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Bing Float Bowl Inspection


Runtoeat

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Hi Roger.  I recall that your discussed a way to do a "field" inspection of the float bowl by keeping all the cables attached and pulling the carb away from the intake but I don't recall the details. I think you may also have indicated there is a video on this?  Would you please provide this information again?  I searched our forum but couldn't find it.  

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Tom and Roger, thanks.  I have had the typical wet drip pan under my right carb for the last year.  Can't really tell where the fuel is coming from but I'm suspicious of the holes in the float bowl where the float posts are located due to the discussion we had about this on our forum a few months ago.  I also know that it can be as simple as the bowl gasket leaking.  Need to have my mechanic pull the bowl off and check it out to tell for sure.  My engine is running good and I hate to change anything so I'll do the "field" bowl removal.  I see Roger's comments about coating the gasket with a light coat of lithium grease and will use this on the new gasket.

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Rub it in real good on the outside edges of the gasket and of course the flat sides too. The most common leak comes from the gasket. It is rare that it would come from a carb post inside. If it leaked it would most likely be out and pouring fuel. Too high a float level will cause this too. I need to make a video on how to measure this, but it is 10.5mm from the edge of the carb bowl and then up to the top flat area of the float arm. The carb must be upside down to do this. Set a rule with mm on top of the carb bowl edge so the rule is straight up in the air. Slide it over towards the float arm. The top flat area of the float arm should be at 10.5mm. That said usually half mm is never a big deal.

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Roger, I now understand how to check the float level based on your comments.  The latest Rotax Owner's Bing 64 video gave some good info too.  The leak only leaves a small amount of fuel in the drip tray after I fly so I might wait until the weather warms up and/or my yearly inspection is due and give both carbs a good inspection.

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Besides the float bowl I had one that leaked a little fuel from the fitting that screws into the carburator where the fuel line connected. This was on one with the metal lines. Sometimes they will loosen up when you remove the line.

 

Is it necessary when removing/replacing the fuel line from the carb, to replace the copper washers on the banjo bolt?  If so, do you know a good source for them?

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Is it necessary when removing/replacing the fuel line from the carb, to replace the copper washers on the banjo bolt?  If so, do you know a good source for them?

 

Andy, I was talking about the earlier airplanes with the stainless steel fuel lines. They have one copper gasket under the fitting that screws into the carb. It also gets some blue Loctite. If you have the orange Teflon line and take it loose you should replace the copper gaskets. The Rotax part number for the gasket is 950-141, and it takes 2 for the metal lines and 6 for the Teflon lines if you do both carbs. I have not tried sourcing them from anyplace but a Rotax distributor.

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Hi Andy,

 

Rotax and many will always advise to replace. After many years of working on these I have found that so long as it is torque properly (tight:)) that reusing them hasn't been an issue. I have NEVER had one leak that I have reused.

 

Bottom line the choice is yours.

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Hi Andy,

 

Rotax and many will always advise to replace. After many years of working on these I have found that so long as it is torque properly (tight:)) that reusing them hasn't been an issue. I have NEVER had one leak that I have reused.

 

Bottom line the choice is yours.

 

Roger, would you please explain how you would sign off the maintenance records after performing work on an airplane and not replacing the copper gaskets when performing the work?

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Because copper gaskets aren't a mandated replacement. They are recommended. What is the purpose of a gasket? To prevent leaks. If it doesn't leak isn't the copper gasket doing it's job? Same with many screws nuts and bolts. Some recommend replacement every time they are removed, but most don't do it.

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Because copper gaskets aren't a mandated replacement. They are recommended. What is the purpose of a gasket? To prevent leaks. If it doesn't leak isn't the copper gasket doing it's job? Same with many screws nuts and bolts. Some recommend replacement every time they are removed, but most don't do it.

 

Roger, I know the translation of the manual is kind of poor, but the way I read the manual it says "At reassembly of the engine, replace all sealing rings, gaskets, securing elements, O-rings, and oil seals.". I take that to mean when I am putting something back together after it has been apart. That is certainly what I was taught when I did my Rotax training. The part we are talking about is called a gasket ring, and that certainly falls under the scope of the parts that Rotax says to replace.

 

So if this work was done as part of a condition inspection would you still sign off that the work was done per the manufacture's maintenance and inspection procedures?

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Hi Tom,

I'm not trying to sound like a smart ass here just show that common sense plays a part in all our maintenance practices with all owners and all mechanics. One guy may chide you for not doing something they think is important when it's not. Years of experience really helps weed out the differences for some people.

 

 

When you pull a carb bowl gasket off do you put in a new gasket? Do you always put a new nut on a bolt? Do you always pull carbs off at 200 hrs. and fully dismantle them? Most don't.  Do we perform an overhaul at 1500 - 2000 hrs just because Rotax says it's mandatory? Do we always change a fuel pump at the 5 year rubber change? Most don't.

Do you always buy parts from FD that have a part number in their parts manual? Legally you're supposed to according to the FAA. That would include things like screws and nuts.

Have you quit using NGK plugs because they aren't allowed in aircraft according to NGK?

I actually only know a couple of guys that change the crush washer on the oil tank every oil change. Most may use it several times. If it doesn't leak it is serving its purpose. Do you have to put safety wire through both holes in the mag plug or will one suffice?

All these Rotax wants and much more I didn't list. Common sense has to be part of this to me.

 

I could name a ton of things in the manuals that Rotax or FD wants done all the time, but we don't always do them. Common sense does seem to play a part and I think it should.

 

We as individuals also seem to pick which items are important to us to do or not to do. It may or may not be right, but seems to be human nature.

 

This crush washer replacement every time one is loosened is no real difference that many having poor logbook documentation. Some say it meets the legal requirement  and then call better documentation over theirs fluff. It's all within our mental scope and detail  and puts us in the mental safe condition to fly.  :eyebrow-1057:

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Hi Tom,

 

When you pull a carb bowl gasket off do you put in a new gasket? Do you always put a new nut on a bolt? Do you always pull carbs off at 200 hrs. and fully dismantle them? Most don't.  Do we perform an overhaul at 1500 - 2000 hrs just because Rotax says it's mandatory? Do we always change a fuel pump at the 5 year rubber change? Most don't.

Do you always buy parts from FD that have a part number in their parts manual? Legally you're supposed to according to the FAA. That would include things like screws and nuts.

Have you quit using NGK plugs because they aren't allowed in aircraft according to NGK?

I actually only know a couple of guys that change the crush washer on the oil tank every oil change. Most may use it several times. If it doesn't leak it is serving its purpose. Do you have to put safety wire through both holes in the mag plug or will one suffice?

All these Rotax wants and much more I didn't list. Common sense has to be part of this to me.

 

 

 

Roger,

 

If I remove the gasket I replace it. I replace locking nuts when removed. Regular nuts and screws are not required to be replaced unless damaged. I do perform 200 hour carb inspections, and replace all removed gaskets when doing so. I haven't had to deal with an overhaul yet, but if I did I would expect that all parts that require replacement would be replaced. I do change fuel pumps on the 5 year hose replacement. That is one of the reasons my parts prices are higher.

 

As for FD parts, not all parts that have a FD parts number must be bought from FD. If the part description has a manufactures part number or it provides a specification it may be sourced from another supplier. This is the way the FAA has ruled on part for quite some time. An example is wheel bearings. Cessna just provides a part number in their catalog with a description of wheel bearing, Piper has a part number with a description that say Timkem XYZ. You can buy the wheel bearing for the Piper from any place that has Timken XYZ, but Cessna's wheel bearing must be bought from Cessna. FD provides specifications for hardware, so as long as you buy hardware that meets those specifications you are legal. If you don't believe me check with the FAA again.

 

I order sparkplugs from a Rotax distributor by a Rotax part number.

 

Now you know one more guy who changes the crush gasket on the oil tank every time it is removed. Replacing crush gaskets is considered standard practice when working on aircraft, any god A&P mechanic would know that.

 

When I make a simple sign off without all the fluff, stating that I performed an inspection IAW Rotax procedures I mean it.

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Hi Tom,

 

Please take no offense to our friendly debate. No malicious or misgivings on my end. 

 

Not everyone changes locknuts (Nylocs) every time. I was taught if they can be turned by hand they had to be replaced. here's my point. Different teachings and different practices. Bottom line they both work or aircraft would be failing.

 

So every time you pull the carb bowl off for any reason (not an inspection) you always without fail put a new gasket in? I don't know a single person that does this.

 

The FAA told me directly that if FD  or any other aircraft Mfg. had a numbered part you had to get it from them because it is possible it went through additional testing. They said you were only supposed to deviate from that if they had a published okay to do otherwise. I will call the FAA and see if they have a different stance now.

 

Have you ever lifted up the intake manifold? Have you always replaced those "O" rings or how about taking a valve cover off. That "O" ring set is about $65.

 

I don't see us using NGK plugs for a lot longer unless you don't change. It says right on the box not to use them in aircraft, but you choose to do it anyway.

 

 

Your points kind of prove my point. No matter where you go in the nation and no matter what owner or mechanic you talk to they all have their pet peeves, their way of doing things and it may not be exactly like yours. Even school teachings vary from school to school and instructor to instructor.

 

So it boils down to personal preference.

 

Like my Chevy's vs Ford's I always quote.

 

 

When anyone uses IAW I can ALWAYS find things they didn't do whether they knew about it or not. They said the all encompassing IAW and that's extremely rare that they are 100%.

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Hi Tom,

 

Please take no offense to our friendly debate. No malicious or misgivings on my end. 

 

Roger,

 

Certainly no problem on my end. If anyone were going to be mad over this discussion I would expect it to be you. Because I am challenging you.

 

I wasn't really looking for a long debate on what parts or procedures should or should not be replaced or done.

 

My original question was how do you document the work performed when you choose not to follow Rotax's recommendations? I was simply looking for a sample logbook entry stating what procedure you used to perform the work.

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Only the aircraft manufacturer can set a maintenance requirement, not an engine manufacturer, correct?  In that case, if the replacement of washers and o-rings is not mandated in the aircraft maintenance manual, it's not required.  Do I have that right?

 

Yes, except FD says for "engine maintenance and inspection refer to the valid original Rotax manuals".

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"Refer" is not "must be followed".  Get yer lawyer on!

 

Andy, If you read the FD maintenance manual where it says refer to Rotax you have no other option for maintenance of the engine than follow Rotax instructions. To perform maintenance the FAA requires that you follow a procedure. FD offers no procedures for maintenance of the engine other than referring to the Rotax manuals.

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Andy, If you read the FD maintenance manual where it says refer to Rotax you have no other option for maintenance of the engine than follow Rotax instructions. To perform maintenance the FAA requires that you follow a procedure. FD offers no procedures for maintenance of the engine other than referring to the Rotax manuals.

 

I was really just joking.

 

But in seriousness, what does "refer" mean here in a legal context?  Does that mean use the Rotax manual as guidance, or that you must follow any recommendations there to the letter?  I don't know.  But it's not clear to what degree "referring" to a document makes it legally binding on us.

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