lml@lancaironline.net Mailing List Archive

At the strong recommendation of Lancair builder/flyer Bill Harrelson, I installed backup “steam gauges” for attitude, altitude and airspeed…just to the right of my 2-screen Chelton EFIS…on my IV-P panel. I have had three failures/shut downs of at least part of the EFIS in two years/500 flying hours, not counting periodic GPS loss of signal/LOI/accuracy. In all three cases, the remaining components of the EFIS continued to work. Two cases were in VMC conditions. In the third case, the PFD failed/power cycled on final approach in instrument conditions at night. The MFD immediately and automatically changed to PFD display—as it’s supposed to; but I transitioned to the steam gauges anyway for the rest of the approach. I have not seen that specific failure before or since. Static discharge?? …who knows…

My assessment is that safe operation of the airplane was not compromised during any of the above, but like others on this list, I believe that it’s only a matter of time/place for a failure of any part of the airplane; and especially for any piece of avionics gear. Redundancy, backups, and practice with them are requirements for me.

Bob

From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of John Hafen
Sent: Monday, June 21, 2010 12:22 PM
To: lml@lancaironline.net
Subject: [LML] Glass Panel Suggestions?

On one of my first solo take-offs after "finishing" my IVP, I had a GADAHARS failure, on climb-out.

I was VFR and the weather was good, so it wasn't an extreme emergency, but I was pretty happy I had installed full size airspeed, attitude and altitude steam gages to back up my Cheltons.

A new software update quickly fixed the GADAHARS which has performed flawlessly for the last 250 hours. But I'm still happy to have the backup gages.

My steam gage attitude indicator does not have an internal battery backup. If the recession ever ends, I may look into replacing that unit with one that has a battery backup.

John Hafen

IVP 413AJ

On Jun 18, 2010, at 1:00 PM, vtailjeff@aol.com wrote:

Stan,

Were it not for the mechanical backup guages I installed in my IVP we would not be having this conversation. If you are only concerned about lightning you are only looking at a small portion of the hazard. Brent Regan has posted extensively on this subject-- his remarks are worth their weight in gold.

Jeff

It would be

interesting to know how many pilots flying dual EFIS panels with backup gauges

were forced to rely on the gauges at some point.

-----Original Message-----
From: Stan Fields <sdfields@austin.rr.com>
To: lml@lancaironline.net
Sent: Thu, Jun 17, 2010 5:07 am
Subject: [LML] Re: Legacy Glass Panel Suggestions?

Hello Tom,

I was afraid someone would say that. Obviously looking at all the panels in our

fleet, most have steam gauges as primary or backup. While I don't intend to

joust with Thor, it may be unavoidable some day. It may not be possible to

isolate all of the electronics from a lightning event but I'd hoped the state of

the art had advanced enough to make that risk acceptably small. It would be

interesting to know how many pilots flying dual EFIS panels with backup gauges

were forced to rely on the gauges at some point.

Building electronic redundancy gobbles up panel space but perhaps with a little

shuffling I can fit in a 3 pack - even with a small Legacy panel.

Stan

-----Original Message-----

From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of Tom

Thibault

Sent: Wednesday, June 16, 2010 10:58 AM

To: lml@lancaironline.net

Subject: [LML] Re: Legacy Glass Panel Suggestions?

Stan,

You wrote "I am an electrical engineer and worked for 8 years at Cessna as an

instrumentation engineer".  You also said "I want to eliminate "steam gages" but

want equivalent electronic redundancy."

Please elaborate on your reasoning for elimination of steam gauges.  It seems

that current generation GA certified airplanes still include steam backup.  For

example, the Corvalis TT and Mooney Ovation web sites still shows airspeed,

attitude, altitude steam gauges right beside the G1000 equipped panels.

Are you planning VFR only, for example?

For me, who went through the same decision process for an IFR solution in a 360

model, the answer came out retain the steam.  The considerations also included a

history of prior p-static upsets of electronics in the cockpit when flying IFR

through rain.  Of course, 360s are mostly E-glass, so static wicks to drain the

build up do not work, where they should on your Legacy.  Regardless, I believe

in relying on multiple types of physics for flight instruments.  Pretty sure it

was Brent Reagan who recommended that first here in the mail list.

In the event of p-static or lighting events, ALL the electronics could be taken

out, no matter how isolated, redundant, or battery backed up they may be.  In

that event, at least basic aircraft control info would still be available and a

hand held comm/nav (not connected to any systems on the ship) could then be used

to communicate and navigate out of the current instrument conditions.

Hopefully a reasoned, non-emotional, discussion will ensue.

Tom Thibault

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