Quick drain on bottom of Fuel Selector

[doakes]

Is there a kit to install a quick drain on the bottom of the fuel selector or does one have to buy parts?

Does many of you 170 drivers have such a thing?

Thanks
Dave

[mit]

I installed one in mine.

[Joe Moilanen]

I installed one on mine also. Not sure which model you have but on mine it was a matter of unscrewing the plug on the bottom of the selector and screwing in the quick drain.

Joe
4518C

[GAHorn]

Is there a kit to install a quick drain on the bottom of the fuel selector or does one have to buy parts?

Does many of you 170 drivers have such a thing?

Thanks
Dave

Yes, there are TWO kits. Both of them STC'd for the 170B. (The 170 and 170A are not approved for this mod.)
Kit number one nomenclature is: CM-170 and contains the drain valve (CAV110D) and the approval basis to install it, along with the STC paperwork and cockpit placard, and instructions. It's cost is $25.
Kit number two nomenclature is: CM-170-L and contains all the above except that the valve is a CAV-110H-4D which is slightly longer because it ends in a hose-barb, allowing one to slip a 1/4" fuel drain hose onto it if one want to drain into a bucket, etc. The longer valve also is somewhat easier to activate without "getting any on you" and this kit costs $30.

The STC holder is: C-Mods, Inc., P. O. Box 15388, Durham, NC 27704-0388 PH: 919-471-9492 email: cmodsinc@aol.com website: http://www.c-mods.com/

TIC170A assisted him in developing this STC so it'd be legal for our aircraft, and he has donated one kit as a door-prize for our TIC170A Convention in Tehachipi, CA . I hope we will support this gentleman's efforts to service our aircraft with this nice mod. (Installation of valves without an STC or without some other basis of approval such as a field approval is not legal. The original pipe-plug on the bottom of the fuel selector MUST be drained each annual inspection per the inspection schedule for this aircraft. This nice mod makes this not only a labor saver for you at annual, but it adds important safety to each flight as it allows the pilot to drain the ACTUAL low point in the aircraft's fuel system before flight. While the gascolator will collect water, it may eventually become overwhelmed and sediment may not fully reach the gascolator since it may be trapped at the low point,...the fuel selector, unless...you have the capability to drain that selector valve. This kit provides that capability.)

In each kit's case, I checked at FalconCrest aircraft supplies and found that the valve itself retails for $22 and $24 respectively, without approval basis or the necessary paperwork to make the installation legal, so I believe these kits are not only a great idea but a great value as well. While similar, these are NOT the same valves as may be commonly found at discount catalog stores. The correct valves for this STC have provisions for safety-wiring which is a good idea since they are located where they may not be seen in-flight.

P.S. Do not use tape or thread lube when installing these valves on the fuel selector valve. These are pipe-threads.

[mit]

I considered it a minor alteration.

[zero.one.victor]

The fuel selector is NOT the low point of the fuel system for an A or B model. Check it out on your own airplane. The fuel lines on these models run aft from the tank fittings & down the aft door post. The lines then run forward (& uphill, when parked-- aka,in the 3 point attitude) to the selector. So you can still have water in the lines aft of the selector.
The selector isn't really the low point for a ragwing either,even though the fuel lines run from the tank fittings forward & down the forward door posts. The fuel selector in a ragwing is in one of two different locations,both of which are forward of where the selector is in an A or B model. The most aft of the 2 locations (in front of the flap handle) is still forward ( & uphill) of the forward door posts.
I'm sure it doesn't hurt to have the extra drain, but I'm not convinced it does all that much good either.

Eric

[zero.one.victor]

............. The original pipe-plug on the bottom of the fuel selector MUST be drained each annual inspection per the inspection schedule for this aircraft. This nice mod makes this not only a labor saver for you at annual, but it adds important safety to each flight as it allows the pilot to drain the ACTUAL low point in the aircraft's fuel system before flight.................

I was wondering about the inspection schedule cited. I looked in my 1948 owner's manual,at the list of inspection items. Only noted two related items:
Section II Engine check,item 9:remove & clean gascolator bowl.
Section III wing inspection,item 7: drain wing fuel tank sumps
Was the fuel selector draining requirement added by service bulletin? It's a good idea,no doubt, but is it a requirement per Cessna or just some mechanic's 2 cents worth?
Like I said in my last post,it doesn't seem as though the fuel selector is really the low point in the system if you trace out the fuel line routing,so is water and/or other debris accumulating in the selector really a problem?

Eric

[GAHorn]

From FAR1.1: "Major alteration means an alteration not listed in the aircraft, aircraft engine, or propeller specifications...." Since this drain valve replaces an original part with different operation (a plug) it is a major alteration. I personally know a mechanic whose certificate was suspended for 90 days because he actually wrote in a logbook "I consider this a minor alteration." contrary to FAR 1.1. He was also required to attend remedial training to reinstate his certificate.

When these airplanes are levelled the lowest point in a B model (the only ones approved for the quick-drain) is the fuel selector valve. When they are running, even on the ground, the fuel flows to the lowest point which collects any water. That is the fuel selector valve. When the airplanes are flown, pointed up, pointed level, pointed down, like in most complete flights, ...the fuel contaminates will congregate at the lowest point which existed in the system...which in a B model is still the fuel selector valve.

The Cessna 100 Series Service Manual, 1962 and Prior, 100 hour inspection schedule, page 2-8 states, item 4, "Fuel line drain plugs or valves - Every 100 hours, remove plugs, drain off any water and sediment, reinstall plugs, and resafety. Some aircraft use drain valves instead of drain plugs."
Notice this is specifically a separate item from item 5 "Fuel Tank sump drains".

[zero.one.victor]

I'm curious as to the operational aspect of draining the fuel selector. Before each flight,do you have to remove an inspection cover to drain it?
Or is there a hole ( with winky-button installed?) right below the drain,that you can just stick a fuel-sumper up thru? Or is the preferred set-up to use the -4D hose-barbed drain,with a length of hose poked down thru the belly that you can push up on? That'd be the easiest,but it seems like it'd be subject to being rubbed up against by brush,etc with the result being an accidental draining of fuel.(airplane incontinence )

Eric

[zero.one.victor]

After George's explanation, I'll concede that the fuel selector would tend to accumulate some water. But not much--how much of a cavity is in the bottom (sump) of the selector? Also, I'd think that any water there would tend to migrate downstream thru the system in flight,due to pitch changes & fuel flow. The fuel line takes a pretty good uphill curve forward of the gascolator (at least on mine) so I still think the place to drain is at the gascolator, since you can't drain at the lowest at-rest location.
I still don't buy the requirement to drain the selector at annual time. As I understand it,the Cessna 100 series service manual is not specifically applicable to the 170. I say the inspection schedule in the owner's manual is the only one applicable to the 170.

Eric

[mit]

From FAR1.1: "Major alteration means an alteration not listed in the aircraft, aircraft engine, or propeller specifications...." Since this drain valve replaces an original part with different operation (a plug) it is a major alteration. I personally know a mechanic whose certificate was suspended for 90 days because he actually wrote in a logbook "I consider this a minor alteration." contrary to FAR 1.1. He was also required to attend remedial training to reinstate his certificate.

When these airplanes are levelled the lowest point in a B model (the only ones approved for the quick-drain) is the fuel selector valve. When they are running, even on the ground, the fuel flows to the lowest point which collects any water. That is the fuel selector valve. When the airplanes are flown, pointed up, pointed level, pointed down, like in most complete flights, ...the fuel contaminates will congregate at the lowest point which existed in the system...which in a B model is still the fuel selector valve.

The Cessna 100 Series Service Manual, 1962 and Prior, 100 hour inspection schedule, page 2-8 states, item 4, "Fuel line drain plugs or valves - Every 100 hours, remove plugs, drain off any water and sediment, reinstall plugs, and resafety. Some aircraft use drain valves instead of drain plugs."
Notice this is specifically a separate item from item 5 "Fuel Tank sump drains".

Sounds like somebody got screwed on that deal remember some FSDO's think that installing radio's are major's and some don't. and the rest of part 1 def (1) That might appreciably affect weight , Balance, structural strength, performance, powerplant operation, flight characterisictics,or other qualities affecting airworthiness; or
(2) That is not done according to accepted practices or cannot be done by elementary operations.

adding a drain valve doesn't fall into that definition.

[GAHorn]

Tim, I understand (and actually agree with) the practicality of this matter. The def'n of FAR 1.1 applies to this because the selector valve drain plug conversion to a quick-drain is an alteration of a PMA'd part that should the alteration fail....will "appreciably affect....performance, engine operation..." etc., as explained by my (ordinarily very reasonable) FSDO inspector.
Since the C-mods STC'd kit is so very nearly the same price as the valve alone, it seems a no-brainer to me to simply buy the legal kit and be done with it.

Eric, you are correct that the gascolator should be drained each preflight, as it is the main device designed to trap contaminates. A fuel line running uphill from there to the carb is logical for that purpose. The problem is that on the majority of A and all B models have the fuel selector below even the gascolator. It's an uphill run from the selector to the gascolator. Water and contaminates can puddle there, and further, contaminates like grit and dirt can cut/injure the selector valve O-rings. It's difficult for dirt/grit to run uphill in a gravity system.
Yes, the Service Manual is not specific/exclusive to the 170 model...but it INCLUDES the 170 model and the inspection forms in that manual are applicable to ALL 100 series aircraft.
But if that isn't sufficient reason for one to find cause to drain that fuel selector valve at the plug, then one may consult the 170B Owner's Manual Section VI, 100 Hour Inspection, Item V. 4. "Drain sediment and water from fuel line at plug located on the belly of the airplane." The only such plug is the one in the fuel selector valve.
The kit utilizes a Saf-Air type valve that works like the wing-sump drains and can be activated either by a sump-jar or a finger. The one with the hose-barb is longer and does not lock open however. I'm making a suggestion to the STC holder to offer that option. No inspection covers need be removed to operate the valve,...only to install it. It protrudes through the 1" hole that already resides below the original plug.

[N73087]

I'm going to send in my money and buy one of these kits and install it on my A model.
Just one question:
Do I need to drain the tanks? Will the fuel flow with the selector in the OFF position?
Dave

[doakes]

I sent in my money today for the "long" model.

I think it will be a good thing.
DaveO

[GAHorn]

I'm going to send in my money and buy one of these kits and install it on my A model.
Just one question:
Do I need to drain the tanks? Will the fuel flow with the selector in the OFF position?
Dave

Yes, the wing drains are a separate event and will still need to be sampled....as will the gascolator. In other words, not changes to the ordinary pre-flight occurs except to drain the new fuel selector drain.