The private pilot/owner of the experimental, amateur-built Zenith CH 750 reported that, about 15 minutes into the local flight, the engine started “skipping” before completely losing power.
He set up for a forced landing to an open area near DeLeon Springs, Florida.
During the descent, he maneuvered to clear power lines. The airplane touched down at a steep descent angle, nosed over, and came to rest inverted, which resulted in substantial damage to the airframe.
The airplane’s engine used an electronic control unit instead of magnetos and required at least one of the airplane’s two onboard batteries to provide electrical energy to the ignition system for the engine to operate.
Post-accident 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 airplane’s electrical system, and thus charge the airplane’s 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 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.
The pilot also reported that he did not use a checklist when operating the airplane.
It is likely he failed to activate the airplane’s alternator, which resulted in a discharge of the selected battery during the 15-minute flight. The subsequent loss of electrical power eventually resulted in the total loss of engine power.
Additionally, the airplane was not equipped with an alternator warning light as recommended by the engine manufacturer. Had the airplane been equipped with such a light, the pilot might have realized that he had failed to turn the alternator on and that it was not providing energy to the electrical system to sustain the charge of the selected battery.
Probable cause: The pilot’s operation of the airplane with the alternator switch in the off position, which allowed the selected battery to discharge and resulted in an ignition system failure and a total loss of engine power.
NTSB Identification: ERA18TA263
This September 2018 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.
Thank Jim I meant power lever
I think that what is important here is to understand that the EAB category provides the builder with a lot of latitude in how they create their systems. Unfortunately not all builders will strive for excellence and while thyr will do a great job on the airframe itself the systems are just thrown together to be quick, simple and inexpensive.
There was a good bit of pilot error in this situation but also a good bit of builder error as well. Apparently they chose to not fully research the guidance from the engine provider and used an older version of the electrical system recommendations. Also they chose to not take advantage of the possibilities to provide such simple features as visible indicators of problems with the electrical system, especially a warning light for low bus voltage. I cannot understand how the DAR or FAA employee that signed off the aircraft allowed for there to be unlabeled switches for something as important as the electrical system but maybe the guidance on that does not require it.
This is a good example of why organizations like the EAA with their network of local chapters and counselors are vital for the safe completion of a homebuilt aircraft. Maybe that help was available in this instance and ignored but then considering the apparent attitude of the builder such advice was probably never sought out.
The bottom line is that when building your own aircraft you MUST strive for excellence and not just look for what is quick and inexpensive.
Thus the original reasoning for mags vs externally powered ignition systems dependent on switches, batteries, wiring runs, connections, alternators, regulators….and of course….something else for the pilot, who always need retraining, seminars and refreshers, to remember….lol
My question is: Does electronic control unit means Full authority Digital Engine Control (FADEC) system/
If so thus system requires electric power to operate the engine, If the alternator is not supplying power for any reason then the system will depend on the main battery,then the stand by battery if provided,once no electric power is supplied to the (FADEC)then the engine will quit.
My self i prefer the old magnetos equipped engine because the engine will continue to run even if the electrical system is lost, but not the (FADEC) equipped airplane, I like single engine control lever but not (FADEC) System
ignition system
The ECU controls the ignition timing and the fuel injection. Most installations will use a fixed pitch prop. So there is only a throttle control.
Auto conversions don’t/can’t use magnetos, so they rely on having electrical power to run the engine.
They can be configured with dual batteries, as the Viking does, and some warning and monitoring equipment, like an ‘alternator off’ warning light and a voltmeter, or 2, to show the state of charge of the battery[s].
Then, the amp-hour rating of the battery should ensure at least 30 minutes, [ or more], of engine run time on the battery [s].
There are experimental versions of Lycoming and Continental engines that replace one or both of the magnetos with electronic ignition units.
The electronic ignition units provide a hotter spark for better fuel burn , and include timing advance for better economy at lower power settings.
Thank Jim so for both system (ECU and FADEC), the electric power is required to keep the engine running. The (FADEC) equipped airplanes are provided with constant speed propeller too.
Any way I am talking about airplanes powered with diesel engine like Cessna172TD
best regards
Ali,
Yes , the ECU and FADEC operate similarly.
But in a diesel, there is no throttle. There is a fuel control only, and in an aircraft a ‘map’ is used to control the prop too.
It will be interesting to watch the development of a turbo diesel with FADEC.
Classic accident chain.
No warning light, no checklist, unlabeled switch(es), didn’t keep updated on changes OR follow manufacturer’s instructions.
We know the result, hopefully he wasn’t hurt.
Here’s a good “know your airplane’s electrical system” exercise: “What does/does not work if component X fails?”
I’ve been fooling around with airplanes almost half a century now, and in my experience, most pilots, builders and even mechanics do. not. have. a. clue. about how electrical systems work. I’m also an AGI, taught part time for eleven years, and for a while I had a part time gig at a flight school teaching their CFIs how to teach their students. Most of them were good at flying the airplane (many of them better than I am), but very very few of them had any real idea of how it works. The high point (low point?) was when one of the CFIs actually asked me “what’s a cylinder?” and he wasn’t kidding!
Hopefully, your mileage may vary . . .
I can’t imagine his pain. All that build time thrown in the toilet for no good reason. What about at engine runup checking the ammeter to see that it is charging…oh yeah… another, didn’t use the checklist item. No wonder our insurance is so high. Wow, he didn’t conform to manf recommendations, didn’t label his panel, didn’t use a checklist, didn’t follow the proper startup procedure, didn’t follow the proper runup procedure and didn’t land properly in an airplane designed to land off field.. Checklists are supposed to BACKUP proper procedure knowledge and performance. I’d love to know when the last successful Flight Review was performed. There isn’t a link that isn’t a broken link in this accident chain. Just because you built it well doesn’t mean you can fly it well. Build quality can be inspected on the ground to a high degree. Pilot quality cannot be measured on the ground but it must be measured and proficiency must be maintained else these very sad events will continue and our insurance premiums will climb.
“ didn’t land properly in an airplane designed to land off field.. ”
Not a fair criticism, considering that this was a forced landing brought upon by a complete loss of power (I will admit that I have not read the full accident investigation report).
The builder and current owner failed to follow the recommendations from Viking.;
– not installing a dual voltmeter to monitor the 2 batteries, and no alternator off/fail light.
– Then, not labeling the switches functions.!
The Viking wiring diagram has problems.;
– don’t wire the alternator field circuit through the ‘ignition/starter’ switch.
There is no need to switch the field circuit on a single engine aircraft,
– the field circuit needs a pull-able breaker. .
An ammeter would be another indicator of the status of the charging system.
It looks to be somewhat unreliable that Viking indicates to wire the engine ecu through the battery contactors., rather than to a hard wired switch [s] directly connected to each battery. .
There is already an ecu1 vs ecu2 switch.
Hey Jim, the wiring diagram you are referring is very old, our website has stated for years to update it to the latest version. The alternator does have to be in a switch in order to shut down the engine, since the engine will continue to operate on battery 1, battery 2, or the alternator. If you didn’t have one, the engine wouldn’t stop. It’s unreal fortunate the builder didn’t update the wiring as stated, along with many other problems mentioned.
I was referring to the wiring diagram that I found on the Viking website and the installation and operation manual.
I find it strange that in order to shut down the engine that the electrical power to the entire aircraft has to be shut off as well.!
It’s interesting that the alternator will continue to supply power with the voltage removed from the main bus and the field circuit.!?
You should have identified yourself as an employee of Viking.
BTW, most pilots are most familiar with turning on the master switch, which connects the battery to the main bus.
Then turning in the mags ,[ or engine ignition system], which enables the engine to start and run.
Then the starter is engaged to start the engine.
With the way that the Viking is wired, with the battery turned on, if the propeller is moved the engine could start.
Why not install an ‘ignition ‘ switch to the ECU to be able to shut down the engine and leave the power to the bus and instruments and the remainder of the electrical system.?
I did note in the Viking videos that the engine will continue to run with the battery[s] ‘off’ and the alternator ‘on’.