FlyingMonkey Posted April 2, 2014 Report Share Posted April 2, 2014 So I have started to put out feelers for services in the area, since my annual is coming up in early July and I have some avionics work I want to have done (mainly autopilot install...I have a TruTrak out of another CT). One of the shops replied immediately with some pricing, and he said if it's a 200hr annual (it is, airplane is at 176hrs annual due at 202hrs) then the carbs need to be rebuilt, for which he quoted $300. Two questions: 1) is it required to have the carbs rebuilt at/every 200hrs? I had not heard this before 2) Is $300 a good price for these rebuilds? Link to comment Share on other sites More sharing options...
CT4ME Posted April 2, 2014 Report Share Posted April 2, 2014 That's the first time I've heard that... no rebuild necessary on CT#1, with 550+ hours on it. Maybe he's confusing this with 2-stroke maintenance time. Carb rebuild kit at CPS is $245 Link to comment Share on other sites More sharing options...
Tom Baker Posted April 2, 2014 Report Share Posted April 2, 2014 First off rebuilding the carburetor is something only the manufaturer can do acording to CFR 43. The carbs require a 200 hour inspection per the checklist. It takes me about 1 hour per carb to remove, disassemble, inspect, reassemble, and reinstall unless I have any problems. After both carbs are reinstalled then you have balance them. A repair kit from Lockwood is $44.95 for all the needed gaskets. Normally you don't need floats, diaphrams, or any other parts. Link to comment Share on other sites More sharing options...
Ed Cesnalis Posted April 2, 2014 Report Share Posted April 2, 2014 Float failure can be scary and expensive. If the carb has a couple hundred hours since new floats and uses mogas why not change it? Link to comment Share on other sites More sharing options...
Roger Lee Posted April 2, 2014 Report Share Posted April 2, 2014 Find another mechanic he already doesn't know what he's talking about. The 200 hr. carb inspection is just that, only an inspection. If we went to a Rotax class he would know this. No where in any Rotax manual does it give any time table for a re-build. I see carbs from all across the US. Some come from the early 1990"s and some from just a couple of years ago. Unless they don't sync or your having some other trouble from them leave them alone. Some like to re-build at the 5 year rubber replacement. Some don't do it until 1000 hrs. or 8 years. I would do it on condition and not just pick an arbitrary number and especially not an aircraft only a few years old with low hours and no signs of problems. Have a good reason to do them. Link to comment Share on other sites More sharing options...
Anticept Posted April 2, 2014 Report Share Posted April 2, 2014 Often people call it a "rebuild" when they mean "inspection". Just bad terminology. It takes about 2-3 hours to disassemble, inspect, reassemble, and sync the carbs. $300 bucks for complete start to finish carb disassembly, replacement of o-rings, and reinstall and retune actually sounds about right. $300 bucks on top of labor is not. the 200 hour inspection for a CT is ridiculous though. Dean Vogel from Lockwood even said it's overkill for a CT. It's more meant for some aircraft which don't cushion the engine vibrations very well and starts cracking the needles in the carb. Still, rotax says do it, so we do it. Link to comment Share on other sites More sharing options...
Roger Lee Posted April 3, 2014 Report Share Posted April 3, 2014 My personal preference is leave it be at 200 hr. I give my clients a choice. I agree with Dean, It is over kill unless the 200 hr. mark is 6-8+ years old. That means it has done a lot of sitting and "O" rings crack and split. I have seen many that way. If the mechanic is on his toes and actually knows there are no issues then sync and go. With all the hoses changes going on I do always pull the carb bowels to take a look. Link to comment Share on other sites More sharing options...
Doug G. Posted April 3, 2014 Report Share Posted April 3, 2014 Hmmm...and I am advised to change the oil no matter what at inspection time.Does anyone clean the spark plugs and keep them to 200 hrs. IAW the Rotax Line Maintenance Manual? Link to comment Share on other sites More sharing options...
FlyingMonkey Posted April 3, 2014 Author Report Share Posted April 3, 2014 My airplane has less than 200hrs, but it's a 2007 so it did sit a lot for about six years before I got it. I have no indication of leaks or other carb problems. My right drip tray has some discoloration and stains in it, but they are old, always dry, and have been there since I got the airplane. The $300 quoted was total parts and labor for both carbs, and is in addition to a quote for $750 for the annual which includes the 100hr Rotax service. I think this shop has a good reputation, and I didn't get the idea they didn't know their trade or were trying to pad the bill, but it never hurts to ask the opinions of others. I think they read this forum, too. . This was one of two shops I requested info/pricing from, the other was Lockwood who has not yet responded. If anybody knows another shop I should look at in the southeast, I'm open to suggestions. Link to comment Share on other sites More sharing options...
Roger Lee Posted April 3, 2014 Report Share Posted April 3, 2014 "Does anyone clean the spark plugs and keep them to 200 hrs. IAW the Rotax Line Maintenance Manual?" No and I have never heard of anyone actually teaching that either. Link to comment Share on other sites More sharing options...
Anticept Posted April 3, 2014 Report Share Posted April 3, 2014 Keep in mind my CT is used in flight training, so for liability concerns, I try to stick to the manual. Link to comment Share on other sites More sharing options...
FredG Posted April 3, 2014 Report Share Posted April 3, 2014 My Rotax and FD trained mechanic did remove and carefully inspect my carbs at 600 hours (2006 CTsw). I was finding fresh fuel in the drip trays. I assisted (watched) the maintenance. There were signs of use (observable but not severe wear on the float pins and float brackets) but nothing that appeared especially problematic. The drip may have been due to debris affecting the seating of the float needle valve or to the fuel level in the bowls. All rubber parts were in good condition. If my carbs were performing well with no problems, I would have low enthusiasm for a "rebuild". Just my experience, yours may be different. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted April 3, 2014 Author Report Share Posted April 3, 2014 My inclination would be that an "inspection" is warranted, but not a "rebuild" unless some problem is found. I'm a firm believer in the Mike Busch ( http://www.savvyaviator.com/ ) philosophy of condition-based maintenance, which basically says if something is working properly and showing no signs of risk of failure, don't mess with it. This is what the airlines and military does, and they experience a lot less failures than many GA operators as a result. Link to comment Share on other sites More sharing options...
Roger Lee Posted April 3, 2014 Report Share Posted April 3, 2014 Fuel in the drip tray is usually only the carb bowl gasket and is fairly common. I keep half a dozen bowl gaskets on hand at all times. Link to comment Share on other sites More sharing options...
FastEddieB Posted April 4, 2014 Report Share Posted April 4, 2014 Roger just did mine. First time they've been off the plane. I thought 7 years and about 370 hours was about right*. As an aside, the same basic Bings are found on "airhead" BMW motorcycles. It is known that the diaphragms can gradually become subtly porous over time. When they do, the only symptom I know of is slight power loss at full throttle, as the vacuum can no longer lift the slide fully. In addition, the o-rings on the butterfly shaft can become squared and brittle, as can other o-rings. But my layman's thoughts are that every 200 hours is a bit much. FWIW. *I need to fly more! Link to comment Share on other sites More sharing options...
FlyingMonkey Posted April 4, 2014 Author Report Share Posted April 4, 2014 I'm certainly not worried about the hours, just wondering if the six years it sat and only got 100hrs total might contribute to damaged components like diaphragms and o-rings. Link to comment Share on other sites More sharing options...
FastEddieB Posted April 4, 2014 Report Share Posted April 4, 2014 At 6 years I think a rebuild is the Most Conservative Action. Time and ozone and possibly ethanol can all affect the rubber parts. There are certainly Bings out there that have gone 10 years, even 20 years and never been touched. Ours might easily go that long as well. But given the possible consequences of reduced performance when you need it, I'd plan for it within the next few years regardless. Link to comment Share on other sites More sharing options...
Runtoeat Posted April 4, 2014 Report Share Posted April 4, 2014 FredG, what was the outcome of your carb inspection regarding fuel in the drip trays? Did this stop the fuel in the trays? What do you think was causing this? Maybe worn float needle rubber tips or gritt in the float needles? Or, leaking float bowl gaskets? Link to comment Share on other sites More sharing options...
Tom Baker Posted April 4, 2014 Report Share Posted April 4, 2014 Andy, was the Rotax 5 year rubber replacement done on your airplane? Link to comment Share on other sites More sharing options...
FlyingMonkey Posted April 4, 2014 Author Report Share Posted April 4, 2014 Andy, was the Rotax 5 year rubber replacement done on your airplane? Yes, just before I took delivery of the airplane last July. Link to comment Share on other sites More sharing options...
FredG Posted April 4, 2014 Report Share Posted April 4, 2014 "FredG, what was the outcome of your carb inspection regarding fuel in the drip trays? Did this stop the fuel in the trays? What do you think was causing this? Maybe worn float needle rubber tips or gritt in the float needles? Or, leaking float bowl gaskets?" Dick, the bowls were not leaking from the gaskets. The float needles were replaced and, by adjusting the "arm" on the float bracket, the fuel levels in the bowls were lowered slightly. The carbs no longer drip. Not sure which change made the difference. It is my personal opinion (based on some CT observations and my experience with Bing carbs on my old motorcycle (as also mentioned by Ed B )), that the carbs are pretty sensitive to small changes in float height setting. Just my limited observations from a small sample. Link to comment Share on other sites More sharing options...
Anticept Posted April 4, 2014 Report Share Posted April 4, 2014 Carbs are designed to have the fuel level sit JUST below the end of the discharge nozzle, or it will drip fuel. If it is too low, your mixture will run lean, as the float level acts as head pressure in float carbs to push the fuel to the edge of the discharge nozzle, where the airstream will take care of the rest. All carbs are actually quite sensitive to this, even the old radials. Carb leaking is quite common as the seat wears, and it's even an FAA test question for Powerplant written tests. Link to comment Share on other sites More sharing options...
Tom Baker Posted April 4, 2014 Report Share Posted April 4, 2014 Yes, just before I took delivery of the airplane last July. The diaphrams in the carb are part of the parts Rotax says to replace, so it should have been changed. I also think that the needle tips get harder with age and are more likely to leak. Check the records and see what was done to the carbs at the 5 year rubber replacement. If seals and gaskets were not replaced then I would do those along with new float needles. Also inspect the floats real close for cracks in the finish and flaking. Link to comment Share on other sites More sharing options...
Rogerck Posted April 13, 2014 Report Share Posted April 13, 2014 Some time ago I had a small but pesky amount of fuel in my left carb drip tray consistently after flying (06CT). The float bowl gasket was changed, carb inspected for external leaks and fuel stains, there were none, and problem continued. It turns out that the clamp screw where the carb is attached to the manifold was not snugged down. Tightened screw and have not had problem since. Roger Kuhn Link to comment Share on other sites More sharing options...
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