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Topic Options
#406638 - 09/20/20 08:46 PM Raw fuel smell on descent
Kentucky Captain Offline
Gold Pilot

Registered: 06/13/14
Posts: 1379
Loc: Louisville, KY
I don't know why I get all of the weird issues, but, here goes:

My daughter and I went from BRY to 2I3 for a fly-in yesterday. To give you the basic info:

The trip is only about 50 miles.
We fueled the airplane before departure
We climbed to 4500' on the way out and 5500' on the way back.

As we started our descent into 2I3, we noticed the smell of fuel. We didn't get any of that until the descent.

On the way back home, we didn't smell any fuel at all until we started our descent from 5500', where we got it again.

Nothing on climb-out or level flight, only on the descent. We had burned about 5 gallons off flying out so the tanks weren't full there as we had burned about 10 gallons off by the time we started the descent back into Bardstown.

I don't ever recall this happening before. Anyone have any explanation of what is going on here. Over in the avionics section, I have another puzzler if you guys could help me out. Thanks.
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#406647 - 09/21/20 04:26 AM Re: Raw fuel smell on descent [Re: Kentucky Captain]
Challenger1 Offline
Gold Pilot

Registered: 03/23/16
Posts: 2433
Loc: Cincinnati, Ohio
Sounds likely that one of the new sending units is leaking? Or you have another leak somewhere. Start looking for blue streaks on the wings.

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#406648 - 09/21/20 10:15 AM Re: Raw fuel smell on descent [Re: Challenger1]
magman Offline
Gold Pilot

Registered: 10/10/12
Posts: 1463
Loc: buffalo NY
The Vent interconnect has rubber tubing UNDER the headliner.

It may be old and cracking .

Gaining access to see is sue

Once there SLIGHT pressure and soap n water can confirm.

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#406649 - 09/21/20 10:39 AM Re: Raw fuel smell on descent [Re: magman]
Challenger1 Offline
Gold Pilot

Registered: 03/23/16
Posts: 2433
Loc: Cincinnati, Ohio




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#406650 - 09/21/20 11:00 AM Re: Raw fuel smell on descent [Re: Challenger1]
Underdog Offline
Pilot in Command

Registered: 10/27/12
Posts: 319
Loc: OR
Ditto on the vent interconnect. The newer models have six 3" rubber tubes connecting them. Older models just two. Pretty much never get replaced because you need skinny arms to get to them. I have replaced them on both types (I guess I have skinny arms). They usually will need to be cut off with a sharp razor. If you do it, make sure that you cut along the tube, in a direction parallel to the tubing so as to prevent nicking the aluminum tubing.

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#406652 - 09/21/20 08:57 PM Re: Raw fuel smell on descent [Re: Underdog]
wildduk Offline
Second in Command

Registered: 07/07/17
Posts: 180
Loc: georgia
If posting pics was easier I could show you one of our 6 rubber hoses that has worn and had cuts and was leaking.....

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#406653 - 09/22/20 04:56 AM Re: Raw fuel smell on descent [Re: wildduk]
propizza Offline
Pilot in Command

Registered: 09/22/16
Posts: 273
Loc: Punta Gorda Fl
Lucky I only have 2, replace the right side when I had the tank out for a strap repair. Left side is still holding out.

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#406661 - 09/22/20 12:24 PM Re: Raw fuel smell on descent [Re: propizza]
magman Offline
Gold Pilot

Registered: 10/10/12
Posts: 1463
Loc: buffalo NY
When your shoes are off is a great time to change socks.

Also applies to aircraft.

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#406662 - 09/22/20 01:35 PM Re: Raw fuel smell on descent [Re: magman]
Challenger1 Offline
Gold Pilot

Registered: 03/23/16
Posts: 2433
Loc: Cincinnati, Ohio
What type of clamp should be used?

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#406663 - 09/22/20 02:05 PM Re: Raw fuel smell on descent [Re: Challenger1]
propizza Offline
Pilot in Command

Registered: 09/22/16
Posts: 273
Loc: Punta Gorda Fl
I believe I used BREEZE clamps

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#406670 - 09/22/20 09:10 PM Re: Raw fuel smell on descent [Re: propizza]
Kentucky Captain Offline
Gold Pilot

Registered: 06/13/14
Posts: 1379
Loc: Louisville, KY
Thanks for all of the ideas. I have not seen any streaking on the wing to indicate a fuel leak since the CIES senders went in. My airplane is a 76 M model. How many tubes would it have? I never even thought about the vent interconnect. I guess now I have to tear into the headliner again. Haven't done that in five years when I put in the B.A.S. shoulder harnesses.


Edited by Kentucky Captain (09/22/20 09:12 PM)
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#406672 - 09/22/20 09:20 PM Re: Raw fuel smell on descent [Re: Challenger1]
Kentucky Captain Offline
Gold Pilot

Registered: 06/13/14
Posts: 1379
Loc: Louisville, KY
Originally Posted By: Challenger1



What the heck is that attached to the scat tubing?
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#406680 - 09/23/20 07:07 AM Re: Raw fuel smell on descent [Re: Kentucky Captain]
Dave W Offline
Bronze Pilot

Registered: 03/23/14
Posts: 547
Loc: Northern Virginia
Originally Posted By: Kentucky Captain
Originally Posted By: Challenger1



What the heck is that attached to the scat tubing?


Thatís the rear passenger placebo adjustable air vent. We had the same fuel smell issue. After removing the headliner I could see the blue dye streaking from the rubber hoses.

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#406699 - 09/24/20 03:29 AM Re: Raw fuel smell on descent [Re: Kentucky Captain]
RickG Offline
Pilot in Command

Registered: 09/30/10
Posts: 393
Loc: Durham, NC
Originally Posted By: Kentucky Captain
I guess now I have to tear into the headliner again.

Don't rule out the odor may be coming from a leaking fuel selector. Pulling back the carpet and a couple of inspection plates on the floor is a much easier job than the headliner. Seals on the fuel selector can go bad as well (we've seen this happen on other aircraft at the field). How often do you move the fuel selection lever / switch tanks?
_________________________
'64 C172E
Durham, NC (8NC8)
http://www.lakeridgeaero.com

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#406725 - 09/24/20 09:56 PM Re: Raw fuel smell on descent [Re: RickG]
Kentucky Captain Offline
Gold Pilot

Registered: 06/13/14
Posts: 1379
Loc: Louisville, KY
Originally Posted By: RickG
Originally Posted By: Kentucky Captain
I guess now I have to tear into the headliner again.

Don't rule out the odor may be coming from a leaking fuel selector. Pulling back the carpet and a couple of inspection plates on the floor is a much easier job than the headliner. Seals on the fuel selector can go bad as well (we've seen this happen on other aircraft at the field). How often do you move the fuel selection lever / switch tanks?


After the first avionics upgrade five years ago, I did get a little smell from the tank switch. The airplane sat in the hanger for two months with the tanks empty and I think that everything got dried out. After a couple of flights, I didn't get it anymore and haven't in the last five years.

This time it is only on the descent. I always turn my fuel selector to off when fueling. That way I don't get any cross-bleed during fueling and can get the tanks full and I know I have 38 gallons for entry into the JPI.

I also have a healthy respect for making sure that I don't take off with the fuel selector in any configuration other than both. Even if I have just shut the airplane off to refuel, I always have to prime it to start. If the selector is off, no fuel pumps when you try to prime. Makes it fairly stupid-proof.

Fuel selector on both is also in my checklist several times prior to takeoff.
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#406727 - 09/25/20 04:14 AM Re: Raw fuel smell on descent [Re: Kentucky Captain]
Flubber4.0 Offline
Gold Pilot

Registered: 08/22/14
Posts: 1241
Loc: blue marble
I had fuel smell only on decents a long time ago and it was a corroded vent line, not the rubber hoses. We only found it by surprise, just a tiny hole in the aluminium tube.
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Never give up, never surrender. Activate the Omega-13.

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#407422 - 10/22/20 10:42 PM Re: Raw fuel smell on descent [Re: Flubber4.0]
Kentucky Captain Offline
Gold Pilot

Registered: 06/13/14
Posts: 1379
Loc: Louisville, KY
Originally Posted By: Flubber4.0
I had fuel smell only on decents a long time ago and it was a corroded vent line, not the rubber hoses. We only found it by surprise, just a tiny hole in the aluminium tube.


Where in the vent line was the hole? I'm not familiar with the routing of those lines. I'll have to see if I can find them in my manual.
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#407432 - 10/23/20 07:45 AM Re: Raw fuel smell on descent [Re: Kentucky Captain]
Challenger1 Offline
Gold Pilot

Registered: 03/23/16
Posts: 2433
Loc: Cincinnati, Ohio
Not my plane but are my pictures. Looks to me someone has already replaced these rubber couplers and screw clamps. I would have used better clamps, permanent clamps.







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#407457 - Yesterday at 02:12 AM Re: Raw fuel smell on descent [Re: Challenger1]
Kentucky Captain Offline
Gold Pilot

Registered: 06/13/14
Posts: 1379
Loc: Louisville, KY
I had heard that there were four of those hoses. Looks like I will have to take the entire ceiling out to check. Thanks for the pics.
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