peevee Posted January 9, 2017 Report Posted January 9, 2017 are the outboard drain valves the same as the inboard? (F391-53S}
kortopates Posted January 9, 2017 Report Posted January 9, 2017 12 minutes ago, peevee said: are the outboard drain valves the same as the inboard? (F391-53S} Yes. be careful replacing them. They can be easily overly torqued.
Danb Posted January 9, 2017 Report Posted January 9, 2017 It depends on the model, my Bravo has the same drain as prior to the installation, I also only have one filler cap per wing, I believe mike has two per wing, could be different between long body and short. Jose.....where are you
carusoam Posted January 9, 2017 Report Posted January 9, 2017 I've only been emptying one tank drain per side in the O' 100+ gal... Should I be looking for another set? Best regards, -a-
peevee Posted January 9, 2017 Author Report Posted January 9, 2017 1 hour ago, kortopates said: Yes. be careful replacing them. They can be easily overly torqued. I'm surprised they aren't safety wired. I'll supply the part and let the A&P handle it, too critical and easy to mess up as you say.
peevee Posted January 9, 2017 Author Report Posted January 9, 2017 33 minutes ago, carusoam said: I've only been emptying one tank drain per side in the O' 100+ gal... Should I be looking for another set? Best regards, -a- The monroy tanks do. I don't know about any other model than the K. 1
kortopates Posted January 9, 2017 Report Posted January 9, 2017 13 minutes ago, peevee said: The monroy tanks do. I don't know about any other model than the K. Exactly, they are for the extra bay filled by the Monroy tanks. Safety wiring is essentially impossible. The only thing to safety wire the flush drain would be on the inside of the tank. They are not hard to re-install, just use a torque wrench and stop. Too many people, including A&P's, will keep tightening trying to stop a drip and before you know it they have over stressed the 2 little rivets holding the nut plate on. If it's dripping, it needs to come back out and clean up whatever is the problem. Usually it goes easily but with gas pouring out of an undrained tank its a pain. Pull it out on the ramp to replace it and be ready and quick when the old drain comes out - so you don't let gas get all over you.
peevee Posted January 9, 2017 Author Report Posted January 9, 2017 What's the torque spec? Do you know offhand?
peevee Posted January 9, 2017 Author Report Posted January 9, 2017 80-85in lbs per the safe air specs. Found it.
kortopates Posted January 9, 2017 Report Posted January 9, 2017 1 minute ago, peevee said: 80-85in lbs per the safe air specs. Found it. Go by Mooney's SB20-188A or the Mooney MM http://www.mooney.com/en/sb/M20-188A.pdf note they indicate only 40-65 in/lb 1
peevee Posted January 9, 2017 Author Report Posted January 9, 2017 (edited) Ouch, thanks. On the bright side the nut plate is probably riveted since it's an add on. I hope. Maybe that's worse. Another leak point. Edited January 9, 2017 by peevee
carusoam Posted January 9, 2017 Report Posted January 9, 2017 It is hard to damage the wing by over torquing the fuel drain. The self sacrificial drain snaps in half at a relatively low torque. My mechanic gave me this advice, then I went out and seated it in my old C, and gave it about a 1/4 turn or something similar. Dreaded click... Best regards, -a-
peevee Posted January 9, 2017 Author Report Posted January 9, 2017 (edited) Anyone else a little frightened their fuel supply is only held captive by 60in lbs and no safety wire? The more little things I do on these, the less I want to fly them. Especially when I saw how the speed brakes attached. Edited January 9, 2017 by peevee
carusoam Posted January 9, 2017 Report Posted January 9, 2017 What happens if the speed brakes break? Other than 'watch out below', the asymmetrical deployment doesn't have much of an effect that I can tell. My experience comes from using them as their clutches wear out . Sooner or later one doesn't operate. One thing for sure, Braking will be half the normal rate. As far as the tank drain goes... there must be something holding it in (friction). Because, if it vibrated out until the safety wire holds it. The fuel is going to leak out along the threads anyway, just slowly at first... Reminds me to get those CIES floats and compare fuel used to the fuel totalizer's fuel used. If they are different, something is leaking... Thinking out loud, -a-
Piloto Posted January 9, 2017 Report Posted January 9, 2017 The Long Range tanks fuel drain valves are: F391-72. They are available at Aircraft Spruce: http://www.aircraftspruce.com/search/search.php?s=F391-72&x=19&y=13 No need to over torque them. José 1
peevee Posted January 9, 2017 Author Report Posted January 9, 2017 (edited) 7 minutes ago, carusoam said: What happens if the speed brakes break? Other than 'watch out below', the asymmetrical deployment doesn't have much of an effect that I can tell. My experience comes from using them as their clutches wear out . Sooner or later one doesn't operate. One thing for sure, Braking will be half the normal rate. As far as the tank drain goes... there must be something holding it in (friction). Because, if it vibrated out until the safety wire holds it. The fuel is going to leak out along the threads anyway, just slowly at first... Reminds me to get those CIES floats and compare fuel used to the fuel totalizer's fuel used. If they are different, something is leaking... Thinking out loud, -a- The brakes I'd worry about popping the bottom bolts or coming loose and tearing a wing skin. Lots of torque applied to that upper skin. I guess if they depart the airframe its probably more annoying than anything. They say asymmetrical deployment is a non event. Never happened to me but ours are pretty flaky right now so it'll happen eventually Edited January 9, 2017 by peevee 1
peevee Posted January 9, 2017 Author Report Posted January 9, 2017 4 minutes ago, Piloto said: The Long Range tanks fuel drain valves are: F391-72. They are available at Aircraft Spruce: http://www.aircraftspruce.com/search/search.php?s=F391-72&x=19&y=13 No need to over torque them. José Thanks
carusoam Posted January 9, 2017 Report Posted January 9, 2017 PV The like button is probably not the proper response for having a wing skin get torn. But the 'I see your point' button wasn't available... What keeps me mildly less fearful of this situation is the flock mentality. I have one mooney, built the same as so many other Mooneys... if something simple goes awry because a failure of design, materials or construction.... I will probably not be the first person to become aware of the issue. Having MS available adds and subtracts from my comfort level. Some things I learn about, I would have never considered... Best regards, -a-
WheelPantsOff Posted December 26, 2025 Report Posted December 26, 2025 What's 9 years among friends for a bump... Now that I have time to clean the airplane while the exhaust gets repaired, I cleaned up really good under the four drain valves (I have the Monroy LR tanks). The outboard (LR) valves persistently get dirtier and leak-ier than the main valves. I cleaned them so good that now I can read the P/N and see that the outboard ones are the same P/N as the inboard drains. All four of them are F391-53S. I see that my outboard tanks require the F391-72. Anyone know the difference between the two? The 'proper' one looks taller than the factory drain. Thanks as always.
Marc_B Posted December 26, 2025 Report Posted December 26, 2025 The thread pattern and torque spec is the same for both. But it’s a total length, location of initial drain hole and size of the outer o-ring. I presumed it was a difference of how much material you needed to pass to get inside tank. Does the aux tank go through a wing rib hence need for a thicker thread? Below are the Saf Air valves. A little stiffer to sump but cheaper with viton o-rings that are replaceable. No need to over torque…they don’t need much. Apply a very light layer of fuel lube avoiding last two threads 1
LANCECASPER Posted December 26, 2025 Report Posted December 26, 2025 1 hour ago, WheelPantsOff said: What's 9 years among friends for a bump... Now that I have time to clean the airplane while the exhaust gets repaired, I cleaned up really good under the four drain valves (I have the Monroy LR tanks). The outboard (LR) valves persistently get dirtier and leak-ier than the main valves. I cleaned them so good that now I can read the P/N and see that the outboard ones are the same P/N as the inboard drains. All four of them are F391-53S. I see that my outboard tanks require the F391-72. Anyone know the difference between the two? The 'proper' one looks taller than the factory drain. Thanks as always. Here are the two at Aircraft Spruce for comparison: https://www.aircraftspruce.com/catalog/pnpages/05-00037.php https://www.aircraftspruce.com/catalog/appages/mdiflushdrainvalve_05-01877.php
Z W Posted December 26, 2025 Report Posted December 26, 2025 When I went through this to replace a leaking Monroy tank valve, I read on here (possibly from this thread) that the Monroy tanks would take a different valve than the inboard tanks. I ordered a CCA-2800 which corresponds to the F391-72 or SA-72. It did not match the one I removed. I ended up replacing it with a SA53S which matched the existing valve, and which matches the valves in the inboard tanks. I carry a spare one of those in the plane now. Fuel lube and a 1/4" drive torque wrench that does inch/lbs are recommended for the swap. I also needed an adapter to go from 1/4" to 3/8" drive for the large socket that fits the drain valve. After the swap, despite me trying to be gentle, one of the rivets that holds in the drain valve threads inside the wing started to seep. Rubbing on a little Oil-Tite stopped the leak and it has been stable for over two years now. 1
Marc_B Posted December 26, 2025 Report Posted December 26, 2025 2 hours ago, Z W said: When I went through this to replace a leaking Monroy tank valve, I read on here (possibly from this thread) that the Monroy tanks would take a different valve than the inboard tanks. I ordered a CCA-2800 which corresponds to the F391-72 or SA-72. It did not match the one I removed. This is interesting. When I replaced mine, the Monroy tanks had F391-72 sumps. Not sure why the difference? Perhaps replaced unknowingly in the past? Can anyone who has installed the Monroy Aux Tanks weigh in on why and where the -72 sumps were used?
LANCECASPER Posted December 26, 2025 Report Posted December 26, 2025 23 minutes ago, Marc_B said: This is interesting. When I replaced mine, the Monroy tanks had F391-72 sumps. Not sure why the difference? Perhaps replaced unknowingly in the past? Can anyone who has installed the Monroy Aux Tanks weigh in on why and where the -72 sumps were used? Because Jose Monroy aka @Piloto said so . . lol. I'm sure he had a good reason . But most importantly the STC installation instructions that I have for my airplane list the -72 in the parts list - so that's the approved part. I carry one of these and one of the other sumps with me in case I have a leaking sump on a trip. Earlier in this post back in 2017 Jose Monroy weighed in on it:
Recommended Posts