Crashes in the News - Thread

[dave wolfe]

I can definitely confirm your question. We had a battery fire and the engine stopped. The setup has 2 ignition systems available so I am recommending a switchable 2 battery system.

My question would be, how is the shortcoming in system design being introduced? I think the electrical schematics at viking include a backup. Is the basic CH-XXX wiring system being used with an EFI/elec ignition installation?

There is a trend happening here. Not enough awareness of additional redundancy needed for elec dependent engines.

 

[Wanttaja]

My question would be, how is the shortcoming in system design being introduced? I think the electrical schematics at viking include a backup. Is the basic CH-XXX wiring system being used with an EFI/elec ignition installation?

There is a trend happening here. Not enough awareness of additional redundancy needed for elec dependent engines.

Checked my database for Zenair CH-750 accidents involving failures related to engine controllers or electronic ignition. Found four, all with Viking engines.

CEN14LA441 - Engine failure after loss of electrical power. "The engine manufacturers initial installation used a single battery with a series of breakers and relays to provide power to the engine components and other equipment. This design was subsequently replaced by a dual-battery design that incorporated a simpler wiring harness. The airplane was originally wired for a single-battery operation, and a second battery was subsequently added. However, the simpler wiring harness was not used; instead the electrical path from the alternator to the alternator sense wire used a complex series of fuses to provide power to the components; one of these fuses was found open, which is indicative of an electrical power failure and would have led to the loss of engine power."

CEN18LA042 - Not a power failure issue; ECU ran the engine too lean

ERA18TA263 - Operator error. "The airplanes engine used an electronic control unit instead of magnetos and required at least one of the airplanes two onboard batteries to provide electrical energy to the ignition system for the engine to operate. Postaccident examination of the airplane revealed that both of its batteries were discharged. After the batteries were charged, the engine was started and ran normally. The alternator also charged the batteries normally. The cockpit instrument panel switch that enabled the alternator to supply energy to the airplanes electrical system, and thus charge the airplanes batteries, was unlabeled. When the switch was placed in the unlabeled on position, the alternator field wire received power and the alternator charged normally. The pilot reported that he may have inadvertently left it in the off position during the flight. With the switch in this position, the engine would have continued to run until the selected battery lost its charge. "

CEN20LA412 - Apparent short. "Postaccident examination of the airplane revealed the main fuse block, located behind and under the instrument panel, was discolored and exhibited internal thermal damage. An automotive blade-type fuse, that connected to both primary and secondary fuel pumps and primary and back up ECUs, displayed arching signatures and had failed. According to the engine manufacturer, who responded to the accident site, the primary and secondary ECUs should have been wired directly to the main buss and should not have contained a fuse. After bypassing the failed electrical system, an engine test run was performed. The engine started and operated normally with no mechanical issues noted."

Ron Wanttaja

 

[Vigilant1]

Is the historical data on the CH701 significantly more robust than the 750? The 701 has been around a lot longer, and if there are enough similarities in engine installations, etc, maybe there's some utility in aggregating the data.

 

[Stolch]

My understanding from my early engine research days when building my 701 is that there are far more 750s than 701s with the Viking or "other than Rotax" battery-dependent engines but Ron's the man with the data. As I stated earlier, the Zenith 750 is a focus market for Viking. If you peek at the Viking website that will be evident as well. I personally did not want to be behind an engine that had to have a working battery to keep the engine running but to each his own. I am curious about the battery fire mentioned earlier as well. I have the EarthX 680 LifePo battery in my Rotax-equipped 701 but it has a Battery Management System that should prevent the battery from a thermal runaway.

 

[Wanttaja]

My understanding from my early engine research days when building my 701 is that there are far more 750s than 701s with the Viking or "other than Rotax" battery-dependent engines but Ron's the man with the data. As I stated earlier, the Zenith 750 is a focus market for Viking. If you peek at the Viking website that will be evident as well. I personally did not want to be behind an engine that had to have a working battery to keep the engine running but to each his own. I am curious about the battery fire mentioned earlier as well. I have the EarthX 680 LifePo battery in my Rotax-equipped 701 but it has a Battery Management System that should prevent the battery from a thermal runaway.

I'm not showing any CH-701 accidents due to issues with engine controllers. I see two accidents with CH-701s carrying Viking engines; one is a pilot issue, the other is a failure of the flywheel drive assembly.

I've got 13 accidents where the NTSB indicated it had a Viking engine (the NTSB is more reliable this way than the FAA registry, but mistakes are still made). Seven of the 13 were due to unexpected power loss (not necessarily attributed to the Viking itself). This ratio is typical of auto-engine conversions (although the sample size is small).

Eight of the 13 are various Zeniths.

Ron Wanttaja

 

[AdrianS]

Ron, how do VW / half VW compare to other auto engine conversions?

 

[Wanttaja]

Ron, how do VW / half VW compare to other auto engine conversions?

Don't have data on half-VWs.

Otherwise, Volkswagens are the largest portion of the auto engines in my database. About 41% of the auto-engined fixed-wing homebuilt accidents are Volkswagen, with Subaru in the #2 position at ~25%. In about half the cases for both, the accident was due to loss of engine power.

One bit of curiosity: When looking at Gyro accidents only, about 84% are powered by converted Subarus. And only 16% of the accidents are due to power issues.

Ron Wanttaja

 

[TFF]

Most gyros are not constrained with cowling like an airplane is. An airplane pushes everything into a tight cowling, where the gyros can take up double the real estate to mount the same stuff and almost no one balks on looks or aerodynamics.

 

[Pops]

did he test it or alert you to the issues?........

Alerted me. Easiest to just add about 5 mph to the approach speed to give you a little more time before it stops flying. Also with the huge drag increase that comes with the higher AOA the landing roll out is very short. Brakes are rarely needed.
I usually land it with the tail wheel about one foot off the ground. Not to get to the high AOA as doing a 3 point landing. When the tail wheel hits the ground with full up elevator, you are almost stopped from the high AOA drag and the light weight.

Here is a wheel landing with extra speed on the 900' field. And here is a takeoff on the 900' field with trees.

 

[raytol]

I take it you only had one battery but could you let us benefit from the lessons learned in more detail.....what kind of battery, why the battery fire, custom design system or recommended/purchased system design from others........if explained somewhere else maybe a link....this is the kind of information we all can learn from.....thanks ahead of time

Hi Proppastie,
Not much to tell really. The builder of the kit we supplied signed a waver to be able to use a Li-ion battery. Jump started the aircraft with his car. Spiked the battery which took a while to exotherm, fiberglass battery box melted and the battery fell out. No electrons to CDI, motor stopped. Both CDI's work off same battery. Luckily still in circuit! landed safely. Has there been any warnings about jump starting with Li-ion batteries?

 

[Sraight'nlevel]

Very interesting crash/accident at 10:30...from the Flying Pancake history:

 

[AdrianS]

Don't have data on half-VWs.

Otherwise, Volkswagens are the largest portion of the auto engines in my database. About 41% of the auto-engined fixed-wing homebuilt accidents are Volkswagen, with Subaru in the #2 position at ~25%. In about half the cases for both, the accident was due to loss of engine power.

One bit of curiosity: When looking at Gyro accidents only, about 84% are powered by converted Subarus. And only 16% of the accidents are due to power issues.

Ron Wanttaja

Thanks.
I asked because the VW is about the simplest auto conversion - no ECU, and can be built with magneto ignition & mechanical fuel pump, so a lot less failure points.

 

[Stolch]

Raytol, my EarthX users manual explicitly warns the user not to attempt a conventional jump start and why. LifePo batteries are only to be charged with a special charger or other very strictly described options, this too is clearly described in the manual and on their website.

 

[b7gwap]

I’ve had a model airplane lithium power battery explode, I can’t imagine having to deal with that in the air. Thank god you got her down.

 

[n45bm]

One man's flock is another man's herd!

NTSB to investigate as pilot survives plane crash after hitting birds near Angier

View attachment 120730

Yep. She's a broke. Sad loss for the airplane, good news of minor injuries only to the pilot. That was a nice example of a CX4, I may consider building one, since I still have the plans.

 

[BJC]

... good news of minor injuries only to the pilot.

Two cracked vertebrae that will (or already have) require surgery, plus a fractured rib.

Certainly could have been worse, but it could have been better. The tree he hit is just off, and to the side, of the end of the runway.


BJC

 

[Rhino]

Two cracked vertebrae that will (or already have) require surgery, plus a fractured rib.

Certainly could have been worse, but it could have been better. The tree he hit is just off, and to the side, of the end of the runway.

Luckily they're only cracked. Mine was crushed, and seven years later it's still disabling.

 

[Daleandee]

There is a weight penalty to using the Odyssey PC-680 battery that I use in my plane but they do seem to be a little bit safer.

 

[gtae07]

I’ve had a model airplane lithium power battery explode, I can’t imagine having to deal with that in the air. Thank god you got her down.

That's a completely different battery chemistry (LiPo - lithium polymer). It's used in portable electronics, cellphones, model aircraft/"drones" etc. because it can pack a lot of energy in a small mass/volume and the pack can be different shapes.

EarthX and other such batteries are lithium iron phosphate (LiFePO4) which isn't quite as energy dense but safer, less prone to thermal runaway, and less energetic when it happens.

These lithium batteries save a bunch of weight, but you can't just throw them in and abuse them like many have become accustomed to doing with lead-acid. You shouldn't jump start them, you need to be a little more careful with your mounting arrangements, and you need to look very carefully at the capacity and discharge curves if reserve power (for keeping things running after an alternator failure) is important to you. The lithium batteries are more efficient at high discharge rates, so for equal "starting power" (generally depicted as PbEq or lead-acid equivalent amp-hours) the lithium is smaller, with less reserve capacity. For equal reserve capacity, the lithium will have much more starting power. EarthX does a good job depicting actual discharge curves in their manuals, showing voltage vs time for different discharge rates.

 

[b7gwap]

I’m familiar with both Li-Po and LiFePO4 as a modeler; and concur that LiFePO4 is a safer choice for manned aircraft.