Originally Posted by
Pilot DAR
That said, I'm not sure I see how an alternator failure would cause a need for an urgent landing, or parachute deployment . The aircraft will be certified for 30 minutes flying on the battery, and thereafter the engine will still run, even with a flat battery.
Here is the answer from the report "The alternator driven gear (No 4 on Figure 3), situated at the front right side of the engine was found embedded in the inner left wall of
the engine housing which was pierced, also puncturing a machined oil duct in the housing (see Figure 4)."
So not only the pilot failed to recognize the lack of charging for nearly 20 minutes (out of the certified 30 minutes on battery), he also failed to recognize the escape of oil from the engine. He elected to make a precautionary landing due to reduction of engine power, which means that the engine was out of lubrication by that time. Although the report doesn't specify when the alternator-driven gear pierced the oil line, it is not so difficult to imagine that it also happened at the time of the alternator failure.
Which even more underlines that while troubleshooting one problem, we shouldn't develop a tunnel vision for many reasons. One of them is that multiple systems may be effected, more than the one we currently focus on.