PTK Posted June 2, 2013 Report Posted June 2, 2013 Yesterday I landed back home after an approx. two hour flight . As it is my normal routine, I rotated the prop to horizontal to facilitate tug. My copilot and I proceeded to clean off bugs from the windshield and leading edges. (I have delegated these powers to my copilot but was helping her being the nice guy I am!) The ramp fellow arrived with the tug and pushed the plane into the hangar. I proceeded to clean further around the cowl. When I was bending to clean around the pilot side front cowl area my ear was in front of the air intake where the air filter is. Not certain it came from engine or prop but it was in that general area. I noticed a "whoooooshhhhhhhhhhhhhh" sound combined with some burbling. Sounded like some pressure was being relieved. Also it seemed to me that the sound was accompanied with some heat, although I may be wrong as the engine was already hot from flight. The only thing I did was rotate the prop maybe 20 or 30 degrees to bring it horizontal. The time from when I moved the prop to when I heard it was maybe 5 to 10 minutes absolute max. I'm thinking it was pressure relieved from within a cylinder through an exhaust valve. Has anyone else heard something like this? Am I correct in my thinking? Quote
Parker_Woodruff Posted June 2, 2013 Report Posted June 2, 2013 Both Lycoming IO-360 engines I've owned (one on a C172 and one on an M20J) made an intermittent burbling sound after shutdown. I can't quantify your "whoosh" sound, but I think I heard something similar before. Quote
1964-M20E Posted June 2, 2013 Report Posted June 2, 2013 I've heard similar sounds. As to what they are most likely oil or fuel moving about. Quote
wishboneash Posted June 2, 2013 Report Posted June 2, 2013 I get this gurgling sound after every shut down. I think it is some pressure getting relieved within the engine and probably quite normal. Lasts about 30s or so. Quote
TWinter Posted June 2, 2013 Report Posted June 2, 2013 I hear the same sounds while putting her back in the hanger..Nothing to worry about, I just consider it part of the cool-down process. I've noticed it since day one of owning it. Our little airport is self-serve hanger service, that means (me) pushing it back in the hanger. I hear the same exact noises as I assume the pilot push position at the front cowl. I do usually wait and head back to the airport later in the day or next day to allow for engine cool-down before putting covers and cowl plugs back in. I think what you hear is A-Okay. Quote
Alan Fox Posted June 2, 2013 Report Posted June 2, 2013 What this sound is is the fuel in the spider , and lines boiling and spewing out of the injectors into the intake ports......It is normal , and is why hot starts are easily flooded... Next question please..... Quote
Jamie Posted June 2, 2013 Report Posted June 2, 2013 How safe is it to move the prop? I'd like to, just to make it easier to push into the hangar, but I thought moving the prop was a no-no. Quote
Rich Posted June 2, 2013 Report Posted June 2, 2013 It's fuel remaining in the fuel lines and injectors dripping into the cylinders (what I've been told by a mechanic).nRegarding the hot starts, I've been using a different technique than I was taught. I start with throttle and mixture in normal idle position. As soon as the engine fires, I add low boost pump. This works most of the time- and much quicker than mixture in cut off position. Quote
PTK Posted June 2, 2013 Author Report Posted June 2, 2013 To all you guys a whole big THANK YOU!! Sounds like it's normal and I'm happy! I just hadn't heard this before! Quote
PTK Posted June 2, 2013 Author Report Posted June 2, 2013 How safe is it to move the prop? I'd like to, just to make it easier to push into the hangar, but I thought moving the prop was a no-no.Pushing or pulling the airplane from the prop is a no-no with me. This is why I insist on a tug or help pushing on the wing root area. I rotate the prop backwards to bring it horizontal as needed for tug after shutdown. I do this with mags off and verify keys are in my pocket. Quote
wiseng Posted June 2, 2013 Report Posted June 2, 2013 Just to make sure. Verify you have an RPM drop on both mags during runup. If one or both does not you have a hot mag. The P lead has come loose or you have some other problem. There have been serious accidents because of this.. Quote
PTK Posted June 2, 2013 Author Report Posted June 2, 2013 Thank you Wiseng. You're absolutely correct about P lead. It's paramount to safety with the prop and requires utmost respect. As an added precaution whenever I rotate it it's always backwards. I actually perform run up using egt's on edm and lean rather than rpm drop. Making sure that all rise and none drop on each mag. I abandoned rpm drop a long time ago. Quote
N201MKTurbo Posted June 2, 2013 Report Posted June 2, 2013 I always stand next to the prop when I'm moving it, and just move it by the prop tip. That way if the engine pops I can get my hand out of the way before the prop comes around. When moving the prop on a hot engine always assume it will start and be happy when it doesn't. Quote
jetdriven Posted June 2, 2013 Report Posted June 2, 2013 Pushing or pulling the airplane from the prop is a no-no with me. This is why I insist on a tug or help pushing on the wing root area. I rotate the prop backwards to bring it horizontal as needed for tug after shutdown. I do this with mags off and verify keys are in my pocket. You shouldnt rotate your prop backwards. You might ruin your accessory gears, mags, vacuum, pump, alternator, or engine mounts. None of those are rated to run in reverse. "You just never know" Quote
jetdriven Posted June 2, 2013 Report Posted June 2, 2013 I always stand next to the prop when I'm moving it, and just move it by the prop tip. That way if the engine pops I can get my hand out of the way before the prop comes around. When moving the prop on a hot engine always assume it will start and be happy when it doesn't. If you do the magneto grounding check just before shutdown on every flight, you never have to worry about losing your head or hands to a rotating propeller. Quote
Hank Posted June 2, 2013 Report Posted June 2, 2013 I rotate the prop forward when needed to attach the tow bar. Push on tow bar and corner of the cowl; when available, someone will push on a wing root. There's no need to put the prop horizontal if putting the plane in a hangar, is there? I have to put my 3-blade vertical up to tow, and leave her vertical down when parking outside overnight if the FBO isn't going to move her. Quote
Jamie Posted June 3, 2013 Report Posted June 3, 2013 I guess I'm doing it wrong, then. Hank, pushing on the cowl seems like a bad idea to me, but that's only because I can see cracks around the inlets on mine. Obviously, I'm no engineer, but I can't believe the cowl is designed to transmit a force like that to the rest of the airplane. But then, neither is the prop, and that's what I push on. I have the tow bar in my right hand (steering) and push on the prop near the hub with my left. If this is a horrible idea, I need to know, and I need a viable one person alternative. Suggestions? Quote
wiseng Posted June 3, 2013 Report Posted June 3, 2013 The way I move mine is use the tow bar and pushing both the bar and placing my hand on the thickest part of the prop right next to the spinner. I have been doing this for 16 years on my 78J and never had any problems other than it is a bitch when you have full tanks and have an incline to go up Ha. 2 Quote
larryb Posted June 3, 2013 Report Posted June 3, 2013 I guess I'm doing it wrong, then. Hank, pushing on the cowl seems like a bad idea to me, but that's only because I can see cracks around the inlets on mine. Obviously, I'm no engineer, but I can't believe the cowl is designed to transmit a force like that to the rest of the airplane. But then, neither is the prop, and that's what I push on. I have the tow bar in my right hand (steering) and push on the prop near the hub with my left. If this is a horrible idea, I need to know, and I need a viable one person alternative. Suggestions? Lets see. The prop handles 200hp or more and pulls the plane through the air at 150kt or more. And I'm going to hurt it by pushing, on the thickest part, with maybe 100 lb force max??? I really don't think so. Quote
Alan Fox Posted June 3, 2013 Report Posted June 3, 2013 Lets see. The prop handles 200hp or more and pulls the plane through the air at 150kt or more. And I'm going to hurt it by pushing, on the thickest part, with maybe 100 lb force max??? I really don't think so. You also forgot to mention mention that a prop blade weighing 18 lbs , being spun at 2500 rpm probably weighs about 3 to 5 tons (x2) , against the prop hub..... The Docs reasoning is not because of damaging the prop , but for safety...... Quote
Alan Fox Posted June 3, 2013 Report Posted June 3, 2013 You shouldnt rotate your prop backwards. You might ruin your accessory gears, mags, vacuum, pump, alternator, or engine mounts. None of those are rated to run in reverse. "You just never know" The only thing that could possibly be damaged is a Vacuum pump (dry) and that is if its close to failure anyway..... I have seen these engines pre ignite on attempted startup , and spin backwards two or three rotations, on many occasions ....It doesn't hurt anything.... Quote
thinwing Posted June 3, 2013 Report Posted June 3, 2013 Besides rotating backwards is a standard movement to find TDC during differential conp test..it does no harm to do by hand especially compared to a backfire/preigntion event during a failed start Quote
jetdriven Posted June 3, 2013 Report Posted June 3, 2013 I was spoofing on the "dont pull your airplane by the prop" argument. The key in the argument against doing so is "You just never know". You never know about a lot of things, come to think of it Quote
triple8s Posted June 3, 2013 Report Posted June 3, 2013 If the "Good Dr." would burp his baby before he put her to bed she wouldnt gurgle so, its a wonder she desnt get the colic. 1 Quote
fantom Posted June 4, 2013 Report Posted June 4, 2013 If the "Good Dr." would burp his baby before he put her to bed she wouldnt gurgle so, its a wonder she desnt get the colic. Let's keep in mind that he's a Dent, not Dr. Maybe he just needs to floss 1 Quote
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