Ground Connector - Caution

Last Monday, on departure from PWK (Palwaukee, just north of ORD at Chicago), I suffered a complete electrical failure shortly after takeoff. I was on an IFR flight plan, although fortunately I was still in VMC when this happened.

The problem turned out to be a connector which carries the ground connections from all the cockpit electronics (avionics, Battery Master switch, etc.) to the Ground Buss bar mounted on the engine side of the firewall. The connector is located more or less opposite the copilot’s left knee. It’s held in by a couple of screws which vibrated loose. The result was that everything switched off.

The fix was simple - tighten the screws. I’ve been told that there’s a good possibility that my airplane is missing some nylon capture-nuts that would have prevented this from happening. I’ll check on that at the first opportunity.

  • Mike.

Scary stuff Mike. At what point are AD’s going to be required to get CD’s attention re quality control? Opinions anyone. Gary

Last Monday, on departure from PWK (Palwaukee, just north of ORD at Chicago), I suffered a complete electrical failure shortly after takeoff. I was on an IFR flight plan, although fortunately I was still in VMC when this happened.

The problem turned out to be a connector which carries the ground connections from all the cockpit electronics (avionics, Battery Master switch, etc.) to the Ground Buss bar mounted on the engine side of the firewall. The connector is located more or less opposite the copilot’s left knee. It’s held in by a couple of screws which vibrated loose. The result was that everything switched off.

The fix was simple - tighten the screws. I’ve been told that there’s a good possibility that my airplane is missing some nylon capture-nuts that would have prevented this from happening. I’ll check on that at the first opportunity.

  • Mike.

Mike,

Sorry, I don’t recall if you have an SR-20 or -22. I’d hope you couldn’t get a complete electrical failure on a -22 from such a problem given the dual bus structure.

-Curt

Mike -

I’m assuming this occured in an SR20. Does the SR22 use two ground bus bars for it’s electrical system (realizing that there are two busses)?

Chris (45 days to an SR22)

Last Monday, on departure from PWK (Palwaukee, just north of ORD at Chicago), I suffered a complete electrical failure shortly after takeoff. I was on an IFR flight plan, although fortunately I was still in VMC when this happened.

The problem turned out to be a connector which carries the ground connections from all the cockpit electronics (avionics, Battery Master switch, etc.) to the Ground Buss bar mounted on the engine side of the firewall. The connector is located more or less opposite the copilot’s left knee. It’s held in by a couple of screws which vibrated loose. The result was that everything switched off.

The fix was simple - tighten the screws. I’ve been told that there’s a good possibility that my airplane is missing some nylon capture-nuts that would have prevented this from happening. I’ll check on that at the first opportunity.

  • Mike.

Mike,

Sorry, I don’t recall if you have an SR-20 or -22. I’d hope you couldn’t get a complete electrical failure on a -22 from such a problem given the dual bus structure.

-Curt

Could you ‘post a pic’ showing the exact location of this??? I have had 3 connectors fail/vibrate loose which didn’t cause total failure but rather flickering gauages and the 'lOW VOLTAGE" alarm. EVERYONE should be immediatley (thereafter often) checking these NUTS for security.

Thanks from all of us,

Don

Last Monday, on departure from PWK (Palwaukee, just north of ORD at Chicago), I suffered a complete electrical failure shortly after takeoff. I was on an IFR flight plan, although fortunately I was still in VMC when this happened.

The problem turned out to be a connector which carries the ground connections from all the cockpit electronics (avionics, Battery Master switch, etc.) to the Ground Buss bar mounted on the engine side of the firewall. The connector is located more or less opposite the copilot’s left knee. It’s held in by a couple of screws which vibrated loose. The result was that everything switched off.

The fix was simple - tighten the screws. I’ve been told that there’s a good possibility that my airplane is missing some nylon capture-nuts that would have prevented this from happening. I’ll check on that at the first opportunity.

  • Mike.

I was concerned about the possibility of a single-point-of-failure in the SR22’s electrical system. I know how hard it can be to be sure there isn’t one. So when I was in DLH, I spoke with the fellow, a Mr. Crawford, who designed the MCU. The MCU controls both electrical systems. He convinced me that they had at least given the subject some intelligent thought. But that doesn’t mean that there isn’t a single wire that couldn’t take out the whole electrical system.

Btw, Cirrus has had q/c problems with the MCU. THey are bringing production in-house to try to solve these problems. My a/c is on its second MCU and probably needs another one. The symptom is that sometimes in hot weather, the ALT 2 light will flash and the ALT 2 current will spike to maximum deflection. Yet, the bus voltage is normal and ALT 1 current is normal and no CB’s pop. So it must be the current sensor for ALT 2 and this is in the MCU. Also, pop’ing the ALT 2 CB and turning off ALT 2 have no effect on the max-current indications, but one can see the effect of turning off ALT 2 by the slight increase in the ALT 1 current as ALT 1 picks up the load.

Last Monday, on departure from PWK (Palwaukee, just north of ORD at Chicago), I suffered a complete electrical failure shortly after takeoff. I was on an IFR flight plan, although fortunately I was still in VMC when this happened.

The problem turned out to be a connector which carries the ground connections from all the cockpit electronics (avionics, Battery Master switch, etc.) to the Ground Buss bar mounted on the engine side of the firewall. The connector is located more or less opposite the copilot’s left knee. It’s held in by a couple of screws which vibrated loose. The result was that everything switched off.

The fix was simple - tighten the screws. I’ve been told that there’s a good possibility that my airplane is missing some nylon capture-nuts that would have prevented this from happening. I’ll check on that at the first opportunity.

  • Mike.

From what I have seen QC can miss things very easily givin the time frame needed for inspections.I have seen some of these guys pissed because the plane needed to be inspected quick and moved on to make it to the next spot in production.Some of these inspections take quite a while for a good qc inspector AND qc hates to be rushed.Some qc’s are very thourough and some jam through it.Cirrus does make sure at their best the plane is done right.But when you have a fast production line where time and speed is needed somebody might not get their pickles on their burger if that makes any sense.Stuff like these screws im sure cirrus will go back and look at who did what and make sure it never hapens again -j

Sorry, I don’t recall if you have an SR-20 or -22. I’d hope you couldn’t get a complete electrical failure on a -22 from such a problem given the dual bus structure.

-Curt

Curt-

 A complete electrical failure is possible.They said the titanic would never be sunk.Also read the report on United Flight 232.They had to deal with a complete hydro failure on the DC-10.Engineers never thought that to be possible but newtons law was active on that one.Never say never in aviation because you never know.Think of every scenerio that could go wrong and think what you would do to resolve it.BTW ,The flight crew on United 232 showed us some of the best airmanship of the 20th century. -j

Curt-

A complete electrical failure is possible.They said the titanic would never be sunk…

Oh, I fully believe we can get full electrical failure. I think the most likely scenario has already played out–smoke in the cockpit prompting the pilot to shut down both busses. But I didn’t think the problem Mike was describing would cause full failure.

-Curt

Curt-
A complete electrical failure is possible.They said the titanic would never be sunk…

Oh, I fully believe we can get full electrical failure. I think the most likely scenario has already played out–smoke in the cockpit prompting the pilot to shut down both busses. But I didn’t think the problem Mike was describing would cause full failure.

-Curt
Curt,
I’m not qualified to comment one way or the other, since N84MR is an SR20, not an SR22 - but please check with someone who knows.

Mike.

Could you ‘post a pic’ showing the exact location of this??? I have had 3 connectors fail/vibrate loose which didn’t cause total failure but rather flickering gauages and the 'lOW VOLTAGE" alarm. EVERYONE should be immediatley (thereafter often) checking these NUTS for security.

Thanks from all of us,

Don

Don,

I tried to look at it during my own preflight inspection; but I couldn’t find it with the kick panel in place. I could be wrong, but I think that the panel must come off to see it. Anyone else?

  • Mike.

PS - Have flown about 13 trouble-free hours since that event.