Cessna 310 fuel pump noise

[JOhnH]

Maybe this is normal. A friend of mine bought a Cessna 310. When it is in the hangar and he turns on the master switch, the fuel pump comes on. We figured out that it is connected to the same circuit breaker as the Nav lights, so we could turn it off since we weren't going to start it, but inside the hangar, the fuel pump in the left side tip tank is awfully loud. It is a loud banging metalic sound. He said it doesn't sound so loud outside of the hangar, and the guy that sold it to him (an A&P) said it is normal. But it just didn't sound normal to me. Of course, it is a Cessna; not a Bonanza, so WTFDIK?

 

[PaulS]

Maybe this is normal. A friend of mine bought a Cessna 310. When it is in the hangar and he turns on the master switch, the fuel pump comes on. We figured out that it is connected to the same circuit breaker as the Nav lights, so we could turn it off since we weren't going to start it, but inside the hangar, the fuel pump in the left side tip tank is awfully loud. It is a loud banging metalic sound. He said it doesn't sound so loud outside of the hangar, and the guy that sold it to him (an A&P) said it is normal. But it just didn't sound normal to me. Of course, it is a Cessna; not a Bonanza, so WTFDIK?

I always question something that I'm told is normal that doesn't sound normal, but that's just me.

 

[JOhnH]

I always question something that I'm told is normal that doesn't sound normal, but that's just me.

Yeah, that's why I'm questioning it. But since it isn't mine and he lives in another state and I don't know his A&P, this seems the best place for me to do the questioning.

 

[Doc Holliday]

That pump you are hearing is the tank recirculating pump. They are suppose to be on anytime the aircraft has electrical power applied.

As to the noise, worth investigating. They are not difficult to change out, remove the aft cover to the tank and it’s right there.

 

[Kyrpto]

If you're concerned squawk the issue and see if the mechanics find anything.

 

[GRG55]

"tank recirculating pump"? What on earth us that for? To supply constant suction pressure to the fuel injection pumps? What happens if it fails in flight?
Just curious...

 

[Doc Holliday]

"tank recirculating pump"? What on earth us that for? To supply constant suction pressure to the fuel injection pumps? What happens if it fails in flight?
Just curious...

IIRC the re-circulation pumps were put in for low fuel levels to move the fuel from one end of the tank to the other, mainly to prevent unporting during descent.

I do believe the tanks must be really low for a pump failure to be noticeable. Remember the tip tanks on a 310 are the mains.

 

[James_Dean]

The transfer pumps come on with the master switch and make a noticeable clicking sound. You should listen for them carefully and they should sound the same. Attached PDF describes the system.

 

[Radar Contact]

"tank recirculating pump"? What on earth us that for? To supply constant suction pressure to the fuel injection pumps? What happens if it fails in flight?
Just curious...

It’s to send fuel from the back of the mains to the front to ensure it doesn’t unport. This is needed on the 310 because the acceleration is so tremendous that it causes all the fuel to be pinned in the aft portion of the tank.

 

[JAWS]

"Tick tick tick tick tick".

 

[GRG55]

IIRC the re-circulation pumps were put in for low fuel levels to move the fuel from one end of the tank to the other, mainly to prevent unporting during descent.

I do believe the tanks must be really low for a pump failure to be noticeable. Remember the tip tanks on a 310 are the mains.

The transfer pumps come on with the master switch and make a noticeable clicking sound. You should listen for them carefully and they should sound the same. Attached PDF describes the system.

Thank you @Doc Holliday and @James_Dean That was an interesting new learning for me.

It’s to send fuel from the back of the mains to the front to ensure it doesn’t unport. This is needed on the 310 because the acceleration is so tremendous that it causes all the fuel to be pinned in the aft portion of the tank.

Apparently my list of reasons to upgrade from a lowly Aztec to a breathtaking 310 just expanded by one more entry.

 

[Fracpilot]

The transfer pumps come on with the master switch and make a noticeable clicking sound. You should listen for them carefully and they should sound the same. Attached PDF describes the system.

This.

Yes that is a normal clicking sound. And the CB for the pumps should be on the landing lights, not the nav light.

What year and model 310.?


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[Plano Pilot]

It’s to send fuel from the back of the mains to the front to ensure it doesn’t unport. This is needed on the 310 because the acceleration is so tremendous that it causes all the fuel to be pinned in the aft portion of the tank.

Actually it pumps fuel the other way, from the front.

 

[weilke]

"Tick tick tick tick tick".

It's a dollar counter.

 

[JOhnH]

This.

Yes that is a normal clicking sound. And the CB for the pumps should be on the landing lights, not the nav light.

What year and model 310.?


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You are right, I got it wrong. The pump was on the same CB as the landing lights. Regardless, it wasn't something you could find by looking.

And I can understand a clicking noise being normal. But the sound I heard was not a normal clicking noise. But I have told him what I think and it is up to him to investigate. He lives in a huge air park and there is bound to be other 310s around he could compare it to.

 

[Radar Contact]

Actually it pumps fuel the other way, from the front.

I was just joking with my Aztec driving friend...hence the . I realize it’s for steep descents with lower quantities in the mains...the unporting was accurate.

 

[Twin_Flyer]

It’s to send fuel from the back of the mains to the front to ensure it doesn’t unport. This is needed on the 310 because the acceleration is so tremendous that it causes all the fuel to be pinned in the aft portion of the tank.

+1