banner graphic
Airport Webcams
Who's Online
16 registered (Leadnut, Steven Untiet, ChadB, jpflys1, Skyblazer, Rafael Sierra, Bigdoggh, Toehead12, Whitehawk, apple guy, Teg916, Showboatsix, CaptPenner, Joeman434, Kinhop, 1 invisible), 76 Guests and 0 Spiders online.
Key: Admin, Global Mod, Mod
Newest Members
NZWB 172, RDKJ172, ChadB, Kevin Summerlin, jai999
8588 Registered Users
Top Posters
Bargain Bob 148778
vettdvr 7471
Cessna Dude 6628
Rusty Rudder 6475
California Flyer 5441
Willie 4385
Clyde Cessna 3654
Joeman434 3420
Don Tedrow 2938
Peedie Montgomery 2815
wrecksum 2704
Ward Holbrook 2436
XP Driver 2394
November X-ray 2096
ytodd 1920
oilwell1415 1906
Jim_1 1834
Nightowl 1826
Nintendo Pilot 1723
Glenn Darr 1708
Bigdoggh 1661
RodneyHooverCFI 1645
Fred R Ali 1633
Pilawt 1608
EdW 1412
Shuswap 1283
Pilot110 1264
Showboatsix 1243
Henry M. 1156
JD Casteel 1147
Top Posters (30 Days)
Bargain Bob 2714
Joeman434 93
Kentucky Captain 67
Rusty Rudder 59
Peedie Montgomery 58
vettdvr 55
Flubber4.0 39
N5479R 30
Kinhop 28
Don Tedrow 27
California Flyer 24
November X-ray 23
Wayne R 22
Dave W 20
Viper_96 18
Pilot110 17
Shifty 17
thomasdr72 14
Mike492 13
Willie 13
Curious1 13
XP Driver 12
magman 12
3hawks 11
OldMech 11
Mayday 11
Clyde Cessna 10
Flyboy712 9
Jim_1 9
Henry M. 8
Topic Options
#73922 - 03/31/12 04:09 PM uneven fuel flow
mattcyyz Offline
New Member

Registered: 03/23/11
Posts: 1
Loc: ontario canada
This is my first post on the cessna 172 club forum but i have read many threads and have gained alot of useful infromation wich has helped with my purchase and restoration of a 1969 172 K so thanks to everyone on the site!! My 172 sat in a hanger for ten years so naturally there were some bugs to work out I have basically fixed or replaced anything that could be affected by age or decay including complemply overhauling the engine, prop replacing the lord mounts, starter, alternater, mags, and wiring harness. I have also redone the panel. But I'am now finding that i have an uneven fuel flow from my left and right tanks. my left tank drains at a three to one ratio compared to my right tank. Is this normal or maybe user induced? i have yet to take the tanks below half. any advice or info any one would have will be greatly apprcieted

thanks

Top
#73923 - 03/31/12 04:15 PM Re: uneven fuel flow [Re: mattcyyz]
California Flyer Offline
Diamond Pilot

Registered: 10/21/09
Posts: 5441
Loc: Groveland, California
Hi Matt! Glad you have found this club to be a useful place for knowledge.

My 2000 SP model also draws fuel unevenly during the first third of the flight. It will draw from the left tank until about 10 gallons are gone, then it will start drawing from the right tank. Things even out from there, though sometimes I will fly with the selector switched to just the right tank for a bit to balance things out. So far it hasn't been a problem for me, it's just one of those quirks I have gotten used to. When I was renting, the other Cessnas in the rental fleet all did that too, to varying degrees.
_________________________
Co-Conspirator, Cessna 172 Club and Forum
http://www.cessna172club.com


Owner of N291ME, a 2000 Cessna 172SP

Top
#73924 - 03/31/12 04:27 PM Re: uneven fuel flow [Re: California Flyer]
Bigdoggh Online   content
Gold Pilot

Registered: 05/26/11
Posts: 1661
Loc: Georgia
Mine does the same.
_________________________
George - 1972 C-172L


Top
#74005 - 04/01/12 06:56 AM Re: uneven fuel flow [Re: Bigdoggh]
wrecksum Offline
SVP Public Relations
Platinum Pilot

Registered: 09/26/10
Posts: 2704
Loc: Dominican Republic
Same here.
Left tank drains faster.
On long legs I equalise the tanks but it's just one of those quirks it seems.
_________________________
A person without a sense of humour is like a wagon without springs.It's jolted by every pebble in the road.

Cessna 172, C172, C-172, Cessna Skyhawk fan.
www.cessna172club.com

Top
#74008 - 04/01/12 08:05 AM Re: uneven fuel flow [Re: wrecksum]
Bigdoggh Online   content
Gold Pilot

Registered: 05/26/11
Posts: 1661
Loc: Georgia
Actually, mine drains the left tank faster on full tanks. Like Susie, the burn evens out as more fuel is consumed. Since most of my CC are over 5k, I switch tanks as well.
_________________________
George - 1972 C-172L


Top
#74010 - 04/01/12 08:13 AM Re: uneven fuel flow [Re: Bigdoggh]
Dr Nick Offline
Bronze Pilot

Registered: 04/27/11
Posts: 721
Loc: Nebraska
My 69 does this as well. Evens out as you draw more.

The left draws faster because the left is where the fat guy controlling the plane is seated so that your more evened out on landing. My theory anyways.
_________________________
Life is tough, I got your back!

1969 C~172K N79105

http://www.linnchiro.com


Top
#74017 - 04/01/12 10:01 AM Re: uneven fuel flow [Re: Dr Nick]
Don Tedrow Offline
Platinum Pilot

Registered: 07/16/10
Posts: 2938
Loc: Bastrop, TX
Originally Posted By: Dr Nick

The left draws faster because the left is where the fat guy controlling the plane is seated so that your more evened out on landing. My theory anyways.


+1! Works for me. grin

My understanding of the issue is that both tanks are feeding properly, the issue is that the main fuel vent is below the left wing, and both wings have dihedral. What that means is the slightly higher head pressure in the left tank is forcing fuel through the crossover line to the right tank. When the fuel level in the left tank gets to about half full, then air, not fuel is flowing to the right tank, and fuel levels even out. That's from the CPA tech notes, and is exactly how my Skyhawk acts. They do recommend that you double check the exact positioning of the fuel vent behind the left strut. There are some precise measurements for that vent to act properly and to avoid blockage in icing conditions. +/- .03" in my service manual.
_________________________
1972 C172L



Top
#74026 - 04/01/12 12:04 PM Re: uneven fuel flow [Re: Don Tedrow]
Dr Nick Offline
Bronze Pilot

Registered: 04/27/11
Posts: 721
Loc: Nebraska
Originally Posted By: Don Tedrow


+1! Works for me. grin

My understanding of the issue is that both tanks are feeding properly, the issue is that the main fuel vent is below the left wing, and both wings have dihedral. What that means is the slightly higher head pressure in the left tank is forcing fuel through the crossover line to the right tank. When the fuel level in the left tank gets to about half full, then air, not fuel is flowing to the right tank, and fuel levels even out. That's from the CPA tech notes, and is exactly how my Skyhawk acts. They do recommend that you double check the exact positioning of the fuel vent behind the left strut. There are some precise measurements for that vent to act properly and to avoid blockage in icing conditions. +/- .03" in my service manual.


Yep, that to.
_________________________
Life is tough, I got your back!

1969 C~172K N79105

http://www.linnchiro.com


Top
#74036 - 04/01/12 03:58 PM Re: uneven fuel flow [Re: mattcyyz]
Jim_1 Offline
Gold Pilot

Registered: 04/06/11
Posts: 1834
Loc: ON, Canada
Hey Matt

Welcome to the forum.
I like yourself drove myself crazy worrying about this trying to determine why my left tank emptied so much quicker than the right. Many experienced folks here and they also aided my in realizing its absolutely normal.

Good luck and welcome to the forum.


Jim - also from ontario
_________________________

Top
#74043 - 04/01/12 04:46 PM Re: uneven fuel flow [Re: Jim_1]
joelaff Offline
Bronze Pilot

Registered: 04/08/11
Posts: 626
Loc: Missouri, USA
Cessna Pilot's Association has a Tech Note on this issue... And it is, as othes have said, normal.


Edited by joelaff (04/01/12 04:55 PM)
_________________________


Top
#74047 - 04/01/12 05:12 PM Re: uneven fuel flow [Re: joelaff]
tedh Offline
Safety Pilot

Registered: 03/13/11
Posts: 50
Loc: Dripping Springs TX
The 152 does the same. I think it is caused by uneven air flow across the filler caps, which is caused by the rotating air of the props.

Top
#74095 - 04/01/12 10:45 PM Re: uneven fuel flow [Re: tedh]
Adger Smith Offline
Second in Command

Registered: 02/27/12
Posts: 188
Loc: East Texas
Ditto: my 1961 172B does it too....
_________________________
Adger Smith
Adger Smith Performance Engines
2802 W 7th St
Texarkana Tx 75501
903 794 7223 shop
903 824 4924 cell

Top
#74272 - 04/03/12 02:14 AM Re: uneven fuel flow [Re: Adger Smith]
RixxoN Offline
New Member

Registered: 05/13/11
Posts: 1
Loc: Germany
My 1976 172M draws left faster too

Top
#74367 - 04/03/12 09:36 PM Re: uneven fuel flow [Re: RixxoN]
RodneyHooverCFI Offline
The Cessna Sensei
Gold Pilot

Registered: 02/16/10
Posts: 1645
Loc: Pasadena, MD
Don Tedrow's post on the reason for uneven fuel flow is spot on. If they had an identical vent in the same location behind the right strut, it would help, but not necessarily fix the issue 100% as there are other contributing factors.
_________________________
Flight Instructor- ASEL and Instrument Airplane
Commercial Pilot with Instrument Rating- ASEL & AMEL
Assistant Chief Instructor at W00, Freeway Aviation.
States I've flown to-

Airport list map:
http://goo.gl/maps/qh1Tc

Top


Cessna172 Tribute
THIS MONTH'S SPONSOR
Special thanks to:
You!
Thank you for making this site great
Fredericksburg TX '15 Countdown
September 25-27, 2015 T82
Today's Birthdays
TaylorSp, Wright
Member Map
Where in the world are the Cessna 172 Club Members?

View the map

Helpful Links
100LL Price Finder
AD Directory
Aging GA Aircraft
Aircraft Directory
Airplane Report
AirNav
Airport Facilities Directory
AOPA
Aviation Weather
Barnstormers
BaseOps
C172 History
Cessna
Controller
Crash Records
DUAT Voyager Planner
DUATS
FAA
FltPlan
Flight Aware
Flying Tools (Files)
Google Earth
Ground Speed Records
National METAR Map
Sky Vector
Trade-A-Plane
Uvalde Flight Ctr
All the Webcams
Shout Box

AOPA
AOPA
Weather Lookup
Airport code:
(separate multiple codes with spaces)

List of stations