I’ve done a terrible job and posting lately… my apologies… What can I say… busy… busy, I guess.
Remember these fly and ski trips??
Sadly… I haven’t done one in a while.
Of course, I was away and without an airplane for a while but now that I’m back. Nothing but poor excuses… very busy at work, worried about how the messed up arm will take it, being too fat to fit into my ski clothes, etc… All are contributing factors.
A couple months ago, I decided it was time to try again. The snow at the Wolf Creek Ski area near Pagosa Springs, CO was awesome. My flying buddy has his car there and confirmed that the snow was indeed very, very good.
At the crack of dawn on the appointed day I was ready to go, pushed the airplane out, and fired her up.
Uh… oh…
Something wasn’t quite right. It seemed a cylinder was missing – as in not firing (as opposed to someone stole it) – while operating on only the right magneto.
If you recall, I replaced the left magneto (here) with a P-Mag. That new P-Mag ignition system was running normally. The old magneto magneto ignition system was not running so normally.
This had happened once before and the condition cleared itself. I decided to take off with my flying buddy and hope that it went away. This isn’t quite as bad as it sounds as the magneto is doing very little when working combination with a p-mag. The p-mag spark is so significant and timing advanced that by the time the magneto fires, most of the work is done.
No matter what variable was tried (mixture rich, mixture lean, carb heat, high rpm, low rpm, all electronics on/off, etc.), the problem persisted so I sent my buddy off without me to enjoy the fantastic snow conditions. I focused on gathering some data. It was clearly cylinder #3. The EGT would climb very high, 1500+, when running on just the magneto. I’m not certain of this but I think I read somewhere that this is an indication that the fuel/air mixture was burning in the exhaust pipe instead of the cylinder.
If not already obvious, I’m not a fan of magneto’s so this was the very opportunity that I had been waiting for!
YAY!
As soon as business hours arrived, I was on the phone ordering a P-Mag from Emag Air. They very quickly shipped it out and I began preparing the airplane for it.
Sadly, I was so focused on the change that I completely forgot to take photos!! I know… terrible…
That preparation involved removed the old magneto, spark plugs, and plug harness. The p-mag requires power and ground as well as providing a signal for the tach. So, some wiring work was needed. All the same tasks as the last time around.
A couple days later the p-mag arrived and I went to work installing it. That is a very simple task – especially with all the prep work completed. If you’ve never timed a p-mag – it is something to behold. All the work that is required for a magneto?? Nope – none of that with a p-mag. Synchronizing the two of them – very simple!
When it was time to test, she fired right up and the previous problem was gone!!
DOUBLE YAY!!
I’ve put a good number of hours on the RV-4 since the installation of the second p-mag ignition system and I am very happy with it.
When running one p-mag and one magneto, the difference between them is fairly significant. The rpm drop when running from both to just the p-mag was nearly zero. Between just the p-mag and mag was 100+ rpm. Switching in-flight was VERY noticeable. With two p-mags, there is a 40 rpm drop going from both to just one of them. Individually, they seem to run exactly the same and that feeling is MUCH better than running on one mag. Meaning, the engine sounds and feels like it is running normally as opposed to just ‘sorta running’.
I would have never gone flying with a failed mag check, reads as you did though.
Thanks for your tech update on the P Mag and performance. The Bendix mag is a tough old gal but prone to failures. So I think you have a solid ignition system now. Keep us updated on the Vans 4, I enjoy all the fixing you are doing.
My last two flights ( taking instruction or Dual ) did not go so well. I had a lot of fun and saw amazing mountains up close but I failed to check airspeed before a forward tumble. There is a giant difference between 80kts and 150kts that I used. The owner in the camera chase plane said it looked awesome, then he found the damage I had caused. On the last flip, the windshield was hit with a lot of black oil. I only had side vision until I dove and blew it off. Still, I had to look through brown smear back to the airport. I thought the air/oil separator had come open. It turned out to be prop hub……
So a week later I had to go up with the owner and master acro pilot and prove I actually know how to fly. After a reasonable amount of ( ass chewing ), we got into another airplane and I taxied and took off. The flying went well and I had to show my sloppy acro abilities and then he took me sightseeing. Running rocky canyons with him was very fun. Then back to the airport to do five touch and goes in a 25 mph crosswind, The 38 mph gusts finally got me and he landed. I asked him to taxi back as the winds were getting worse quickly. He is OK with me and said I was one damn good tailwheel pilot. So I can fly at his school whenever I can afford it. He is taking over as my instructor though.
Be safe and keep flying.
Good morning John from a former Q2 guy in Canada.
Always interesting reading you, back in the 90’s we did exchange quit a bit about the Q’s. I was one of the first to implement the Gall fix after exchanging back and forth with him. That made my first flight possible and encouraged many more in a short time period and receiving many thanks for the documentation on the implementation. Sold the Q2 and built a Zenith 601-hds that I sold after a life changer event. Was out of the plane world for a while and bought a Zenith CH-300 4 years ago and went thru about the same scenario with the P-Mag. The plane had a slick and one of the very first edition of Lightspeed. One day the slick started causing issues so I decided to replace it with a P-Mag for all the good reasons. Was happy with the two electronic system, B U T something was not totally right, I had the impression that it was missing a beat occasionally. After a lot of reading and questions I figured that the Power curve of the two was not identical. So I removed the old Lightspeed and replaced it with a second P-mag. They are now dancing together and NO missing beat…
Michel…..
Regards
Hi Michel – great to hear from you again!! Yes, dual p-mags is working very well for me as well! I’m very happy. I also love the automotive plugs and the fact that I can replace all eight of them each year for less than half the cost of ONE new aviation plug!