Yourpilotincommand Posted October 30, 2020 Report Posted October 30, 2020 Where the heck do I find this? My POH does not have this info. Or I need somebody to shoot me for being an idiot. Thanks! Quote
David Lloyd Posted October 30, 2020 Report Posted October 30, 2020 It is in the Type Certificate. TCDS. Think a copy is in the download section. Here is what it says: for the M20B, M20C, M20D, M20E, and M20G; 15.0 lb. (+48.4). And that +48.4 is inches aft of datum. NOPE!!! Pay attention to the punctuation Dave! See the red print DMM has highlighted a few posts below. Here's what it says: 3.4 lbs. (+48.4) for the M20B, M20C, M20D, M20E, and M20G Sorry for misleading. I got bladders and that is still different. 1 Quote
Rjfanjet Posted October 31, 2020 Report Posted October 31, 2020 My 68C says 52 gallons, all useable. 1 Quote
Janat83 Posted October 31, 2020 Report Posted October 31, 2020 1 hour ago, Rjfanjet said: My 68C says 52 gallons, all useable. Did you checks that by yourself, I drained my fuel tanks and then top off, right wing 25.4 gallons, left tank 25.5, I plan 50 gallons as totally capacity and 8 gallons reserve, so at any flight I don't exceed 41 gallons of usable fuel, 68 M20C too. Quote
carusoam Posted October 31, 2020 Report Posted October 31, 2020 YPIC, Which POH are you using? The latest M20C POH states 52gallons... In real life... you have to prove the actual useable fuel that you have... because systems and documentation have not always matched so well... over decades... If you don’t have a copy of the latest POH for your plane... you are missing tons of data... that applies. PP thoughts only, not a mechanic... Best regards, -a- Quote
Immelman Posted October 31, 2020 Report Posted October 31, 2020 (edited) 21 hours ago, Yourpilotincommand said: Where the heck do I find this? My POH does not have this info. Or I need somebody to shoot me for being an idiot. Thanks! Run a tank dry. Whatever is left is unusable. A great place to calibrate your fuel dip-stick from. I can assure you, since the fuel pickup screen is not level with the very bottom of the tank, there will be a little bit that isn't usable. Edited October 31, 2020 by Immelman 3 Quote
DMM Posted October 31, 2020 Report Posted October 31, 2020 My two cents. Rev 58 of the type cert states: Fuel Capacity 52 gals. (Two integral tanks in wings at +48.4) See NOTE 1 for data on unusable fuel. NOTE 1: Current weight and balance report, including list of equipment included in certificate empty weight and loading instructions when necessary, must be in each aircraft at the time of original certification and at all times thereafter (except in the case of air carrier operators having an approved weight control system.) The certificated empty weight and the corresponding center of gravity location must include unusable fuel (not included in fuel capacity) as follows: 4 lbs. (+47.6) for the M20 and M20A; 3.4 lbs. (+48.4) for the M20B, M20C, M20D, M20E, and M20G; 15.0 lb. (+48.4) for the M20F and M20J; 48.0 lbs. (+48.59) for the M20K (S/N 25-0001 thru 25-0446); 18 lbs. (+48.59) for the M20K (S/N 25-0447 and ON); 36 lbs. (+48.43) for the M20L (S/N 26-0001 and ON); 36 lbs. (+49.23) for the M20M (S/N 27-0001 and ON) and M20R (S/N 29-0001 and ON) and M20S (S/N 30-0001 and ON); 36 lbs. (+49.23) for the M20TN (S/N 31-0001 and ON), M20U (S/Ns 32-0001 and ON), M20V (S/Ns 33-0001 and ON). Note one seems to indicate the 3.4 lbs unusable is in addition to the 52 gallon capacity. 2 1 Quote
Skates97 Posted October 31, 2020 Report Posted October 31, 2020 5 hours ago, Immelman said: Run a tank dry. Whatever is left is unusable. A great place to calibrate your fuel dip-stick from. I can assure you, since the fuel pickup screen is not level with the very bottom of the tank, there will be a little bit that isn't usable. I regularly run a tank dry on long cross country flights. If it's a four hour flight I want the last 10-12 gallons left in one tank instead of split up. When I fill up I regularly put 25.7-25.8 in which leaves me with 0.2-0.3 unusable. That experience lines up with the documentation. There is no listing in the POH for unusable fuel but as previously mentioned the TCDS lists 3.4 lbs which comes to .56 gallons. I took that from each side leaving 25.7 gal useable in each side. 4 Quote
Rjfanjet Posted November 1, 2020 Report Posted November 1, 2020 9 hours ago, Janat83 said: Did you checks that by yourself, I drained my fuel tanks and then top off, right wing 25.4 gallons, left tank 25.5, I plan 50 gallons as totally capacity and 8 gallons reserve, so at any flight I don't exceed 41 gallons of usable fuel, 68 M20C too. Useable includes the reserve. Quote
skydvrboy Posted November 1, 2020 Report Posted November 1, 2020 Just curious, why would anyone need to know how much unusable fuel is left in the plane? After all, you can't use it, so it doesn't do you any good. If you are doing some sort of unusable fuel calculation to mark your fuel stick, that's most likely not the best method. Much more accurate to just stick your tank before you fuel up and make a mark on it where the fuel level shows. Then fill up and subtract that from the total for that tank and label the line you just made. If you label those marks to the nearest 1/10th of gallon, you will soon have a fuel stick that is easily accurate to within a half gallon. Quote
carusoam Posted November 1, 2020 Report Posted November 1, 2020 It may help to know... When I look in the tank, and I see fuel... can it get used..? It turns out... There is a small amount of fuel that the pick-up can’t reach... The pick-up is a screen covered, round, tube, that is slightly off the bottom of the tank... near the trailing edge of the tank, at the inboard corner... Also at this corner... ... is the sump drain... ...and lower than the sump drain is the dregs of the tank... a place where moisture and dirty may collect... How much dregs are in the tank depends on the sump drain characteristics... and if its lower drain holes have been packed with excess sealant or dirt... Seeing DMM give the revision number of the TCDs... I thought it wise to verify if that is the latest one... or possibly a recent one he was familiar with... So... If you are looking for the latest Type Certificate Data Sheet for Mooneys... This link gets you really close, but... I think you still need to type the word ‘Mooney’ in their search box... (important if something gets updated...) https://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/MainFrame?OpenFrameset rev 58 is here... https://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/6ea0f05ecca8304486258305006833cf/$FILE/2A3_Rev_58.pdf Our TCDS is numbered as 2A3... The M20C starts on page 10... The fourth Mooney after the M20, A, B, and then C... The applicable notes start near the end of the document on page 59... Its a cool read if you haven’t taken the opportunity to review it... PP thoughts only, not a mechanic... Best regards, -a- Quote
Skates97 Posted November 1, 2020 Report Posted November 1, 2020 1 hour ago, skydvrboy said: Just curious, why would anyone need to know how much unusable fuel is left in the plane? After all, you can't use it, so it doesn't do you any good. If you are doing some sort of unusable fuel calculation to mark your fuel stick, that's most likely not the best method. Much more accurate to just stick your tank before you fuel up and make a mark on it where the fuel level shows. Then fill up and subtract that from the total for that tank and label the line you just made. If you label those marks to the nearest 1/10th of gallon, you will soon have a fuel stick that is easily accurate to within a half gallon. If you are going to weigh the plane you need to know. Also, depending on the engine monitor you have you want to have it programmed correctly. For a EDM900 one of the items you need to specify when ordering is the amount of unusable fuel. 1 1 Quote
carusoam Posted November 1, 2020 Report Posted November 1, 2020 1) Dregs and unusable fuel... 2) Fuel drain level... still unusable.. 3) Fuel pick-up.... top side of the screen... (fully immersed) start of usable fuel... no air drawn in by fuel pump... 3.5) Fuel reserve essentially starts at this point... (RJF’s point above) 4) fuel float becomes active and floats off the bottom of the tank... helps to have Ceis gauge accuracy for this... 5) fuel float reaches the top of the tank and is bound and no longer moves... 6) Fuel reaches the bottom of the fuel neck... 7) Fuel reaches a hole in the fuel neck signifying some value... (some fuel necks have a calibrated hole) 8) All fuel necks are different... many of the old ones have been swapped out for stainless steel... some got anti-siphon flaps... some got crummy volume limiting length... some hardly exist, just enough to mount the cap in... 9) Mechanical fuel gauges... their floats are in a separate place than the ship’s gauges... 10) Fuel cap location... Also changes with the size of the original fuel tanks... 11) if you look in the tanks... and don’t see fuel straight down.... there isn’t a lot in there... 12) The fuel tanks go significantly up hill... the tank vent is so far up hill, it won’t ever show expansion draining... unless parked on an uneven surface... 13) There are two different styles of tank vents... 60s concentric tubes, up the center of the tank... 90s reverse NACA duct from outside the tank... one is better at handling ice, some get an ice mast, not are susceptible to bug blocking... 14) mini drain holes in the ribs to allow the flow of fuel as it drains.... and air movement as the tank fills... PP thoughts on Mooney fuel tanks from the lowest point, to the highest... All from fuzzy old memories... Best regards, -a- Quote
carusoam Posted November 1, 2020 Report Posted November 1, 2020 15 hours ago, skydvrboy said: Just curious, why would anyone need to know how much unusable fuel is left in the plane? After all, you can't use it, so it doesn't do you any good. If you are doing some sort of unusable fuel calculation to mark your fuel stick, that's most likely not the best method. Much more accurate to just stick your tank before you fuel up and make a mark on it where the fuel level shows. Then fill up and subtract that from the total for that tank and label the line you just made. If you label those marks to the nearest 1/10th of gallon, you will soon have a fuel stick that is easily accurate to within a half gallon. This is purely a weight and balance issue... Somewhere along the way... your plane got weighed... if it got weighed before any fuel was put in the tanks... the unusable would want to be accounted for... It turns out... there isn’t much unusable fuel at the bottom of the standard Mooney tanks... Trying to make the last fuel drops available is a risk of high AOA, and crossed controls... nose up and wing high puts the fuel closer to where the pick-up is mechanically located... PP thoughts only, not a Mooney expert... Best regards, -a- Quote
Yourpilotincommand Posted November 1, 2020 Author Report Posted November 1, 2020 16 hours ago, skydvrboy said: Just curious, why would anyone need to know how much unusable fuel is left in the plane? After all, you can't use it, so it doesn't do you any good. If you are doing some sort of unusable fuel calculation to mark your fuel stick, that's most likely not the best method. Much more accurate to just stick your tank before you fuel up and make a mark on it where the fuel level shows. Then fill up and subtract that from the total for that tank and label the line you just made. If you label those marks to the nearest 1/10th of gallon, you will soon have a fuel stick that is easily accurate to within a half gallon. It’s just trivial information a DPE might ask me at my upcoming commercial check ride. Quote
gsxrpilot Posted November 2, 2020 Report Posted November 2, 2020 7 hours ago, Yourpilotincommand said: It’s just trivial information a DPE might ask me at my upcoming commercial check ride. There were a few similar questions that I was anticipating on my very recent Commercial check ride, that I was a little unsure of the answers. I just proactively gave answers without being prompted with the question. For example on the issue of unusable fuel, as the DPE started in on questions about the airplane, I proactively gave a quick summary including fuel capacity of which X was useable. That way there were no questions specifically about that. Done and moving on. 1 Quote
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