Jump to content

Never Jump Start a CTLS with a Weak or Dead Battery ???


Steven

Recommended Posts

from the 912iS owners manual:

 

1) If Alternator A fails, ECU automatically switches to B. (no power drop is recognizable)

2) Failure of both EMS power supplies result in engine stoppage

Remedy: Switch "On" the backup battery switch. In this case, power supply is provided by the aircraft batttery.

3) Land the plane at the next available opportunity.

 

 

What happened to the magnetos in the Rotax 912iS ? It sounds like the new engine depends on the alternators on the main circuit whereas the old 912 had magnetos and would continue running on one or both magnetos even if the alternator or primary circuit failed.

Link to comment
Share on other sites

Steven,

 

To be accurate, the 912 does not have magnetos.

 

It has electronic ignition which is self-powered, which, like magnetos, leave it immune from electrical system woes.

 

Have not looked into the injected model's ignition, but from paul m's post I believe it is dependent on the electrical system.

 

You've prompted me to check out the link about its redundancy.

Link to comment
Share on other sites

There are magnetos in the 912i, redundant as is everything else. There are no carbs of course, but there are dual rails, and dual injectors on each cylinder.

 

The redundancy in the 912i is off the map...

 

I keep asking you to provide a link or a reference, you never do. Your making this up, the 912iS has an elctronic ignition of course not magnetos. And the 912iS is subject to engine stoppage because it is dependent on electrical power. It has a new level of redundancy to address its new level of risk.

Link to comment
Share on other sites

Eddie is right, there are no magnetos on any 912. On the ULS there are two charging coils that provide power to the two electronic ignition boxes. CTLSi - go to the Rotax site and see what you can find out about the injected engine's ignition, then post it here. You might learn something about this plane you are purchasing.

Link to comment
Share on other sites

The 912 has a CDI ignition. No Mags. It has 5 coil pickups in the fly wheel area. 4 for power and the fifth for the tach.

The power is rated at 20 amps as far as the Rotax manual states, but it is actually 18 max and 16 amps continuous. Remember many things in engine and compressor manuals are either test stand data or theoretical and may not be what you see in the field under actual use. Because of this CDI ignition it is the reason we need a specific rate of rpm at start to generate the needed electrical power for the ignitions and plugs and then of course the rest of the electrical system gets it power once running.

 

Test question in class.

Link to comment
Share on other sites

Eddie is right, there are no magnetos on any 912. On the ULS there are two charging coils that provide power to the two electronic ignition boxes. CTLSi - go to the Rotax site and see what you can find out about the injected engine's ignition, then post it here. You might learn something about this plane you are purchasing.

 

Why spoil things with facts?

Link to comment
Share on other sites

I still do mag checks when I run up, the word is hanging on longer than the technology. Even if the iS had mags it still couldn't run without batter power like the uls does so the new redundancy doesn't call for dancing in the streets, it solved something new not something old.

Link to comment
Share on other sites

  • 1 month later...

I want to submit a number of corrections to this thread about how the operation of the 912 series of engines function as used in flight design aircraft.

 

First off, they do not have traditional aircraft magnetos. But they still have magnetos. A magneto is an electrical generator or alternator which uses permanent magnets to create electricity. References:

Google Search

Wikipedia

Merriam-Webster

 

Rotax 912 ULS heavy maintenance manual references:

71-00-10 Page 13 - Integrated alternator is a permanent magnet single phase alternator

74-00-00 Page 4 - Flywheel has a ten pole magnetic ring attached

 

Rotax 912i heavy maintenance manual references:

24-20-00 Page 4 - The EMS supply consists essentially of 2 permanent magnet generators.

 

As you can see, both engines do in fact, have magnetos. However, they differ from traditional magnetos because they use several coils to drive various systems, and both use capacitive discharge ignition. The 912i takes it a step further though, and uses an ECU to control the discharge.

 

912 ULS engine design

There is only one flywheel alternator. However, there are three separate winding circuits. The main generator circuit, the A side charging coil, and the B side charging coil. Reference: Heavy maintenance manual, 74-00-00, Page 28 and 29 (this is the model of the 912 used in FD aircraft).

 

How it works, is that all three circuits are completely independent from one another. The main generator winding serves the airframe and battery, while the two charging coils serve A and B, respectively. A failure in any of the three systems allows the engine to continue running. As long as both A and B charging coils do not fail simultaneously, the engine will still continue to run, although with reduced performance if either A or B fails.

 

912i engine design

 

There are TWO integrated magneto-generators. One of these generators has the two charging coil windings for the Lane A and Lane B ECU controls. Reference: 912i Heavy Maintenance Manual, 74-00-00 Page 3, and 74-20-00 page 5 diagram. The other solely provides airframe power. Reference: 912i Heavy Maintenance Manual, 74-00-00 Page 3.

 

Additionally as a fall back mode, should the ignition generator fail, main aircraft power can be used to drive the ignition system. Reference: 76-00-00 page 2 diagram. As a side note, main aircraft battery power must be sufficient in order to both turn the engine, and to power the ECU until it becomes self-exciting (Reference: 76-00-00 page 2 diagram, you can see the starter circuit using battery power).

 

 

Lithium Ion Battery Design

 

Lithium Ion batteries are much more sensitive than lead acid batteries. Lithium ion batteries will experience thermal runaway if they get too hot. Reference: http://en.wikipedia...._battery#Safety "If overheated or overcharged, Li-ion batteries may suffer thermal runaway and cell rupture. In extreme cases this can lead to combustion."

 

Additionally, jump starting a lithium ion will send a very large amperage through it, which greatly increases the risk of hitting the temperature threshold. Reference: http://lithiumpros.com/support/faqs-2/ "Can you jump start a dead lithium ion battery?"

 

In conclusion, I submit the following:

  • ALL 912 series engines have magnetos. However, Rotax puts a twist on the way they are constructed and utilized as compared to traditional magnetos.
  • The 912i has more redundancy than the 912ULS due to the use of two integrated magneto-generators. Whether or not FD has provided the fallback switch-over for the ECU backup power source is unknown to me, as I do not have a CTLSi, and I've spent enough time on this subject and have no desire to search their AOI.
  • In ALL 912 series designs, mag-checking is still accomplishing roughly the same thing as old magneto designs, except you are not only checking the magneto-generator itself, but you are also checking individual coils instead of separate magnetos, along with the rest of the ignition system.
  • DO NOT JUMP START LI-ION BATTERIES. The CTLSi uses a Li-Ion battery. You run the risk of causing cell damage, and also an explosion or fire.

Link to comment
Share on other sites

An interesting side note about the 912is engine's flywheel that surrounds the coil pickups. They used rare earth magnets integrated into the flywheel metal and they are so strong you can not pull the flywheel off by hand. It takes a special puller to over come the magnet force and that puller you need to make, but it is a simple tool. When you go to put the flywheel back on if you get your fingers under the edges it will be ugly. This is one strong son of a gun magnet set.

 

The other thing that may take some time is there are a number of misprints in the manuals and only time will get them removed and they are working on it.

Link to comment
Share on other sites

 

CTLSi uses a Li-Ion battery.

 

Since its so easy to confuse them...

 

...does the CTLSi use a Li-Ion battery or a Li-Iron battery, and if a Li-Iron does that mitigate some of the risks? That's of interest to me since I hope to gain abut 12lbs of useful load by swapping my Odyssey for a Li-Iron soon in my Sky Arrow.*

 

Further, I think you've stretched the common usage of "magneto" regarding aircraft ignition or small engine ignition. It's usually meant to mean a device whereby a permanent magnet moving past a coil directly generates voltage for an ignition spark - not indirectly as you put forth.

 

But I will stipulate you sure seem to know your stuff!

 

 

*edited to add: I see Paul picked up on the same point and posted while I was composing my post.

Link to comment
Share on other sites

 

Further, I think you've stretched the common usage of "magneto" regarding aircraft ignition or small engine ignition. It's usually meant to mean a device whereby a permanent magnet moving past a coil directly generates voltage for an ignition spark - not indirectly as you put forth.

 

 

That's why I was making it clear it is not a traditional magneto. In fact, I believe that is why Rotax likes to call it a magneto-generator to avoid semantics :)

 

Also, what is "directly" vs "indirectly"? In traditional aircraft magnetos, the design is not that much different from the magneto-generator.

 

I submit this link for reference to continue explaining:

http://eaa691.org/files/Tech%20Note%20%232%20Magnetos.pdf

 

Anyways, in the Rotax Magneto-Generator, you have three sets of coils on a number of poles. Most of these poles are used for aircraft electrical generation, whereas two of them are used for A and B ignition systems. However, if you look at the link provided, page 3, you can see that traditional magnetos are ALSO driven by permanent magnets, they have capacitors, (condensers), windings... etc. All of the same components as the magneto-generator.

 

Now if we look at the 912 ULS Heavy maintenance manual, 74-00-00, Page 28 and 29, instead of having the secondary ignition coils inside of the magneto, they moved them down-stream. Basically, Rotax took the design of the magneto, and moved everything except the coils outside of the generator assembly. However, component for component, nearly everything is the same as a traditional aircraft magneto.

 

In the 912i, I would agree that it is more indirect. I would define "indirect" here as something that is not mechanically linked to the crank position. The ECU can offset the spark firing based on all kinds of conditions for optimal use of fuel, whereas the 912 ULS fires in the same position every time.

 

Lithium Iron Phosphate batteries:

 

Before we continue, note that I am not an expert on Lithium Iron Phosphate batteries. I have not done much research into them.

 

Combustion is still possible with LiFe batteries, but it is far more difficult. (http://en.wikipedia.org/wiki/Lithium_iron_phosphate_battery#Safety). Therefore, as I imagine the CTLSi probably uses this, it is not a fire or explosion risk.

 

However, I do know that LiFe batteries have a low impedance. Therefore, I submit this theory: while this means they are resistant to heating up while discharging, they will happily accept all the current you can muster through them while charging from a discharged state. Why isn't this an issue while discharging? Batteries can only output so much at a time due to chemical limitations. But, if you put a nuclear power plant behind the charger and are charging a low impedance battery, you will soon have a scorch mark where the battery used to be :-).

 

Also, someone might ask: why don't lead acid batteries suffer this problem? Lead acid batteries go through physical changes in the electrolyte. As they discharge, hydrogen and oxygen are released from the plates into the electrolyte, forming water, and watering it down. For those that don't know: water is a GREAT insulator, it's the impurities in tap water that allow them to conduct. Therefore, as more water is released into the electrolyte, the higher the resistance, and the lower the voltage under load. When you charge the battery, the resistance drops, but the voltage is going up, so it resists charge-runaway throughout the entire cycle.

 

One last thing:

 

This is one people tend to forget. The FAA requires that you must have a backup electrical source that is able to supply the aircraft for at least half an hour. It's a strangely written regulation (they quantify the ampere hours and load of the electrical system) so I am having great difficulty finding the specific reference. But it's out there. If you take off on a jump start, YOU CAN BE VIOLATED. It's happened in St Louis to a pilot who brought his plane into one of my A&P school's instructor's shops, and someone left the master on, so it depleted the battery. A FSDO guy was there on inspection, and the pilot was hand propping the plane to get it started. He took off a few minutes after prop start, and the FSDO guy wrote him up.

Link to comment
Share on other sites

What does it need to supply? My Dynons and my 696 both have their own backup batteries, the engine has its own source. Where's the violation?

 

Will your radios, transponder, and anti-collision lighting (beacon) function if main generator and battery are offline? These require enormous amounts of energy, so I find it hard to believe the dynon backup battery will keep them running for long even if it were able to.

 

The beacon is required to be on at all times.

 

§ 91.209 Aircraft lights.

No person may:

( B) Operate an aircraft that is

equipped with an anticollision light

system, unless it has lighted anticollision lights. However, the anticollision lights need not be lighted

when the pilot-in-command determines

that, because of operating conditions,

it would be in the interest of safety to

turn the lights off.

 

 

 

The transponder is required in all airspace except D, E, and G, and within 30 miles of airports listed in Part 91 App. D. There's a lot of crap in this section, so you might want to read it yourself instead or this post will be huge.

 

§ 91.215 ATC transponder and altitude

reporting equipment and use.

Link to comment
Share on other sites

I know the regulation exists because we discussed it in my A&P class. But as said, it's oddly written. Instead of something simple like "battery reserve", they got technical. Still looking.

 

EDIT: Found it. It will not directly violate you in standard category aircraft, but follow my logic for a moment. Light sport has their own way you can get violated, I'll explain the CTLS in a moment.

 

§ 23.1353 Storage battery design and

installation.

 

 

(h)(1) In the event of a complete loss

of the primary electrical power generating system, the battery must be capable of providing electrical power to

those loads that are essential to continued safe flight and landing for:

(i) At least 30 minutes for airplanes

that are certificated with a maximum

altitude of 25,000 feet or less; and

(ii) At least 60 minutes for airplanes

that are certificated with a maximum

altitude over 25,000 feet.

(2) The time period includes the time

to recognize the loss of generated

power and to take appropriate load

shedding action.

 

 

Now, batteries are required equipment on most standard category aircraft. But to understand how you can be violated, we need to go back and look at required documents. One of them is a valid "Airworthiness Certificate". This airworthiness certificate is only valid if the aircraft conforms to it's type design, and in standard category aircraft, this is laid out in the Type Certificate Data Sheet. In fact, this is why you can be violated for flying an aircraft which may be missing or have malfunctioning equipment. If it's not listed in the TCDS as "optional equipment," listed in the TCDS as REQUIRED equipment, or came installed on the aircraft at time of production, AND does NOT have an approval to fly without that equipment operating (such as ferry permits), then you may be violated for flying the aircraft. Therefore, since the battery does not hold a charge great enough to conform to part 23 certification requirements, this means they will not conform to the TCDS, and therefore, you are missing a required piece of equipment, and further, your airworthiness certificate is invalid.

 

 

As for light sport aircraft:

 

 

§ 91.327 Aircraft having a special airworthiness certificate in the light-

sport category: Operating limitations.

 

 

(d) Each person operating an aircraft

issued a special airworthiness certificate in the light-sport category must

operate the aircraft in accordance with

the aircraft’s operating instructions,

including any provisions for necessary

operating equipment specified in the

aircraft’s equipment list.

 

 

So basically, if you jump start your CTLSi, then you fly it, you just violated 91.327.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...