pfactor

Thanks so much for joining the forum and participating, Andy. I've had my Aspen in my Mooney for 8 years and 1300 flight hours with absolutely no troubles. I had the synthetic vision option with the original unit, but didn't use it all the time due to low frame rates. I just exchanged my old unit for a Pro Max at the start of December 2019, and was really happy with the upgrade. The display is brighter and crisper, and I really like the larger fonts that are easier to read. And the faster processor made it so that I can use synthetic vision all the time. The new Pro Max unit didn't give me any problems for the first 26 hours. Just this weekend, the unit rebooted twice in during a 2.2 hour flight. I'll contact my dealer for help, and I've also got video of the Aspen during the flight if that would help you diagnose things. Contact me directly if you'd like to see that. I had one more 1.6 hour flight after the problematic one above and there were no issues on that flight. Phil

I used to have lots of hot start problems in my 1977 M20J, and asked Mark Rouch at Top Gun for advice. He said if it's been more than 1 hour, use the cold start procedure from the POH. That works like a charm for me.

Here's an update from a couple of years after fixing the broken wire in the magneto secondary coil and switching to Tempest fine wire spark plugs. I have had zero starting problems since doing those things. Hot starts, cold starts, warm starts. It's all great now.

Success! It was pretty much what bradp said above. The magneto overhaul shop found and fixed a break in the secondary coil (they did this for free, since they had just recently done the overhaul). They said that would cause poor spark at low RPMs for start, but would be ok at higher RPMs after starting. Now that's fixed and I also installed Tempest fine wire spark plugs. The plane started right up for my mechanic today. Oh, and we decided not to install the Slick Start. I'm looking forward to flying tomorrow!

What's this? I tried searching for it and couldn't find SI 1625. Do you have a link? I'd like to get 3 knots back. The shop that overhauled the magnetos last time said they would inspect and repair for free (since it's been less than a year since mag overhaul). But I take your point -- it may not even be worth doing that, and just pre-emptively switch over to Bendix mags if Slicks can have the terrible failure modes you described.

When I ordered the factory remanufactured engine in 2007, I don't think I was given a choice about what type of mags to get. So if Lycoming normally ships with Slick mags, that's what I've got. I'm not actually sure but I'll find out when I talk to my mechanic tomorrow. Based on this thread, here's my current plan. 1) Change out the spark plugs for Tempest ones. I haven't decided on massive or fine wire yet. 2) Send the mags back to the overhaul shop for inspection/repair. Test with a known good mag while waiting for that. 3) See if http://www.mooney.com/en/si/M20-59A.pdf was previously done, and if so undo it for my two-mag engine. 4) Check that the fuel drain tubes are not blocked. 5) Maybe install a SlickStart Thanks to everyone for the suggestions and help!

I think I'm going to have to decide between spending around the same amount of money for either a SlickStart or new Tempest fine wires. I'm leaning towards the new spark plugs since I haven't seen any support for the SlickStart idea. Oh, and the shop that overhauled the magnetos last year says they'll re-inspect and fix them for free. So we're going to do that as well.

Good idea. This isn't a conclusive indication, but when I deliberately flooded the engine to try to start, I had fuel coming out the drain tubes (as I was pushing the plane back in after giving up). I was wondering if there could be a problem like too much fuel at start time causing the behavior we're seeing. I'll ask the mechanic to check out the drain tubes.

I think I've only got the impulse coupling on the left mag. I found this SI M20-59, but that's about the landing gear. Did you mean a different one?

I have an impulse coupling. I updated the original post with that now.

I've got a 1977 J model with a Lycoming IO-360-A3B6. The other day I couldn't get it to cold start. Those have never been a problem for me. The prop turned, but there was no sputter or any a hint of combustion. I deliberately flooded the engine and tried a flood start, same deal -- no sputter. My local mechanic took a look, and couldn't figure out what was wrong. The spark plugs are firing, the P-lead is good, he checked the ignition switch and even tried bypassing the switch to see if that would help. Finally he put everything back together and gave it one last try and managed to get it started. He said the engine ran poorly after that start, but it may have had too much fuel after all the previous attempts. But he did get it started, and he told me to try it and see it would start for me. Last Saturday, it started immediately on my first cold start attempt. The runup was perfect, and engine operation was smooth for the 1.5 hour flight, with a good in-flight mag check. Went back to fly last Sunday and I was back to the original no start problem. No sputters, nothing. Flooded start didn't work either. Grrrrrr! So it's back in the shop and my mechanic is stumped. He says he's checked everything he can think of. The spark plugs are firing, the timing is within 2 degrees (he's going to adjust that). The ignition switch seems to work correctly, and bypassing it doesn't help. He mentioned that he's a big fan of SlickStart and has one in his airplane. He's not positive it will fix my problem, but it could help. I've seen mixed reviews in searching. I've been reading some threads that mention switching to Tempest fine wire plugs has helped some people with starting issues. I'm wondering if I should try those over the SlickStart. Other items of note: The magnetos were overhauled last November at annual. I've flown about 60 hours since then. The engine is a factory reman with about 1000 hours on it The spark plugs are REM38E (looking at my logbook -- it doesn't say the brand, but I think they are Champion). They have about 600 hours on them. My mechanic says they tested good. I don't know if he's tested the resistance (I just read up on that this weekend). The plane has an impulse coupling, not a shower of sparks. At my request, my local mechanic has talked with Mark Rouch at Top Gun Aviation. Mark is equally stumped about what's going on. Any ideas or suggestions would be appreciated.

I forgot to follow-up on this thread. We ended up overhauling the alternator. The brushes were worn (as someone suggested earlier in the thread). I think I had two problems: a bad voltage regulator and worn brushes on the alternator. Everything has been peachy since I did both those things. Phil

We had something come up today, so we're out (that's 2 less for lunch). Hope you all have fun! Phil

I'll have myself + my wife. Phil

I can make the 2nd or 10th Phil

Yup. Vy decreases with altitude, and Vx increases with altitude. Also, both are affected by weight. I've also got a J and had no problems with temperatures climbing at Vy all the way up to 17,000ft (see my post on this). The outside air temperature was warmer than standard too. Phil

Generally V speeds are published at max gross weight. Some V speeds are lower at lighter weights. The ones that change with weight are Vs0, Vs1, Vx, Vy, Va and best glide. For these speeds you can calculate the adjusted value with this formula: V' = V * SQRT(actual weight / max gross weight) In plain English, take your actual weight, divide by the max gross weight. Take the square root of that number. Then multiply by the V-speed at max-gross weight. Phil

I posted time to climb data before and after installing the PowerFlow exhaust in my M20J. The post has charts and everything! The short version: Before PowerFlow: 33 minutes to get from sea level to 14,000 indicated (16,000 density altitude). After PowerFlow: 42 minutes to get from sea level to 17,000 indicated (18,000 density altitude). Phil

Someone supply the plane and I'll give it a shot :)

Yeah, I did. The POH says that Vy at 10,000' is 82 kts, and adjusting for weight that's 79 kts. I started out climbing at 84 kts (sea level Vy adjusted for weight), and tried to spread the 5 knot IAS reduction over the climb to 10k. Above 10k, I pretty much kept the same trim setting and went with it. Sometimes I'd try giving a bit more up elevator or up trim, but that didn't seem to help much. Phil

I did my commercial, CFI and CFII check rides in my Mooney with Dick Miller in Caldwell, Idaho. He's a thorough, but fair examiner. I think my commercial exam was about 2 hours of oral and just over 1 hour in the air. Who's the examiner that gives 7 hour PPL check rides? Phil

I got my plane back from annual with the PowerFlow installed, and I'm happy with the results. I repeated the performance tests that I did before installation (see my first post in this thread). Obviously the weather was quite different this past weekend than it was a few weeks ago when I did the before tests. I've tried to equalize that by comparing the actual performance against the POH performance charts. With book performance as the benchmark, the closest I can get to a fair comparison is to see how the actual performance compared to the book. For the time-to-climb performance, I'm comparing the time to the same density altitude which should be equivalent. The aircraft weight was identical for both the before and after flights. After PowerFlow installation test flight 11/14/15 - 16:50 PST / 2350Z - KRHV Aircraft 1977 Mooney M20J Winds 290@11. Temp 16C. Field elevation: 135 ft. Density altitude: 450 ft. Actual weight: 2520 lbs. (max gross 2740 lbs.) Adjust V speeds for weight: V' = V * SQRT(2520 / 2740) Adjusted Vx: 62 kts Adjusted Vy: 84 kts Short-field takeoff: POH chart: 803 ft. ground roll; 1387 ft. over 50 ft. obstacle Actual: 880 ft. ground roll; 1384 ft over 50 ft obstacle I measured the ground roll using video, and the altitude over a 50ft obstacle using CloudAhoy (and the video looks like that value is about right too). I got right at book values for the short-field takeoff, which is also what I had before the PowerFlow was installed. I have a video of the takeoff, which is only from the under-wing camera. The in-cockpit camera didn't record properly. Climb performance The two immediate improvements I saw were in climb performance and cooler CHTs. I was able to climb to 17,000 ft indicated (density altitude 18,240 ft.). See the chart for the Stock vs. PowerFlow climb performance. Right around 9,000 ft density altitude, the PowerFlow climb was slightly better and kept going long. With the stock exhaust, the plane was pretty much done climbing by 16,000' density altitude. With PowerFlow, I was able to climb to 18,240' density altitude (I stopped at 17,000' indicated, and probably could have climbed a bit more but didn't want to bother with an IFR clearance). I've also attached the stock & powerflow climb charts too. CHTs The CHTs were dramatically cooler in the climb and cruise. See the CHT chart. During the climb, I try to keep the highest EGT around 1200F (about what I get when full-rich on a sea-level takeoff), and keep the CHTs below 380F. Normally when doing a cruise climb, I can keep the CHTs down by doing a cruise climb with the cowl flaps trailing open. During these tests, I was climbing at Vy until there was no climb left. During the Vy climb test with the stock exhaust, I had to keep a close eye on the CHTs even with the cowl flaps full open. I had to richen a bit more a few times in the climb to keep the CHTs under 380. With the PowerFlow exhaust, CHTs were much easier to manage. In cruise, the max and average CHTs were way lower with PowerFlow than the stock exhaust. Cruise performance I replicated the PowerFlow Mooney M20J tests at 2500 & 2600 RPM at 11,500 ft, 7,500 ft and 2,500 ft. I couldn't quite get to 2700 RPM so I used 2600 RPM instead. I saw very small increases in true airspeed (1-4 knots) compared to the stock exhaust using the POH as a benchmark. Here's a chart comparing the stock & PowerFlow performance vs. the POH values for the conditions. Small differences from the "before" tests originally posted. When I originally posted my "before" data showing my airplane's performance vs. the POH values, I made some minor errors in doing the interpolation. I've corrected those now and have included updated charts in this post. Finally, I didn't do a cruise performance test at 14,500 during the after test (I did one at 17,000 instead). After getting back home, I realized the cruise performance charts top out at 14,000 so I don't have POH values to compare against for 17,000. I removed the 14,500 cruise performance values from the "before" chart to make it easier to see the difference with the "after" chart. I have also attached the before & after cruise performance charts to this post. You'll notice that the fuel flow was much higher during the PowerFlow test at 2,500 ft. That's because I didn't want to run so close to peak EGT at that high of a power setting (I should have done the same on the before test). Weight penalty For the record, the PowerFlow exhaust weighs 5 lbs. more than the stock exhaust that was removed (20 lbs vs. 15 lbs.). Not a big deal for me, but I wanted to mention this. Overall conclusions I'm happy with my purchase, and I'd make the same decision again if I needed to. The better climb performance and cooler CHTs are worth it. I saw slightly better cruise speeds, but I wouldn't call this a speed mod. Powerflow claims the following for a Mooney 200 HP 5 -7 knots faster cruise speeds 10% – 15% increase in rate of climb 0.5 – 1.5 gph reduction in fuel burn at equivalent airspeed Improved Take-Off Performance (100’ – 300’ reduction in ground roll) Increase in Service Ceiling of 2,000’ – 5,000’ Cooler CHT’s I did not see 5-7 knots faster cruise on my test flight. I spent about 5 minutes at each altitude for the cruise tests. Maybe if I gave it more time, I'd see bigger gains. I'll pay attention to this on future flights. I can probably do some more comparisons against previous flights where I've got true airspeed data available. The climb performance was better. Because the temperatures and density altitudes were different on the two flights, it's hard to do a real apples-to-apples comparison, but I'd say a claim of 10%-15% increase in climb rate is reasonable. I didn't measure the "reduction in fuel burn at equivalent airspeed" this time. I may test that later. For takeoff performance, I did not see a 100'-300' reduction in ground roll. I did see an increase of at least 2,000' of service ceiling, and most definitely saw cooler CHTs. Phil

Thanks! I used the GPS data from my Garmin 796 to upload to CloudAhoy. I'm an engineer and a Mooniacal pilot Phil

Ok, I did the "before" tests. My plane is in the shop for its annual and getting the Power Flow exhaust installed. Here's the results from my before-installation performance tests. 10/24/2015 - 12:30 PDT / 1930Z - KRHV Aircraft 1977 Mooney M20J before installing PowerFlow exhaust Winds calm. Temp 27C. Field elevation: 135 ft. Density altitude: 1,600 ft. Actual weight: 2520 lbs. (max gross 2740 lbs.) Adjust V speeds for weight: V' = V * SQRT(2520 / 2740) Adjusted Vx: 62 kts Adjusted Vy: 84 kts. Short-field takeoff: POH chart: 993 ft. ground roll; 1537 ft. over 50 ft. obstacle Actual: 1100 ft. ground roll; 1500 ft over 50 ft obstacle I measured the actual performance by using a video camera under the wing and looking at when the wheels actually left the ground. Here's the video of the short-field takeoff. Cloud Ahoy says the takeoff distance was 1483 ft. I was pretty happy to get the POH performance . Climb performance: I climbed until I couldn't keep a consistent 200 fpm climb, which was around 14,500 ft indicated altitude (16,000 density altitude). See the before-climb-chart.PNG attached. Cruise performance: I measured cruise performance at 14,500 ft, then I tried to replicate the PowerFlow Mooney M20J tests at 2500 & 2700 RPM at 11,500 ft, 7,500 ft and 2,500 ft. I couldn't quite get to 2700 RPM so I used 2600 RPM instead. I got pretty close to the POH performance (within 5%) at all altitudes. I've attached charts showing the actual speed & fuel flow compared to the POH values both as knots/gph and as a % difference from the POH. When I get the plane back, I'll repeat these tests with the PowerFlow installed. The weather conditions will be different, but hopefully comparing against the POH values will allow for a fair comparison. Phil

Yeah, the tests will certainly be done under different weather conditions. I think all I can do is collect what the actual conditions are on both days.