Source: https://www.avweb.com …-+Friday+March+27%2C+2020
This sounds bad- shoddy maintenance. The link above has much more- poor training, other maintenance issues than those listed below.
...FAA’s initial findings found significant maintenance issues with two of the engines. “Inspection of the engines on the B-17G … established magneto and ignition failures existed. Regarding engine 4, to prevent the magneto P-leads from separating from the magnetos, someone had attempted to rig the magneto leads in place with safety wire. Inspection and testing of engine 4 left magneto revealed the movement of the safety-wired lead caused grounding to the case, which rendered the magneto lead inoperative. In addition, the right magneto of engine 4 was found unserviceable. The cam follower was worn beyond limits and the point gap was less than half the measurement required by service documents. When tested, the magneto produced weak or no spark to four of the nine cylinders. All spark plugs were inspected and required cleaning and all electrode gaps were out of tolerance,”...
FAA’s initial findings found significant maintenance issues with two of the engines. “Inspection of the engines on the B-17G … established magneto and ignition failures existed. Regarding engine 4, to prevent the magneto P-leads from separating from the magnetos, someone had attempted to rig the magneto leads in place with safety wire. Inspection and testing of engine 4 left magneto revealed the movement of the safety-wired lead caused grounding to the case, which rendered the magneto lead inoperative. In addition, the right magneto of engine 4 was found unserviceable. The cam follower was worn beyond limits and the point gap was less than half the measurement required by service documents. When tested, the magneto produced weak or no spark to four of the nine cylinders. All spark plugs were inspected and required cleaning and all electrode gaps were out of tolerance,”