The Sandel uses a rear screen projection bulb that must be replaced at the annual or every 200 hrs., whichever is less. Although this is not a big dollar item ($40 for the bulb, plus labor), suppose the bulb burns out prematurely? The DG and NAV info is lost. Does the 2nd Garmin have its own indicator? If so, you still lost your DG for the sake of a bulb. Maybe, keeping the Century HSI on the “C” SR20 isn’t a bad idea?
Ok, let’s not get carried away here. How many back ups do we really need?
On the C model I count at least 4 heading indicators and 3 of them are better then the good old DG or any HSI beside the Sandel. Remember we still have to be good pilots. Don’t forget we only have one fan up front.
Have a great Cirrus day 
The Sandel uses a rear screen projection bulb that must be replaced at the annual or every 200 hrs., whichever is less. Although this is not a big dollar item ($40 for the bulb, plus labor), suppose the bulb burns out prematurely? The DG and NAV info is lost. Does the 2nd Garmin have its own indicator? If so, you still lost your DG for the sake of a bulb. Maybe, keeping the Century HSI on the “C” SR20 isn’t a bad idea?
2 GPS capable of giving you heading indication to the degree.
Somewhere in that big 10.4" there is a digital DG that can even tell you what you are tracking… DG wont do that.
Let’s not forget that $60.00 item up on top that has worked since it was invented, it only requires to to look at it to make it work… Still having a great Cirrus day…
Woor
I have read a few reviews on the Sandel. This is one. They all address the ‘lamp question’. Here is the pertinent info from the review-the review seems very thorough.
Bill -SR20 wannabe and willbe
Sandel Avionics SN3308 Electronic HSI
What if the projector lamp burns out? Does the entire display go dark?
Yes it does.
As you might imagine, this was a significant issue during FAA certification of the SN3308. Projection lamp failure is considered similar to the failure of a compass card servo mechanism of a conventional HSI, or failure of the CRT or power supply in an EFIS system. Consequently, Sandel has taken steps to ensure that lamp failure is an extremely unlikely event.
The SN3308 has been life-tested in a lab under worst-case conditions – on a shake table under temperature extremes – and the halogen projector lamp was shown to last reliably for at least 400 hours. In an abundance of caution, Sandel specifies that the lamp be replaced at 200 hours or after one year, whichever comes first. For most owner-flown aircraft, the one year will be limiting and the bulb will never reach 200 hours; the lamp will simply be replaced at each annual inspection. Lamp replacement costs $30 and takes about 15 minutes.
According to Gerry Block at Sandel, there has been only one SN3308 projector lamp failure in the field so far. It occurred in a SN3308 that was installed improperly: wired to the aircraft main bus rather than avionics bus, so the instrument was subject to huge voltage excursions during engine start. Predictably, the lamp failed at engine start (on the ground) so there was no hazard. As a result of this failure, Sandel has redesigned the circuitry that regulates lamp supply voltage to make it virtually immune to voltage spikes. Needless to say, like any other piece of avionics equipment, the SN3308 should not be powered from the main bus, nor powered up during engine start. (Duh!)
As part of the lamp regulator redesign, Sandel has added the capability to actually monitor the condition of the bulb filament. By measuring the lamp’s current draw at a precisely-regulated voltage, the software can estimate the amount of metal that has been lost from the lamp filament, and warn when lamp replacement is warranted. Depending on how this new capability works out in the field, it’s conceivable that someday the SN3308 lamp will be replaced “on condition” rather than after a specific number of hours or months.
Part of the SN3308 installation is a lamp dimmer control. Operating the projector lamp at even slightly less than maximum brightness radically increases its life. I find that the instrument can be dimmed somewhat from maximum brightness in virtually all but the eight-o’clock-sun case, and generally do so. Nighttime operation is essentially “free” so far as lamp life is concerned.
The Sandel uses a rear screen projection bulb that must be replaced at the annual or every 200 hrs., whichever is less. Although this is not a big dollar item ($40 for the bulb, plus labor), suppose the bulb burns out prematurely? The DG and NAV info is lost. Does the 2nd Garmin have its own indicator? If so, you still lost your DG for the sake of a bulb. Maybe, keeping the Century HSI on the “C” SR20 isn’t a bad idea?
Here’s the uRL for the article in previous post:
http://www.avweb.com/articles/sandel.html
The Sandel uses a rear screen projection bulb that must be replaced at the annual or every 200 hrs., whichever is less. Although this is not a big dollar item ($40 for the bulb, plus labor), suppose the bulb burns out prematurely? The DG and NAV info is lost. Does the 2nd Garmin have its own indicator? If so, you still lost your DG for the sake of a bulb. Maybe, keeping the Century HSI on the “C” SR20 isn’t a bad idea?
Is the Sandel bulb an owner maintenance replaceable item? Then the owner can replace the bulb at regular intervals and make the appropriate logbook entry. Seems to me that would be an easy way to go. But I understand that the FAA is involved and sensible sometimes isn’t the road they take when looking at stuff like this.
Chris Nowak
The Sandel uses a rear screen projection bulb that must be replaced at the annual or every 200 hrs., whichever is less. Although this is not a big dollar item ($40 for the bulb, plus labor), suppose the bulb burns out prematurely? The DG and NAV info is lost. Does the 2nd Garmin have its own indicator? If so, you still lost your DG for the sake of a bulb. Maybe, keeping the Century HSI on the “C” SR20 isn’t a bad idea?
Gary,
FWIW, I recall an owner at AOPA stunning us when he said that his 140-hour SR20 has had (count em) SIX Century HSI failures…this may even beat Walt Conley’s alternator record!
–Michael
I agree that loss of the Sandel in a Cirrus would only be a minor inconvenience. But as to having other heading sources that are better than a DG: better, but not the same. GPS’s can’t give you heading, only track – no big deal, but it is a difference.
Joe
2 GPS capable of giving you heading indication to the degree.
Somewhere in that big 10.4" there is a digital DG that can even tell you what you are tracking… DG wont do that.
Let’s not forget that $60.00 item up on top that has worked since it was invented, it only requires to to look at it to make it work… Still having a great Cirrus day…
Woor
I agree that loss of the Sandel in a Cirrus would only be a minor inconvenience
Amen to that.
As I mentioned on the 415pj website, I lost my DG during Wings Aloft training.
It was my first time flying in MN.
It was my first IMC since receiving my ticket.
It was my first flight in snow.
We took vectors for the DLH ILS 9 and pretty much just used the ICDS2000 as primary situational awareness device. I should have peed my pants, but never felt safer in my life (Kara was a big help too! :-))
by 7 spare bulbs…then if the bulb BLOWS…get down and take the fifteen minutes to unscrew and replace…the other 6 bulbs are ‘just in case’ the ALL blow quickly…you be holding the ‘lucky 7’ bulb in your hand…of course that will last 1000 hours!
Thinking of carrying 7 spare PROPS as well!
don
I agree that loss of the Sandel in a Cirrus would only be a minor inconvenience
Amen to that.
As I mentioned on the 415pj website, I lost my DG during Wings Aloft training.
It was my first time flying in MN.
It was my first IMC since receiving my ticket.
It was my first flight in snow.
We took vectors for the DLH ILS 9 and pretty much just used the ICDS2000 as primary situational awareness device. I should have peed my pants, but never felt safer in my life (Kara was a big help too! :-))
There is another thing to consider with the loss of the bulb in the Sandel. With a regular DG if you loose it you also loose it’s output to the autopilot. With the Sandel, if you loose the bulb all you loose is the display. It still outputs to the autopilot. You can still command a turn by turning the heading knob (you “guesstamate” how far and make final corrections using another heading source) and if you’re using GPSS the airplane will still follow your flight plan even though you can’t see the DG display.
Certainly a failure of the bulb in VMC is no problem at all. In IMC you still have the autopilot, both Garmins, the ARNAV display, the magnetic compass and all the ATC help you ask for. It shouldn’t be a big deal as long as the pilot doesn’t panic.
Finally, since the majority of bulb failures occur when the bulb is first turned on I would hope that most failures of the Sandel bulb would occur on the ramp prior to taxi.
J. Seckler SR22 #69
With the Sandel, if you loose the bulb all you loose is the display. It still outputs to the autopilot. You can still command a turn by turning the heading knob (you “guesstamate” how far and make final corrections using another heading source) and if you’re using GPSS the airplane will still follow your flight plan even though you can’t see the DG display.
To tie this in with the other thread (Century vs. Sandel), I wanted to point out that it appears that adding GPSS bypasses the HSI, and connects the GPS unit directly to the autopilot.
This is what I did in my (Century-HSI) SR20. So one could re-write Jerrold’s suggestion above as “If you lose the Century, … if you’re using GPSS the airplane will still follow your flight plan…”
For me, adding GPSS was enough redundancy to feel comfortable with the potential of a failing HSI. In other words, as has been stated earlier in this thread, even if one loses the HSI (Century OR Sandel), you still have one other heading indicator, at least two other track indicators - plus the A/P can still fly the plane, if GPSS is installed.
My point is that if it turns out the Sandel option is more expensive than the Century option, maybe adding GPSS is a less-expensive way of still adding a bit of redundancy.
Steve
Oops.
Here is the URL for previous post:
http://www.avweb.com/articles/sandel.html
I have read a few reviews on the Sandel. This is one. They all address the ‘lamp question’. Here is the pertinent info from that review-the review seems very thorough.
Bill -SR20 wannabe and willbe
Sandel Avionics SN3308 Electronic HSI
What if the projector lamp burns out? Does the entire display go dark?
Yes it does.
As you might imagine, this was a significant issue during FAA certification of the SN3308. Projection lamp failure is considered similar to the failure of a compass card servo mechanism of a conventional HSI, or failure of the CRT or power supply in an EFIS system. Consequently, Sandel has taken steps to ensure that lamp failure is an extremely unlikely event.
The SN3308 has been life-tested in a lab under worst-case conditions – on a shake table under temperature extremes – and the halogen projector lamp was shown to last reliably for at least 400 hours. In an abundance of caution, Sandel specifies that the lamp be replaced at 200 hours or after one year, whichever comes first. For most owner-flown aircraft, the one year will be limiting and the bulb will never reach 200 hours; the lamp will simply be replaced at each annual inspection. Lamp replacement costs $30 and takes about 15 minutes.
According to Gerry Block at Sandel, there has been only one SN3308 projector lamp failure in the field so far. It occurred in a SN3308 that was installed improperly: wired to the aircraft main bus rather than avionics bus, so the instrument was subject to huge voltage excursions during engine start. Predictably, the lamp failed at engine start (on the ground) so there was no hazard. As a result of this failure, Sandel has redesigned the circuitry that regulates lamp supply voltage to make it virtually immune to voltage spikes. Needless to say, like any other piece of avionics equipment, the SN3308 should not be powered from the main bus, nor powered up during engine start. (Duh!)
As part of the lamp regulator redesign, Sandel has added the capability to actually monitor the condition of the bulb filament. By measuring the lamp’s current draw at a precisely-regulated voltage, the software can estimate the amount of metal that has been lost from the lamp filament, and warn when lamp replacement is warranted. Depending on how this new capability works out in the field, it’s conceivable that someday the SN3308 lamp will be replaced “on condition” rather than after a specific number of hours or months.
Part of the SN3308 installation is a lamp dimmer control. Operating the projector lamp at even slightly less than maximum brightness radically increases its life. I find that the instrument can be dimmed somewhat from maximum brightness in virtually all but the eight-o’clock-sun case, and generally do so. Nighttime operation is essentially “free” so far as lamp life is concerned.The Sandel uses a rear screen projection bulb that must be replaced at the annual or every 200 hrs., whichever is less. Although this is not a big dollar item ($40 for the bulb, plus labor), suppose the bulb burns out prematurely? The DG and NAV info is lost. Does the 2nd Garmin have its own indicator? If so, you still lost your DG for the sake of a bulb. Maybe, keeping the Century HSI on the “C” SR20 isn’t a bad idea?
The Sandel uses a rear screen projection bulb that must be replaced at the annual or every 200 hrs., whichever is less. Although this is not a big dollar item ($40 for the bulb, plus labor), suppose the bulb burns out prematurely? The DG and NAV info is lost. Does the 2nd Garmin have its own indicator? If so, you still lost your DG for the sake of a bulb. Maybe, keeping the Century HSI on the “C” SR20 isn’t a bad idea?
Gary,
FWIW, I recall an owner at AOPA stunning us when he said that his 140-hour SR20 has had (count em) SIX Century HSI failures…this may even beat Walt Conley’s alternator record!
–Michael
But does it beat his Vac. Pump record;) ?
What about the bulb, is it easy for an owner to replace??
The Sandel uses a rear screen projection bulb that must be replaced at the annual or every 200 hrs., whichever is less. Although this is not a big dollar item ($40 for the bulb, plus labor), suppose the bulb burns out prematurely? The DG and NAV info is lost. Does the 2nd Garmin have its own indicator? If so, you still lost your DG for the sake of a bulb. Maybe, keeping the Century HSI on the “C” SR20 isn’t a bad idea?
Gary,
FWIW, I recall an owner at AOPA stunning us when he said that his 140-hour SR20 has had (count em) SIX Century HSI failures…this may even beat Walt Conley’s alternator record!
–Michael
But does it beat his Vac. Pump record;) ?
What about the bulb, is it easy for an owner to replace??
Right you are, Paul. I meant vacuum pumps. In any case, that problem seems to be solved…