SR 22 Electrical failure (long )

My son Casey who is 19 yr. old and I departed Rapid City regional airport Saturday morning at 7 AM local time for Hayes Kansas. We were flying down to the NCAA division two track and field championships to watch Casey’s friends compete in the regional championships.

We left Rapid City uneventful on a IFR flight plan in severely clear weather. Approximately 65 minutes into the flight I noticed that the amp meter was showing a slight discharge. I went through my checklist supplied by Matt McDaniel’s and started cross referencing some of the things that could be causing this. I could not find anything that was obviously wrong. Within 15 minutes the amp meter was showing a 15 volt discharge, and discharging harder with every strobe light flash. I checked the MFD engine parameters and found that the main bus was showing a 24 volt reading that was in yellow numbers. The essential bus continued to read 28 V. In checking the amp meter the No. 1 alternator was showing a zero charge and the No. 2 alternator were showing a normal slight charge. I recycled the circuit breaker for the number one alternator and nothing changed.

Both my son and I were very anxious to get to Hayes Kansas to watch the finals, however I could not imagine leaving the plane in Hayes Kansas attempting to get repaired and spending 9 hours driving back home. Therefore, I contacted center and explained my situation and ask for an immediate back route home to Rapid City. Center was very cordial and very helpful in all of the entire ordeal and in fact let me know along the entire route where every service center was that they were aware of that had a mechanic on site in case we should need that.

When the amp meter started showing a discharge the voltage for the main bus was reading 21.4 volts. However the Annunciator light for the amp one was not on and did not come on for at least another 15 minutes and even then only intermittently on and off. It wasn’t until we lost the alternator for approximately 35 minutes that the Annunciator light finally came on and then stayed on. At that point I shut the alternator No. 1 switch off and pulled the circuit breaker for the MFD.

So we turned around and headed back home. I started to shut off some of the nonessential equipment such as the landing light, the No. 2 Garmin and make certain that we didn’t have any other unnecessary electrical draw. I turned the MFD back on in an attempt to recycle the circuit breaker. Approximately 20 minutes into the trip back home the MFD began to drop below 20 volts with the main bus. The essential bus continued to read 28 volts. The amp meter continued to show a discharge but only about 7 volts now with all of the other equipment turned off. I thought about turning the MFD off again but when I tried to recycle it, the amp meter did not show any less of a discharge with the breaker pulled, so I just kept it on. We were in severe VFR. weather so I was not to concern about it. I was not sure how long the MFD would stay up and center kept touch with us at least every 10 minutes. Their primary concern was that we had a No. 2 alternator and a No. 2 battery which we informed them that we did.

I kept monitoring the main bus volts wondering when the MFD would be lost and at 17.1 volts we lost the MFD.

Shortly after losing the MFD, both fuel gauges on the center council began to show significantly less fuel then I knew we had in both tanks. I was flying on the left tank and both gauges were slowly dropping from 1/2 tank reading down to within a quarter tank reading within 10 minutes. I knew we were not losing fuel, so I knew that the gauges had to be losing electrical power. It was a bit nerve wracking watching your fuel gauges slowly go down to 0. And within 15 minutes of losing the MFD both fuel gauges read 0. I contacted center to inform them that I was beginning to lose more gauges but that I had all of my essential gauges to continue safe flight in VFR. I also knew from my flight plan that I would land with at least 38 gals of fuel left.

Shortly thereafter center contacted me and said that they were showing a 600 foot difference in my altitude with my reading off the PFD and what they were showing on radar. I cross-referenced this with the Garmin No. 1. The Garmin showed that we were 400 feet higher than the PFD showed but center had me at 600 feet lower for total difference of a thousand feet between Garmen No. 1 and center.

With in ten minutes of this, and about 35 minutes of turning back, Center calls and said they have lost our transponder. Looking down at it it was completely powered off.

Of course with the Garmin No. 2 shut down and the MFD powered off, the Garmin No. 1 had a constant message of no altitude reading and no input data from a number of channels and the storm scope failed message and the error message for no traffic as well.

PFD and Autopilot continued to work fine.

When Center passed us off to Ellsworth Air Force Base, Ellsworth brought me from 11,000 feet down to 5000. I was still about 24 miles from the airports so I asked them to stay at the higher altitude in case I needed altitude for any emergencies so they brought us down to 9000. However within 10 miles of the airport we began our decent to 5000 and upon the decent down I realize that I had lost the electric trim. As we began our dissent down to 5000 feet we then lost the electric RPM. gauge, oil pressure gauge, and oil temperature gauges as well. Everything read the default readings as if they were turned off.

As we began to lose altitude and reached the 5000 foot level Ellsworth Air Force Base passed me off to tower as we were within 5 miles of the airport. Immediately upon entering the downwind I then lost the noise canceling component to my headset and began to get a very load engine background noise in both sides of my headset. I got a little anxious at this point because I thought I lost my communications with the tower but I had already been cleared to land. I contacted tower back and I could barely hear their response with the noise that was in my headset. I tried adjusting squelch and the volume but it did not make any difference. I did hear tower come back and tell me that they could hear me loud and clear and understood that I was having difficulty hearing them. I looked over at the tower I could see the green light.

Upon entering my downwind we descended to four thousand feet which is pattern altitude, slowed the aircraft to 110 knots and tried the flaps with nothing. It took a lot of pressure on the stick as the electric trim was gone and I could not trim it. I informed tower that this was going to be a landing without flaps.

The communication difficulties got me a little bit shook and I turned to my base leg a bit too early. I was going to fast. I found myself over the numbers 300 feet high and 100 knots, and of course without flaps. I was extremely grateful that we had 10,000 feet of concrete. I did not touch down on the concrete until halfway down the runway and still doing 85 knots so it took a bit of breaking action to slow me down to make the alpha 2 turnoff. I still had about another 800 feet concrete but it was a way longer landing then I wanted it to be. However we were on the ground and safe and sound. Tower came back and asked why I did not use my flaps manually. Unbeknownst to them that was not one of my options.

We taxied to the ramp uneventful and shut down. Battery No. 1 was completely dead and battery No. 2 still had some charge and it.

We could smell the smell of burning electrical wiring upon shut down. It was obvious that something electrical had in fact burned out.

We contacted Cirrus’s 800 number and spoke to John who said that it was clear that the alternator No. 1 had burned out and that whenever had caused it to burnout had probably taken the main computer board with it is well. We started to take the battery No. 1 out because they said that it should be charged as quickly as possible to prevent any damage. The local FBO began immediately testing the electrical system to see if they could isolate the problem. Cirrus said that if they called Monday morning they would ship parts out immediately and we would have them Tuesday. Hopefully we could be up and flying by Tuesday evening. Once they find out exactly what the damage was and the problems, we will post them to bring everyone up to date.

Ironically, The number one alternator was just rebuilt last month in our annual. It had less than a dozen hours on the rebuild. We are investigating this.

Greg Scherr Rapid City SD

Hi Greg,

Glad to hear you handled the situation to a successful outcome.

Having an SR20 (and an old, not all-electric one at that), I have a couple questions about your post, and about SR22s in general.

In my dual-alternator SR20, if I lose an alternator (which I have had happen at least 3 times in flight), the remaining alternator picks up the slack, so I have zero drain on the battery. In fact, other than the small light indicating an alternator failure and no current on the ammeter when the bad alternator is selected, I would otherwise have no idea that there was any problem whatsoever.

Do I understand correctly that in the -22, when one alternator dies, systems start coming offline as the battery voltage drops, even if the other alternator is fully functional? It sounds like you were down to a fairly small set of functioning equipment (no flaps, no transponder, no trim, no MFD, etc.) while you still had one perfectly good alternator.

Is that just the way things are on a -22 (or an all-electric -20)? Or is that an indication of something much more serious than just an alternator failure?

Nice job! Thanks for a very detailed post as to what would happen when losing Alternator 1. Everything you posted is what I would expect to occur. Good point about the headset power - good to have some old passive headsets laying around. Thanks for posting the voltages at which equipment dropped out- surprised the MFD stayed up so long. I am going to make a dropout voltage chart & stick it with the checklist.

I had an alternator failure in a 172 and it gets your attention. You did an outstanding job - whoever rebuilt that alternator didn’t.

SR22 G2, 52PJ

In reply to:

Upon entering my downwind we descended to four thousand feet which is pattern altitude, slowed the aircraft to 110 knots and tried the flaps with nothing. It took a lot of pressure on the stick as the electric trim was gone and I could not trim it. I informed tower that this was going to be a landing without flaps.

I seem to remember discussing the other week that the trim can be driven by one
of two sources, the trim hat, which I think works off the main buss and the A/P,
which works off the essential buss. Would it be possible, to get back in trim, to turn
the A/P on to attitude mode (just press hdg?) and let it get the plane trimmed up for you?

Quick question. If you knew you had problems and were going to start losing systems, wasn’t there an airport closer you could land and drive home? So what if the plane is somewhere in the middle of nowhere. FYI Cirrus has designated employees that will fly anywhere to fix a plane.


Good to hear you are okay and I appreciate the details. As I was reading your experience, I’d have to agree with Stuart; instead of pressing on, it would be a much wiser solution to find an airport in the immediate area. If the basic troubleshooting didn’t solve the problem quickly, any electrical issue might turn into an electrical fire (or smoke in the cockpit). Pressing on won’t make the problem any better. Normally it makes the problem worse as you start losing various systems.


Thanks for the account of your electrical problem.

Just fyi, and for others, deep discharging any lead acid battery significantly decreases its life. My plan, should I lose the #1 alternator, is to shed everything from what is subsequently powered only by the #1 battery. Before landing, I might turn it back on just to lower flaps or trim or whatever I really need.

The burning your smelled after landing suggests why it might be a good idea to land asap even if you are in vmc and otherwise not in trouble; there may be some root cause that could get a whole lot worse.

In addition to your failed alternator or MCU (which controls the alternator), it sounds like the alternator failure light also does not work (though the ammeter did work and they are both fed by the same Hall effect sensor circuit in the MCU).

Question: does your electrical failure checklist include shedding load? Or, more generally, do you think whatever checklist you used was helpful, did you deviate it from it, etc.?

Do let us know what the root cause turned out to be and thanks again for taking the time and effort to post your account!

Good job either way. I would agree that landing anywhere is always better. I am curious to see what the issue is. This could all happen to us…in IFR conditions.

I just experienced this exact problem but I was fortunate to have caught it during my run up. Just called Cirrus and have not heard anything back as of yet, but the runup they had me do confirmed that alt 1 was dead. Why???

I had just taken a 30 minute flight to pick up a passenger and everything was fine during this flight so how in 10 minutes on the ground it died who knows. Of course it may have failed on the trip over and I just missed it as I rely on the alt 1 warning light to come on, which it did not nor did it show a warning during any of the runups. Again, why???


If ALT1 fails, the main bus, MBUS, will be powered from BAT1 and will remain
at ~24V until BAT1 discharges enough to start dropping in Voltage.

The essential bus remains powered by ALT2, and should stay ~28.75V

The essential bus is basically disconnected from the main bus, in this situation,
by a diode that is switched off (open) when the EBUS is at a higher voltage
than the MBUS.

The flap motor, trim controls, all engine gages, Garmin #2, MFD, transponder,
internal and external lights and auxiliary power all are powered from the main
bus. Some devices will run at lower voltages than others, so things will drop off
one by one, when the Voltage is no longer high enough to power that device.

The AP and its related servo motors (aileron trim and pitch servo) are powered
by the essential bus, so the AP should continue to work.

This is why its important to conserve juice on the main bus (BAT1) when ALT1
fails, so that engine gages, gage lights and flaps will remain useable. Also it would
be good to land ASAP before BAT1 gives out, so these ‘nice to have’ items
remain useable.



I believe you are correct in all points. One Alt 1 quits, Bat 1 goes down fast if things are not turned off. I should have turned off Bat 1 switch and saved it for flaps and trim upon landing. That would have probably saved me some clean underwear.

I will definitely do it should there be a next time. Alt 2 does not cross over and pick up any main bus elements. Would be nice if it did, but does not. I do not know enough to explain why and maybe others can fill us in on the details.


In reply to:

This is why its important to conserve juice on the main bus (BAT1) when ALT1
fails, so that engine gages, gage lights and flaps will remain useable. Also it would
be good to land ASAP before BAT1 gives out, so these ‘nice to have’ items
remain useable.

I assume the quickest way to do this is by flicking off batt 1 right?

In reply to:

If ALT1 fails, the main bus, MBUS, will be powered from BAT1 and will remain
at ~24V until BAT1 discharges enough to start dropping in Voltage.

Wow, I hadn’t realized that! I had assumed each alternator could take up the slack of the other in case of failure, like in the older SR20s. Thanks for the clarification!

With an ALT1 fail.

If you flick off BAT1, you will lose your engine gages, all gage lights, trim and
flaps and your headset ANR (and the other items listed).
Engine power would then have to be set by position of the power handle, as you
have no MP or RPM readings, and of course no MFD for EMAX data.
So I wouldn’t be too quick to flick off BAT1.

The POH just says to reduce loads.

My opinion would be to pull the CB’s for the MFD and transponder and to turn
off all exterior lights and any unnecessary interior lights and not use the trim, then
land as soon as possible. Engine gages will still operate, trim is available if
required, gage lights will still be working, Aux power for headset ANR is still
working and flaps can be used on approach. If you have longer to go, I’d
shut off more items, to conserve power for gages and flaps.

Of course the essential bus is powering Garmin #1, PFD (or Sandel and flight
instruments) and the AP, so those can stay on indefinitely.


Yes that is correct.

The trim worked fine with the AP. I switched from the GPSS mode to Heading mode once inside the airspace and the trim continued to work. Matt had taught us that on intercepting the ILS in Nav and Heading Modes.

Once I turned off the AP the trim failed manually. I should have went back to AP and flew the base and final with the Heading mode. That would have made the trim much easier to deal with.


Unfortunatly I did not realize that until I was over the badlands and Indian Reservations of South Dakota. With the VRF weather and 35 minutes left to home I pressed on. The only airport would have been on the Reservation or Hot Springs which is only 12 more minutes on to Rapid.

Probably not the best idea to press on once the Bat 1 went completely dead, but felt comfortable going on, as a good friend had a private landing strip half way between RAP and the reservations airport, the 777 buffalo ranch were Kevin Cosner filmed Dances with Wolves .


In reply to:

Normally it makes the problem worse as you start losing various systems.

The other thought is if it is necessary to press on (say flying over an overcast to reach a VFR descent) then it is preferable to put your fate into your own hands – rather than wait for systems to fail one by one, switch off BAT1 and ALT1, fly without the non-essential bus until on the approach, then switch back on so you can have flaps, Aux Fuel Pump, engine instruments, etc. for landing.


I agree. Based on my electrical adventures and reading about others in the Cirrus, I think the training and emergency checklists should be reviewed. The Cirrus is a complicated electrical machine.

It is my position that given any type of significant electrical failure, weather permitting, a landing should be made at the nearest airport. Troubleshooting is much easier on the ground with a cell phone dialed to the 800 line at Cirrus. Also on the ground other cues are available such as odor and smoke that can be masked aloft.

In my flying career too much emphasis in training is placed on troubleshooting electrical problems aloft versus getting on the ground to figure things out. The Canadian accident report on SwissAir 111 is the case study for this issue.



You are definitly more right than wrong. One of the factors I used for pressing on was the fact the western Nebraska and southern South Dakota is primarily badlands, unihabited and Indian Reservations.

I just didn’t have the heart to leave 203RF on the Pine Ridge Indian reservation in need of repairs. Had I had to go any further than Rapid City, I would have set done ASAP once I started losing other systems like the Radios ect.

thanks for the good advise.



the checklist is the list produced and sold by Matt McDaniels from Progressive Aviation. I can not stress strong enough what a great help his list was. Whom ever does not have one should get one just for this purpose. Matt’s training was excellent and lead me through each step during the entire process. One less thing I had to worry about if I was doing the right thing or not.