mkrakoff

I try to taxi very lean (that video was at the runway hold after richening the mixture) and it is happening in both situations, so I'm thinking it's more likely something else.

Thanks Skip. It's always fun working out the kinks.

Quick follow up with savvy's response: Based on what we have to work with so far, and your description of the mild roughness/burble at idle which sounds like Lycoming lopeness I'd suggest looking for induction leakage in #4. At low MAP, both at idle and landing we have the largest differential between MAP and ambient atmospheric pressure so any induction leakage is going to be most symptomatic at this time. Lycoming are famous for leakage in the sniffle valve at idle, so besides typical induction plumbing leakage, be sure to check the cylinder drains and sniffle valves. The sniffle valve has a plastic ball in the line that can become gummy preventing the normal sucking of the engine cylinders from pulling the ball up and sealing it and then allowing air to leak in from the drain. If its a pretty rough idle, one easy test for the sniffle valve, is to pinch off the drain line where it exits the cowling after the valve and see if it improves the idle. Of course this won't fix a hole in the line above the valve (but past the cylinder drain) that could be leaking - so be sure to exhaust all possible sources of leakage doing a soapy water test. Can anyone define the term "Lycoming Lopeness"? Google couldn't

Hey all, I've been troubleshooting an issue (with Savvy) that has been happening. So, after start everything seems fine, I taxi (very lean) and do a run up (rich enough to be smooth and then re-lean). While taxiing to the runway or waiting for departure I've noticed intermittent ( a few times a minute?) small RPM drops and it is accompanied by a very minor audible and engine stumble. I'll attach a video of one the I was able to capture while full rich waiting to take the runway. It doesn't seem to be associated with being cold bc it occurs after landing on taxi in as well (I pulled over and waited after my last flight to check). Thoughts? I submitted a flight for analysis to Savvy that included an in flight mag check which seemed uneventful. I'll pass along results from that when I get them. Engine Stumble.m4v

Whelp, the good news is that I was able to get behind the panels with a camera without actual removing them. The bad news is, it's not the gaskets, it's both tanks and it's along the bottom seam and spar. Unfortunately, not caught on the prebuy. A full reseal is already scheduled, but at least it's the only surprise so far since the purchase. I keep reminding myself of how great a machine it is and how much fun we've had to make me forget about the extra out of pocket $.

Hey all, I am thinking of pulling the lower side cabin panels on my J bc I, like many of you, have a lingering fuel smell when I first open up the cabin door. I don’t see any carpet stains, but I’m betting the sender gaskets or tube is leaking. Are there any particular recommendations on tools, techniques, or tricks to removing the panel? I ask because I’d like to show up prepared, instead of my usual running home for something I’m missing what I really needed to do the job right. Thanks!

Got it thanks. I went flying today but wasn’t able to run the test due to workload. I’ll run a flight dedicated to just this shortly. Also I may wait, as I have an EDM upgrade scheduled next week to a 730/830 from a 700. Right now I don’t have FF connected to the 700 but will after upgrade, so it makes it much more difficult to pull an accurate gami spread. I’ll post as soon as I get good data for you.

Thanks, downloaded!

Just out of curiosity, is that benchmark model publicly available or are you working on a Future project with the data right now.

Amazing. Thank you so much for the detailed and thoughtful post. I’m headed out to fly tomorrow and will let you know how it goes.

So, as a MAPA member, is there an article or link to the key numbers everyone is talking about? I haven't had the opportunity to attend any events yet due to...the current state of the world.

I just downloaded it. That app is awesome...Looks like it uses Lycoming's charts, so it matches up with what I came up with, including the POH discrepancy. I'm assuming Lycoming's chart is the "perfect world, perfect engine" scenario. The POH basically low balls the %pwr by about 4-8% for every MP/RPM/ALT/TEMP combo. Thanks for the info!

Thanks, I'll definitely be working with MAPA in the future. Really, it's just an academic pursuit. I know that actual operations are MUCH less precise, but I just like numbers (i'm weird, I know) and it's interesting to review on those cruddy flying days. Engine-wise, It's an IO-360 A3B6D, so an IO-360 A model. I'm still thinking it's the right chart.

Whelp, beyond just academics, looking to accurately operate at 65% for a LOP and GAMI test. Although the GAMI test is going to be at WOT and 65% or less so that is a bit easier (fly high). IO-360 A36BD, so I believe this is the correct chart. Operationally, it would be nice to have a chart that works for every possible MP/RPM/Temp/ALT combo. The manufactures chart would allow that, but I'd like to know that my numbers are accurate. At the end of the day though, operating LOP, I will just be using GPH to calculate my %HP.

Hi all! I've been flying around a new to me M20J (and loving it!) and am delving into perf charts in the POH and directly from Lycoming. I'm finding a discrepancy b/w their calculations and am wondering if it's me, more accurate manufacturer calculations, or some factor (wrong chart?) I'm missing that is driving the differences. For example, the POH shows 22"/2200 at 4000' and Std temp to = 55% pwr. the Lycoming chart is below and looks like the same MP/RPM/ALT combo yields 118 HP at 4000 and Std Temp. More like 59% Thoughts? Thanks!

I pretty much talked myself out of it, however, I’m still going to speak to the seller about it. Like you said you really don’t know until you’ve looked.

Yeah, that one but I believe I've moved on unless you know something about the A/C that would help make a decision.

I don't believe so. Have some info on a 68F? There's a cheap '67 on Barnstormers that I was looking at but price seems too good to be true. I think I have something else in my sights.

So as this is my first purchase and I think I may actually somewhere else. Is it common to have a plane flown to a pre-buy or more common to find a "local" mechanic that doesn't work on it to do it?

Hey all, I might be about to join the Mooney family! Anyone have a lead on a good pre-buy mechanic in the Morristown, TN area? Thanks! Matt