Narrative:

We were on downwind for [runway] 7L simulated single-engine on our last pattern of the day when I noticed one of the RPM indicators fluctuating and indicating very low even though both engines were clearly at full power. Within a few 15 or 20 seconds the other RPM needle did the same. At that point I realized this was no coincidence and something was wrong. I took a good look at the overall cockpit and couldn't find anything wrong. Because the sun was low and facing us I put my hand over the warning lights to verify they were not on. The altitude light seemed dimly lit. At that point I took the controls; set normal power on both engines and climbed back to a normal pattern altitude (before that; we were around 2;200 MSL because we were simulated single). I told tower we would be full stop (we were going to be anyways) and they advised us of traffic on the south pattern turning to base for [runway] 7R that we would follow to make our full stop on [runway] 7R; but clearly stated: base approved.at this point you can see that there was no time permitting to troubleshoot or even glance at instruments on the opposite side of the panel since I was focused on bringing the airplane back to a normal profile and talking to tower and looking for traffic. When I had a second to spare I looked and saw both altitude switches off. As I went to turn them back on; we had a complete electrical failure and me turning them back on did nothing. I continued the base; looked for the mentioned traffic but only saw it when I was on final and the airplane was less than a quarter mile in front. I did a tight 360 (knowing there was no other traffic in either pattern) and back on final I looked to tower to verify that we had a green light gun signal and rocked my wings to acknowledge. I pulled the emergency gear extension knob since I did not have a 3 green (no electricity) although I did have the nose gear in the mirror. I landed as smoothly as possible and as I exited the runway I took a minute to finally properly troubleshoot the electrical equipment. When I was able to have power back on I briefly explained to ground control that we had lost all electrical power on base. They simply asked if I had seen the light gun signal; I said yes and they cleared us to taxi straight to the ramp.

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Original NASA ASRS Text

Title: A PA-44 instructor discovered during the last training landing of the day that the alternators were OFF but aircraft lost complete power as he turned the switches ON. A safe landing followed.

Narrative: We were on downwind for [Runway] 7L simulated single-engine on our last pattern of the day when I noticed one of the RPM indicators fluctuating and indicating very low even though both engines were clearly at full power. Within a few 15 or 20 seconds the other RPM needle did the same. At that point I realized this was no coincidence and something was wrong. I took a good look at the overall cockpit and couldn't find anything wrong. Because the sun was low and facing us I put my hand over the warning lights to verify they were not on. The ALT light seemed dimly lit. At that point I took the controls; set normal power on both engines and climbed back to a normal pattern altitude (before that; we were around 2;200 MSL because we were simulated single). I told Tower we would be full stop (we were going to be anyways) and they advised us of traffic on the south pattern turning to base for [Runway] 7R that we would follow to make our full stop on [Runway] 7R; but clearly stated: base approved.At this point you can see that there was no time permitting to troubleshoot or even glance at instruments on the opposite side of the panel since I was focused on bringing the airplane back to a normal profile and talking to Tower and looking for traffic. When I had a second to spare I looked and saw both ALT switches off. As I went to turn them back on; we had a complete electrical failure and me turning them back on did nothing. I continued the base; looked for the mentioned traffic but only saw it when I was on final and the airplane was less than a quarter mile in front. I did a tight 360 (knowing there was no other traffic in either pattern) and back on final I looked to Tower to verify that we had a green light gun signal and rocked my wings to acknowledge. I pulled the emergency gear extension knob since I did not have a 3 green (no electricity) although I did have the nose gear in the mirror. I landed as smoothly as possible and as I exited the runway I took a minute to finally properly troubleshoot the electrical equipment. When I was able to have power back on I briefly explained to Ground Control that we had lost all electrical power on base. They simply asked if I had seen the light gun signal; I said yes and they cleared us to taxi straight to the ramp.

Data retrieved from NASA's ASRS site as of July 2013 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.