SR22 2002 Alt 2 light intermittent

See the attached document.

Open up the MCU and look for loose bolts and nuts. Look at page 5 at the picture. See those long bolts with retaining nuts (on the left side and lower center). Current from the alternator and battery flow through those bolts. If a nut is loose, you will get erratic voltage and current readings on your MFD.

You might want to become a member - there is a lot of info like this on the member side.
ALT 2 Fail light problems.pdf (868 KB)

Thanks for that info Paul. This is my second year as a member.

Sorry, I saw this was on the non-member side so I guessed that you were not yet a member. Should have checked first… [:D]

I have owned a G2 for 11 months and I do my best to read up a little every day on COPA. I just saw this post and for the past 11 months I have always have had my ALT 2 ON on the ground and during Taxi. Now I will adjust my preflight procedures accordingly.

So, aside from (1) aggressively leaning on the ground and (2) keeping ALT2 off under 2,000 RPM and (3) flying LOP; is there anything else stated in the Cirrus POH that I might want to “better understand” before I inflict further unnecessary damage to my plane?

Thank you - Greg

Greg:

All three of the items you mentioned are actually not in the POH. That is why we discuss them here. You should read the POH cover to cover but realize what you read there does not cover all the best practices learned in the field.

Hi Brian,

What I was trying to communicate in my previous post is exactly what you stated above. All three items I mentioned are stated in the POH (see my list below), but the solutions are NOT stated in the POH.

  • the POH states that the MIXTURE should be FULL RICH for start up and after startup there is no mention of MIXTURE until Before Takeoff checklist. That would insinuate taxi at FULL RICH with the boost pump ON which will likely lead to fouled plugs, especially at my home airport. Solution = lean aggressively during taxi, boost pump off.
  • the POH states that just after start-up both ALTs are to be ON and maximum continuous engine speed for taxiing is 1000 RPM. In this example, if I follow the POH, I risk damaging the pins or connector J111 in my MCU. Solution = ALT 2 OFF below 2,000 RPM.
  • if I was to always lean for BEST POWER (an option stated in the POH) I could induce damage that would likely not occur if I was to always fly LOP. Solution = cruise LOP.
    As a new pilot and owner I am just finally realizing that there are conflicts that exist if one compares the POH to “Best Practices”. Thankfully there is COPA and CPPP engine management seminars. Now for the usual disclaimer: this post and previous posts and the words stated therein make no claims or recommendations that should be construed as advocating operating any aircraft contrary to the limitations and procedures stated in the Pilots Operating Handbook.

Cheers - Greg

That is the problem. People read the POH literally. None of the best practices are prohibited by the POH. You are merely “filling in the blanks” on how to operate the aircraft from an owner efficient perspective. Only the limitations in section 2 tell you what you cannot do. So your statement: …

“Now for the usual disclaimer: this post and previous posts and the words stated therein make no claims or recommendations that should be construed as advocating operating any aircraft contrary to the limitations and procedures stated in the Pilots Operating Handbook.”

…is really not necessary. Nothing here goes against the POH. Just as the POH does not list all the items you need to learn how to fly; it also does not list all the best ways to fly. That is not the purpose of a POH.

Hi, perhaps someone can help me, I see this topic is from a while but…

I’m flying a 2005 sr22 with avidyne entegra. A few months ago, the ALT 2 started to turn on in cruise flight, with no changes on charge or voltage. This happened in night flights, there wasn’t any trouble flying in daytime.

Past some month it started to turn more often and a slight change in Ess bus voltage that dropped bellow 28.

Last two flights after 10/15 min flight, the alt2 light turns on, and I have a critical drop on e.bus voltage. Yesterday landed with 23 volts.

A month ago, with my annual, we sent this alt for inspection and service center found minor problems and “fixed it”. But I’m still having problems and past time this are becoming more serious.

Now they have no idea where is the problem and ask me to change alt2 for a new one, and alt2 field control. But I believe they have no idea and I don’t want to change a part that is not causing the problem.

Resume:

After I start the flight, 10/15 min my alt 2 signal turns on and my voltage starts to drop.

Any clues or help?

Thankss

There are multiple things that could be going on. Do you have engine data that you can share? That would help us recommend something.

One thing to remember, the only parts of the POH that are regulatory are the limitations section and the weight and balance section. Everything else is just what the manufacturer and their lawyers considered best practices when the POH was published.

This is a SR22 gen2 wirth avidyne entegra serial #1600
I have a IO550N with 200 hours since new.
Alt 2 was sent for inspection since this problem started and there where no issues found.
Never made any change on a MCU or any electrical change.

Thanks for your help

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