JRam Posted September 30, 2018 Report Share Posted September 30, 2018 So I finally got my cannulas and flow meter ordered and delivered from Precise Flight. I got it all put together and tried to turn on the oxygen, and nothing. Up at 10,000 with the flow full opened on the flow meter and nothing. I couldn't get any oxygen out of any of the ports. I'm wondering if I'm just dumb and missing something obvious. From "Off", I can go counterclockwise to "on" about 3/4 of the way around or clockwise to "on" 1/4 of the way. Neither worked but it seemed like counterclockwise was right. Am I dumb or do I need someone to look at the system? Quote Link to comment Share on other sites More sharing options...
N201MKTurbo Posted September 30, 2018 Report Share Posted September 30, 2018 (edited) Open the tail and look at the wire on the cable while someone rotates the knob or run back and forth and make sure it is actuating the valve on the cylinder. Is there oxygen in the cylinder? Are they the correct fittings? Edited September 30, 2018 by N201MKTurbo 1 Quote Link to comment Share on other sites More sharing options...
JRam Posted September 30, 2018 Author Report Share Posted September 30, 2018 3 minutes ago, N201MKTurbo said: Open the tail and look at the wire on the cable while someone rotates the knob or run back and forth and make sure it is actuating the valve on the cylinder. Is there oxygen in the cylinder? Are they the correct fittings? They are the correct fittings, the Scott (green) fitting. There is oxygen in the cylindar, reads about 1500, although it has read more (1800) when I first picked it up so I think it may have a slow leak. I'll take a look at the cable and see if I can make heads or tails. 1 Quote Link to comment Share on other sites More sharing options...
kortopates Posted September 30, 2018 Report Share Posted September 30, 2018 Or you could be turning the knob without turning the shaft of the control under it, if is slipping. A set screw keeps the plastic knob aligned to the shaft. 1 Quote Link to comment Share on other sites More sharing options...
larryb Posted October 1, 2018 Report Share Posted October 1, 2018 Mine is clockwise for the off to on transition. Your knob behavior is similar to mine when the inner cable broke at the knob. You will know when you check the valve in the tail and see if it moves or not when turning the knob. Quote Link to comment Share on other sites More sharing options...
Cayman44 Posted October 1, 2018 Report Share Posted October 1, 2018 See how much force it takes to move the valve at the tank with your hands or a tool. My valve is so tight the cockpit control would not move it and then forcing it, I broke something at the cockpit control head and will go in and look soon. My system is tight so leaving the valve on hardly loses any pressure. Quote Link to comment Share on other sites More sharing options...
jlunseth Posted October 1, 2018 Report Share Posted October 1, 2018 22 hours ago, JRam said: So I finally got my cannulas and flow meter ordered and delivered from Precise Flight. I got it all put together and tried to turn on the oxygen, and nothing. Up at 10,000 with the flow full opened on the flow meter and nothing. I couldn't get any oxygen out of any of the ports. I'm wondering if I'm just dumb and missing something obvious. From "Off", I can go counterclockwise to "on" about 3/4 of the way around or clockwise to "on" 1/4 of the way. Neither worked but it seemed like counterclockwise was right. Am I dumb or do I need someone to look at the system? You have to turn the system on, not just the flow at the Precise Flight flow meter. There should be a pressure gauge somewhere to tell you that you have O2, and then there should be a valve mechanism. On my aircraft it is on the pilot side "door" (there is no door there, but if there were, that is where the system valve and pressure gauge are). It is a knob that you slide forward, that opens the O2 system flow valve. Check to make sure you have pressure (i.e there is O2 in the tank), and the Precise Flight male fittings have two little pins perpendicular to the plug, the fitting must be pushed in with the pins in the slots in the door fittings and then turned until the Precise Flight fitting stops. Even if you do all that, you may have to take the aircraft up to at least 10k to test the system. There is supposed to be an automatic flow shut-off that starts flow at 8k (and obviously stops flow below that). PS Here is what is in my POH (its in the "Supplemental" section). "...while at lower altitudes the reducing valve automatically economizes the flow to conserve oxygen for longer duration or for future availability, without requiring any action by the pilot." The "reducing valve" appears to be the first stage regulator (the regulator on the tank). I don't remember for sure where I got the information that it shuts completely off at lower altitudes, that was years ago, but I believe it was a discussion on this site. Probably nearly a decade ago. Here is the plug with the little pins. Goes all the way in, then turn until it stops. Quote Link to comment Share on other sites More sharing options...
JRam Posted October 1, 2018 Author Report Share Posted October 1, 2018 @jlunseth I'm using that plug on my precise flight and I had the precise flight valve full open. I'll get out and take a picture of the knob I have more close but here's one from a bit further away. The black circle just below the armrest is the one I'm talking about. I've tried to zoom in here: This is supposed to turn on and off the flow of oxygen but I'm not sure if I need to go clockwise or counterclockwise. Neither seemed to work, but from "Off" I could go either way to "on". Clockwise is shorter to "on" but tougher. Counterclockwise seems like it was meant to go that way but it's a much longer distance. I was at 11K when I was trying and was supposed to go to 13k but I amended since I couldn't get it working. I am hoping I'm just doing something dumb. Here is a picture of my flow meter setup: Quote Link to comment Share on other sites More sharing options...
DonMuncy Posted October 1, 2018 Report Share Posted October 1, 2018 I would bet a lot that the problem is the valve pictured. Open the panel on the side of the plane and have someone move the selector valve while you watch the valve on the tank to confirm the cable (wire) operates it properly. 3 Quote Link to comment Share on other sites More sharing options...
milotron Posted October 2, 2018 Report Share Posted October 2, 2018 1 hour ago, DonMuncy said: I would bet a lot that the problem is the valve pictured. Open the panel on the side of the plane and have someone move the selector valve while you watch the valve on the tank to confirm the cable (wire) operates it properly. This know is just a fancier control replacing the lever that used to be there in previous years. It should only turn about 90 degrees at most with limited range. Sounds like the cable is broken or the knob is not engaging the mechanism anymore. My overhead vent knob did this last month and needed reseating with a tiny allen key. 1 Quote Link to comment Share on other sites More sharing options...
gsxrpilot Posted October 2, 2018 Report Share Posted October 2, 2018 4 hours ago, jlunseth said: Even if you do all that, you may have to take the aircraft up to at least 10k to test the system. There is supposed to be an automatic flow shut-off that starts flow at 8k (and obviously stops flow below that). Does the system in my 252 work this way? My O2 works great whenever I use it. But I never can remember which way to turn the valve for on or off, so usually just leave it. It doesn't seem to loose any oxygen after sitting for a couple of weeks without me breathing any of it. If it automatically shuts off below 8K ft. then I should just leave it on all the time. Thanks Quote Link to comment Share on other sites More sharing options...
jlunseth Posted October 2, 2018 Report Share Posted October 2, 2018 Yeah, I am not sure about that Paul. I turn mine off. I am just repeating something I heard years ago, that it shuts off below 8k. But if you don’t lose O2 when you forget to shut it off, that proves it I guess. Quote Link to comment Share on other sites More sharing options...
milotron Posted October 2, 2018 Report Share Posted October 2, 2018 I am pretty sure the system in my 1981 M20K flows on the ground if you turn it on. I had it on the other day and know that it flows at 4000'. Mine will also maintain pressure if the valve is left on and nothing connected. Also, the gauge in my neighbours M20K was stuck at 1200psi, regardless of the tank contents. Do you know the tank is full? 1 Quote Link to comment Share on other sites More sharing options...
JRam Posted October 2, 2018 Author Report Share Posted October 2, 2018 4 hours ago, milotron said: Do you know the tank is full? It was at around 1800 when I picked it up and now shows 1500, so it definitely had oxygen at one time. But maybe now it doesn't. I hate having my plane so far away (1hr+ during late day traffic) that I can't make a quick trip to look. Quote Link to comment Share on other sites More sharing options...
glenn reynolds Posted October 3, 2018 Report Share Posted October 3, 2018 My ovation o2 works anytime I turn the valve on. clockwise rotation for on, counter for off. Do note that my ovation has the complex linkage between the pilot control knob and the valve on the oxygen in the aft compartment. I pulled all my seats and the left panel to wire in a backseat USB port and observed the oxygen control linkage so look in the back and if the tank valve is not opening then remove the seats and the left interior panel. while you have it open to fix the linkage, mcmaster-carr sells some very fine leak detection soap which I used on mine to track down a loose fitting. 1 Quote Link to comment Share on other sites More sharing options...
carusoam Posted October 5, 2018 Report Share Posted October 5, 2018 Eeesh.... O2 system scariness... This is something you want to be very familiar with... Because if it stops working at altitude... it gets harder and harder to understand or figure out ... mooneys have been known to... - break the control cable... - have the wrong twist lock fittings that look incredibly similar... but don’t work. - have all kinds of improper sealing compression fittings / hardware added into the system over time... - We lost a Mooney pilot in recent years on his way to a PPP course. O2 system failure... As far as leakage goes... O2 leaks are unacceptable...because they can light a fire when in contact with flammable materials like oil and grease... just a reminder to take O2 challenges one step higher than other challenges... whether you use it or not... get some training on your specific system... How it is supposed to work Then join the club that fills their own O2 systems... we have that group here as well... so other than accidental fires and falling asleep in the FLs what could go wrong... PP thoughts only, not an O2 aficionado... Best regards, -a- 1 Quote Link to comment Share on other sites More sharing options...
FloridaMan Posted October 5, 2018 Report Share Posted October 5, 2018 I recently added an O2D2 box and silicon masks to my system. I bought the setup used for $1000 from a guy on the field who sold his Baron and had three kits leftover. I can attest from my minimal experience that the O2 lasts at a minimum 4x as long and likely around 8x (2 people on O2 at FL240 seemed to use less than 1/4 of what I would use on my own for the same trip), though other pilots more familiar with the system claim 10x. Of course, it's not the cost of getting your oxygen topped off, it's that scheduling it is a pain and not having enough may dictate how you dispatch. 1 Quote Link to comment Share on other sites More sharing options...
CoffeeCan Posted October 5, 2018 Report Share Posted October 5, 2018 (edited) I appreciate all the replies on this thread. My M20K's oxygen system works fine, but it's good to know that it can fail at the left "door" panel control knob. One more thing to watch out for. As I'm a bit of a physiologist with past experience in mountaineering, I was/am very much aware of the need for O's... not just to meet the FAA regs, but for physiologically significant hypoxia at any altitude. And both the mountaineering literature and the aviation literature are full of stories of failure of regulators, dilution systems, masks, hoses, etc. Based on that knowledge, literally my first purchase for my new-to-me 231 was a couple of pulse oximeters, which I made sure were operable before I did any flights with O's running. My findings have been interesting. Here's what my numbers have shown me: 1) My blood oxygen saturation drops below 90% at indicated altitudes well below 10,000'. Since we consider 93-94% "normal" in a medical setting, levels under 90% are potentially hazardous for pilots. The brain, particularly the visual part of the brain, will not be functioning well if the blood oxygen saturation is in the 80's. This is why the FAA recommends use of O's for pilots at night above 6000'. 2) I don't start feeling "air hunger" until I get up to around 10,000 to 11,000' MSL indicated. By that time, I'm registering sats in the mid-80's. This tells me that my brain's ability to judge whether I'm getting hypoxic isn't very good. Hence the need to have a pulse oximeter in the cockpit and use it. 3) The in-line flow meter my oxygen lines have (nasal cannula only, so far) is calibrated up to 18,000'. How-88%ever, when I'm flying at 17,500' and I have flow meter pegged wide open, my pulse oximeter tells me my SpO2's are only running 85-88%. This tells me that the little ball in the tube isn't necessarily telling the truth. Again, you can't trust your oxygen equipment to say what you think it says... Now, I've ordered a couple of non-rebreather masks with flow meters that go all the way up to 25,000' from Mountain High, but I haven't tested these yet. Stay tuned for that report. 4) If your O's fail you when you're flying at or below 18,000', you will probably be able to tell if you have a sudden failure of your oxygen system and onset of hypoxia in time to make an emergency descent to 12,500 or below in a timely manner. But above FL180, you may pass out from hypoxia before you can take corrective action. As such, it seems highly prudent to me to have the pilot (at least!) wear a pulse oximeter equipped with a warning light/tone at all times when flying in the flight levels. Having an emergency descent profile pre-loaded into your GPS/autopilot for such emergencies seems prudent as well. So that's my dos centavos on this deal. Edited October 5, 2018 by CoffeeCan 1 Quote Link to comment Share on other sites More sharing options...
jlunseth Posted October 5, 2018 Report Share Posted October 5, 2018 Two things. First, if you are in the mid-80's, even in the high 80's, you are severely impaired and probably on the verge of passing out. I am going to take a guess that, since you don't feel that way and haven't passed out, there is some kind of issue with the readings you are getting because they are way too low. My bottom line is 92% and at that point there is probably some mild hypoxia, there definitely is hypoxia at 90%. Second, you have not mentioned what type of cannula you have. There are two, the "Oximizer" and the normal one that is the same as what you see at the hospital. The Precise Flight gauge has a scale for each of them. I have the Oximizer type, but from pulse oximeter readings it became obvious as soon as I got them that there was no "enhancement" effect. I use the gauge scale for normal cannulas on the Precise Flight control, not the one for the Oximizer, which means turning the flow knob on the Precise Flight up a fair amount to get a good flow. Given your levels, I would suggest you just turn it way up until you figure out what is going on. I guess there is a third. Above 18k the pilot needs to be on a mask. Its a little inconvenient because eating and drinking is a problem, but oxygen supply is better and it does not dry your nasal passages out like a cannula will. 1 Quote Link to comment Share on other sites More sharing options...
CoffeeCan Posted October 5, 2018 Report Share Posted October 5, 2018 jlunseth, I too am suspicious that the readings I'm getting from these oximeters are not accurate. I should have refrained from posting any results based on those oximeter readings, so please take them with a grain of salt, but they do illustrate the trend in diminishing SpO2's at relatively low altitudes. I have another oximeter on order at present and will update you when that comes in. And yes, I'm using Oxymizer cannulae, with the MH3 flow meter. Masks at FL180 and above are, of course mandatory. I have a set of masks on order (with MH4 flow meter) to test as well. We likely could have a lively conversation as to the relative values of pulse oximetry readings when compared to actual arterial blood gas numbers... Quote Link to comment Share on other sites More sharing options...
DonMuncy Posted October 5, 2018 Report Share Posted October 5, 2018 Not speaking for the others, but I am a chronic "mouth breather". Using a canula, my O2 level will drop below 90%. Only by consciously breathing through my nose, will the number go back above 90%. Then if I forget to concentrate on nose breathing, it goes back down. I have to be very careful to monitor my oximeter. As I write this, I have just made a decision to buy and use a mask. (Does anyone have one with a built-in microphone they need to get rid of?) 1 Quote Link to comment Share on other sites More sharing options...
N201MKTurbo Posted October 5, 2018 Report Share Posted October 5, 2018 A couple of things... I have researched how pulse oximeters work and they are not prone to errors. I bet that your new oximeter reads the same as your old one. That being said, I have a friend who went to Oshkosh with me in '13. We were on a high altitude leg and I got out the oximeter and I was at 94%. I put it on him and it read 72%!!! I asked him if he felt OK and he said he felt fine. I told him he should be in a hospital. He said doctors always freak out when they put one of those things on him. He said they always read in the 70s. I have no explanation for it, and he said the doctors can't explain it either. I think he is an alien... Quote Link to comment Share on other sites More sharing options...
Andy95W Posted October 5, 2018 Report Share Posted October 5, 2018 Next time, have him put the oximeter on one of his toes. (For new people around here- this is NOT my foot.) 1 Quote Link to comment Share on other sites More sharing options...
jaylw314 Posted October 6, 2018 Report Share Posted October 6, 2018 2 hours ago, N201MKTurbo said: A couple of things... I have researched how pulse oximeters work and they are not prone to errors. I bet that your new oximeter reads the same as your old one. That being said, I have a friend who went to Oshkosh with me in '13. We were on a high altitude leg and I got out the oximeter and I was at 94%. I put it on him and it read 72%!!! I asked him if he felt OK and he said he felt fine. I told him he should be in a hospital. He said doctors always freak out when they put one of those things on him. He said they always read in the 70s. I have no explanation for it, and he said the doctors can't explain it either. I think he is an alien... If he is a smoker (chronic CO exposure), chronic hypoxia from a lung condition, or peripheral circulatory problems, he will feel fine (relatively) at those sort of numbers. Quote Link to comment Share on other sites More sharing options...
gsxrpilot Posted October 6, 2018 Report Share Posted October 6, 2018 3 hours ago, DonMuncy said: Not speaking for the others, but I am a chronic "mouth breather". Using a canula, my O2 level will drop below 90%. Only by consciously breathing through my nose, will the number go back above 90%. Then if I forget to concentrate on nose breathing, it goes back down. I have to be very careful to monitor my oximeter. As I write this, I have just made a decision to buy and use a mask. (Does anyone have one with a built-in microphone they need to get rid of?) I might be able to help you. Quote Link to comment Share on other sites More sharing options...
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