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  #11  
Old 04-23-2021, 10:03 AM
seagull seagull is offline
 
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Location: San Bernardino
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Originally Posted by Walt View Post
I know there are lots of proponents of this philosophy (mostly based on I don't want to spend the money), however, aviation safety/reliability is based on required inspections and repair being performed BEFORE failure occurs based on service history.

I think when you venture outside the normally accepted guidelines for inspections those choices should made very carefully, and be based on fact/solid component history data, rather than on "it ain't broke".

If you carry passengers you have a serious responsibility to them, or maybe you should let them know that you don't believe in accepted aircraft maintenance procedures and prefer to make your own rules, but last time you flew the aircraft "nothing was broken so we should be ok".
Our planes are required to placard the word EXPERIMENTAL where the passengers can see it. That means that it was built by someone, not necessarily factory trained and inspected by someone like you that did not completely dis-assemble it to make sure everything was done correctly.

There are some things that have to be done on the plane (by law) for it to be airworthy, the rest is at pilot discretion. If you do not understand machines you should have a mechanic do your work as prescribed by the mfg. The Mfg set time replacements many times based a on litigious concerns and worst conditions.

Case in point, the -12 nose gear, one fails under extreme conditions, they all need replacement. It is your call, if you don't have students po-go sticking your plane for 1700+ hrs you may decide not to replace it. Should you mention to your passenger that there is a SB on the nose gear but you didn't do it?

Case in point, the mfg recommends changing oil at 100 hrs and plugs at 200 hrs. I do my oil at 50 hrs and plugs at 100, my choice. I do not use 100LL I just feel it is better.

Again, if you don't understand the machine and can't make logical decisions on how the machine has been used and its needs, stick to what the manufacture recommends.
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  #12  
Old 04-23-2021, 11:52 AM
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rvbuilder2002 rvbuilder2002 is offline
 
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Location: Hubbard Oregon
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Originally Posted by cactusman View Post
The following components and systems must be replaced every 5 years:

• Venting hose of the carburetors
• Diaphragm on both carburetors
• Carburetor sockets
• All rubber hoses of the cooling system
• All rubber hoses of the fuel system
See SI-912-022, latest issue.
• All rubber hoses of the lubrication system which are part of the engine supply volume and if they are not in the maintenance schedule of aircraft manufacturer
• Connecting hose of the air intake system
• Venting hose of the fuel pump
• V-belt

https://www.rotax-owner.com/pdf/MML_912_Series_ED4.pdf


Keep in mind the recommended 'overhaul' of these carbs is 200/5 yrs from the more experienced folks out there who deal with 912 engines for a living. The wide variance in gas quality I am sure has something to do with it.

Mine only had 85 hrs. Night and day. My floats were R and weighed fine before i sent them off.
5 year Rubber component replacement has no connection with the inspection interval of the carbs. Some RV-12 have accumulated 200+ hrs per year, so they end up with 3-4 carb inspections by the time they get to a mandatory parts replacement.

I am very familiar with the Rotax Heavy Maint. doc you linked to. Already mention, the checklist in Section 5-20-00 specifies that an inspection be done every 200 hrs. The inspection is detailed in Section 73-00-00. It walks you though all of the steps and specifies replacing parts that don't meet spec.
In my mind an overhaul of the carb would be automatically replacing all minor parts regardless of condition. This is not what is specified, and it is not necessary, as long as proper inspections are being done on the required intervals (and then of course replacing the rubber parts on the 5 year interval, which in my opinion is not reasonable but it is what it is. That standard puts all aircraft in the same time frame requirement. It is not reasonable to lump an aircraft with an un-cowled engine, that sits outside with potential sun exposure 365 day per year, with an aircraft that is fully cowled and is stored in a hangar all year, but I digress)
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Scott McDaniels
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Hubbard, Oregon
RV-6A (aka "Junkyard Special ")
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  #13  
Old 04-23-2021, 12:14 PM
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Piper J3 Piper J3 is online now
 
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Quote:
Originally Posted by seagull View Post
Carb sockets to the JBM ones.
I'm not familiar... what is JBM carb socket?

Thanks in advance.
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  #14  
Old 04-23-2021, 12:41 PM
seagull seagull is offline
 
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Originally Posted by Piper J3 View Post
I'm not familiar... what is JBM carb socket?

Thanks in advance.
http://jbmindustries.com/912socket.html
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  #15  
Old 04-23-2021, 01:22 PM
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cactusman cactusman is offline
 
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https://lockwood.aero/carb-overhaul-kit-889-536.html

https://www.leadingedgeairfoils.com/...rhaul-kit.html

https://www.cps-parts.com/catalog/rtxpages/15-05915.php

Kinda funny that Rotax even has a part no for the "overhaul" kit.
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Last edited by cactusman : 04-23-2021 at 01:24 PM.
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  #16  
Old 04-23-2021, 03:10 PM
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rvbuilder2002 rvbuilder2002 is offline
 
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Originally Posted by cactusman View Post
They have an engine overhaul kit as well, but when we do the engine inspection on each 200 hr interval, we don't disassemble the entire engine and automatically replace all of the parts because it hit 200 hrs

Some times it does make sense to do a complete overhaul of the carburetors.

One of those times is when you are doing a compete overhaul of the engine.
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Opinions, information and comments are my own unless stated otherwise. They do not necessarily represent the direction/opinions of my employer.

Scott McDaniels
Van's Aircraft Engineering Prototype Shop Manager
Hubbard, Oregon
RV-6A (aka "Junkyard Special ")
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  #17  
Old 04-23-2021, 03:41 PM
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cactusman cactusman is offline
 
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Originally Posted by rvbuilder2002 View Post
They have an engine overhaul kit as well, but when we do the engine inspection on each 200 hr interval, we don't disassemble the entire engine and automatically replace all of the parts because it hit 200 hrs

Some times it does make sense to do a complete overhaul of the carburetors.

One of those times is when you are doing a compete overhaul of the engine.
Well I think we all know the later engine is good to 2000 hrs, and then we just ship it Lockwood for an estimate....or a new IS 915 engine maybe....

Since Van's demonstrators/trainers all run on 100LL 100% of the time, I'm not sure you have the same exposure and experience with autogas issues gumming these carbs up like Lockwood and others have. Van himself brought an expert in after some frustration as I recall (RVATOR article he wrote) and the 912 expert found some small amounts of grit inside his main jet.

Just saying that these carbs require (as the OP nobly posted) some extra attention at times. My 2 cents.

PS - 3rd set of floats installed...Marvels on standby.
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  #18  
Old 04-23-2021, 04:59 PM
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rvbuilder2002 rvbuilder2002 is offline
 
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Originally Posted by cactusman View Post
Well I think we all know the later engine is good to 2000 hrs, and then we just ship it Lockwood for an estimate....or a new IS 915 engine maybe....

Since Van's demonstrators/trainers all run on 100LL 100% of the time, I'm not sure you have the same exposure and experience with autogas issues gumming these carbs up like Lockwood and others have. Van himself brought an expert in after some frustration as I recall (RVATOR article he wrote) and the 912 expert found some small amounts of grit inside his main jet.

Just saying that these carbs require (as the OP nobly posted) some extra attention at times. My 2 cents.

PS - 3rd set of floats installed...Marvels on standby.
I don’t know what information you have that would make you say that John. We fly our 12iS demonstrator and our flying club RV 12 ULS exclusively on auto fuel (except when the are away from home base) and we always have.
As for Van’s experience, I’m very familiar with that one. It was immediately after he first started flying the airplane and a carb got contaminated by something that passed through from the system. This does happen on occasion because of contaminants that didn’t get flushed out of the system before the engine was put into service. I don’t think he’s had any problems since that issue was resolved.

By the way, using 100 low lead doesn’t assure no carburetor problems. It actually can cause a whole set of different issues because of the blue dye. That tends to accumulate in the car and after while can make the slides start to stick so the use of 100 low lead doesn’t guarantee less maintenance.
__________________
Opinions, information and comments are my own unless stated otherwise. They do not necessarily represent the direction/opinions of my employer.

Scott McDaniels
Van's Aircraft Engineering Prototype Shop Manager
Hubbard, Oregon
RV-6A (aka "Junkyard Special ")

Last edited by rvbuilder2002 : 04-23-2021 at 05:06 PM.
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  #19  
Old 04-23-2021, 05:35 PM
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cactusman cactusman is offline
 
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Originally Posted by rvbuilder2002 View Post
I don’t know what information you have that would make you say that John. We fly our 12iS demonstrator and our flying club RV 12 ULS exclusively on auto fuel (except when the are away from home base) and we always have.
As for Van’s experience, I’m very familiar with that one. It was immediately after he first started flying the airplane and a carb got contaminated by something that passed through from the system. This does happen on occasion because of contaminants that didn’t get flushed out of the system before the engine was put into service. I don’t think he’s had any problems since that issue was resolved.

By the way, using 100 low lead doesn’t assure no carburetor problems. It actually can cause a whole set of different issues because of the blue dye. That tends to accumulate in the car and after while can make the slides start to stick so the use of 100 low lead doesn’t guarantee less maintenance.
Oh that was the comment Mike S told me when we gassed up using 100LL during a training session a long while back. He said they never use autogas because of logistics...but perhaps that was just his training operation or maybe things have changed. I dunno. My mistake.

I think that rubber diaphragm is very susceptible as well. Maybe temp extremes here have created more of an event too. Anything rubber or battery powered seems to have a 3 year life span in AZ. Can almost set your clock to it....in fact most locals do - get the 3 year battery warranty and take it back to Costco on 2 years and 364 days.
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  #20  
Old 04-23-2021, 08:17 PM
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DanH DanH is offline
 
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Originally Posted by cactusman View Post
,,, I'm not sure you have the same exposure and experience with autogas issues gumming these carbs up like Lockwood and others have.
John, as previously noted, Bing CV's have been hanging on motorcycles about 50 years, maybe more. They've seen every kind of gas in every country in the world. Care and feeding is not much harder than a pet rock.
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