Carbon Cub EX-3 Engine Failure (N40DT)

[Neal]

Good info and I look forward to what you come up with. I agree, the powersonic is not something I want to rely on and this accident (N40DT) has pushed me to the point of it's time to do something about it.

I haven't pulled my right interior panel yet to explore the EarthX backup battery option to see if it will fit. But I think we/I need to also not be forced into placing an ignition backup battery in that location. We should discuss alternate location ideas. I'd say there's plenty of room behind the panel as the EarthX backup battery I have fits in my hand. It could sit right behind the GDU with ease. The question is will it cause any type of interference? I'm not sure where the wires are running from to get to the right interior panel and how hard it may be to change that wire path.

I'll add that I think I owe full transparency in that I posted a question to the CubCrafters "Official Product Support" Facebook group on October 15th asking about the EarthX backup battery as an alternate ignition backup battery and to date the message has not been approved and I don't expect that it will. I have a screenshot of my post which I don't feel the need to share "yet" but I am beyond disappointed that CubCrafters has chosen not to share this situation for lessons learned and help address concerns and alternate options for an ignition backup battery. I am a customer and this kind of treatment is absolutely unsatisfactory. I can't answer why they haven't approved my post and this is not the first time they've done this as they did with my coil pack situation a year ago which I expressed my extreme disappointment to them about. I needed help diagnosing the situation, no ranting was involved, I just explained the problem yet they wouldn't approve my post. This is why I invite all to come here to Flightinfo.com to share tips with one another to avoid censorship. The Facebook group is for owner support. If they are allowing non-owners in and they are fearing marketing concerns, they failed by allowing non-owners in a private group which they created to become their official support channel for owners. An aviation company relying on Facebook for support is baffling but Pete via email has always been outstanding and remains so.

This forum is not private and topics here have already come up by prospective owners asking about situations they are learning about here and YouTube. I will continue to ask questions and share as we learn this lesson in the Air Force to learn from accidents to prevent others. It seems some want to hide them and not address them. Very disappointed.

So let's continue to work together to see what we can come up with as we all know we CANNOT depend on the quality of battery CubCrafters uses for the ignition backup battery. While spec wise a 2 AH battery should suffice, this battery has proven to degrade fast and not knowing if we are ever recharging it fully to maintain battery health is another concern. This is why I plan to add a pigtail that I already purchased to my EarthX backup battery so I can put it on a charger a few times a year as cell balancing is crucial to LiFePO4 batteries and I can't trust the aircraft charger to be properly maintaining it.

 

[Cactus Charlie]

You guys are missing the essential fact that if you are alerted immediately for alternator failure, and manage the electrical systems properly, you have at least an hour for a diversion before needing to consider the emergency ignition battery.

That said, I plan to fit 3 AH TCW IBBS instead of the existing 2 AH emergency ignition battery. If for no other reason than I am confident it will have a far longer life if it is never used.

It is not trivial to fit an IBBS instead of the AGM battery. I have been considering the design options for a while and have decided on, and bench tested, the configuration I plan to use. However, I will not publish anything until it has been tested in the aircraft.

 

[Neal]

You guys are missing the essential fact that if you are alerted immediately for alternator failure, and manage the electrical systems properly, you have at least an hour for a diversion before needing to consider the emergency ignition battery

You’re assuming a healthy and fully charged battery. The health of these concerns me the most. Paranoid? Maybe. I’ll take extreme caution over complacency.

 

[Cactus Charlie]

You’re assuming a healthy and fully charged battery.

Perhaps you misunderstood. I assumed your paranoia was directed at the AGM emergency ignition battery. I am only assuming a healthy and full charged MAIN /STARTER battery.

Do you willingly fly with a weak, uncharged, main battery? Some people do and get way with it because they have magnetos. Not wise with electronic ignition.

 

[Neal]

My starter battery is a fully charged and well maintained EarthX ETX-900. My concern is the powersonic.

 

[Cactus Charlie]

You lost me. You said "You’re assuming a healthy and fully charged battery. " and then you say "My starter battery is a fully charged and well maintained " which was exactly my assumption.

Given those conditions you have at least an hour to land even if the ignition battery is worthless assuming you follow a reasonable load shedding plan.

 

[Cactus Charlie]

assuming you follow a reasonable load shedding plan.

Do you know how to force G3X Touch system to use IBBS rather than main battery? I'll bet that most owners do not.

 

[Neal]

Do you know how to force G3X Touch system to use IBBS rather than main battery? I'll bet that most owners do not.

I do not. I would imagine Master off would drive it to IBBS like on the ground. Do share.

On that note, are there any switches or breakers that one should NOT turned off when conserving power? Sadly the education on use of these planes is nill and I hate being ignorant about my airframe which is completely opposite of our training in the Air Force. This is why I paid the fortune for TacAero training as I needed any training I could get. So please share...I'm all ears in learning.

 

[Neal]

Do you know how to force G3X Touch system to use IBBS rather than main battery? I'll bet that most owners do not.

Maybe start a new thread (or threads) to help educate on things you've learned that maybe others don't know and you can share the knowledge?

 

[Cactus Charlie]

Some people like to read novels. I like to read schematics. My PDF FX-3 schematics are covered with comments just like the schematics for my amateur radio equipment.

IBBS is interesting because it can be installed in two very different ways:

1. One way is to configure the IBBS as a "pass-through" for normal power. When sensed IBBS charging voltage is lower than about 11 V the IBBS switches to internal battery and drives the same output pins that were used to output pass-through power. This configuration is typically used when the powered equipment has only one power input.

2. The other way is to have no pass-through. In this case the IBBS output pins only have voltage when sensed charging voltage is low. This configuration is used when the powered equipment has two power inputs and draws power from which ever of those two power feeds has the higher voltage (Diode OR power feed).

The core G3X Touch system is the GDU 46x, the GSU 25C, and the GEA 24. All of these units have dual power inputs. In the FX-3, and I assume all other CubCrafters aircraft with G3X Touch systems, the GDU, GSU, and GEA are installed with one power input pin wired to MAIN bus via a circuit breaker and the other power input pin wired directly to IBBS.

In the FX-3 configuration the IBBS output is only live when charging voltage is low and IBBS is "enabled". This happens every time MASTER is Off and IBBS switch is On.

With alternator failure the quickest and simplest way to force G3X to use IBBS is to turn off MASTER. This keeps all the main battery stored charge for ignition. That should perhaps be the first action in day VFR when not being controlled.

However, there will be times when something powered by MAIN bus needs to stay on. Perhaps it's NAV lights at night, perhaps its the transponder in Class B airspace, perhaps it the COM radio when planning to land at a controlled airport. So how do we get G3X system off the battery and onto IBBS so we can save that battery energy for ignition?

First pull the IBBS breaker. This drops the IBBS charging voltage to zero and, if IBBS switch is On, IBBS output voltage becomes live. Remember that G3X LRU will pull power from whichever power input pin has the higher voltage. If MAIN bus is the higher voltage the aircraft battery will continue to power these units and use energy that we should be saving for ignition.

Second pull the PFD, GSU and GEA circuit breakers. This leaves each of those units with only IBBS power. Main battery power cannot be used by them. A good IBBS will power the G3X Touch system for well over an hour. I have tested for 2 hours more than once.

A good main battery will keep the engine running for over an hour after alternator failure. The time can be extended by running only one ignition system. Land at nearest suitable airport or landing site and don't push to get home.

All of the above is my personal opinion and I welcome comments or challenges.

 

[Cubonaut875]

That is excellent. Off to the hangar today to run through that. Thank you.

 

[Neal]

I learned about the IBBS power when I struggled for 6 months to determine why I got an "IBBS in use" alert on my G3X. I then discovered the pink wire detached from the breaker as the screw dropped out months before. I saw the screw and saved it not knowing where it came from. But yes, when the IBBS breaker is pulled, it causes the IBBS to trigger.

I bought these breaker colored caps months ago. Main reason was to put it on the trim breaker should the trim runaway. I now have another use. I put yellow on the trim, I think I'm going to put red ones on IBBS, PFD, GEA, and GSU breakers. The red set means they are all for the same purpose.

Amazon.com

I bought my set from Aircraft Spruce which you can buy individually by color or a set. I like the style from Aircraft Spruce better than the Amazon set above per the picture.

Color Coded Circuit Breaker Cap Green PE7000-8 | Aircraft Spruce ®

Color Coded Circuit Breaker Cap Green PE7000-8 These color coded caps can easily be installed and removed from Klixon and similar type circuit breakers. Colored caps are used to

www.aircraftspruce.com

 

[Cactus Charlie]

Fun fact - The "IBBS In Use" alert doesn't actually mean IBBS is in use. CubCrafters used an IBBS output signal that indicates that charging voltage is below 11 volts. TCW intended this signal to be used as a low voltage alarm. There is at least one circumstance in which this could be very misleading.

Assume that for some reason, or by accident, you fly with IBBS switch off. If alternator fails, and MAIN bus voltage drops to 11 V, IBBS IN Use will be annunciated. However, IBBS is not in use and is not powering the G3X Touch system. G3X Touch system will continue to be powered by MAIN bus and the PFD will go dark when MAIN bus voltage drops to about 8 V (about 11 V if Earth X battery is used).

IBBS cannot actually be in use unless the IBBS switch is On which actually arms the IBBS rather than turning it on. Output power of the G3X IBBS is only live if IBBS switch is On and charging input less that about 11 V.