The Inside of the Rotax Fuel Pump

[Roger Lee]

You can fill out a CSIR to report the seepage. It doesn't happen to all pumps and it doesn't happen all the time. The service centers know too.

 

Rotax already knows. They knew within the first year out. It isn't a secret to them. I have it right from Rotax that the new Corona pumps can seep at times and that's why they have the drain tube.

[N456TS]

You would have to be the one filling out the SCIR.  I'm not seeing new pump seals failing quickly like you're seeing.  You see a lot more A/C then I. 

 

Do you have documentation?  I would love to see something stating a leaking seal is deemed ok. 

 

A seal shouldn't leak.  There can not be a dispute to that.  It may be a common issue, however, that doesn't mean it's "normal".  At best, it could be consider "typical" or "common".  That doesn't make it acceptable. 

This means:

1.  A part/design problem

2.  Environmental issue

3.  Installation issue 

 

I believe if you oil the seal's circuit prior to the install, you will find you no longer see this problem.  (Worse case for you, your customers no longer have leaking pumps). 

 

If oil is making it's way down and out the drain hose, that more then a seep.  You're leaking. 

 

I believe the older pumps also had drains, however there wasn't a hose barb.  It was just a small hole.  So, in a failed state, it would leak oil and/or fuel directly on the engine.  This created a fire hazard.  As a result, the hose drain solution was added for safety. 

[Anticept]

This is one of those "undocumented" features

 

You can always write to your local service center and ask about it.

[N456TS]

It's sounding, more and more, like they are not being installed correctly.  I guess Rotax needs update their manual. 

 

Here, I came to post a few photos of the pump to show others who haven't had a chance to see it.  I somehow get incorrectly accused of replacing a pump when I shouldn't, despite a clear failure.  A Rotax shouldn't be oiling the underside of an aircraft.  Maybe, some consider it typical, but I don't consider it normal.  Nor should any reasonable customer. 

 

You folks don't need to take my advise.  It doesn't benefit you; only your customers. 

Frankly, this is getting absurd. 

[Anticept]

We're just repeating what Rotax and the distributor network tells us. Don't shoot the messengers.

 

Have you been to a Rotax class? Suggest you do, the guys that teach the classes are one step away from Rotax tech support and engineers. If you take a Rotax heavy class, you'll usually meet Eric Tucker, who runs the whole training network in North and South America, and regularly flies to Germany to work with the engineers. They'll tell you all about the little known issues.

 

A seal shouldn't leak. There can not be a dispute to that. It may be a common issue, however, that doesn't mean it's "normal". At best, it could be consider "typical" or "common". That doesn't make it acceptable.

This means:

1. A part/design problem

2. Environmental issue

3. Installation issue

 

I believe if you oil the seal's circuit prior to the install, you will find you no longer see this problem. (Worse case for you, your customers no longer have leaking pumps).

This falls under the "part" problem, but installation is always a factor if it's done poorly. Rotax uses a lot of off the shelf parts. The first pump they had on rotax for years was a phenomenal pump. Then Siemens bought out the manufacturer and said NO AIRCRAFT PARTS. Every pump since has had their own problems.

 

Also, it is taught in Rotax classes that ALL seals, gaskets, and o-rings should be lubricated before installation. I don't remember exactly if Eric specifically said to lube the fuel pump seal, but unless the manual says not to, I'm lubricating it.

 

You're right on the part with the manual, a lot of us in the field would like to see the manuals have more information and documentation.

 

The ceramic water pump seal drips a little in the cold weather too. It also is a known issue.

 

EDIT: Also be sure to review the "Running Modifications" service bulletin SI-912-020 when you do mx, sometimes they put in new procedures there before the manuals get updated.

[Roger Lee]

Hi N456TS,

 

 

We are an information sharing group. Remember black and white print can be misinterpreted, but all of us only try to help each other.

Not a single person accused you of anything. I posted information from Rotax in the hopes people would learn. People here will tell you I'm only here to help. Info is not always put in print nor is it fast in dissemination. I try to bridge that gap on our forum.

People can replace all the pumps they want, but could be putting the same thing right back on which will hurt the pocketbook.

I'm a Rotax instructor and have been doing this for a long time and attend Rotax classes in the US and the Bahamas every year and get my info directly from them.

 

This isn't the gasket we are talking about.

Not every pump will seep and not every pump that seeps (drops not running fluid) will do it all the time. Rotax told me it was intermittent. I have seen a few pumps with some droplets of fluid. The CSIR is for owners to fill out and send either through a regional distributor or through the Rotax Flying and Safety Club which are the people that handle all warranties.

 

p.s.

You will get oil vapors on the bottom of the plane because that is where the oil tank breather tube vents for the oil tank. This is the only vent for the engine and should never be blocked or put in a vacuum or positive pressure area. As the oil heats up to operating temps the heat boils off impurities and in this is are oil vapors and over time a thin yellowish film will develop on the bottom. This is normal and you should just use some degreaser every so often and wipe the bottom of the plane.

 

A preflight look of the bottom of the plane is always a good idea because if you have any fluid leaks this is the first place it will show up and it is usually easy to see.

[N456TS]

This seems like a case of the "Rotax isolation bubble". 

I'm trying to help you folks, not the other way around...  Your posts around the web have been helpful in the past, however, this thread is just a brick wall. 

I'm not talking about the fuel pump gasket, nor the oil tank breather.  I'm talking about the need to lubricate the oil circuit for the pump's shaft seal.  It's only a small hole you have to inject engine oil into.  Roger, if you do this during new pump installs, you will no longer find the seals leaking prematurely.  If you don't, the shaft seal will be operated dry for many (1,000+?) cycles before lube enters.  This causes the shaft seal to fail before EOL.  Yes, I'm Rotax certified and on the map. 

 

I'm aware you're an instructor, however, please understand everyone can learn something new everyday. 

 

So, photos are above for those who are interested.  Other then that, I think I'm done.  Anything else will just be off topic. 

[Doug G.]

I'm talking about the need to lubricate the oil circuit for the pump's shaft seal.

Where did you get this information? Seems like a serious omission to not include this information in either the box with the pump or in the Service Bulletin.

[FredG]

And, we see why CT Flier is becoming increasingly marginalized.  

 

Frankly, it appears to me that the local talent is convinced that everyone else knows little or nothing.  I hope that comment doesn't get me banned - my goal is to make this somewhat stagnant forum a bit more appealing to a wider group of pilots and airplane owner.

 

Thanks. 

[Roger Lee]

Is this Bradley?

 

The shaft seal is where and why the pump could ooze a few drops of fluid once in awhile. These Corona pumps are made in Italy. The pump may never leak, it may leak in 200 hrs. no one knows. It is usually just a few drops. When I was back in Nassau we had a discussion about this because the centers where getting a number of calls.

 

"Frankly, it appears to me that the local talent is convinced that everyone else knows little or nothing."

 

I don't believe that is true. I do believe that some see more issues during a year because they may work on 20-30 engines versus a single owner. These people have been trying to pass on helpful tips. Then there are others that go to current Rotax classes that get new info and try to pass it on. Same with FD. New info gets passed on quickly here after a phone call or two. I'm very lucky to have a couple of good friends at Rotax so when I hear something new when I call them I try and pass it along and it may not even be in the field yet or a class. Some people like to post where others like just to read or post once in awhile.

 

As we have all heard in our lives, we have to look at the big picture and many times that may have several artist as contributors.

​Now days it may be just graffiti.   

[Anticept]

I'm not talking about the fuel pump gasket, nor the oil tank breather.  I'm talking about the need to lubricate the oil circuit for the pump's shaft seal.  It's only a small hole you have to inject engine oil into.  Roger, if you do this during new pump installs, you will no longer find the seals leaking prematurely.  If you don't, the shaft seal will be operated dry for many (1,000+?) cycles before lube enters.  This causes the shaft seal to fail before EOL.  Yes, I'm Rotax certified and on the map.

 

Interesting; no one told me about that little hole. Strange this isn't lubricated in the first place. But, I think I see which one you are talking about. Point taken!

 

And, we see why CT Flier is becoming increasingly marginalized.

 

Frankly, it appears to me that the local talent is convinced that everyone else knows little or nothing. I hope that comment doesn't get me banned - my goal is to make this somewhat stagnant forum a bit more appealing to a wider group of pilots and airplane owner.

This happens everywhere due to misunderstandings, especially online. I kept thinking he was talking about some gasket and was extremely confused as to his insistence. It's just a lot more difficult to interpret text vs saying "this thing right here" and point to it in your hand.

 

CTflier is one of the more mild places. Pilotsofamerica for example can turn into a straight up bitchfest with people insulting each other back and forth.

[Roger Lee]

Hi Corey,

 

I didn't quite understand either. I'm good now.

[FredG]

The fact that CTflier is not as bad as POA is hardly comforting.  Look at VAF for an example of a site where many contribute and few (if any) act as if others are clueless.

 

I went back and re-read the posts in the current thread.  The fact that the OP was misunderstood looks a lot like jumping to conclusions about his knowledge and skills without much effort to understand his point.  I am well aware that written communication about mechanical issues is difficult.  All the more reason to ask what is meant rather than immediately assume what is meant.  

 

Roger, your explanation - that some are so much more experienced that others - is true, of course.  It also kinda proves my point.  

 

I will add no more on this topic.  I've made my observation and, bluntly, it was dismissed.  

[FlyingMonkey]

The fact that CTflier is not as bad as POA is hardly comforting.  Look at VAF for an example of a site where many contribute and few (if any) act as if others are clueless.

 

 

Yeah, but RV owners have their own special brand of douchebaggery.  Not all of them, but many.  Here's an exchange that happened at Oshkosh while talking to an RV builder:

 

RV:  "Did you guys fly into the show?"

 

ME: "Yeah, my first time flying into Oshkosh, it was great!"

 

RV: "That's really cool.  Where are you from?"

 

ME: "The Atlanta area."

 

RV:  "Oh yeah?  There are a lot of RVs and RV builders down there."

 

ME:  "That's true, but I'm not an RV guy."

 

[smile freezes on RV's face, immediately becomes insincere]

 

RV:  "Oh.  Well...at least you have room for personal improvement in your life."

 

My friends and I see this attitude play out a LOT in the RV community.  One of my friends is building an RV-7, and almost didn't buy the kit because he didn't want to be associated with the Walter Mitty "if you don't fly an RV, you don't fly a man's airplane" mindset.

[Anticept]

I will add no more on this topic.  I've made my observation and, bluntly, it was dismissed.

 

It wasn't dismissed, it was commented upon. I'm (really am) sorry if you take offense to that. It may not look like it, but I'm taking your point and will try to be conscious of it in the future.

 

Also, being a mechanic and dealing with people on a day to day business does jade a person sometimes and it can reflect in the way I type messages. I don't want to treat people like they don't know anything, but the fact is... most people don't. It's why mechanics exist, and that's why we're hired to do a job. If everyone knew what they were doing and always did everything right, we wouldn't have a need for part 65 mechanics.

 

In fact, it is sometimes dangerous to assume that people actually do know anything, especially when it comes to aircraft maintenance. There's also a lot of people who claim they know what they are doing who actually don't, and they are dangerous. Listening to them can lead to costly mistakes and possibly lives lost.

 

In N456TS's case, I had no info to go on for his experience other than the "LSRM-A" in his signature and what he's told us. He claimed "A Rotax shouldn't be leaking." which is contrary to what everyone in the field says regarding these fuel pumps. So, I took the conservative approach. I'm more inclined to trust my distributor who has an overhaul shop and deals with these things all the time, and the manufacturer, over someone I only know the first name of. If he didn't make that claim, I would not have written him off.

 

He's one of the extremely rare cases of people who DID turn out to know what they are doing when making a claim against the norm, but unfortunately, for every person who goes against the grain and knows what they are doing, there's a dozen crackpots who don't, and I reiterate, those people are dangerous. Unfortunately, they also tend to be loud and drown out the people who do do know what they are doing.

 

I'm glad he persisted and got through the misunderstanding, and I'm thanking him for it.

[Runtoeat]

Although Bradley is a new poster here, my impression is that he has experience with Rotax engines and has taken Rotax training.   Anecdotally, Bradley makes the case for priming the pump before installation yet it troubles me that this is not required officially by Rotax.  There is little doubt that Roger is very experienced with Rotax and I find it strange that Bradley's experience tells him the priming is needed but Roger hasn't heard of this even with his inside connections with Rotax. Based on what I've read here, It appears that the priming is needed and it doesn't appear it can hurt to put a shot of oil into the pump prior to installation.  Could someone please point out where the hole is located on the pump that the oil is applied?

[Anticept]

I am assuming he means the hole on the shaft side of the pump, 6th image, left side.

 

Since I'm seeing a rubber seal on the diaphragm side, it seems like it might be wise to use a syringe to put just a drop into the drain tube fitting too, right on the shaft.

 

I haven't messed with the fuel pumps much. We didn't really even look at them in rotax class because the training engine didn't have the new pump.

[Roger Lee]

I shot an email to Rotax about this to get their take.

[N456TS]

I am assuming he means the hole on the shaft side of the pump, 5th image, left side.

 

Since I'm seeing a rubber seal on the diaphragm side, it seems like it might be wise to use a syringe to put just a drop into the drain tube fitting too, right on the shaft.

 

Yes on the little hole shown on the 6th photo.  And it couldn't hurt to lube the shaft via the drain prior to install.  Makes sense - I haven't tried that. 

The goal is to avoid running the seal dry, so (thumbs up icon here).