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  #231  
Old 09-27-2014, 12:11 PM
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DanH DanH is offline
 
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Location: 08A
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Quick note on manometer usage.

It's really a differential pressure meter. Obviously one nipple connects to the vinyl tube from the breather system, but don't fail to consider what to do with the meter's other hose nipple.

When in flight, cabin pressure probably doesn't equal static pressure. Some measurements (for example, cooling plenum pressure) will require connecting to the aircraft static system to get a reasonably true differential.

Other, larger pressures make the error less important when the meter port is simply open to the cabin. That's probably true for this case pressure measurement. For example, 2.5 in Hg is about 34 in H20, so static error of a few inches H2O more or less isn't going to confuse the result...you'll still know if you have reasonable negative pressure. Just be aware your reading might not be perfectly accurate.

Yeah, I've done so much of this that 'ole 5551 has a permanent cabin tap point in the aircraft static line, and miniature pressure port fittings through the firewall
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RV-8 SS
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  #232  
Old 09-27-2014, 01:47 PM
deek deek is offline
 
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Location: Flathead Lake Montana - 8S1
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Quote:
Originally Posted by DanH View Post
There are valves of various quality out there, so let's ID the ones that have failed. The NAPA 2-29000 seems to have a good reputation
This is the valve I've been using, and I dissect them after their (arbitrary) 500 hour life. I've seen nothing suggesting these won't last > 500 hours, but it's cheap insurance. I remove the breather hose and blow through it every annual with my calibrated mouth to ensure it's still working
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  #233  
Old 09-28-2014, 01:40 AM
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rvmills rvmills is offline
 
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Manometer on the way here too. There's a coupler with a date with a drill 'n tap on my workbench.

Parker is where I purchased these hoses as well. When I was in the store yesterday, the fella said he has better hose than what I bought last time, so I must not have 'splained to them that it was for petroleum products that day. Will go with the fuel hose I have?thumbs up from the Parker fella, and good for petrochemisty!

Since I have OTS couplers and Ts for now, will go with the rig as drawn above, and get the bypass valve in place?prepping for a couple Raven shows, so need to be underway, and will get the man-o-meter in place ASAP.

Found the failed CVV today, and did a bit of forensics. Looks like the center rivet that holds the diaphragm together failed?in fact its gone (the rivet). Here are a few pics of the valve, another ASA-supplied valve (silver) and a couple NAPA 2-29000 valves (gold):

Here is the old failed valve, flanked by the NAPA (L) and the second ASA valve (R). Interesting how discolored the old valve is after 40 hours, while the second valve looks to be in good shape, after 100 hours:



Here are the valves flipped over, and seen from the threaded opening side (in order from failed valve, to ASA replacement valve, to NAPA valve:







Here is the pass in review of the valves, with the dissected failed valve splayed out. I'm thinking' this valve may have failed early in its life, resulting in the burnt look and dirty (by comparison) innards:





The stripe on the right Napa valve is a shallow bandsaw blade cut i put in. This will be the safety valve, and my plan is to put some light screen material over the opening, and safety-wire it in place?using that cut as a capture ring for the wire?might be overkill, but might keep stuff out of the valve.

Install tomorrow, test flight when it stops rainin' (though we need it!).

Cheers,
Bob
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RV-6 "Rocket Six" N49VM
Reno-Stead, NV (KRTS)
President/Sport 47/49, Sport Class Air Racing
President, Formation Flying Inc (FFI)
Flight Lead, Lightning Formation Airshows
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  #234  
Old 09-29-2014, 11:59 PM
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rvmills rvmills is offline
 
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Completed the install of the additional check valve as a safety valve today. Here are a few pics:

From the breather (R) to the ASA Air Oil Separator (L). 5/8 to 3/4 black plastic coupler is where the tap for the manometer will go. Figured I'd use a barbed fitting from one of the extra (old) O2 regulators I have. Dan, are you using Tygon tube, or standard pitot-static line? Also figure I'll tap into the static line under the panel to my Dynons.



From the ASA AOS, through the T, and down to the safety valve. I initially did a fancy job of adel clamping to the engine mount, but it all became so stiff, that I thought it might start working the spigot weld in the pipe (recalling my early faux-paux of adelling the spigot itself to the mount, which Dan quickly threw the penalty flag on, saving me more cracked welds!). Two flexible stand-offs keep it from banging the engine mount, but it all stay flexible enough to absorb the start-up/shut-down shakes.



The base of the T goes to the primary CVV in the ex pipe.




Put it all together, and had great Wx for test flying. Test ran the engine, and still saw a leak under the oil cooler. New cooler hose and fittings all good, but cooler showed a little suspicious wetness, and the runs on the mount were right below that area. Pressure tested the cooler with a little soapy water, and it bubbled from within?dern it. Stole the cooler from my hangar-mate's F1 Rocket, and ordered him a new one. Will fly upon return from this week's work trip, and report impact on leaks, and progress on man-o-meter install (it shipped today).

Cheers,
Bob
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RV-6 "Rocket Six" N49VM
Reno-Stead, NV (KRTS)
President/Sport 47/49, Sport Class Air Racing
President, Formation Flying Inc (FFI)
Flight Lead, Lightning Formation Airshows
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  #235  
Old 09-30-2014, 01:20 AM
eddieseve eddieseve is offline
 
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Location: Sydney, Australia
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Hi Guys,

The first valve that I received about 1.5 years ago failed in exactly the same way as Ron's description above, the rivet let go and the valve coked up around the diaphram causing the nose seal to blow out, l was close to the airport so it was not a real drama.

The current valve has nearly 50 hours on it and I am watching it closely.

Cheers
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  #236  
Old 09-30-2014, 06:48 AM
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DanH DanH is offline
 
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Quote:
Originally Posted by rvmills View Post
Completed the install of the additional check valve as a safety valve today.
That might be messy. There is some small amount of oil in the suction line down to the exhaust tap. Hanging the safety valve straight down from the separator and branching the exhaust line will surely have some small quantity of oil dripping from the safety valve over time. Gravity is soooo reliable.

Suggest you orient the stem of the tee so it points upwards, and put the safety valve there (right, below):



Quote:
..are you using Tygon tube, or standard pitot-static line? Also figure I'll tap into the static line under the panel to my Dynons.
I've been using tygon, but cheap vinyl tubing seems to work ok.

Note that tapping the aircraft static system, for this measurement or any other, can create a safety problem of its own. A leak (or later, a missing plug) will result in a flight instrument error.

For this measurement, cabin pressure on the static side of the manometer shouldn't make a lot of difference. If you really want a static system tap, find a location which allows easy access and preflight inspection. For example, in my -8 the tap is near the floor, 6" forward of the main spar on the right, visible in flight and every time I board.
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  #237  
Old 09-30-2014, 07:47 AM
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Walt Walt is offline
 
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Wow, 24 pages and 236 posts in this thread..

Sorry can't help myself but I have to ask: can someone please remind me what the ACTUAL benefit is to adding all this "stuff" to your engine that has the potential of causing some very serious problems

Please don't tell me to keep the belly clean.
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EXP Aircraft Services LLC
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  #238  
Old 09-30-2014, 08:06 AM
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CharlieWaffles CharlieWaffles is offline
 
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Walt, I believe the argument in favor is the checkvalve and exhaust draw a slight pressure on the crankcase which is proported to I've a few HP boost.
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  #239  
Old 09-30-2014, 08:08 AM
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rvmills rvmills is offline
 
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Dan,

Thanks?easy fix?and I have plenty of hose left! Good gouge on the static tap?also easy to incorporate?thx!

Walt, one possible benefit is a slight HP boost, reportedly from decreasing the case pressure, and thus increasing the relative pressure between the top of the piston and the bottom of the piston. That is one way it gets described. Of course, driving our A&P buddies crazy is another side-effect?it has that effect locally here too!

Cheers,
Bob
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Bob Mills
RV-6 "Rocket Six" N49VM
Reno-Stead, NV (KRTS)
President/Sport 47/49, Sport Class Air Racing
President, Formation Flying Inc (FFI)
Flight Lead, Lightning Formation Airshows
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  #240  
Old 09-30-2014, 08:09 AM
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dpansier dpansier is online now
 
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Location: Green Bay, WI (GRB)
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Bob,
I noticed in one of your photos you have 300 ohm twin lead running down the engine mount, what's the purpose and how does it perform?
Regards
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