 

The only time that the 'drainage hose' should ever see any fuel, is if the diaphragm is ruptured, or fails, within the five years recommended service life, which is very doubtfull knowing Rotax quality. More than likely, it would probabily go ten years or more, just like the old ones did.

 

Additionally the current Rotax parts book for the 912, (Sect 73-10-00 page 6) doesn't even show or list the 'drainage tube' as a part at all...........................Maj......

 

 

[bilby54]

bilby, In reference to your post #18 there is no current SI 912-022 R7 listed . You may have ment SI 912-020 R7 ?....dated 2013-05-01 'Running modifications' , which is current and lists with many others, the fuel pump upgrade.Maj......

Purely a typo...... made that contribution to RFDS yet??

 

 

[Guest Maj Millard]

:gagged:O

 

Purely a typo...... made that contribution to RFDS yet??

Don't worry they get their share of my money !....why don't you take that $1000 or so (at keast) that it would cost you to get a certified aircraft upgrade done, and give it to them also ?..................Maj....

 

 

[bilby54]

I have no idea what you are on about.

 

I will put this as plainly as I can. You made assumptions and ascertations about me that were untrue. You gave out false information and completely misidentified why the manufacturer changed their product. I am not happy with you and I am requesting a formal appology - if you have the courage to do so.

 

I for one am concerned that this forum has grown into a boys club and those of us in the isolated regions that ask for some guidance from our so called more knowledgable aviator 'mates' get castigated. As far as I am concerned except for a small handful of people who genuinely have something to contribute the rest is what comes out of the back end of a bull.

 

Genuinely dissappointed

 

 

[Guest Maj Millard]

Bilby,

 

Yesterday was a particularly busy day for me with many board Emails to read, with a lot going on there.

 

However, I still managed to find time to help a fellow board member with a technical enquiry to the best of my ability , as I have done many times before, for other forum members, and will continue to do in the future if time permits.

 

And you were listening well until around post # 8, when it appears you ceased liking what you were hearing, and became less than appreciative of efforts to put you on the right track, with your easily surmountable problem.

 

I wish you well with your endeavour , but I certainly have no desire or intention to offer any form of apology for my attempt to assist you.........Also genuinely disappointed!.....Maj.........

 

 

[bilby54]

Hey Maj, next time you have a bad/busy/frustrating day, please take a Bex and have a good lie down.

 

If you are going to be judge, jury and executioner in these forums then please sum up all of the evidence before swinging the axe will ya! You got upset with me disagreeing with your opinion in post 8 and you still have not ackowledged that I was fitting a new engine complete with a new fuel pump and the Caution note 4.4 in the Rotax buletin - you know the one that YOU accused me of not reading - clearly states to have contact with the aircraft manufacturer. Apparently you must have had a momentary blind eye on that one. You also stated that it was not a drain line for fuel in the case of pump failure and refuse to acknowledge that.

 

I personally would like to publicly congratulate you on your work with the RAA board but if you are going to give advice of any kind, you had better make sure it is correct and if you are having a busy day, don't take you frustrations out on me or anyone else because it is just not professional. I feel certain that a lot of people are going to disagree with some of your decisions as a board member so you might be in for a bunch of bad days here Maj!

 

I have never had an issue with you before and I do not know why you decided to go down this track now. You should've been happy that a lowly isolated L2 asked for clarification on this and not assume anything else.

 

Now, can we get back to the things that matter please? Note - No "cool" sunglasses!