Airways Posted December 29, 2019 Report Posted December 29, 2019 (edited) This is what my EDM700 told me during today’s flight. I decided to return to my home base (10’ to het back) instead of continuing to the destination. The indication was accompanied by a kind of vibration that I felt in the yoke. According to the EDM manual this was due to an “intake valve not opening fully; faulty valve lifter”. Was I right to get down asap or is this something that can be adressed at a later stage during scheduled maintenance ? My interpretation was; cylinder nr 5 is not happy and he might upset the other cylinders if you wait long enough... Edited December 29, 2019 by Airways Wrong picture 1
carusoam Posted December 29, 2019 Report Posted December 29, 2019 Amazingly, There is an exact duplicate going on in another thread from yesterday... And possibly another one without the JPI data, a few days older... My memory hasn’t been this good in a while... Best regards, -a-
carusoam Posted December 29, 2019 Report Posted December 29, 2019 to end a flight early, or keep going.... We usually end the flight early, receive lots of pats on the back... and then go on.... 1) cylinders departing from the JPI... are obvious unknowns..... 2) It is possible you could go on all night... 3) Or it could be the first step of a cylinder departing before the flight is done... 4) To know better what is happening.... send the data to savvy.com... allow for sharing the data... 5) Post the link here... Call this problem solving MS style... can be at the mercy of group think... and amateur opinions... there are also people who have been there before... 6) Do a really good run-up while collecting data... and post that graph as well... 7) When a cylinder goes LOP before the others.... you get some signs... one looks like the pic you are showing above... 8) You have the tools to define what is going on... you just need to use them in a more elaborate way to make the decision to continue on or not... start with downloading the data you already have... 9) be on the look out for a blocked FI... are you familiar? Got a mechanic to work with? Best regards, -a- 1
Airways Posted December 30, 2019 Author Report Posted December 30, 2019 I’ll download the data after my shift. Here is some extra footage of the event IMG_7862.mov
Airways Posted December 30, 2019 Author Report Posted December 30, 2019 I downloaded the data and have a link to the info here . Today I performed a run-up (2000 rpm) and no anomaly was detected. My maintenance shop is closed these days and now I'm wondering whether to do a test flight.
carusoam Posted December 31, 2019 Report Posted December 31, 2019 On the savvy site... they give an example of ‘saw tooth’ EGT graphs... The cause of the saw tooth pattern is often a sticky valve... the kind that keeps the valve from rotating... First thing people do with this data... is decide to look at the valves using a dental camera... Something is not working right... what would be the reason to take it into the air? It looks as if the sticky valve may not be sealing properly... How far back in time has this been going on? You can skip back months of time looking for that same jagged saw tooth pattern... Sticky valves that show that pattern have a clear signature when viewed with a dental camera... when it looks like a pizza, that is a good sign... this particular valve won’t look like a pizza... compare to the others... PP thoughts only, not a mechanic or dentist... Best regards, -a- 1
Airways Posted December 31, 2019 Author Report Posted December 31, 2019 This was the one and only time this happened. Yesterday during run-up (2000 rpm for about 5’) I was unable to reproduce it. Is there a chance the valve was dealing with lead deposits and got rid of it on its own ?
ArtVandelay Posted December 31, 2019 Report Posted December 31, 2019 A bad valve will cause the saw tooth pattern because a part of the valve has deteriorated.A sticking valve will not, it looks normal until it sticks, then EGTs go cold, no power until it unsticks. They usually happen at startup at first. MMO can be used to treat sticking valves. They can also be an indicator of a deteriorating cam, because it’s easier for valve to stick if it has less movement.A fully clogged injector looks like a sticking valve (no combustion), they can clear themselves, usually occur after recent maintenance in my experience.Tom 1
carusoam Posted January 1, 2020 Report Posted January 1, 2020 For additional info regarding sticking valves... look up ‘morning sickness’ This is something that occurs before the engine warms up.... and it appears to fix itself until the engine cools again... The cure for morning sickness is getting the valve guides reamed of all their carbon build up... PP thoughts only, not a mechanic... there are plenty of people more knowledgable than I... Best regards, -a-
Airways Posted January 2, 2020 Author Report Posted January 2, 2020 Thank you for that hint, @carusoam. It cost me an hour of sleep, but it was worth it It seems however that exactly the opposite happened with my engine. It ran OK ‘till it was warm and then egt nr 5 went breakdancing. Savvy believes it’s a probe/connection issue and I tend to agree because it really came out of nowhere. The previous flights gave no indication of upcoming valve issues.
carusoam Posted January 3, 2020 Report Posted January 3, 2020 8 hours ago, Airways said: Thank you for that hint, @carusoam. It cost me an hour of sleep, but it was worth it It seems however that exactly the opposite happened with my engine. It ran OK ‘till it was warm and then egt nr 5 went breakdancing. Savvy believes it’s a probe/connection issue and I tend to agree because it really came out of nowhere. The previous flights gave no indication of upcoming valve issues. Some of the best PP only ideas come out after midnight! when really wacky data shows... and it doesn’t fit the known issues... verify the sensors are working properly... a quick way to do this is swap the wires between two sensors... if the problem goes with the sensor wire... you have found the issue... If you still get the break dancing, swap the sensors as well.... A wire, inside the sensor or outside may be going away... Look up what it cost to get a new EGT sensor... it might be worth having a spare...? PP thoughts only, not a mechanic... Best regards, -a- 1
Airways Posted January 3, 2020 Author Report Posted January 3, 2020 Well, the EDM700 gets replaced by an EDM900 by april. Hopefully I can bridge those couple of months...
Daneshgari Posted January 3, 2020 Report Posted January 3, 2020 What year Mooney is yours. Also, what program do you use to chart the engine data? Perry
Airways Posted January 3, 2020 Author Report Posted January 3, 2020 It’s a ‘87 model and I just upload the data to the Savvy website.
Gagarin Posted January 3, 2020 Report Posted January 3, 2020 (edited) 14 hours ago, carusoam said: Some of the best PP only ideas come out after midnight! when really wacky data shows... and it doesn’t fit the known issues... verify the sensors are working properly... a quick way to do this is swap the wires between two sensors... if the problem goes with the sensor wire... you have found the issue... If you still get the break dancing, swap the sensors as well.... A wire, inside the sensor or outside may be going away... Look up what it cost to get a new EGT sensor... it might be worth having a spare...? PP thoughts only, not a mechanic... Best regards, -a- I agree this looks more like a probe connection problem. Edited January 3, 2020 by Gagarin 1
ArtVandelay Posted January 3, 2020 Report Posted January 3, 2020 In my experience, if probe or connection is bad, the JPI will flag as a bad probe, because it goes to 0. This isn’t doing that?Secondly OP said it was accompanied by a vibration, bad probes don’t cause vibrations.Tom
Airways Posted January 3, 2020 Author Report Posted January 3, 2020 Although I did feel a low freq vibration, it might have been totally unrelated. It was a kind of vibration that I would have discarded if it wasn’t for the erratic behaviour of nr 5’s EGT which alarmed me already. The main reasons for thinking about a probe issue are: absolutely no indications of an oncoming valve failure during the previous flights and no correlation visible between engine rpm and valve misbehaviour. I don’t think the probe would flag zero, because there was a continuous EGT readout from cylinder 5. It was however going up and down like a jojo.
carusoam Posted January 4, 2020 Report Posted January 4, 2020 Google translate calls that a yoyo... Just to keep everyone in the loop... not picking on anyone’s spelling... pero, mi amigo Rolando dice yoyo, y lo escribe jojo... (something like that) Fortunately, the EGT sensor wires are pretty easy to chase... from one end to the other... they provide micro volt scale of voltage so a dirty/oxidized/loose connection is all it takes to provide wild data... Best regards, -a-
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