Fuel cap
Moderators: GAHorn, Karl Towle, Bruce Fenstermacher
- wa4jr
- Posts: 437
- Joined: Mon Apr 29, 2002 2:44 am
Hey George!...your reasoning seemed to work with Monarch
He checked his paperwork and said that the premium vented caps are indeed certified in pairs, but that the "classic 120/140 caps" were not, and he would be willing to sell just one seeing as how it would require an FAA field approval anyway. So seems like I will be able to have a decent vented cap after all, and I'll be sure to get that field approval right away
Thanks for the tip, George.


John, 2734C in Summit Point, WV
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- Posts: 116
- Joined: Mon Apr 22, 2002 11:51 pm
Gaskets
Since I started this thread I guess I should update on what I have done.
I ordered two fuel cap gaskets from Wag-Aero, Page 51 E-422-000 $6.95 ea.
I used one on the unvented left fuel tank cap and used the other new one to replace the gasket on the oil filler cap. The vented fuel cap on the right tank is not leaking. Next I intend to plug the two small holes in the back of the fuel vent tube. That should take care of my fuel leaking problems on the top of the wing. I will expect to have a small amount of fuel leak out of the fuel vent tube on occasion due to turbulence or rough taxing conditions.
Bob
I ordered two fuel cap gaskets from Wag-Aero, Page 51 E-422-000 $6.95 ea.

Bob
- Kyle Wolfe
- Posts: 706
- Joined: Mon Mar 17, 2003 12:30 am
Got newer style vented caps on both sides. I do get fuel leaking on the tops of the wings after flight. Not a lot, just enough to make me mad and constantly a pain to clean.
Anyone know how I can discern if it's the cap gaskets, the vent, or the filler neck?
Anyone know how I can discern if it's the cap gaskets, the vent, or the filler neck?
Kyle
54 B N1932C
57 BMW Isetta
Best original 170B - Dearborn, MI 2005
54 B N1932C
57 BMW Isetta
Best original 170B - Dearborn, MI 2005
- GAHorn
- Posts: 21295
- Joined: Fri Apr 12, 2002 8:45 pm
The vent is visible from beneath the opened cap. It is a small cylinder with a red-"silicone rubber" flapper valve which seals 3 small vent-holes. See them on the caps on the right.

The valve allows air to enter the tanks yet blocks fuel from leaving via the vent. Visually check the condition of that flapper. (Be gentle.... they can be destroyed if too much pulling is made on them. They cannot be exchanged between caps without swapping the entire valve assembly.) When the valve's flappers get old, they curl away from their valve-assy's and leak fuel overboard.
Place the cap on a filler neck that's been removed (or other such device...some auto-inspection facilities have a pressure-cap tester in their shops) and test it for 3-5 psi of pressure. It should not leak.
New gaskets may be the cheapest test. They are available from Spruce for about $2.50 last time I bought them. I'll try to locate a PN and post it.
Spruce. Their pn:FC2651, $1.50 (877-477-7823)
http://www.aircraftspruce.com/catalog/a ... elcaps.php
The gaskets are intended for the caps shown below:

The valve allows air to enter the tanks yet blocks fuel from leaving via the vent. Visually check the condition of that flapper. (Be gentle.... they can be destroyed if too much pulling is made on them. They cannot be exchanged between caps without swapping the entire valve assembly.) When the valve's flappers get old, they curl away from their valve-assy's and leak fuel overboard.
Place the cap on a filler neck that's been removed (or other such device...some auto-inspection facilities have a pressure-cap tester in their shops) and test it for 3-5 psi of pressure. It should not leak.
New gaskets may be the cheapest test. They are available from Spruce for about $2.50 last time I bought them. I'll try to locate a PN and post it.
Spruce. Their pn:FC2651, $1.50 (877-477-7823)
http://www.aircraftspruce.com/catalog/a ... elcaps.php
The gaskets are intended for the caps shown below:

'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.

- Kyle Wolfe
- Posts: 706
- Joined: Mon Mar 17, 2003 12:30 am
Thanks George. My caps look like those to the right in your picture. Checked them today and the rubber check valve looks to be flat against both caps, but I'm thinking maybe it's just time to replace.
Spruce doesn't list them. Anyone but Cessna have those gas caps?
Or anyone carry the valve assembly that you mention?
Spruce doesn't list them. Anyone but Cessna have those gas caps?
Or anyone carry the valve assembly that you mention?
Kyle
54 B N1932C
57 BMW Isetta
Best original 170B - Dearborn, MI 2005
54 B N1932C
57 BMW Isetta
Best original 170B - Dearborn, MI 2005
- GAHorn
- Posts: 21295
- Joined: Fri Apr 12, 2002 8:45 pm
My own caps vents were damaged and I salvaged valves from 182 caps that were replaced due to AD notes against them. (The 182 caps were condemmed for reasons other than the still-serviceable valves in them, which I salvaged.) Otherwise,... I do not know of a ready source for them. Sorry.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.

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- Posts: 78
- Joined: Tue Mar 14, 2006 1:59 am
George, I tried the link http://www.monarch-air.com/ but it didn't work for me. I kept getting airline ticketing links. Is there another way of contacting them. I currently have brand new Cessna vented caps on both sides and they leak like a screen window in any attitude other than straight and level. It really irritates me after paying $30 each for them and they still leak. I'm going to paint the airplane soon, and I don't want fuel spilling over my shiny white paint. Help!
Dave
Dave
- jrenwick
- Posts: 2045
- Joined: Thu Apr 01, 2004 8:34 pm
Dave,
I Googled "Monarch Air" and got this hit: http://www.monarchair.com/parts.html
Is it what you wanted?
John
I Googled "Monarch Air" and got this hit: http://www.monarchair.com/parts.html
Is it what you wanted?
John
John Renwick
Minneapolis, MN
Former owner, '55 C-170B, N4401B
'42 J-3 Cub, N62088
'50 Swift GC-1B, N2431B, Oshkosh 2009 Outstanding Swift Award, 2016 Best Continuously Maintained Swift
Minneapolis, MN
Former owner, '55 C-170B, N4401B
'42 J-3 Cub, N62088
'50 Swift GC-1B, N2431B, Oshkosh 2009 Outstanding Swift Award, 2016 Best Continuously Maintained Swift
- GAHorn
- Posts: 21295
- Joined: Fri Apr 12, 2002 8:45 pm
Monarch (the gas cap people) are now OUT OF BUSINESS. (legal troubles I'm told)
The second link is to a different company with a similar name.
The Monarch gas caps had gotten into trouble for making unapproved parts and marketing them for airplanes.(so the rumor goes.)
The second link is to a different company with a similar name.
The Monarch gas caps had gotten into trouble for making unapproved parts and marketing them for airplanes.(so the rumor goes.)
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.

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- Posts: 1373
- Joined: Tue Apr 23, 2002 2:06 am
Monarch Air went out of business (or otherwise closed up shop... don't know the full story) a couple years ago. The Monarch product line was picked up by Hartwig and can be found here:
http://www.monarchcaps.com/
I don't believe Hartwig continued the caps for the 170. You can call and ask, but the last time I talked to them (shortly after they took over the Monarch line) they had no plans on producing the 170 caps. I hope that has changed, but I don't think so.
Here's a quote from their website:
The Monarch Premium Fuel Caps are certified for installation on Cessna models 177, 180, 182, 185, 188, 205, 206, and 210 for bladder cells and wet wings. These caps will also fit and function on Cessna models 190 and 195, but these models require a field approval--our customers with these models have had no problems getting these. It does require moving nutplates to install on the 190 and 195.
http://www.monarchcaps.com/
I don't believe Hartwig continued the caps for the 170. You can call and ask, but the last time I talked to them (shortly after they took over the Monarch line) they had no plans on producing the 170 caps. I hope that has changed, but I don't think so.
Here's a quote from their website:
The Monarch Premium Fuel Caps are certified for installation on Cessna models 177, 180, 182, 185, 188, 205, 206, and 210 for bladder cells and wet wings. These caps will also fit and function on Cessna models 190 and 195, but these models require a field approval--our customers with these models have had no problems getting these. It does require moving nutplates to install on the 190 and 195.
Doug
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- Posts: 6
- Joined: Sun Oct 16, 2005 2:30 am
Just recieved a field approval for installation of the Hartwig caps on my rag wing. This will be a big improvement over the old leaky caps. Seems like my Dad was always draiing water from the tanks with those old caps.
This mod also adds vented caps to the rag wing, which was not part of the AD. This is an easy modification to accomplish during wing re-cover.
This mod also adds vented caps to the rag wing, which was not part of the AD. This is an easy modification to accomplish during wing re-cover.
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- Posts: 163
- Joined: Tue May 06, 2003 2:13 am
Fuel Caps and gaskets?
The follow is about a 170 accident in May. Note what the probable cause will be. GB
NTSB Identification: ANC07FA037
14 CFR Part 91: General Aviation
Accident occurred Friday, May 04, 2007 in Wasilla, AK
Aircraft: Cessna 170, registration: N4217V
Injuries: 1 Fatal.
This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed.
On May 4, 2007, about 1548 Alaska daylight time, a tundra tire-equipped Cessna 170 airplane, N4217V, sustained substantial damage when it collided with trees during a forced landing after takeoff from the Wolf Lake Airport, Wasilla, Alaska. The airplane was being operated as a visual flight rules (VFR) local area personal flight under Title 14, CFR Part 91, when the accident occurred. The airplane was operated by the pilot. The private certificated pilot, the sole occupant, received fatal injuries. Visual meteorological conditions prevailed, and no flight plan was filed.
A witness reported that he saw the airplane depart on runway 19 at Wolf Lake. The airplane climbed to about 200 feet, and the witness heard the engine lose power. The pilot made a right turn toward the north, and descended toward a residential area adjacent to the airport. The airplane collided with several trees, and then the ground, next to a residence.
The National Transportation Safety Board (NTSB) investigator-in-charge (IIC), and Federal Aviation Administration (FAA) inspectors, examined the airplane at the scene. The examination revealed that the wings, fuselage and landing gear were extensively damaged. The engine propeller received minor aft bending at the outboard tip of one propeller blade, but was otherwise undamaged. Blue colored fuel was present in the wing fuel tanks, and at the carburetor. The forward edge of the carburetor's mounting flange was broken at the engine mounting bolts, and the air filter/carburetor heat box was crushed. The airframe gascolator contained sediment, a small amount of water droplets, and evidence of corrosion around the base of the gascolator screen and the gascolator base. The wing fuel tanks contained small amounts of water.
The right wing fuel cap had a rubber gasket seal. The left wing fuel cap had a cork gasket seal.
On May 8, 2007, the engine was placed on an engine test stand, and a replacement carburetor was installed. The engine was started and produced full power. An examination of the accident carburetor revealed that it contained sediment contamination, and small amounts of water droplets.
NTSB Identification: ANC07FA037
14 CFR Part 91: General Aviation
Accident occurred Friday, May 04, 2007 in Wasilla, AK
Aircraft: Cessna 170, registration: N4217V
Injuries: 1 Fatal.
This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed.
On May 4, 2007, about 1548 Alaska daylight time, a tundra tire-equipped Cessna 170 airplane, N4217V, sustained substantial damage when it collided with trees during a forced landing after takeoff from the Wolf Lake Airport, Wasilla, Alaska. The airplane was being operated as a visual flight rules (VFR) local area personal flight under Title 14, CFR Part 91, when the accident occurred. The airplane was operated by the pilot. The private certificated pilot, the sole occupant, received fatal injuries. Visual meteorological conditions prevailed, and no flight plan was filed.
A witness reported that he saw the airplane depart on runway 19 at Wolf Lake. The airplane climbed to about 200 feet, and the witness heard the engine lose power. The pilot made a right turn toward the north, and descended toward a residential area adjacent to the airport. The airplane collided with several trees, and then the ground, next to a residence.
The National Transportation Safety Board (NTSB) investigator-in-charge (IIC), and Federal Aviation Administration (FAA) inspectors, examined the airplane at the scene. The examination revealed that the wings, fuselage and landing gear were extensively damaged. The engine propeller received minor aft bending at the outboard tip of one propeller blade, but was otherwise undamaged. Blue colored fuel was present in the wing fuel tanks, and at the carburetor. The forward edge of the carburetor's mounting flange was broken at the engine mounting bolts, and the air filter/carburetor heat box was crushed. The airframe gascolator contained sediment, a small amount of water droplets, and evidence of corrosion around the base of the gascolator screen and the gascolator base. The wing fuel tanks contained small amounts of water.
The right wing fuel cap had a rubber gasket seal. The left wing fuel cap had a cork gasket seal.
On May 8, 2007, the engine was placed on an engine test stand, and a replacement carburetor was installed. The engine was started and produced full power. An examination of the accident carburetor revealed that it contained sediment contamination, and small amounts of water droplets.
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- Posts: 17
- Joined: Thu Apr 19, 2007 7:07 pm
Fuel Cap
TG,
I tried to send Hartwig an email question as to which caps would work on the ragwing but it bounced back. So I will go with experience on the issue. Which caps did you get? How much are they? Can you put them on without tearing up the fabric? Did they seem to help the leaking/staining problem?
Thanks for your help,
Ryan
I tried to send Hartwig an email question as to which caps would work on the ragwing but it bounced back. So I will go with experience on the issue. Which caps did you get? How much are they? Can you put them on without tearing up the fabric? Did they seem to help the leaking/staining problem?
Thanks for your help,
Ryan
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