cferr59 Posted May 2, 2020 Report Posted May 2, 2020 I have a 1965 Mooney M20C. The fuel pressure on the EDM-930 tends to alarm on the ground, but typically not in the air. I noticed that the fuel pressure was running a bit higher than normal and the EDM alarmed during cruise. I decided that it would be a good idea to check the gascolator and make sure there wasn't any debris. I have attached images of what I found. - Any thoughts on what happened? My guess is the gasket was rubbing against the sharp edges of the filter screen and got shredded. - Has this happened to anyone before? - Any idea what the part number is for the gasket? I checked the parts manual and can't quite tell... - Any idea of how to prevent this from happening in the future? - While I don't believe any of the debris got past the filter screen, is there anything else I should do to confirm that there is no contamination in the fuel system? - Does this seem likely to cause higher than normal fuel pressure? 1 Quote
carusoam Posted May 2, 2020 Report Posted May 2, 2020 Looks like 50 years seems to be the limit on that rubber part... Check your logs for when that got replaced... My 65C... I don’t recall the rubber seal being separate from the screen... (?) Check with Lasar for replacement parts... they have a kit for the selector valve, And drain to go with that... back to the important part... did any of those black bits get past the screen.... before it was taken apart...? If they got past the screen... they could have gotten into the pumps... If they got past the pumps... they could get to the carb... I believe the carb has one more screen to get past... A low pressure alarm would indicate there may be a restriction before the pressure sensor... A high pressure alarm would indicate there may be a restriction after the pressure sensor... Did you get any indications of the FF not being where you expected it? Got any JPI data to review and compare from previous flights... Load the FP and FF data into Savvy to get started on the data trail... the advantage of the FF sensor... it won’t matter where the restriction is... if there is one, the FF will be lower than expected... Otherwise, cleaning the fuel system is going to be a touch painful... as it is probably the proper course of action... What is your alarm set for 6psi? How high did it go, 6.1? PP thoughts only, check in with your mechanic to determine if some crud is going to block your FF... Best regards, -a- Quote
MB65E Posted May 2, 2020 Report Posted May 2, 2020 Holy crap! Brown aircraft can make the seals to fit. just tell them you have a Mooney gascolator. replace the stat-o-seal washer too. 15in lbs. -Matt 1 Quote
MB65E Posted May 2, 2020 Report Posted May 2, 2020 Find a new IA as well. He’s not doing you any favors by not checking it annually. -Matt 1 Quote
Vance Harral Posted May 2, 2020 Report Posted May 2, 2020 The large gasket is Mooney P/N 940057-001, it's about $50 if you actually purchase the OEM part. No idea why it's so expensive other than being a Mooney-specific P/N. The stat-o-seal washer (that goes on the bolt that attaches the bowl to the rest of the selector) is P/N 600-0101-10, couple of bucks. The screen is P/N 10543-1, about $10. LASAR has all these parts in stock, or at least they did when I ordered them a couple of months ago. Be very careful reassembling the bowl. If it drips fuel on reassembly, don't try to fix it by torquing the bolt past the 15 in-lb limit MB65E mentions. Doing so can break the fuel selector, and parts are very hard to find. Ask me how I know. 1 Quote
cferr59 Posted May 2, 2020 Author Report Posted May 2, 2020 @carusoam I just pulled the JPI logs and it looks like it was hitting about 6.1 - 6.2, but it did get up to 6.5. After looking at past data, I don't think the fuel pressure is actually higher and I was just being paranoid. The fuel pressure generally runs at about 7 on the ground and sets the alarm off. The nature of the debris is such that I don't think it could get past the screen, but I am starting to think it might be worth checking the carb screen for good measure. It looks like it will be nightmare to resafety wire, but I might do it anyway. 1 Quote
cferr59 Posted May 2, 2020 Author Report Posted May 2, 2020 51 minutes ago, MB65E said: Find a new IA as well. He’s not doing you any favors by not checking it annually. -Matt The last annual was done at a reputable MSC so I am hopeful it was checked. I'm hoping to do owner assisted in the future so I can become more familiar with the airplane. 1 Quote
Prior owner Posted May 2, 2020 Report Posted May 2, 2020 (edited) Take yourself out for a drink to celebrate that you didn’t lose all your fuel or burst into flames... Either this most basic inspection item was neglected multiple times, or that seal is not the correct part. Very curious about this. LASAR sells the seal Edited May 2, 2020 by PilotCoyote 1 1 Quote
Guest Posted May 2, 2020 Report Posted May 2, 2020 (edited) While it doesn’t have part numbers which are already supplied, this SB is applicable. https://cdn2.hubspot.net/hubfs/4147179/technical_documents/service_bulletins/sbm20-200-1.pdf I would definitely look at the carburetor inlet screen and drain the bowl as well. Clarence Edited May 2, 2020 by M20Doc Quote
cferr59 Posted May 2, 2020 Author Report Posted May 2, 2020 32 minutes ago, Vance Harral said: The large gasket is Mooney P/N 940057-001, it's about $50 if you actually purchase the OEM part. No idea why it's so expensive other than being a Mooney-specific P/N. The stat-o-seal washer (that goes on the bolt that attaches the bowl to the rest of the selector) is P/N 600-0101-10, couple of bucks. The screen is P/N 10543-1, about $10. LASAR has all these parts in stock, or at least they did when I ordered them a couple of months ago. Be very careful reassembling the bowl. If it drips fuel on reassembly, don't try to fix it by torquing the bolt past the 15 in-lb limit MB65E mentions. Doing so can break the fuel selector, and parts are very hard to find. Ask me how I know. I can't find the screen on their site with that part number. I did find this one which looks similar and has a different part number: https://lasar.com/fuel-system-1/fuel-selector-screen-486-293?rq=screen However it is out of stock. Interestingly there is a Piper screen with the same part number that I can get from SkyGeek. @Vance Harral Were the edges of your screen sharp? Mine are and I am wondering if this is what shredded the gasket. Quote
MB65E Posted May 2, 2020 Report Posted May 2, 2020 Geez, Im kinda tired of this MSC business. The Piper and Cessna screen (edit seal)are both too thick and lip out when you go to tighten. I believe it’s 1/16 thick. Brown does a nice job. -Matt 1 Quote
Vance Harral Posted May 3, 2020 Report Posted May 3, 2020 3 hours ago, cferr59 said: I can't find the screen on their site with that part number. I did find this one which looks similar and has a different part number: https://lasar.com/fuel-system-1/fuel-selector-screen-486-293?rq=screen However it is out of stock. Interestingly there is a Piper screen with the same part number that I can get from SkyGeek. @Vance Harral Were the edges of your screen sharp? Mine are and I am wondering if this is what shredded the gasket. The part number I quoted is what was shipped to us for our 1976 M20F with the Duke's selector, by LASAR a couple of months ago. I believe it's the same selector used in your aircraft, but it's possible I'm wrong. To be honest, the screen wasn't an absolutely perfect fit for us - the inner "doughnut hole" was a little on the small side and had to be slightly stretched around the center port of the selector. I don't know what the difference is between the P/N I quoted and the one you found on LASAR's site, or if that has anything to do with the fit. In any case, strongly suggest you just call the LASAR parts department Monday morning and chat with them. This is the kind of thing where you're going to get a lot better answer from a human on the phone than from browsing a web site. Your order wouldn't ship until Monday if you placed it on the web this weekend, so there's no reason not to call. As for the screen itself, I wouldn't say the edges of it are "sharp". But they're just cut out of a mesh screen material, they don't have any kind of refined edge that keeps them from fraying if mis-handled. I do have a hard time believing your screen shredded your gasket through pinching and/or vibration, though. The screen material just isn't that robust, and the assembly shouldn't result in the screen grinding hard on the gasket anyway. It looks more to me like the rubber gasket just got brittle and crumbled over a long period of use without replacement. Just a guess on my part, I'm not an A&P and don't have that much experience working on selectors. I have zero experience with the gaskets from Brown mentioned by MB65E, but it's likely they're fine. Uou're not going to get that Mooney-specific P/N gasket from Mooney themselves anyway, at least not at the moment. My airplane partner has been trying to get a hold of them all week, and they are returning neither phone calls nor e-mail. So the choices are LASAR or other MSC, or Brown. Quote
carusoam Posted May 3, 2020 Report Posted May 3, 2020 Talking with Dan at Lasar May be very helpful... Dan seems to know the most detail about Mooney parts... Send him the pics of what you have too... It isn’t normal to have a seal shred and cause more problems than the screen can remove... Some Mooney fuel injector hoses have been known to shed parts to be found later stuck in the injectors... having a fuel blockage is terrible... at least with a JPI you may see it occurring... +1 checking the screen downstream... 6psi isn’t much pressure to begin with.... it wouldn’t be hard to hold back... PP thoughts only, not a mechanic... Best regards, -a- Quote
DXB Posted May 3, 2020 Report Posted May 3, 2020 6 hours ago, cferr59 said: I have a 1965 Mooney M20C. The fuel pressure on the EDM-930 tends to alarm on the ground, but typically not in the air. I noticed that the fuel pressure was running a bit higher than normal and the EDM alarmed during cruise. I decided that it would be a good idea to check the gascolator and make sure there wasn't any debris. I have attached images of what I found. - Any thoughts on what happened? My guess is the gasket was rubbing against the sharp edges of the filter screen and got shredded. - Has this happened to anyone before? - Any idea what the part number is for the gasket? I checked the parts manual and can't quite tell... - Any idea of how to prevent this from happening in the future? - While I don't believe any of the debris got past the filter screen, is there anything else I should do to confirm that there is no contamination in the fuel system? - Does this seem likely to cause higher than normal fuel pressure? Chris I'm curious what the person who did your annual would make of how this might have happened- it is a reputable shop, and I bet he'd want to know. I don't get how the gasket would get shredded that way. Quote
carusoam Posted May 3, 2020 Report Posted May 3, 2020 The dark color in the bottom of the separator is interesting as well... It may be dissolved parts of the rubber? Something sunk to the bottom... and plated the surface... Any odd fuels or fuel additives being used? When downstream, look to see if this gunk travelled... Look upstream to see if tank sealant has been washed away and moving downstream... Check logs for what seal got used in there... it looks like it isn’t very fuel resistant... or a solvent got in there that the seal isn’t compliant with... The gray oxide color is a smooth hard coating... it should be mostly clean... normally. Odd observations by a PP, not a mechanic... Best regards, -a- 1 Quote
MikeOH Posted May 3, 2020 Report Posted May 3, 2020 Just now, carusoam said: The dark color in the bottom of the separator is interesting as well... It may be dissolved parts of the rubber? Something sunk to the bottom... and plated the surface... Any odd fuels or fuel additives being used? When downstream, look to see if this gunk travelled... Look upstream to see if tank sealant has been washed away and moving downstream... Odd observations by a PP, not a mechanic... Best regards, -a- I agree. It looks like some chemical/additive attacked the rubber; just doesn't look like 'normal' age...even 50 years. Like someone filled the gascolator with acetone and let it soak to 'clean it.'. Or, maybe did that in the tank? That might explain the brownish residue on the bottom. 1 Quote
Prior owner Posted May 3, 2020 Report Posted May 3, 2020 (edited) Ethanol? Fuel stabilizer? What would do that? If auto gas or something weird was added to the fuel and it did that the gascolator seal, I’d be looking at every seal, o-ring and hose, including the engine driven fuel pump diaphragm and fuel tank interconnect hoses. That is too weird to ignore. Edited May 3, 2020 by PilotCoyote 1 Quote
cferr59 Posted May 3, 2020 Author Report Posted May 3, 2020 I have only fueled with 100LL and I highly doubt the previous owner would have used something else. The brown coating at the bottom appears to be tank sealant. It looks like it was painted there intentionally, but I can't think of any reason that someone would do that. The tanks were resealed in 2018 by Wet Wingologists. I'm going to drain the carb bowl and check the carb filter tomorrow. I also have been in contact with a local A&P regarding the fuel system. I am really wondering what could cause the gasket to end up like that... Quote
Jim Peace Posted May 3, 2020 Report Posted May 3, 2020 (edited) On 5/2/2020 at 5:23 PM, cferr59 said: The last annual was done at a reputable MSC so I am hopeful it was checked. LOL...that does not mean anything.... I get it about doing mx at a service center, that is where mine are done as well,,,but all that means is that they may have some extra parts on hand and maybe at one time sent a mechanic or two through airplane specific training. It does not mean that the mechanic that is doing your hands on work knows anything. It could have been delegated to him/her from a more knowledgeable mechanic and that part of the check or lack of a check went unsupervised..... I have stories and stories about this..... How about a MSC disassembling my carb heat system then telling me I am good to go....LOL..... Edited May 3, 2020 by Jim Peace 1 1 Quote
BDPetersen Posted May 3, 2020 Report Posted May 3, 2020 Just bought a supply of gaskets from Brown Aircraft Supply. About $8/ea. 2 Quote
ArtVandelay Posted May 3, 2020 Report Posted May 3, 2020 15 hours ago, MB65E said: Find a new IA as well. He’s not doing you any favors by not checking it annually. -Matt How do they check it? Quote
cferr59 Posted May 3, 2020 Author Report Posted May 3, 2020 1 hour ago, ArtVandelay said: How do they check it? Its not hard to check. On the C model, it is right under the fuel selector so you have to pull the panel and then there is just one bolt holding it together. Remove the bolt and the line connecting it to the fuel selector. You do need to disconnect the gear door linkage to get enough room to remove the panel. I don't have a J so I'm not sure how different it is. Quote
cferr59 Posted May 3, 2020 Author Report Posted May 3, 2020 So I pulled the filter screen and drained the carb. There was a small amount of a similar looking material in the screen and some gritty material in the carb bowl. Unfortunately, my method of catching the contents of the carb bowl did not work as planned so there may have been a larger quantity of the gritty material. 1 Quote
MB65E Posted May 3, 2020 Report Posted May 3, 2020 4 hours ago, ArtVandelay said: How do they check it? It needs to be removed and cleaned annually. It’s the last place to get contaminants out of the fuel prior to the engine. On the duke fuel pumps, there is one more screen to catch debris from the pump if the pump fails. On the older airplanes it’s a bit of a pain, I jack mine, retract the gear, remove the left cowl “exhaust” panel, (the screws are hard to get to with out scratching paint if the nose gear door is open.) then pull the gascolator apart. Remove the seal and clean the screen. I have often thought about splitting that lower panel as I keep mine sealed against the firewall. Splitting it would allow you to keep the front half sealed to the Firewall. Anyway, I just find it hard to believe that seal deteriorated in a year On the OP Airplane. -Matt Quote
carusoam Posted May 3, 2020 Report Posted May 3, 2020 Starting to look like somebody struggled with various ideas of seals and screens...? Instead of getting the proper stat-o-seal (mentioned above) and 100LL proof seal around the screen... They guessed/assumed tank sealant and any rubber seal will work... Glad the OP has made sense of what he saw... There is a special solvent used for removing tank sealant... if needed. +1 for getting everything cleaned up properly... +1 for ordering the proper parts... the whole thing can be brought back to new.... Go MS! Best regards, -a- Quote
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.