Narrative:

This is the combined recollection of first officer and me. I was the pilot not flying; he was the pilot flying. At FL450 we noticed the battery 1 indication on the mfd was amber and increasing. When the first officer first noticed it was around 29.5V but rising quickly. I grabbed the QRH but within a few seconds the voltage had reached about 31v and still rising. About this time the amber 'batt exceedence' cas message appeared. We both agreed (per the QRH checklist) we should turn the batt 1 switch off; which we did. By that time we had pulled up the electrical system page on the mfd. We noticed that gen 1 was putting out very high voltage and the amperage appeared fluctuating. If I recall correctly; we started the process of now looking up the QRH for a gen 1 failure; but within the next 10-15 seconds the cas lit up with about 20 messages simultaneously (enough [so that]they couldn't all be displayed at once). At the same time; numerous indications failed. The ihsi went away. The autopilot disconnected and the cabin began to climb (we think both prsov's closed). We both remembered there was no 'golden' cas message. We never received a 'gen 1 fail' cas message. At this point we donned O2 masks; began an emergency descent; and declared an emergency. However; we couldn't get any additional drag on the plane as the spoilers and landing gear were both failed (flaps as well). What resulted was a bit of a tug of war between knowing we needed to get to a safe altitude and trying not to overspeed the plane; or not to overspeed it too much. The overspeed we had was only in the higher altitudes as a mach overspeed (mmo). Once down to thicker air; we were able to find an acceptable rate of descent by keeping it way below the vmo speed. In the initial descent we had a resolution advisory (RA) with another aircraft that we were in visual contact with the entire time. Sometime (perhaps 45-60 seconds into the event); as the cabin was climbing through around 10;000 ft; we decided to manually deploy the O2 masks for our two passengers as well. There were several more system failures on the way down including all fuel indications 'X's over all items on the fuel synoptic (strangely enough; I seem to remember the right fuel gauge started working again somewhere on the way down); and a few other ones we can't remember but just know more messages appeared. We are not sure exactly all of the items that had failed but in retrospect; it is possible that items on both the number 1 and 2 side had failed due to the #1 gen dragging down the system voltage. On the way down our transponder was also malfunctioning. It was apparently 'stuck' at some altitude. Also; at some point (not sure exactly when or at exactly what altitude) we had an RA with another aircraft. I saw the plane 3 to 5 miles away and had already turned away; but we got the RA anyway. Sometime after this ATC had us turn the transponder either off or just on; without an altitude squawk. We got clearance to descend all the way to 10;000 ft. Once there; and stabilized; we removed our oxygen masks and began a more in-depth review of what happened. It was obvious to us that gen 1 was malfunctioning; though not obvious why it was still showing green in the electrical system (though only putting out around 14V and a few amps). We could not find any electrical emergency or abnormal procedure that encompassed our current situation in the checklist. We decided since the generator was obviously not acting normal; and we definitely could not harm the system any more by doing so; that we would start by turning it off. Once we put the switch in the off position; systems immediately started working again. The number of cas messages began to reduce; until we eventually were able to eliminate most all of them except for gen 1 off; shed bus off (normal for that condition) and bleed 2 off. The right prsov never opened again. We considered flipping the switch off and back on; but the aircraft was fine and wewanted to leave well enough alone. With the aircraft mostly restored to normal operation; we decided to divert to a major metropolitan airport instead of land at a country airport nearby; with the assumption maintenance would be more readily available and services would be available to our passengers. The weather conditions were solid VFR between us and the airport and everything was stabilized system wise.in retrospect; we feel like embraer needs to address the situation of generator over-voltage in their emergency checklist as no such procedure currently exists. Our company will be in communication with them as a result of this incident. Perhaps it is because the generator is supposed to automatically remove itself from the buses; which it did not do in this case. The multiple failures that occurred when the bad generator dragged down the remaining bus voltages created an overwhelming array of failures that distracted and prevented us from being able to deal with the problem until we had descended an had the aircraft stabilized.

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Original NASA ASRS Text

Title: A Phenom 300 at FL450 developed a GEN 1 over voltage which caused a BATT EXCEEDENCE CAS message. After turning BATT 1 OFF; numerous system failures occurred including the HPSOV valves closing. An emergency descent was begun and reaching 10;000 FT most systems returned so the crew diverted for maintenance. No checklist was found for a generator over voltage condition.

Narrative: This is the combined recollection of First Officer and me. I was the pilot not flying; he was the pilot flying. At FL450 we noticed the battery 1 indication on the MFD was amber and increasing. When the First Officer first noticed it was around 29.5V but rising quickly. I grabbed the QRH but within a few seconds the voltage had reached about 31v and still rising. About this time the amber 'BATT Exceedence' CAS message appeared. We both agreed (per the QRH Checklist) we should turn the BATT 1 switch OFF; which we did. By that time we had pulled up the Electrical System page on the MFD. We noticed that Gen 1 was putting out very high voltage and the amperage appeared fluctuating. If I recall correctly; we started the process of now looking up the QRH for a GEN 1 failure; but within the next 10-15 seconds the CAS lit up with about 20 messages simultaneously (enough [so that]they couldn't all be displayed at once). At the same time; numerous indications failed. The IHSI went away. The autopilot disconnected and the cabin began to climb (we think both PRSOV's closed). We both remembered there was no 'golden' CAS message. We never received a 'GEN 1 FAIL' CAS message. At this point we donned O2 masks; began an emergency descent; and declared an emergency. However; we couldn't get any additional drag on the plane as the spoilers and landing gear were both failed (flaps as well). What resulted was a bit of a tug of war between knowing we needed to get to a safe altitude and trying not to overspeed the plane; or not to overspeed it too much. The overspeed we had was only in the higher altitudes as a Mach overspeed (Mmo). Once down to thicker air; we were able to find an acceptable rate of descent by keeping it way below the Vmo speed. In the initial descent we had a Resolution Advisory (RA) with another aircraft that we were in visual contact with the entire time. Sometime (perhaps 45-60 seconds into the event); as the cabin was climbing through around 10;000 FT; we decided to manually deploy the O2 masks for our two passengers as well. There were several more system failures on the way down including all fuel indications 'X's over all items on the fuel synoptic (strangely enough; I seem to remember the right fuel gauge started working again somewhere on the way down); and a few other ones we can't remember but just know more messages appeared. We are not sure exactly all of the items that had failed but in retrospect; it is possible that items on both the number 1 and 2 side had failed due to the #1 Gen dragging down the system voltage. On the way down our transponder was also malfunctioning. It was apparently 'stuck' at some altitude. Also; at some point (not sure exactly when or at exactly what altitude) we had an RA with another aircraft. I saw the plane 3 to 5 miles away and had already turned away; but we got the RA anyway. Sometime after this ATC had us turn the transponder either OFF or just ON; without an ALT squawk. We got clearance to descend all the way to 10;000 FT. Once there; and stabilized; we removed our oxygen masks and began a more in-depth review of what happened. It was obvious to us that GEN 1 was malfunctioning; though not obvious why it was still showing green in the electrical system (though only putting out around 14V and a few amps). We could not find any electrical emergency or abnormal procedure that encompassed our current situation in the checklist. We decided since the generator was obviously not acting normal; and we definitely could not harm the system any more by doing so; that we would start by turning it OFF. Once we put the switch in the OFF position; systems immediately started working again. The number of CAS messages began to reduce; until we eventually were able to eliminate most all of them except for Gen 1 OFF; SHED BUS OFF (normal for that condition) and BLEED 2 OFF. The right PRSOV never opened again. We considered flipping the switch OFF and back ON; but the aircraft was fine and wewanted to leave well enough alone. With the aircraft mostly restored to normal operation; we decided to divert to a major metropolitan airport instead of land at a country airport nearby; with the assumption maintenance would be more readily available and services would be available to our passengers. The weather conditions were solid VFR between us and the airport and everything was stabilized system wise.In retrospect; we feel like Embraer needs to address the situation of generator over-voltage in their Emergency Checklist as no such procedure currently exists. Our company will be in communication with them as a result of this incident. Perhaps it is because the generator is supposed to automatically remove itself from the buses; which it did not do in this case. The multiple failures that occurred when the bad generator dragged down the remaining bus voltages created an overwhelming array of failures that distracted and prevented us from being able to deal with the problem until we had descended an had the aircraft stabilized.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.