As a product manufacturer we get calls from customers with problems from time to time ranging from no start conditions to intermittent running. We have to try to solve most of these over the phone or by email. It can be challenging at times, trying to diagnose the issue based on customer observations which are sometimes not very reliable. The EFI is often the first thing customers blame.
In the last 2 years, we had 3 no start conditions. Two on new build Lycomings and one on a BBC. After weeks of head scratching by the customers and suggesting the most common places to look, we were finally sent videos of the engines cranking. I could tell right away that there was no compression. Turns out the cams on all these were installed 180 degrees out. Now if an engine builder can't get that right, you might wonder what other things they got wrong inside...
Chafing wiring is often good for intermittent running issues but can take a while to narrow down. This usually comes down to poor wiring practices or insufficient attention to chafe protection. A blown breaker is almost always a sure sign of some power wire touching ground
Recently had a Lycoming which was hard to start and finally broke a starter and some ring gear teeth. Sometimes this can be caused by slow cranking due to a weak battery or poor cabling. Customer was asked to replace the battery which he didn't do. On testing, cranking voltage was dipping into the 7s, rather than the minimum 9V a good setup should show. Flying an electrically dependent aircraft with a marginal battery isn't the best idea in any case.
With boosting, there was still kickback. Finally, with a timing light and phone filming the timing marks during cranking, in slow motion, we could see sparking happening well before TDC. Plug wires separated got rid of some extra sparking noticed in the video but the main problem was the flywheel was placed on the crank incorrectly which isn't good when the ignition system trigger magnets are mounted on the flywheel. This is hard to do since there is a master lug which is .025 larger than the other 5. I guess they just drew it down with the prop bolts. Customer warned to check flywheel for cracking around lug hole. Many hours wasted on this one.
Finally, had a customer that lost one ECU on a dual system in flight, on 2 separate occasions. Sent back the ECUs and the temp sensor inputs were fried both times. Strange, never seen that before in 30 years. Finally sent us photos of the installation and we saw that the IAT and CHT sensor cables were tie wrapped for a couple feet to the spark plug wires- an absolute no-no. This was done by an avionics tech who should have known better. Inductive and capacitance coupling is real when you have parallel wires close together with one having 30,000 volts on it.
Of course, we've had hundreds more experiences over 30 years but these recent ones stand out.
Anyway, a few more items added to the troubleshooting section of the manual and our collective mental database.
In the last 2 years, we had 3 no start conditions. Two on new build Lycomings and one on a BBC. After weeks of head scratching by the customers and suggesting the most common places to look, we were finally sent videos of the engines cranking. I could tell right away that there was no compression. Turns out the cams on all these were installed 180 degrees out. Now if an engine builder can't get that right, you might wonder what other things they got wrong inside...
Chafing wiring is often good for intermittent running issues but can take a while to narrow down. This usually comes down to poor wiring practices or insufficient attention to chafe protection. A blown breaker is almost always a sure sign of some power wire touching ground
Recently had a Lycoming which was hard to start and finally broke a starter and some ring gear teeth. Sometimes this can be caused by slow cranking due to a weak battery or poor cabling. Customer was asked to replace the battery which he didn't do. On testing, cranking voltage was dipping into the 7s, rather than the minimum 9V a good setup should show. Flying an electrically dependent aircraft with a marginal battery isn't the best idea in any case.
With boosting, there was still kickback. Finally, with a timing light and phone filming the timing marks during cranking, in slow motion, we could see sparking happening well before TDC. Plug wires separated got rid of some extra sparking noticed in the video but the main problem was the flywheel was placed on the crank incorrectly which isn't good when the ignition system trigger magnets are mounted on the flywheel. This is hard to do since there is a master lug which is .025 larger than the other 5. I guess they just drew it down with the prop bolts. Customer warned to check flywheel for cracking around lug hole. Many hours wasted on this one.
Finally, had a customer that lost one ECU on a dual system in flight, on 2 separate occasions. Sent back the ECUs and the temp sensor inputs were fried both times. Strange, never seen that before in 30 years. Finally sent us photos of the installation and we saw that the IAT and CHT sensor cables were tie wrapped for a couple feet to the spark plug wires- an absolute no-no. This was done by an avionics tech who should have known better. Inductive and capacitance coupling is real when you have parallel wires close together with one having 30,000 volts on it.
Of course, we've had hundreds more experiences over 30 years but these recent ones stand out.
Anyway, a few more items added to the troubleshooting section of the manual and our collective mental database.
Last edited:
