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As has been mentioned, a fuel flow check verifies that the filter is not clogged. Does this fuel flow check then constitute an inspection given that it will achieve the intended purpose?.

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2 hours ago, Tom Baker said:

I don't think bore scoping the pistons is on the checklist. I have never found any significant metal on a magnetic plug, should I based on that not check the magnetic plug at the recommended interval? I have not found any metal in a Rotax oil filter, should I stop cutting them open? The checklist provides a minimum of what should be check, and in my opinion the inspection intervals on the checklist should be followed.

I think you missed my point:  Just because it’s on a checklist or in a maintenance document doesn’t mean it’s a good idea, or that the specified interval is ideal.

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13 minutes ago, ct9000 said:

As has been mentioned, a fuel flow check verifies that the filter is not clogged. Does this fuel flow check then constitute an inspection given that it will achieve the intended purpose?.

That doesn’t give a good idea of the trend of sediment accumulation.  You could have acceptable flow and the filter could be 0.1% clogged and no issue or 90% clogged and a couple of paint flakes away from an engine stoppage.  With that method you are inferring condition and not actually verifying condition.

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2 minutes ago, FlyingMonkey said:

That doesn’t give a good idea of the trend of sediment accumulation.  You could have acceptable flow and the filter could be 0.1% clogged and no issue or 90% clogged and a couple of paint flakes away from an engine stoppage.  With that method you are inferring condition and not actually verifying condition.

I kinda knew that my post would raise some comment.

As far as the trend of accumulation the fuel flow test is a very good guide. I regularly do a flow test and at each service I actually write it down. I would know as soon as there was a

partial blockage of any sort. Whilst I could not see a 0.1% change, I would see any significant change very easily and certainly a long time before a problem is likely.

Bear in mind that the gravity feed is close to 1 l/min. this is triple what your engine needs. I am with Roger on this as I pull the filter at 200 and never find anything, also my flow test has never shown any restriction at all. 

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26 minutes ago, FlyingMonkey said:

I think you missed my point:  Just because it’s on a checklist or in a maintenance document doesn’t mean it’s a good idea, or that the specified interval is ideal.

I understand your point. My point is that someone way above our pay grade put on the checklist, and I don't think our small sample size is enought to change the recomended inspection intervals. 

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9 hours ago, Tom Baker said:

I understand your point. My point is that someone way above our pay grade put on the checklist, and I don't think our small sample size is enought to change the recomended inspection intervals. 

Well, there's a balance.  It's true that factory personnel have access to more data, or at least different data than we do.  But it's also true that just because they are from the factory doesn't mean they have all the answers.  Sometimes engineers just make guesses based on the info they have, and then if it doesn't ever come up again if there is not a problem.

The fuel filter inspection interval is something that appears from owner experiences to justify revisiting and review 

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I’m going to play “devil’s advocate” here. If I know that my fuel flow has been consistent over the past three years (and the filter has been checked during that time, can I make any assumptions about the condition of the filter? It would seem that I could.

I will check it anyway, but I would not expect to find anything of consequence.

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I never expect to find anything of consequence, but I check them anyway. I am always surprised if I do find something. Only once did I find one almost 50% covered up. It looked like bug carcasses to me.

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+1

1 hour ago, SportFlyer1 said:

Guys we've gone on for 4 pages about a fuel filter, my eyes are starting to cross.

 

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2 hours ago, SportFlyer1 said:

Guys we've gone on for 4 pages about a fuel filter, my eyes are starting to cross.

Suggest you skip rest of thread and give eyes a good rest.

Eyes are good here . . . keep it coming. It's all good information.

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It'll never make 20 pages. Andy didn't start it. :giggle-3307:

Good thing this wasn't about spark plug color again. :bad_day-3329::clap-3332:

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Doing my first annual and wanted to add a comment here . . . I tested my fuel flow and was way below the minimum. But, I read here (from Roger) that the gas flow was much better with the gascolator bowl removed during this test. So today I re-tested my left (slower) tank with the gascolator bowl removed, and the flow was well above 10 gph. I was already psyching myself up to pulling the wings, so I was very happy that I tried the flow test this way. Thanks Roger, you are once again my hero!!! I will email Arian at FD and recommend that they state that my be required. In my case the gascolator drain valve was limiting the flow and nothing I would have done would improve the flow thru it. 

Jezzz, that fuel filter is hard to get to!!! Sure was relieved that I had the metal one!!!

ET

 

 

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The gascolators that are installed are not fully tapped for the drain valve, so it's not run fully down. They barely open when you look at them from the inside, and the o-ring gets cut up rubbing against the threads.

I've retapped 3 of them so far and the drain valve works so much better.

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