40Cal Posted October 12, 2021 Report Share Posted October 12, 2021 (edited) I just got my 1964 M20C back from the mechanic: new sky tech starter, plane power alternator to replace the old generator, and an oil change. On the short flight back to my home base I noticed oil mist on the windshield. When I landed this is what I found (pics below). Thoughts? They had to pull the prop to install the belt on the alternator so maybe a bad seal? Not a very mechanical guy, so hoping to take advantage of the community expertise. New to the forum, btw. First post. Edited October 12, 2021 by 40Cal Quote Link to comment Share on other sites More sharing options...
carusoam Posted October 12, 2021 Report Share Posted October 12, 2021 Yikes! Welcome aboard 40Cal… Lets de cowl her and have a look! That isn’t normal. Was there a post maintenance flight? Have you called the mechanic to discuss? (Do this asap, share the pics with him… he will want to know…) Starters and alternators don’t use oil… oil changes not completed properly… they use lots of oil… PP thoughts only, not a mechanic… Definitely in the running for the craziest first post ever… Best regards, -a- Quote Link to comment Share on other sites More sharing options...
KNorton Posted October 12, 2021 Report Share Posted October 12, 2021 (edited) Welcome! Sorry to hear about this bad experience. It will require inspection but I suspect the seal between the crank and prop hub. If the mechanic isn’t careful when installing the prop, the seal can be damaged or pushed out of position. Worst case, they removed it and forgot to re-install it. Regardless, it probably should have been caught during the after maintenance testing. A&P IA thoughts only. No one will know for sure without looking at it more closely. Edited October 12, 2021 by KNorton 4 Quote Link to comment Share on other sites More sharing options...
carusoam Posted October 12, 2021 Report Share Posted October 12, 2021 +1 for KN’s observation regarding the prop seal…. When the prop got pulled for the alternator belt… an oil seal is part of that operation… Best regards, -a- Quote Link to comment Share on other sites More sharing options...
markgrue Posted October 12, 2021 Report Share Posted October 12, 2021 Second the prop o ring. $2 part. 2 hour of work. Probably nicked it when the propeller went on. Mark Quote Link to comment Share on other sites More sharing options...
neilpilot Posted October 12, 2021 Report Share Posted October 12, 2021 Wonder if they cheaped out and left the old seal in place Quote Link to comment Share on other sites More sharing options...
N201MKTurbo Posted October 12, 2021 Report Share Posted October 12, 2021 The only way that much oil would come out of the prop seal is if it popped out. That is a serious leak. Something is busted or falling off. Quote Link to comment Share on other sites More sharing options...
N201MKTurbo Posted October 12, 2021 Report Share Posted October 12, 2021 Might have forgotten to tighten and safety the oil filter. Quote Link to comment Share on other sites More sharing options...
ArtVandelay Posted October 12, 2021 Report Share Posted October 12, 2021 A loose oil pressure or temperature sensor? Quote Link to comment Share on other sites More sharing options...
40Cal Posted October 12, 2021 Author Report Share Posted October 12, 2021 Thanks for all the great feedback everyone! What a group! The mechanic is going to fly over to my home airport today to check it out. It’s too much oil for me to feel comfortable flying it back to his shop, even though it’s not very far. I’ll let you know what it turns out to be. Hopefully something simple and cheap! (If it is something he did—which seems likely given it happened on the first flight out of maintenance—there will be no charge. If it’s something else…) Quote Link to comment Share on other sites More sharing options...
Ragsf15e Posted October 12, 2021 Report Share Posted October 12, 2021 55 minutes ago, 40Cal said: Thanks for all the great feedback everyone! What a group! The mechanic is going to fly over to my home airport today to check it out. It’s too much oil for me to feel comfortable flying it back to his shop, even though it’s not very far. I’ll let you know what it turns out to be. Hopefully something simple and cheap! (If it is something he did—which seems likely given it happened on the first flight out of maintenance—there will be no charge. If it’s something else…) Good call, definitely wouldn’t fly it anywhere until it’s fixed. Let us know what he finds. 1 Quote Link to comment Share on other sites More sharing options...
40Cal Posted October 12, 2021 Author Report Share Posted October 12, 2021 Ok, turned out to be a very easy fix. The nut that connects the prop oil line hadn’t been tightened down (to the point that it could still be tightened by hand). The prop seal is brand new and seems to be fine. A few turns of the wrench to tighten it down was all it took. Did another short maintenance flight afterwards and everything seems to be ok. Will definitely keep an eye on it, but very relieved that it was such an easy fix. Definitely a sickening feeling to see that much oil on the outside of the plane! Thanks again to everyone for the input. Happy to join the group! 3 Quote Link to comment Share on other sites More sharing options...
N201MKTurbo Posted October 12, 2021 Report Share Posted October 12, 2021 I wish I could say I've never done anything like that. But, I always run an engine before I cowl it back up and look for anything leaking. It would have caught that. 91.407 Operation after maintenance, preventive maintenance, rebuilding, or alteration. (a) No person may operate any aircraft that has undergone maintenance, preventive maintenance, rebuilding, or alteration unless - (1) It has been approved for return to service by a person authorized under § 43.7 of this chapter; and (2) The maintenance record entry required by § 43.9 or § 43.11, as applicable, of this chapter has been made. (b) No person may carry any person (other than crewmembers) in an aircraft that has been maintained, rebuilt, or altered in a manner that may have appreciably changed its flight characteristics or substantially affected its operation in flight until an appropriately rated pilot with at least a private pilot certificate flies the aircraft, makes an operational check of the maintenance performed or alteration made, and logs the flight in the aircraft records. (c) The aircraft does not have to be flown as required by paragraph (b) of this section if, prior to flight, ground tests, inspection, or both show conclusively that the maintenance, preventive maintenance, rebuilding, or alteration has not appreciably changed the flight characteristics or substantially affected the flight operation of the aircraft. 2 Quote Link to comment Share on other sites More sharing options...
47U Posted October 12, 2021 Report Share Posted October 12, 2021 This B-nut? Was it loosened as part of the maintenance to install the alternator? Some mechs will apply a stripe of torque seal to aid in detecting loosening of critical fasteners. Regardless, it’s good to find the smoking gun, and that it wasn’t something more insidious (although this was pretty serious). Agree with everything Rich says above. ^^^^ 1 Quote Link to comment Share on other sites More sharing options...
40Cal Posted October 12, 2021 Author Report Share Posted October 12, 2021 19 minutes ago, 47U said: This B-nut? Was it loosened as part of the maintenance to install the alternator? Some mechs will apply a stripe of torque seal to aid in detecting loosening of critical fasteners. Regardless, it’s good to find the smoking gun, and that it wasn’t something more insidious (although this was pretty serious). Agree with everything Rich says above. ^^^^ Yes, that nut. And yes, he applied the torque seal this time, right after realizing that’s what happened and tightening it. Quote Link to comment Share on other sites More sharing options...
Ragsf15e Posted October 12, 2021 Report Share Posted October 12, 2021 2 hours ago, 40Cal said: Ok, turned out to be a very easy fix. The nut that connects the prop oil line hadn’t been tightened down (to the point that it could still be tightened by hand). The prop seal is brand new and seems to be fine. A few turns of the wrench to tighten it down was all it took. Did another short maintenance flight afterwards and everything seems to be ok. Will definitely keep an eye on it, but very relieved that it was such an easy fix. Definitely a sickening feeling to see that much oil on the outside of the plane! Thanks again to everyone for the input. Happy to join the group! Great that you found it! Stuff happens. I noticed noisy radios after a pretty extensive annual once and started thinking through what we had done and what was causing it. Could have been anything from tip to tail and the noise was real bad. I was getting worried about ripping everything apart again when I read a post about loose spark plug harnesses… so I did a mag check and it was slightly changed but still there. Still, I checked the plug wires and found all 4 on the pilot side were barely finger tight! Mechanic apologized and said he must have got interrupted putting her back together. It doesn’t take much. Quote Link to comment Share on other sites More sharing options...
40Cal Posted October 12, 2021 Author Report Share Posted October 12, 2021 2 hours ago, 40Cal said: Yes, that nut. And yes, he applied the torque seal this time, right after realizing that’s what happened and tightening it. And yes, he had to disconnect the hose in order to install the alternator belt. Must have gotten distracted putting it all back together. Quote Link to comment Share on other sites More sharing options...
Guest Posted October 12, 2021 Report Share Posted October 12, 2021 Stuff goes wrong, it’s called Human Factors. Distractions are a real thing. Clarence Quote Link to comment Share on other sites More sharing options...
AIREMATT Posted October 13, 2021 Report Share Posted October 13, 2021 2 hours ago, M20Doc said: Stuff goes wrong, it’s called Human Factors. Distractions are a real thing. Clarence Not just for pilots while flying either… Quote Link to comment Share on other sites More sharing options...
carusoam Posted October 13, 2021 Report Share Posted October 13, 2021 40Cal, Great follow-up… +1 on not flying… with a known unknown… +1 on short post maintenance flights… while your mechanic is still there… +1 on discussions regarding distractions… they can occur at any time anywhere… and the results may become obvious days later… You proved you have a good mechanic… he’s human… Best regards, -a- Quote Link to comment Share on other sites More sharing options...
Hank Posted October 13, 2021 Report Share Posted October 13, 2021 19 minutes ago, carusoam said: 40Cal, Great follow-up… You proved you have a good mechanic… He owned up to his mistake, came to you and made it right. Remember this part much more than the leaky fitting! Remember him at Christmas, too. 1 Quote Link to comment Share on other sites More sharing options...
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.