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zeroairspeed

As350 Fuel Drain

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Seems to be a difference of options on if you put to boost pumps on to do your fuel drain first thing.

I was under the understanding that they should be OFF. As you are recirculating the fuel if you have them ON and mixing the fuel and water (if any) and will not get a good read on it.

 

But, in the Supplement for the A/F fuel filter. It states, Boost pumps ON.

 

In the pre-flight in the FM. it dos'nt state to do any fuel drain.

 

Know on other machines, fuel is not recirculated, just pressured up.

 

thoughts

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Seems to be a difference of options on if you put to boost pumps on to do your fuel drain first thing.

I was under the understanding that they should be OFF. As you are recirculating the fuel if you have them ON and mixing the fuel and water (if any) and will not get a good read on it.

 

But, in the Supplement for the A/F fuel filter. It states, Boost pumps ON.

 

In the pre-flight in the FM. it dos'nt state to do any fuel drain.

 

Know on other machines, fuel is not recirculated, just pressured up.

 

thoughts

I don't know much about the As350 but "standard practice" to me would be first drain the sumps with pumps off. You are right in thinking there is the possibility of fuel and water mixing. Then, fuel valve(s) open and A/F pump(s) on to pressurize the system and drain any A/F and engine filters.

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Zero I think you are right with the fuel re-circulating in the tanks on the AS 350. I was taught filter drains (both) pump(s) off. I can't remember if the D models are the same though procedure though. I would have to look into that. Well spose it doesn't matter as they are getting phased out for BA & B2's.

 

Cheers

 

 

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When doing the sump drain, boost pumps off.

 

When draining the filters, boost pumps on.

 

If the pumps are off, the only way for the fuel to drain from the filter is by displacing it with air.

I know the FCU is a self-purging unit, but why create the extra grief.

That's why the pumps get turned on.

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The Arriel is a self purging system, so you could drain fuel with out the boost pump on. But as Ray said why and any grief.

 

Now the LTS is a whole different story, you have to run the boost pumps to drain the fuel. By not running them air will get into the system and it is NOT self purging. So this could get ugly later.

 

What I suggest is to run the boost pump every time.

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Part of the reason it states to run the boost pumps while draining the 2 A/F fuel filters is that without running the pumps you may not know that your drain **** it stuck in the open position. Then if you go flying you will be draining all your fuel at a much faster rate causing a slight problem. and that's not just theory it has happened

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I'm surprised i haven't heard the obvious. What does the POH say? Assuming it has been kept up to date do what it says. If it's not up to date.....well now you have another project. Having said that i believe Eurocopter is changing or has changed the procedure. Will be checking the next time i go to work.

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Zero I think you are right with the fuel re-circulating in the tanks on the AS 350. I was taught filter drains (both) pump(s) off. I can't remember if the D models are the same though procedure though. I would have to look into that. Well spose it doesn't matter as they are getting phased out for BA & B2's.

 

Cheers

 

 

what about upgrading of the AS350 to a soloy D2 or D, that's getting more popular as the engines are more effecient and cheaper to run. As for the draining, I do the fuel tank sump first (no boost, as this is where the water will collect) and then the STC a/f filtre with boost and then the A/F filtre with boost. If you're careful with your fuel supply and use waterblock filters on the bowser and don't leave the fuel cap off you should be fine. All you have to worry about is condensation. The worst thing for any machine is to sit for extended periods.

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The BA and B2 have a recirculation fuel system, so if you have the pumps on the fuel will be in motion, therefor any contaminants will be suspended in the moving fuel. The system will purge with in 30 sec, this is why boost pumps on for 30 sec before start, to remove any air before start.

 

Sump & A/F filter, pumps off. ( its ok for air to be sucked into the filter)

 

The DA and D2 have a closed system like the jet ranger, fuel is not in motion and the system is not self purging, if you create an opening with no pressure fuel will be displaced by air, and air doesn't burn very well. No recirculation so air will not be purged, and head to the injectors.

 

Sump pumps off, filters pumps on.

 

 

Rob

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