912UL no-start resolution
in General Tech Discussion
13 years ago
This post is to report the resolution to a no-start problem on my 912UL.
Background: Aircraft is 2005 DTA Voyageur 2, experimental WSCL LSA, engine SN 4407166, TTSN 330 hr, one owner/maintainer & always hangared. I never attempted to do "spark checks" with the ignition system/plugs etc. not fully assembled or otherwise give cause for an ignition system failure.
Symptoms: Last year, the engine became increasingly hard to start. It either started immediately or did not start no matter what I tried. (RPM was always 350 or more on the aircraft tach.) First I changed the original battery to a more powerful motorcycle battery and kept a battery tender on it. That worked for a while, then I could not start unless I had the tender connected to the battery during start. Then, when that did not work, I tried a new Odyssey PC 680. That did not work, even if using the battery tender during start. I suspected the ignition because all starts were instant, if it was going to start. My checks of the fuel system, carb sync (when I could get it started), and ignition switch showed no problem. I finally got my hands on an IgnitionMate, which confirmed no spark. On the advice of Dean at Lockwood Aviation, I pulled the two ignition modules and sent them in for test. (Thanks Dean.) One was confirmed bad. When I installed the new module ($925 later) along with the other good module, the engine starts every time. I do not understand why replacing only one module fixed the problem since the ignition circuits are independent. I have a key start ignition switch ("off, R, L, both, start" switch positions), so I can not start on only a single ignition circuit. However, when I check each circuit immediately after start, they are both working.
When I searched the Internet for others with this problem on a 912 UL, I found only one other instance. The resolution was the same although discovered by chance: one new ignition module fixed the problem. There is much counseling on the Web that 912 start problems are almost never ignition problems. Hopefully this post will help someone with a 912 start problem be a little more suspicious of the ignition.
Background: Aircraft is 2005 DTA Voyageur 2, experimental WSCL LSA, engine SN 4407166, TTSN 330 hr, one owner/maintainer & always hangared. I never attempted to do "spark checks" with the ignition system/plugs etc. not fully assembled or otherwise give cause for an ignition system failure.
Symptoms: Last year, the engine became increasingly hard to start. It either started immediately or did not start no matter what I tried. (RPM was always 350 or more on the aircraft tach.) First I changed the original battery to a more powerful motorcycle battery and kept a battery tender on it. That worked for a while, then I could not start unless I had the tender connected to the battery during start. Then, when that did not work, I tried a new Odyssey PC 680. That did not work, even if using the battery tender during start. I suspected the ignition because all starts were instant, if it was going to start. My checks of the fuel system, carb sync (when I could get it started), and ignition switch showed no problem. I finally got my hands on an IgnitionMate, which confirmed no spark. On the advice of Dean at Lockwood Aviation, I pulled the two ignition modules and sent them in for test. (Thanks Dean.) One was confirmed bad. When I installed the new module ($925 later) along with the other good module, the engine starts every time. I do not understand why replacing only one module fixed the problem since the ignition circuits are independent. I have a key start ignition switch ("off, R, L, both, start" switch positions), so I can not start on only a single ignition circuit. However, when I check each circuit immediately after start, they are both working.
When I searched the Internet for others with this problem on a 912 UL, I found only one other instance. The resolution was the same although discovered by chance: one new ignition module fixed the problem. There is much counseling on the Web that 912 start problems are almost never ignition problems. Hopefully this post will help someone with a 912 start problem be a little more suspicious of the ignition.
