DXB

Kinda sad data, and I have IO390 envy now. I probably wouldn't have put on that Powerflow exhaust if I'd known this innate limitation of the O-360 a few years back, and I ought to get around to setting my Surefly to fixed timing mode, despite this setup approaching stock E model performance. As a Mooney pilot, I have a hard time pulling the power back and just enjoying the efficiency dividend.

Great analysis - this is exactly the kind of fleet that is suited to do well-controlled trials for all kinds of things in aviation; the problem is who's gonna fund it. I can attest to the significant cooling issues with parallel valve lycomings BTW - will take the heat on that.

It doesn't mitigate this tragedy in any way, but that's still good to hear. I'm still a bit surprised the spar snapped before loss of consciousness led to letting go of the back pressure on the controls.

It's a fair point - my comment wasn't really meant as a rebuttal of yours, though in retrospect I realize it comes off that way. Dinging up people's planes probably correlates well with carelessness in other domains.

Like it or not, the market and margins from piston aircraft maintenance do not allow them to operate like the service department of a high end exotic sportscar dealer, even though the price point of the vehicle is similar. And frankly I need the handful of honest, trustworthy, and capable shops out there more than they need me, so I find it counterproductive to antagonize by sweating the small stuff. My list of priorities in aviation maintenance: (1) Please don't do anything that might kill or maim me when the plane returns to service (2) Please don't break anything major that works, including totaling my airframe in a freak shop accident (3) Actually do the work (and related paperwork) I request in a quality manner (4) Be honest and accountable when I find things that went wrong under items 1-3 (5) Listen to me and engage me in thoughtful discussion regarding problems found by me or the shop before "fixing" anything (6) Charge me a fair amount for the work done (7) Complete the work in a reasonable time frame. ............. (99) Don't return my plane substantially filthier than you found it (100) Don't put a paint scratch on my 56 year old plane. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> A previously reliable shop for me suddenly flunked #1 #,3, #4, #5, and #7 all at once a few years ago during annual, causing me to switch. Right now I'm ecstatic to have been working with a shop that has done #1-7 pretty reliably since then. I wouldn't care if they put a little scratch on it. My main concern if it became a common occurrence would be that their efforts under items #1-3 might also be suffering - in your situation I might switch, but not because of the scratch itself.

If there are large fields vs. a busy roadway I think I'd take the former every time and probably put it in gear up unless surface is very hospitable. Not only is there less ethical quandary but also I'm still likely to walk away if I keep my head and have better chance of avoiding obstructions and cars. If only alternative is the tree tops of a hardwood forest, I might pick the road in an effort to improve my chances (unless it's rush hour). A desolate road without many obstructions might tempt me to also try to save the plane. This plane was a Lancair 360 - I think these approach and stall about 10kt faster than a typical Mooney, adding further challenge. Good job by the pilot here it seems.

I agree - I think the dual ports are interconnected in the tubing in the tail, so what transducers read out is an average, which might be handy with a crosswind component across the nose or yaw. And it could save your bacon if one side gets blocked. I suppose if flow over one were reduced or turbulent due to a popped door that could also create some artifact, but I have no clue if this happens to any meaningful extent.

This makes little sense to me right now, but if your statement is true, it's certainly worth resolving my ignorance on this topic. Could the popped door could create an artifactual reading at the static port behind? I have no clue. All I would expect is a slight increase in parasitic drag. I can't imagine how it would change AOA directly. FWIW my door has popped many times (long painful door mechanics story), but I've never noted the slightest difference in aircraft handling. A 10kt increase in when it stalls is dramatic when landing and would have led to a surprise when lifting the nose once over the runway to land.

The engine: Lycoming O-360 in a '68 M20C. Running well, happily blowing 1qt/4hrs, and the oil turns black fast, but consumption been stable recently with no clear single offending cylinder, so I feel no rush to do anything. The history: Three years ago my A&P did the Loc-tite + vacuum trick on my leaking lower case seam, and it seemed to work very well. At the same time I had him change my 17 year old Curtis quick drain valve, which always seemed to have a drop of oil hanging off of it, replacing it with one of the SAF-AIR ones: https://www.aircraftspruce.com/pages/ep/oilsystems_oildrain/safOilDrainValves_07-00879.php The new problem: Increasing oil leakage over the last year. After it sits several days, there's enough oil leak to drip a fair amount on my front tire. Last time that happened, a nut was about to fall off a mag, so I take the new leakage pretty seriously. On exam of engine, the accessory case and fire wall are bone dry. The case seam looks pretty dry except at the very front. In that area, there's also oil on the Powerflow heat exchanger, the base of jug #1, the oil line to the prop hub, the back of the alternator, and on top of the air box. There's a bit of oil at the base of jug #2 and also around the top seam for the oil sump and on the bottom of the oil sump. The O-ring seals on the pushrod tubes seem dry along with the rest of the top of the engine and around the front crank shaft seal. My amateurish diagnosis attempt: I clean everything up, add florescent dye to the oil, and ground run it- I then see nothing leaking directly or by UV illumination. I then go fly a couple laps in the pattern. Again it's bone dry when I get back, including the quick drain valve. Figuring I should get the non-FAA blessed dye out of the oil (which has 25 hrs on it and is black), I do a quick oil change without changing the filter, not spilling a drop in the process. I still wipe everything down again. I then come back two weeks later to fly, and there's now CLEAN oil in my bottom cowl and on my front tire . The rest of the engine still looks dry. My question: Could this all be from an imperceptibly slow leak out the SAF-AIR quick drain valve?? Any other thoughts?? I'm wishing I stayed with a Curtis valve.

@bcgI love the resourcefulness and innovation here - a low cost design that has no risk of chewing up the front tire (like the Sidewinder and Robotow) would be very desirable.

Reviving this thread as I consider engine overhaul - I think probably will order a Lycoming factory rebuilt or overhaul for my O-360-A1D, exchanging the core. I'm heading into annual this year soon and would hope to do the swap at annual next year. My question is, do any of the other major shops provide similar service (i.e. provide an overhauled engine with core swap)? At first glance, places like Western Skyways, Signature, Poplar Grove? I'm just trying to gather a bit more info before I start calling around... @Alan Fox @jetdriven

My Aspen Pro Max has always been too sluggish in initiating turns in GPSS mode when driving my STEC-30 autopilot. It it anticipates the turn per instruction from the GTN-650 but still overshoots and then turns back to re-intercept the course. My internet “research” indicates there’s a GPSS gain setting that can be adjusted on the Aspen in “maintenance mode.” Supposedly the gain scale is 1.0 to 2.0, with 1.0 being the default but 1.5 to 1.75 being recommended for STEC autopilots. Does anyone here have any guidance on this issue and how to accomplish this adjustment? Thank you in advance!

Interesting discussion. We clearly need eLORAN technology. Unfortunately, a world where bad actors successfully render GPS useless will probably not be all that conducive to my continuing to fly as a fun hobby either.

Definitely left - the added ease of starting if you put it on that side is spectacular.

I had seen similar behavior on the old analog gauge that brought a fuel line all the way into the cockpit before the JPI was put in 10 years ago. The new sensor is mounted roughly at the same height as the old gauge, so pressure may be an underestimate in either situation, since the sensor is well above the carb. I believe the JPI gauge reading though I can't exclude there's some issue like vapor lock in the line from the carb to the sensor. Regardless, I at least partly believe the low reading because there was a small but measurable drop in fuel flow, which is measured distal to the engine driven pump before the carb and temporally correlates with the drop in fuel flow.

Yeah I'm trying to avoid replacing my engine driven pump out of general uneasiness without knowing it is the problem... My JPI fuel pressure readings are broad trends not rapid fluctuations.

Thanks for the very thoughtful response - a few notes: - engine driven pump is old - ~1650 SMOH in 2000, well before I owned the plane. I observed similar fuel pressure behavior (though not dropping deep below redline) when I first got the plane >1000 hours ago in 2014. I'm reluctant to replace it without clear evidence it's the problem though. - I don't know if the fuel pump case drain leaks - I see no obvious evidence of it - e.g. fuel dripping or fuel smell in the cowl after shutdown. However I suppose a brief full power ground run followed by re-inspecting might make sense? - My tank was near full when it happened, was filled starting from <10 gal the night before at the fbo. Later in that flight I tried a full power climb with boost pump off to test it out, and I could not reproduce the issue. My second recent flight when I stressed the system and could not reproduce the issue was on the opposite tank. I have bladders, and no tank work has been done since their install ~11 years ago. - I do wonder if ice crystals lodged in one of the screens - I of course sumped tanks on that very cold morning after the plane was refueled at the fbo. Ice or debris that cleared in a screen might explain the behavior. I kinda hope that's it. Screens were addressed at annual last April; I agree that should be done again (except the problem seems to have disappeared now :/ ) - It's a '68 C - the boost pump and engine driven pump are in series, not parallel.

M20C owner here - O-360-A1D, Marvel Schleber MA-4-5 carb, JPI EDM900. I've rpeviously had fuel pressure drops during climb close to redline (0.5psi) but without discernable effect on fuel flow. The behavior was similar before and after I had the JPI installed (the factory configuration was a fuel line all the way to the gauge in the cockpit :/ ). The behavior occurred when I first got the plane in 2014, but I haven't seen the issue in the last few years of flying regularly. The consensus had been that these events may reflect vapor lock in the fuel line to the pressure transducer, which comes off a separate port on the carb. Last week it happened again in more dramatic fashion, with fuel pressure dropping well below redline all the way to 0.1psi early in my climb shortly after turning off my boost pump, leading me to turn it back on. There was a slight drop in fuel flow (~1gph) as the pressure fell below redline, making me think this is a real sentinel event. But it ran fine and EGTs didn't budge, suggesting no fuel starvation to the engine. The behavior repeated on further brief attempts to turn off the boost pump during climb up to 6500, so I left the pump on until I leveled off. I then had no problem turning the pump off in cruise with the fuel pressure holding 2.5psi when level. Later in the same flight, I intentionally stressed the system by climbing full rich at max power with the boost pump off for 1000 feet, raising the pitch up to 10 degrees. I could not reproduce that issue - fuel pressure held at >4 psi. Yesterday, externally I inspected the fuel system on the ground from boost pump forward, with the system pressurized by turning the pump on. Everything looked normal, and I saw no evidence of a fuel leak. I then took it flying, again stressed the system with steep climbs at full power, boost pump off, at various altitudes and could not reproduce the issue. The only thing different about the day the problem happened was very cold ambient temps (high teens F) and cold soaked engine with CHTs in the 30s at startup despite the engine heater being plugged in at the remote fbo overnight. I did take on full fuel there the night before. What the heck?? Since there was a modest drop in fuel flow, it seems like this isn't just an issue in the separate line to the fuel pressure transducer. Should I investigate further? Could this been some ice passing through the fuel system and/or a transient partial obstruction in one of the fuel screens? Or is there an intermittent fuel leak between the boost pump and the engine driven pump? Or is this my engine-driven pump telling me it's going to die suddenly at an inopportune moment?

Easiest to say = fewest syllables - Id pick N3GG , N1MM or similar

What people choose to do with with their borescope during off hours in the privacy of their own hangar is their own business

This is an awesome idea if it works - having to drop the exhaust every year is a setup for other maintenance induced issues.

The metal is thicker on the powerflow, which may contribute to durability. There was a modest useful load loss when mine went in for this reason. Installing it did have dramatic effects on my carb'd O-360. Depending on how you run it, there's more efficiency or more power (and unfortunately more heat as well). The IO-360s don't seem to derive the same level of benefit - perhaps their factory exhaust design is better.

It's a really cool engine, but it sacrifices about 90 lb of useful load though in swapping for a 180HP lycoming O-360 I think. ...and something tells me the STCs for vintage Mooneys are not at the top of the list.

Great tip, and glad you’re back in the air!