The sport pilot was conducting a cross-country flight when the experimental amateur-built airplane experienced a loss of engine power. He made a forced landing to a field near Grady, Arkansas, and the Zodiac 601XL sustained substantial damage.
Post-accident examination of the airplane revealed a broken wire to the alternator. This specific wire supplied electrical power to the alternator field coil. Because the wire was broken, the alternator was rendered inoperative.
The pilot would not have been able to detect the broken alternator wire without removing the engine cowl, which is not normally part of a preflight examination.
The airplane’s engine had been modified to use an ignition system that operated from the airplane’s electrical system, which included a battery and the alternator to maintain the battery’s charge. Once the alternator field wire had broken, the ignition system relied completely on the airplane battery’s reserve power as the source of ignition power. Once the battery power was depleted, the ignition system could not operate, and the engine lost power due to the lack of ignition.
Probable cause: The loss of engine power due to a lack of ignition resulting from a broken alternator wire.
NTSB Identification: CEN17LA313
This July 2017 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.
Brad Dement
E-MAG Ignitions
The report underscores the value of independent ignition power. E-MAG has been producing electronic ignitions with an internal miniature alternator for 14 years. E-MAGs also have a secondary connection to aircraft power. In a dual configuration the ignition system has three sources of operating power. (1) Internal alternator in LEFT, (2) Internal alternator in RIGHT, and (3) aircraft power to both LEFT and RIGHT. E-MAGs are a hybrid that has the advantages of electronic ignition, plus independent operating power advantage of a traditional magneto.
Added alternators and added batteries and this and that may be a safeguard, but it’s more money, more installation problems, and more system complexity. Lots of people grouse and whine about how magnetos are old-school, and all that. But it has to be remembered that having two mags, like having two spark plugs per cylinders, are redundant for a very good reason. Also, with mags, the entire aircraft electrical system can go up in smoke, and as long as the engine has fuel and as it, the mags will supply the spark. I don’t care how old-school they may be. Never had an issue with the 600-series Slicks, or the big shower of sparks Bendix mags on the TCM 470 and 520 engines.
Most electronic ignition systems offer significant fuel savings through the use of variable timing curves and better reliability than magnetos. However, a part of that reliability picture for the ignition is the charging system. If the charging system isn’t reliable, then neither is anything that depends on it, including the ignition.
Folks seem to be focused on primary and backup battery scenarios for electronic ignitions. Doing so leaves the pilot with few options in the case of an alternator failure. It is still an issue requiring an immediate landing and you are grounded until it can be repaired. Rather inconvenient when traveling further than the $100 hamburger.
A simple configuration change to resolve that issue for the same weight is to install a light weight standby alternator to the vacuum pump mount, and continue using a single battery. In case of a charging failure, you minimize the electrical loads and toggle over to the standby alternator and continue your flight. A simple idiot light to show no charge on the panel (or in the EFIS) should alert the pilot to switch to the backup alternator long before the battery is dead. With this scenario, an alternator failure is only a minor inconvenience to be noted and can be addressed after you arrive at your planned destination, or even back home in your own hangar. A light weight standby alternator costs more than a standby battery, but typically fits within the same weight budget and doesn’t have to be replaced every 5 years.
The “good old” Bendix D-2000 mag. Single drive, two mags in one housing. I recall these mags well. Too well in fact. I don’t believe there was another magneto in aviation history that had so many service letters and service bulletins. I removed, disassembled, inspected and replaced many of these on a regular and repetitive basis back when they came available, and for years afterwards. But I never had one fail….ever.
Electronic ignition systems are awesome, but if you are going to eliminate both mags, you need something to indicate that the alternator is not producing power and the backup battery is in operation.
Some electronic ignition systems retain one magneto for this reason. Electronic ignition offers better starting, lower fuel burn, lower idle, and generally more smooth operations. It’s been really great in our demo aircraft (my employer is now an installation center for one of the electronic ignition systems). We were pretty skeptical but it really proved itself.
I did some looking for pictures of the accident aircraft with the hope of seeing what was available for instrumentation but none appear to exist. Given that this was an Experimental Amateur Built aircraft there were considerable options available for instrumentation of the engine and its related systems. Any good engine analyzer would be able to monitor both Voltage and Amperage and provide alerts if either of those parameters were out of the norm.
It is only a conjecture but I think the builder used the simple round dial instrumentation that is so common in GA aircraft. With that type of installation attention would have to be given to whatever electrical system instruments were installed and they are usually small and away from the normal scan pattern.
It should be noted that FAR 91.205 which specifies the minimum equipment requirements for GA aircraft there is no mention of either a Voltmeter or Ammeter . The aircraft was not required to have either of those key instruments but it is possible that the FAA inspector who signed off the aircraft might have required one or both given the setup of the ignition system. Just a side note, the aircraft’s registration previously belonged to an E55 Baron that ran out of fuel and crashed killing both occupants, not a very lucky N number.
Looking at 91.205, I’m wondering why there is no requirement to monitor the electrical system, even for VFR night flight; just lights, and… ‘ an adequate source of electrical energy…’ meaning a total loss battery is ok.
For IFR flight, it requires a , ‘ generator or alternator of adequate capacity’, along with the night VFR requirements.
The lack of requirement for monitoring electrical equipment is ‘nuts’.!
We’re required to have a minimum of 3 instruments to monitor the engine, gauges to monitor the fuel, but NO requirement to monitor the electrical system, [ if it has one ].
With the current common use of electronic instruments and engine ignition, there needs to be requirements for more monitoring equipment and maybe a 2nd battery and back up alternator.
There are permanent magnet alternators that will generate 25 amp without the need for a battery.
There’s a lot to learn from this crash;
– The CH601 had a Lyconing O-235 installed. Replacing both mags with electronic ignition is usually not recommended, and gains little performance. If the electrical system fails, the engine will still make good power on one mag.
– either this a/c did not have a back-up battery for the ignition, or it did not have sufficient charge to run the engine for very long.
– Also, during the run-up, it would be smart to check the state of charge of both batteries. But a voltmeter is required to do this.!
– Looking at the docket pics, the alternator field terminal and screw were rusty, indicating poor maint.
– The normal starting procedure is, after engine start, to look for oil pressure and the ammeter to be showing a positive charge. If this a/c did not have an ammeter or voltmeter [ more useful], this is another ‘Stupid Pilot Trick’.
When I flew a C152 with the same engine, I used 6.0 gph for fuel burn, not 5.5 gph. But, the electronic ignition may have allowed for more leaning.?
This pilot was very concerned about the fuel use, from his calculations. Too bad he didn’t take as much care with the electrical system ?
So, this is a good example of how not to maintain and equip an aircraft.
It pays to scan the panel.
You are so correct. Scan the gages and determine if they are working for you. Look at trends of the systems within the aircraft. If one sees voltage dropping land and check it out. ASAP
I think I’ll stick with airplanes that have a self-sustaining dual mag system.
And what do you do when you have a dual mag failure? Certain certificated engines have what are known as suicide mags — both driven by a single shaft. If either end of that shaft has problems, your mags are not going to work well if at all.
How about the Lance in the Indy area that had both mags fail within 10 minutes on a repositioning flight? Landed in a parking lot, hit a tree and the insurance totaled that airplane. The pilot walked away wishing he had had 30 more feet — I know because I know the pilot and he contacted me after landing to try to diagnose why the engine just quit producing power.
BTW — that engine and the mags had less than 100 hours since major overhaul. And the NTSB has been unable to determine why both mags failed in flight.
And this Zodiac aircraft had neither an ammeter or voltmeter installed in the panel? I find that to be quite a stretch.