Garmin G5s and their batteries

N194SP has been having some electrical issues lately. I’m hoping we have it figured out now, but intermittent gremlins are always the worst kind. Along the way, it’s demonstrated both the strengths and a couple weaknesses of the G5s in the plane.

First, a little primer on how the G5s are powered. The top G5, called the PFD or AI, is powered off the main electrical bus. When you flip the red switch, you should expect to see it power on. The lower G5, the HSI, is powered off the avionics bus. When the white switch flips up, expect this G5 to come on. Each G5 also has its own backup battery plugged into the back. This battery, when fully charged, provides three to four hours of power to the unit. Of course, both units will also run off the plane’s battery in the event of an alternator failure as well.

That pair of backup batteries provides excellent peace of mind when flying with the units. The long backup time means you are likely to run out of fuel before you run out of battery during an electrical failure. As it turns out, this long batter run time also points out a weakness: the phenomenon of the latent fault. Failure of electrical power in the plane means the G5s will revert to the battery. A message will pop up, asking that you push any button on the unit, but after that, it will operate normally.

In the case where we had intermittent problems with the charging system, the G5s would revert to battery, depleting the backup battery. However, since the problem was difficult to find and the plane was returned to service, the battery didn’t always recharge fully. This led to a condition where the battery backup you thought you had wasn’t really there. It’s also happened that the G5s have remained on after the plane has shut down. It doesn’t take much: any touch of the controls on the G5 during the 45-second countdown to off will cause it to remain on until turned off manually.

I suggest two new checklist items for pilots flying my plane. First, during preflight with mains and avionics on, press the power button once on each G5. That will bring up the power display, which includes the battery life. If it’s not 100%, make a judgement about whether this is an impediment to your planned flight. Second, after shutdown, verify that both G5 go through their 45 second countdown and turn off. This will ensure that the next pilot is not faced with dead backup batteries.

Overall, though, the G5s are a huge step up from the vacuum-driven gyros that were there before. More reliable, longer lasting, more functional, and they even weigh less! Enjoy flying N194SP!

Garmin G5s and their batteries

New avionics!

The redo of the panel avionics is done!

There is much to like here. The new panel is far more functional than the outgoing one.

Transponder – Garmin GTX-345

Kicking off this upgrade is the transponder, as ADS-B is the real reason this whole process started. Sitting where the Bendix/King KT-76C used to be, now lonely out on the right stack, is the GTX-345 ADS-B In and Out transponder. The plane is now fully 2020 compliant. The box also gets all the ADS-B In goodies displayed on the GTN-750. You now have Traffic and Weather available.

Note: you do not need to touch this box, so far away. It is paired up with the GTN-750, so the essential functions are all available from the much closer touchscreen. Though unassuming, this box should greatly increase situational awareness in the cockpit.

GPS Navigator – Garmin GTN-750

The star of the show is what replaced the Bendix/King KLN 94, KMD 550, and one of the KX 155A. The big and clear screen of the GTN-750 now dominates the center stack. There is no better GPS/NAV/COM on the market today.

As this is a WAAS receiver, the plane now has the capability of doing LPV approaches, something the KLN 94 could not. The GTX 345 feeds it ADS-B info to display and you can control the transponder with touchscreen controls on the GTN-750. Though the G5, it can now direct the autopilot with GPSS. Also, the CDI for this box is the G5.

NAV/COM Radio – Bendix/King KX 155A

This is a holdover from the previous panel. The old COM1 is now COM2. With a previously upgraded LED display to replace the failing EL display, this now means the plane has two glideslope receivers. The CDI for this box is still in upper location, as the GTN-750 uses the G5 for the CDI. This radio is still one of the best on the market and is actually a bit better than the one in the Garmin box.

Attitude Indicator – Garmin G5 AI

Commanding your attention in the middle of the six-pack is a Garmin G5 AI to replace the previous vacuum instrument. More than an AI, it includes airspeed, altimeter, VSI,  heading, and other functions. Though only primary for the AI, it renders the other round dials next to it redundant. This device is backed up with a battery, so that it will continue to run for nearly as long as a full tank of fuel.

Horizontal Situation Indicator – Garmin G5 HSI

Paired with the G5 AI above it, the G5 HSI introduces much new functionality. Replacing the previous vacuum DG, this is now a fully functional HSI being driven by the GTN-750. Also battery backed, it can be put into reversion mode to become an AI should the primary AI above it fail. Another bonus is that this box now runs GPSS! Turn on GPSS on the HSI and put the KAP-140 into HDG mode, and you now have perfect GPSS complete with turn anticipation. Watch the plane fly holds and approaches for you nearly hands off.

USB Ports – EI USB-6A

I got tired of noisy and inconvenient car chargers. On the left and right of this device are 2.1A of USB power. The top and the middle provide 1A. Your stuff stays charged, that simple.

Vacuum System – GONE

Yep. No more vacuum instruments. Goodbye vacuum issues. The only thing remaining from the old vacuum system is the inop gauge, and only because it’s shared with amp gauge.


This was a pricey upgrade, running about $36,000. Parts cost was roughly:

  • Garmin GTN-750: $14,800
  • Garmin GTX-345: $4,500
  • Garmin G5 AI: $2,100
  • Garmin G5 HSI: $2,800
  • EI USB-6A: $190
  • Vacuum removal: $150
  • Breaker panel: $240
  • Wiring: $160
  • Static system: $120

Pacific Coast Avionics charged 125 hours of labor to install all of this at $85/hour for a total of $10,600. It took four calendar weeks.

I’m raising the cost of a Hobbs hour to $164. I think this is quite fair, as the function is much increased, but is still a significant savings over the G1000 Skyhawks.


New avionics!

New panel underway!

A week ago, I flew the plane from Palo Alto out to Oregon to have major surgery done on the panel. The shop was a few days behind, but now the exciting work is underway!

There’s much to be done to the plane, and it will be significantly more functional when it gets back. What do you think I’ve got going in? Here’s some hints I’ve already dropped:

  • It’s definitely getting a Garmin GTX-345. There’s no way this work was going to happen without an ADS-B solution. The plane will be 100% ready for 2020 when we’re all done here!
  • There will not longer be a pair of vacuum to drive any instruments. Take a peek at the picture…the AI and the DG are already missing!

Here’s another hint: although every piece of avionics has been removed from the plane, some of it will be coming back. And some will be entirely new. Can you guess what my the plane will have when done? (There’s some hints in the pictures as to what might be going and what might be staying.

New panel underway!

Fuel gauge upgrade

I can’t even explain how this could happen, though I’m told that it’s not entirely rare. The needle on the Rochester fuel gauge in N194SP fell off. Just…fell off. You can see it on the right gauge, hanging out at the bottom of the gauge as if it has not a care in the world. I was notified of this event by an email from Sally at WVFC on March 20 of this year. Little did I know that that would start a month-long, ridiculously expensive journey to fix this airworthiness item.

The plane was, of course, immediately grounded. There’s no flying without a fuel gauge. The email from Sally also indicated the standard fix: new Rochester fuel gauge. It also highlighted the Textron pricing: $3,400 for a new gauge. I did a double-take on that crazy number. Fortunately, I already knew that that was not going to happen.

If you’ve been reading the blog, you know that this isn’t my first go-around with flaky parts in the fuel measuring department. I have already done much research. I already had CiES fuel senders purchased from when the last time things had gone wrong ($800).  There wasn’t an opportunity to install them then, but I certainly wasn’t paying $3400 for a new crappy Rochester gauge, so it was time to bite the bullet and get new senders installed along with a new gauge.

Initially, I wanted a full engine monitor. However, that would have held the plane down for three months while parts arrived and work was done. The better choice was just to grab the fuel gauge specified for the CiES fuel senders: the Aerospace Logic FL202D. This gauge is not available from retailers, so it must be ordered directly from Aerospace Logic. A bit pricey that way: $875 full retail plus $123 FedEx Red shipping from Canada. FedEx screwed up and lost the invoice, so it got held up in customs. Aerospace Logic rescued the unit, but it did extend what should have been overnight shipping arriving on a Friday to a much longer arrival on Tuesday the next week.

Here came my first surprise. Once he saw the parts, Jasper at WVFC’s maintenance department refused the work. Outside his wheelhouse, he claimed, and asked me to find another shop to do the work. The first suggestion was my usual avionics shop, Aerial over at KRHV. With the plane unairworthy, that would have required a ferry permit. I wanted to explore local options first. FAA isn’t fun to deal with.

The next suggestion was Peninsula Avionics. The initial reaction from Art at Peninsula was promising. He interrupted his lunch plans to come to the airport and quote the work in the window I had available to meet with him. Sadly, this ended poorly. After a quick chat, Art took a peek at the plane in its tiedown to see the work to be done. On understanding the job, he turned his back and started walking away. I had to yell after him to understand what was happening. He was also refusing the job. It was pretty rude; I wasn’t happy.

That left Rossi. I won’t get into it here, but the rumors are that Rossi and WVFC have a rather contentious relationship. Neighbors, they run competing fuel services at KPAO. There was something about a fuel truck and plane damage and insurance: I don’t know; I wasn’t there. With a bit of trepidation, it was time to call them up.

They would take the work. A protracted quoting process ensued. Alberto Rossi got sick at the start, delaying things. On guidance from CiES, they quoted a longish 16 hours for this install. I wasn’t happy, but I didn’t have many options left. I signed the quote.

Well, it didn’t take two days. It took a week. The claim from Rossi is that the documentation for the fuel gauge from Aerospace Logic was insufficient, so they spent the time playing phone tag with their technical support. Scott Philiben of CiES eventually dug them out of their technical hole, as he was answering questions.

The plane, nearly a month later, was flying again. The shiny new digital gauge should be much more accurate and reliable.

Why am I finally posting on this? Well, I got the bill from Rossi today. It’s…high. 22 hours were charged, not 16. $300 in fuel was charged, as they disposed of the other fuel. The total bill from Rossi was $2750, bringing the actual cost of debacle up to $4600, not counting the lost time on the aircraft.

$4600. That was a damn expensive needle.

Fuel gauge upgrade


Maker:S,Date:2017-12-18,Ver:6,Lens:Kan03,Act:Lar02,E-YWell, you probably thought this was going to be about the fuel gauge, but that comes soon. I haven’t received the invoice yet and I like to have full info before posting.

Nope, this one is about the shiny new muffler on N194SP (and four other WVFC aircraft). It appears that Aerospace Welding, the maker of the muffler on the 172 SP did a poor job of making the original muffler. Bad enough to kick off AD 2018-02-04. Although an inspection would be sufficient to hold off replacing the muffler for up to a year, every muffler that’s been inspected has failed. Mine was just straight replaced. New Inconel muffler has been installed!

$1200 covered that. 4 hours labor and a $650 muffler.


New cylinder and more


Some updates on the unkind month of January! For a recap, a triple dose of unluck hit N194SP. A bad coil in the left magneto left it stranded in Watsonville. A tumbling AI needed an overhaul. And a bad #1 cylinder wouldn’t hold compression. None of these alone should cause an immediate safety concern for the aircraft, but they definitely aren’t situations that can be allowed for further flight. This is why the plane has two magnetos. And why we train partial panel. And, of course, even with a cylinder only holding 20 psi, it was still smoothly making full power.

Still, it had to all be fixed. As I mentioned in the last post, a new $1500 Slick magento was popped onto the plane in Watsonville with four and half hours labor. That got it back home. It turned out the other magneto was due for its 500-hour inspection. Three hours of labor and $60 in parts made sure that the right mag is now behaving just as well as the new left.

The AI was a simple swap. $1000 for the overhauled unit and an hour to swap it out. I’ve flown the plane since the overhaul, and it’s now nice and stable.

The cylinder was more involved. First, it was an $1100 part, though it was fortunately available off the shelf. Overnight shipping and ten hours of labor later, and a new cylinder graced the Lycoming engine. Total bill: $2325. Unfortunately, it wasn’t done yet. The cylinder needed to be broken in for ten hours of tach time before it could be flown as a rental. A couple other ferry pilots got some time, but I did most of the break-in time, flying all weekend. I got several new airports in my logbook, which was great. Not so great is that I had to do it solo. I always have more fun when I can share!

Other items that were done during the 100 hour:

  • New ELT battery was installed.
  • New right main tire.
  • Leaking fuel strainer valve was replaced
  • New ground strap on the left elevator
  • Fixed the bad screw in the cowl.


New cylinder and more

Some downtime for the engine

Sometimes in plane ownership, luck is not with you. The engine on N194SP decided it needed to get some heavy maintenance at its half-life. Nothing too terrible, but January has had some downtime for the aircraft.

First, the left magneto gave up the ghost. The coil failed in the magneto during a flight to Watsonville. Of course, the right magneto continued humming along nicely, so there was no threat to the safety of the flight, but it doesn’t leave the plane in a condition to be flown home. WVFC’s chief mechanic flew to KWVI to swap out the magneto. Four hours of labor and a $1500 part, and the plane was flying again.

The good times lasted another couple weeks. The plane went in for a 100-hour inspection, and they found that one of cylinders had lost compression. It was still producing power, but something is dreadfully wrong with it. An overhauled cylinder is being put on, and we’ll hopefully be flying in a week or two!

Some downtime for the engine

Autopilot issues

So, you may have noticed there have been some issues with the autopilot lately. Turns out, there are probably two things causing that. The roll servo was intermittent in one direction. That would mean the plane would roll one way, but be unable to roll back the other. The roll servo was overhauled to the tune of $2,250. As a result, Roll and Heading modes should work perfect again!

Nav mode, however, is more troublesome. While in the shop with Aerial Avionics, we noticed that the reported OBS to the KLN 94 would get stuck at 47 degrees or 227 degrees, depending on the TO/FROM flag. But only intermittently! The culprits could be the CDI (around $1200 to overhaul), the GPS/NAV switch ($1200 for a button!), or just dirty or loose connections. After clean-up, it does not appear to be having problems anymore, but please keep watching it and let me or WVFC know if you see issues with the AP in Nav mode.

While there, we got ready to fix two other issues. The clock has been having issues. I ordered a new one for $600, so that should get replaced very soon. Also, the display on COM1 can be unreadable when cold. This is a known issue with the EL displays on KX155A. An LED replacement display has been swapped in and we’re just waiting to get it installed. Should be about $1500.

Lastly, there have been a couple reports of the HI becoming intermittent. Please keep watching it. I need to either overhaul it, if it’s bad, at $1500, or replace it with a Garmin G5 for about $4000.

Happy flying, everyone!

Autopilot issues

Made some KLN 94 tweaks

Hello all. I had a chance, as a result of the issues the KLN 94 GPS has been having with reading a correct OBS from the CDI to tweak some of the configuration of the KLN.

  • Hopefully fixed the issue with the CDI. Could you all monitor it to see if it’s really fixed? The issue was that the CDI’s OBS was being read as 45 degrees off by the KLN. It’s been adjusted, and let’s watch it to ensure it stays accurate.
  • QuickTune! If you search for a frequency in the KLN, you can now push it to COM 2 or NAV 2 by just moving the cursor to the frequency and pressing ENT. I can actually configure it work with COM 1, COM 2, or both. I chose to only go to COM 2 and NAV 2. This skips the step of selecting the radio to send the frequency to and also allows you to put the NAV frequency into a CDI that isn’t being used already by the GPS.
  • The connection to the KMD 550 MFD was made more robust. More information should now show up on the large moving map.
  • The configuration for the KAP 140 autopilot’s interface with the KLN 94 was improved. The autopilot should behave better now.

I hope you all enjoy the improvements. Let me know if something goes wrong or if the stuff doesn’t work like you’d want it to.

Made some KLN 94 tweaks

Flying again, but no sender type change

Well, N194SP is flying again. It’s been way too long that the plane wasn’t flying, and for that, I apologize. This has been a painful lesson in how things work in the aviation industry. I now know what I should have done in hindsight, but each decision sure made sense when I was making them.

First, you’ll see that the fuel gauge in the plane hasn’t changed as it was supposed to. That’s because it’s flying on the Rochester part. Granted, it’s a brand new part, sourced from Air Power for $650. The CiES units and all the parts and work that go along with putting them in were going to take another month. I couldn’t afford that. So, the stock Cessna part went back in. Of course, that’s what I should have done from the first, but live and learn.

Second, I still ordered the CiES units. They’ll arrive in about a week. I don’t know how I’m going to show the level. There are three options: convert the signal to resistance and show it on the stock gauge, buy the Aerospace Logic fuel gauge for almost $1000, or get an EI CGR-30P engine monitor for $3500 (plus lots of labor). If I do anything with them, it will probably be right around annual.

So, question to my flyers: What’s an engine monitor worth to you? I’d need to add a few dollars an hour to account for the cost of the system. Is it worth that to you?

Flying again, but no sender type change