The International Cessna 170 Association

Hi ... pulled the fuel selector valve today and installed an approved overhaul kit ... good thing as the small "O" rings in the left and right fuel inlet ports were deteriorating. The kit came from McFarlane.

Question: I think George Horn or another member made mention of installing a quick drain valve at the bottom of the fuel selector. Information or details? It seems like a good idea. Thanks! R/Lee (N1967C ... a "fun work in progress"!)

Hi Lee. I installed one on my '52 B model a few years ago. Simple as pie. I used a SAF-AIR CAV-110H-4 drain. It has a tube that extends down below the fuselage about 1" when installed. This has at least 2 advantages: (1) if the drain ever drips or leaks, it will drip or leak below/away from the fuselage and not into the bottom of the fuselage (mine has never leaked); and (2) it makes it really easy to find and use the drain when you look under the fuselage. You just just find the little tube, and stick your fuel tester into it. Simple.

It was really easy to install on my plane. There was a little "Wilkie" button plug under my fuel valve. I just removed it, giving me access to the drain plug on the bottom of the fuel valve. After making sure the fuel valve was in the OFF position, I then removed the plug and screwed in the quick drain with a little fuel lube ("E-Z Lube") on the threads. Took all of about 5 minutes. Don't over tighten/torque the drain into the fuel valve, as you don't want to damage the fuel valve casing. I then drilled a hole in the Wilkie button plug for the tube of the drain to go through and replaced the button plug. That took about another 5 minutes. (You may find that the button plug is not centered under the drain plug of the fuel valve. Mine wasn't. So the hole I drilled in the button plug needed to be off center.)

It makes draining the lowest point of the fuel system a snap now.

The drain lines up with a hole if you have serial 20286 and later. Otherwise you have the early valve* and the drain doesn't line up.

Many consider this a minor alteration. There is an STC to do this but not sure of it's current status. The Association decided not to buy the STC when approached a few years ago.

While a new valve is available from spruce at a cost but recieved a email from Mc Farlanes the other day advising they are releasing a new valve {PMA} for a Cessna 170 at a reasonable cost . What is reasonable? ? At least we have a little more choice .

I saw the new valve at their booth at Oshkosh, it didn’t have a price displayed. It had a red exterior, obviously an attempt to make the new unit more desirable.

So is this new McFarlene valve a replacement for the new style machined valve or the old case style Weather head? As the later style is rebuildable with a few dollars worth of 0-rings, just don't lose any parts, it would be much more interesting if this valve was a replacement for the old style which can only be serviced by lapping so much. Wonder if anyone asked. Wonder if McFarlene understands there are 4 valves used in the 170 model line?

It’s the square block style, not the early valve. I think I mentioned my tale of woe with my fuel S/O valve here in the forums: I pushed my plane out of my hangar, with intentions to begin a trip to Oshkosh. Turned the fuel valve on and fuel almost immediately fuel flowed out of the belly. I tend to shut my fuel off whenever I leave my plane alone. There’s a camp out there that never shuts their fuel off. I replaced the seals and all is good now but there is wear on my valve to the bore hole in top plate of the valve. Eventually it will leak again and either I’ll need a new plate and seals or I’ll need a new valve.

It’s been reported that it,s a red color so if you fit this will the aircraft fly faster? The way I have interpreted the email it replaces all the different type of valves . My valve is badly worn in all areas and has had a O ring replacement but still has a very small internal leak. At least I have options. I am convinced Cessna hung the valve from the ceiling and built the aircraft around it .

Cessna certainly did as you mentioned for the fuel valve AND for the fuel tanks!

Here's the pic of the CAV-110H4 drain valve. Do NOT use "Teflon" tape as a sealant. Teflon tape should never be used in a fuel system because small particles will tear off and might clog small orifices in the system and carburetor. Use ordinary Permatex Non-Hardening No. 2 Aviation Gasket paste, and only a "dab". Do NOT overtighten this when installing. Remember.... the only pressure on that system is GRAVITY.... there's no need to tighten the smithereens out of it unless you want to buy a $5K plus fuel selector valve and tear the skin off your forearms replacing it.

McFarlane painted the fuel valve red in an attempt to SLOW DOWN the fuel flow

They only painted the OUTSIDE of the valve...not where the fuel flows. (They did so to fool relative wind resistance to ignore it.)

Hi All,

Reviving an old thread. My '54B has a belly drain which was installed per the logbook in 1985. No STC or 337.

I just discovered the C-Mods STC but they no longer seem to exist, and the STC is dated 2004.

Any chance there is any obtainable STC for this now? Hope not to reignite the major/minor alteration debate.

Thanks,

Bob

rnealon1 wrote:Hi All,

Reviving an old thread. My '54B has a belly drain which was installed per the logbook in 1985. No STC or 337.

I just discovered the C-Mods STC but they no longer seem to exist, and the STC is dated 2004.

Any chance there is any obtainable STC for this now? Hope not to reignite the major/minor alteration debate.

Thanks,

Bob

The so-called “STC” offered with the purchase of the C-Mods valve was a small scrap of paper with an official-appearing declarative statement.
What should be obvious (but overlooked by virtually everyone installing the drain) is.... an STC (Supplemental Type Certificate) is only appropriate to a MAJOR alteration.
Any Major alteration (or repair) REQUIRES a Form 337 to be completed. Virtually NO ONE did that ... because... it was considered to be “minor”. (The selector valve has provision for drain already in the form of a threaded plug. All the new drain did was substitute an operable drain for a plug... exactly the same activity as applied to the wing-sump-drains on Cessnas and others.)
I may have the original scrap of paper still and will copy it for you if so.

Thanks George!