zuutroy Posted February 13, 2019 Report Share Posted February 13, 2019 I got my J back from annual and on the return the EDM800 went a little crazy and told me cyl 1 had a bad probe about 20 mins into the first flight. No big deal. Today I was on an IR lesson and everything was good. Battery was reading 14.2 V on run up. Some time later during the flight (possibly around the time the EGT probe started giving silly values again) it started barking at me that the voltage was only 12.0 V. I kept an eye on it and there was no change. Also no annunciator light at any time. On final with landing light on it was showing 11.5 V! Still nothing from the annunciator though. When I popped the landing light off during taxi it went up to 11.8 V. The flight was about an hour in total, and I've done 3.5 hours since the inspection. Alternator brushes were inspected as part of it. Do I believe the EDM or the annunciator? From mx manual I believe the VOLTS light should come on at anything less than 12.5 V. I guess if it really is that low it won't turn over next time so I'll know then! Quote Link to comment Share on other sites More sharing options...
Guest Posted February 13, 2019 Report Share Posted February 13, 2019 I would believe the JPI, it’s telling you that something is wrong. Clarence Quote Link to comment Share on other sites More sharing options...
bradp Posted February 14, 2019 Report Share Posted February 14, 2019 You try resetting the alternator field? Sounds like you weren’t getting any juice. Quote Link to comment Share on other sites More sharing options...
carusoam Posted February 14, 2019 Report Share Posted February 14, 2019 Zuu, Based on the information you gave... Doc gave you the best response possible... because he is a pro... 1) Me... I have the freedom to speculate... see if you can follow along... 2) Your JPI is showing the voltage it was reading... 3) Your annunciator shows a different voltage source ... (did you push the test button on the annunciator?) 4) Do you have a volt meter? (Now would be the time to get it out) 5) Expect that the battery isn’t being charged... the only way to know is with an independent volt meter... (a couple of bucks, pounds, lira, or euros... if you don’t have one) 6) what alternator do you have? Make sure the field wire is still attached... at both ends... 7) what voltage regulator do you have? Does it have any LEDs to indicate problems? (Some do... some have these lights remoted to the panel too...) 8) My favorite Mooney charging challenge... how tight is the alternator belt? A simple drip of oil can have it slipping slow enough that the alternator doesn’t charge... looks tight, but isn’t.... 9) There is a procedure to follow if the belt is taught enough... important to do if you intend to fly in IMC... 10) Start charging the battery now, if it is low... a good slow overnight charge is best to be ready for the next flight... 11) A jump start on a dead battery is not a good way to go fly... tough on both the battery and the charging system... PP thoughts only, not a mechanic... if you can answer this list of questions, you might be able to get more help out of your mechanic... Best regards, -a- Quote Link to comment Share on other sites More sharing options...
zuutroy Posted February 14, 2019 Author Report Share Posted February 14, 2019 Thanks, I'm not sure what alternator and regulator I have. I'll take a multimeter out at the weekend and do a bit of detective work. I'll also ground run it for a while and see what I see. I know the mechanic tidied some wiring at the annual (my first one) so it could have something to do with that. 1 Quote Link to comment Share on other sites More sharing options...
ArtVandelay Posted February 14, 2019 Report Share Posted February 14, 2019 The annunciators on the Js are old, there are pots inside that can be used to recalibrate it, not much documentation on it, service manual has some detail.When I added my JPI 900, I removed my annunciator.Tom Quote Link to comment Share on other sites More sharing options...
Steve2 Posted February 16, 2019 Report Share Posted February 16, 2019 It certainly sounds like a failure in the charging system, did you notice a discharge indiction on the ammeter during the flight? I would guess that your battery is now significantly discharged and possibly incapable of turning the engine over, if that's the case I'd suggest charging it overnight rather than jumping it - much easier on the battery. Quote Link to comment Share on other sites More sharing options...
zuutroy Posted February 16, 2019 Author Report Share Posted February 16, 2019 Field wire had snapped at the ring connector. All sorted and battery recharged overnight 1 Quote Link to comment Share on other sites More sharing options...
carusoam Posted February 16, 2019 Report Share Posted February 16, 2019 Welcome aboard, Steve! How Long have you had the O? ZUU, great follow-up! We must be seeing a broken field wire about once each month or two... at MS... and those are only the ones that get reported... Best regards, -a- 1 Quote Link to comment Share on other sites More sharing options...
zuutroy Posted February 16, 2019 Author Report Share Posted February 16, 2019 Diagnosed and repaired by the 76 year old father of my father-and-son mechanic shop who lives 100 miles away but just happened to be in the area on a Saturday in his camper van! 1 Quote Link to comment Share on other sites More sharing options...
Steve2 Posted February 17, 2019 Report Share Posted February 17, 2019 Thanks carusoam, we've had the O since around May 2018, always been a Mooney fan - I had an 88 J as my 1st aircraft back in 2000, swapped that for a FIKI Bravo in '03. 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.