G5 vs SI 275

[murphey]

Dithering. Do I want the G5 HSI or the GI-275 HSI?
Considerations:

• $1300 retail difference (G5 cheaper)
• Already have the G5 AI installed
• G5 has 4 hr battery backup, GI 275 only 1 hour backup (according to Garmin website)
• Don't need the Enhanced HSI option on the GI 275, will have GPS 355 and the iPad for redundancy
• [another update] GI 275 has bigger and brighter display
• [update] No plans for AP

I'm dithering. Plan is for Aug or Sept for install along with the GPS

 

[chemgeek]

I'd get the matched set of G5s. The GI 275 has a nice screen, but won't make you fly better. There are lots of G5s in service, and if you have a legacy rate-based AP, a G5 will work well, and someone has figured out the proper configuration already.

On the Grumman Gang, a pilot reported the consequences of a total electrical failure in flight with dual G5s, and it was indeed comforting to see an emergency countdown timer showing in excess of 4 hours of backup power. If flying IFR, this is important indeed.

The biggest installation challenge is finding a good spot for the GMU-11.

 

[asicer]

Dithering. Do I want the G5 HSI or the SI-275 HSI?

The GI-275 is easier to install if it's going into a round hole. Will it save you 10-12 hours of labor?

BTW, it's "GI-275", not "SI-275". It's a Garmin product, not a Sandel product.

it was indeed comforting to see an emergency countdown timer showing in excess of 4 hours of backup power. If flying IFR, this is important indeed.

If I suffer an electrical failure flying IFR and put myself in a position where I'm going to need more than 1 hour of backup then I need to plan better.

 

[murphey]

The GI-275 is easier to install if it's going into a round hole. Will it save you 10-12 hours of labor?

Not sure. Original quote is for the round thingy. I'm not devoted to round or square.

BTW, it's "GI-275", not "SI-275". It's a Garmin product, not a Sandel product.

snorf.

If I suffer an electrical failure flying IFR and put myself in a position where I'm going to need more than 1 hour of backup then I need to plan better.

Very true

 

[NordicDave]

Get the 2nd G5, you will not be sorry. My opinion, the 275 is trying to do too many things in a small space.

 

[murphey]

But then there's also the highly anticipated AV-30 HSI at considerably less money.

 

[asicer]

But then there's also the highly anticipated AV-30 HSI at considerably less money.

Technically the AV-30 is not a true HSI but rather just a DG, at least initially but this may change in the near (or far off) future.

 

[chemgeek]

But then there's also the highly anticipated AV-30 HSI at considerably less money.

Why would you want to mix and match a Frankenglass panel and make the gyros even more difficult to communicate with each other? The G5s interconnect, allowing display of certain nav information on both instruments, and provide instant AI redundancy should the need arise. The AV30 does not include a remote magnetometer.

What are your current or future nav and AP plans? Having different AI and HSI devices will likely make a hash out of interconnecting these devices to them. Or anyone else who will own the plane in the future.

 

[chemgeek]

If I suffer an electrical failure flying IFR and put myself in a position where I'm going to need more than 1 hour of backup then I need to plan better.

This assumes your batteries maintain 100% of their original capacity over time, or are fully charged on startup. If I haven't flown in a while, the G5 batteries will not register 100% on startup. So your 1 hour of reserve might be considerably less than an hour as batteries age. If the G5 batteries lose half their capacity over time, they are still generous in an emergency.

 

[chartbundle]

This assumes your batteries maintain 100% of their original capacity over time, or are fully charged on startup. If I haven't flown in a while, the G5 batteries will not register 100% on startup. So your 1 hour of reserve might be considerably less than an hour as batteries age. If the G5 batteries lose half their capacity over time, they are still generous in an emergency.

Although it's not required for many types of operations I know the ICA for most of these devices with battery backups have a test procedure or a replacement requirement. I think even if not required it's probably a really good idea if you use them for IFR. My RC Allen battery requires replacement every 3 years. The GI-275 requires a test every 12 months with a minimum rundown time of at least 30 minutes for aircraft approved for flights at 25,000 or less.

Obviously until they're out in the field there's no way to know if the average time when new is 61 minutes or 3 hours.

 

[murphey]

Why would you want to mix and match a Frankenglass panel and make the gyros even more difficult to communicate with each other? The G5s interconnect, allowing display of certain nav information on both instruments, and provide instant AI redundancy should the need arise. The AV30 does not include a remote magnetometer.

[update] No plans for AP.

What are your current or future nav and AP plans? Having different AI and HSI devices will likely make a hash out of interconnecting these devices to them. Or anyone else who will own the plane in the future.

 

[David Megginson]

But then there's also the highly anticipated AV-30 HSI at considerably less money.

Unfortunately, it turns out the AV-30 in HSI mode isn't certified as the primary CDI (unlike a G5 or GI-275), so it's not comparable. The HSI display is "advisory only", and works only for RNAV, not for VNAV.

It's too bad. I was excited about the AV-30 at first--because of the round form-factor--but it turns out the certified version will be almost as expensive as a G5, but will do a lot less (no GPSS, no CDI, no heading output to the A/P, no magnetometer option, etc). As it stands now, it's just an expensive toy rather than a cheap HSI.

 

[David Megginson]

Dithering. Do I want the G5 HSI or the GI-275 HSI?
Considerations:

• $1300 retail difference (G5 cheaper)
• Already have the G5 AI installed
• G5 has 4 hr battery backup, GI 275 only 1 hour backup (according to Garmin website)
• Don't need the Enhanced HSI option on the GI 275, will have GPS 355 and the iPad for redundancy
• [another update] GI 275 has bigger and brighter display
• [update] No plans for AP

I'm dithering. Plan is for Aug or Sept for install along with the GPS

The much-higher resolution and round form factor for the GI 275 look nice. The downside (besides shorter backup batter, higher price, and lack of GFC-500 compatibility) is that it locks you into buying database subscriptions from Garmin for some features, while the G5 itself doesn't.

But I still can't imagine myself ruining my panel with the ugly square G5 displays (much less an even-uglier E5 rectangle), so I don't know what I'll do when my mechanical AI and DG wear out. Let's hope they keep running for a while.

 

[bnt83]

Imho G5 all the way, the standby batteries cost half and the units themselves are almost half.

also, front mounted they are easier to service despite the possibility of being more work to install initially.

unless you have compatible interfaces like WAAS GPS and ADS-B in and/or pay for options the GI275 is gonna be a blank looking thing similar to the G5 anyway, at double the cost

 

[murphey]

No longer dithering. I need a car more than I need the GPS and associated accoutremonts. Maybe next spring.

 

[flyingcheesehead]

If you already have a G5, a second G5 is the way to go... And I say this as someone who's about to install a GI 275.

 

[bradg33]

The GI-275 is easier to install if it's going into a round hole. Will it save you 10-12 hours of labor?

BTW, it's "GI-275", not "SI-275". It's a Garmin product, not a Sandel product.


If I suffer an electrical failure flying IFR and put myself in a position where I'm going to need more than 1 hour of backup then I need to plan better.

The G5 will mount into a round hole just fine. It's made to do so. Different if you want to flush mount it, but the "Standard" mount goes right into an existing round hole.

 

[asicer]

The G5 will mount into a round hole just fine. It's made to do so. Different if you want to flush mount it, but the "Standard" mount goes right into an existing round hole.

You are also assuming that there is adequate spacing around the holes. That's not always the case.

 

[bradg33]

You are also assuming that there is adequate spacing around the holes. That's not always the case.

Fair point, though I think many common airplanes do have adequate spacing. But my Super Viking has a spacing problem, which is one of several reasons we haven't actually pulled the trigger on G5s yet...

 

[flyingcheesehead]

You are also assuming that there is adequate spacing around the holes. That's not always the case.

One other consideration is the size of the G5 vs. the GI 275. There's a LOT more "guts" in the GI 275 so it's significantly longer behind the panel:

Far right on the lower row is the AV-20. Top and bottom in the middle are G5s, with the top one having a backup battery. Top and bottom to the left of the G5s are the GI 275s. The difference in size is significant.

This is from Kitplanes' review of the GI 275, which is a good read. Keep in mind that the prices they quote there are for experimentals, though they're not as far below the certified prices as you might think.

 

[bkspero]

In an installation of two '275s as attitude indicator and HSI, it looks like it will be an issue replacing the backup battery on the lower unit. Not so much for 2 G5s.

 

[Jdm]

We have both and prefer the 275. Much better display. We have 2 flush mounted G5’s which are great, but our 275 is amazingly easy to use in comparison. I find myself using the 275 more than the G5’s on approaches because it’s just so freaking nice to look at.

We are having a little Installation issue with the 275 that will require a trip back to the shop. It’s not picking up the GS when coupled to our #2 nav source (GNC 255). It works fine coupled up to the #1 (GTN650Xi).

 

[bnt83]

We have both and prefer the 275. Much better display. We have 2 flush mounted G5’s which are great, but our 275 is amazingly easy to use in comparison. I find myself using the 275 more than the G5’s on approaches because it’s just so freaking nice to look at.

I kinda with the G5s were touchscreen but maybe long term durability may be better off without it. IDK.

The actual chassis of the GI275 look a lot better. IDK if its worth the extra money tho when today we can buy replacement G5s brand new for $1289.