When the Panel Goes Dark: Electrical Failures, Mountain Hazards, and What Every Pilot Should Know

Back in January of 2023, Cessna Pilot Magazine ran an article by one of our members, Jack Henion. The incident occurred over the Rocky Mountains in Colorado, in his beautiful 1979 Cessna 210N, while en route from Ithaca, New York, to Salt Lake City. 

Long story short, while flying IFR  past the Medicine Bow VOR, Jack noticed a major electrical discrepancy in his PFD and MFD, and the ammeter on the JPI 930 indicated a discharge. None of these is ever a good sign, especially when flying in the clouds. Thankfully, conditions were not IMC, so after shutting down all electronics except the Garmin GTN 750, he decided to head back to the departure airport, Fort Collins (KFNL). 

Radio contact was lost around 30 miles north of KFNL, and all avionics went dark as the battery was fully discharged. Thankfully, Jack had a handheld iCom radio for just such an emergency, although the range on these is only a few miles without hooking into an exterior antenna (NOTE: the author can attest to this; we used iCom A6’s on the ground at KFLV, and they would only reach a mile or so on a good day).

Let’s take a look at some of the best practices to stay safe and sound when something happens, and how you can get on the ground when they do. 

Electrical Failures Rarely Happen All at Once

While electrical failures can happen out of the blue, this is generally not what happens. There are usually signs along the way if you are willing to listen to them and watch for the signs.  

Electrical failures often appear sudden in the cockpit, but they usually develop through a chain of smaller warning signs. One of the most common problems with electrical systems is the alternator. It is a simple part that has remained relatively unchanged for decades, and is one of the weakest links, so to speak. Here are some of the clues to look for:

Early Warning Signs

Alternator problems almost never go from a perfectly functioning unit to a dead one without any signs. Here are the most common symptoms:

• A slightly reduced bus voltage or fluctuations that do not match normal load changes.
• Ammeter indications that trend toward discharge, or bounce in unusual ways that do not match the load applied. 
• Unusual glitches in panel equipment, like brief resets, dimming, or strange annunciator behavior. 

On Jack’s flight, the obvious indicators appeared when he passed the Medicine Bow VOR, and both his PFD and MFD flagged red. Also, his ammeter indicated a major discharge, all key indicators that there was a real-world mechanical failure with an electrical component, in this case, the alternator. 

Partial vs. Total Electrical Failure

The bulk of electrical events start as partial failures rather than instant, airplane-wide blackouts. The ability to recognize the distinction is a clutch skill that gives pilots the latitude to decide how aggressively they need to shed the load and use the remaining time left on the battery. 

When the alternator goes offline, but the battery is still healthy, there is a window of time where the pilot can turn off nonessential avionics and lights, preserve a single source of navigation or communication radio, and re-evaluate routing, terrain, and destination. 

Jack did exactly this. Once he recognized that he had a real electrical discharge on his hands, he shut down all electronics except the Garmin GTN 750, then worked to return to his departure airport, where maintenance capabilities were known. This was a decisive decision to shed the electrical load as much as possible to preserve battery power for the return leg. 

The Cascade Effect

Unlike automobile engines, where the alternator is always a belt-driven accessory, piston aircraft often use a direct-drive configuration that is very solid and reliable. However, if the alternator fails internally, it can send shavings into the engine, whereas a belt-drive simply dies. 

In this case, though, the impending failure gave some clues that it might be on the way out. For Jack’s aircraft, it was revealed in professional oil analysis, a process that is common for aircraft of all sizes. In this case, it was revealed prior to the event that elevated iron levels in the oil indicated something was happening. 

What these oil analyses don’t tell you is what system; rather, they are a tool to observe the overall health of the engine. It is there to give you the best opportunity to have a healthy and reliable engine and provide you with some key indicators that something is happening, but it doesn’t tell you what or where. 

With that said, mechanical failures tend to propagate through multiple systems, especially with a direct-drive component like a hydraulic pump or an alternator that is tied into the engine system and not an accessory powered separately. 

The Hidden Risk of Direct-Drive Alternators

The root cause of the incident was not simply an alternator failure; it was actually a design flaw. Well, sort of. An alternator failure is bad no matter when it happens, but the damage can vary. An externally mounted alternator will generally affect only the alternator; if it goes out, it goes out. 

Direct-drive alternators, though, when they fail, leave things in the engine. And not the kinds of things you want in your engine. They leave metal shavings, particles, or even pieces of the damage, leading to very bad consequences.

The Failure Mechanism in This Case

In this case, the after-incident investigation revealed that a cotter pin and the alternator castle nut had been installed incorrectly. It had been pushed through the castle nut, but the prongs had never been separated. It poses an inherent problem if a castle nut and cotter pin are installed but not spread properly, because the cotter pin is the mechanism that actually holds it in place. See, a castle nut is not intended to be torqued down to a high torque value and, usually, not even a torque value at all; it is supposed to be hand-tightened or finger-tightened, and the cotter pin holds it in position. 

Over time, since the cotter pin was installed incorrectly, vibration set in, forcing it to work its way loose. The alternator clutch gear began to wobble against the crankshaft face gear, causing metal shavings. And since this was a direct drive alternator, the shavings went directly into the engine’s lubrication system. 

Frankly, it’s a small miracle that it took 430 hours for this to happen. Yet, it couldn’t have picked a worse time to do it than in the mountains, on an instrument flight plan. Thankfully, all ended well in this instance. 

A Known Safety Concern

The FAA and EASA later issued Service Information Bulletin SAIB-18-16, which documented a fatal Bonanza crash involving the same IO-550 engine family and a similar alternator drive failure.

In 2015, a fatal accident occurred in Plainville, Massachusetts, on a Beechcraft A36 Bonanza. Investigators ultimately found that the alternator drive coupling had failed, causing a catastrophic engine failure. The same could have happened with the Cessna 210 in this instance. The FAA determined the need does not rise to the level requiring a mandatory airworthiness directive, so a bulletin was issued instead. 

The takeaway is simple but important: Factory zero-time does not guarantee factory-perfect assembly.

When Electrical Problems Happen in the Mountains

An electrical failure is terrifying anywhere it happens. It’s a challenging situation, but over mountainous terrain, this problem gets significantly more worrying. Where are you going to put it down? Can you make the next airport? These are questions you have in mind, especially if you’re flying on an IFR flight plan and it’s instrument meteorological conditions. 

Thankfully, the conditions were not IMC on this flight–even though he was flying an IFR flight plan–but he did have somewhat limited diversion options. A lot of that had to do with the very limited maintenance that he could expect on the ground. Now, had he been flying in IMC conditions or been further along in the route, things would have been different. Jack had some time to work with because he wasn’t that far along, and the conditions outside were good, so he was able to return to his point of departure. He chose to do this because the support on the ground would have been much better there than at a small en route airport. Of course, had the electrical situation been worse, he would have been forced to deal with whatever he could get to.  

A degraded electrical system can therefore remove multiple layers of situational awareness, even though it shouldn’t; thanks to the ancient technology in the magneto, the engine will continue running regardless of electrical status, and that is a major win.  

When the Electricity Is Gone, the Airplane Still Works

We touched on this lightly in the last section, but when the electricity goes out, an airplane still works, and that’s a real win for pilots. The panel may have gone dark, which is a problem, but the airplane remains controllable. As long as you have fuel, you have time. Of course, there are situations where you are no longer able to operate, but these are the exception, not the rule. Experienced pilots keep a bag full of tools that pilots would have killed for a quarter century ago. They can, in a pinch, help you out a lot when your panel goes out. 

Take, for example, handheld backup radios. There are certain models now that even have a built-in VOR and GPS (iCom IC-A25N), or even VOR and ILS (Yaesu FTA-550 NAV-COM). Would you want to bet the farm on that? Absolutely not. But if your panel goes out and the conditions are IMC, it’s a lot better than nothing. 

The list of useful items to keep in your flight bag for emergencies is long enough to warrant its own article. And that’s not the point of this. The point is that even when your electrical power goes out, as long as you aren’t out of gas and your control surfaces are all functioning, you have some time to work with to figure out the problem. Obviously, the more technical the aircraft, the more you have to worry about. In this case, without electricity, he had to manually extend the gear. So it’s a good idea to practice manual gear extensions routinely in a non-emergency environment. 

A lot of this comes down to practice and familiarity with the systems. Jack was able to make it back without a serious incident because he planned ahead. His backup ICOM radio was fully charged. He had good situational awareness as to where he was when the problem occurred and how he could get back to his departure airport. He kept in contact with air traffic control; they gave him vectors to get back, and he dealt with the mechanical issue as much as he could in the air, to have an idea what he was dealing with once he got back in the pattern. 

A few other things to think about would be:

• No flap landings at high elevation airports
• How an electrical failure removes access to flaps, which it definitely does on this aircraft

This creates additional considerations in the mountains as it leads to:

• Higher approach speeds
• Longer landing distances
• Increased effects in density altitude

So these are important things to keep in mind, especially if your alternate airport is very short. Again, situational awareness and planning remain undefeated here. 

At high-elevation airports common in mountainous regions, this creates additional considerations:

• higher approach speeds
• longer landing distances
• increased effects of density altitude
  

These factors make advanced knowledge of aircraft performance especially important.

Maintenance Lessons That Matter

This incident is a great example of why maintenance matters, and paying close attention to what your maintenance is telling you matters.

For instance, the oil analysis already indicated problems, with increased iron levels. While this does not necessarily tell you what will fail or when, it does give you some idea of the problems to come.  

Incidents like this highlight the importance of careful maintenance practices and proactive aircraft ownership. A few important things to note:

1. Get to know your airplane. We highly recommend attending an in-person or online course for your aircraft models. They are hosted by some of the most experienced Cessna-specific A&Ps in the world with decades of dedicated experience. 
2. Talk to your mechanic during annual maintenance or other service visits and ask if they notice anything. Also, ask them about common failure points that they are seeing on other similar aircraft engines. In this case, since the IO-550 is used on many aircraft, engine problems are not necessarily limited to the C-210N. 
3. Make sure to research any bulletins specific to your engine or aircraft model, and ensure they have been complied with. 
4. A factory-completed task does not always mean it was done right! This incident involved a factory-installed component installed incorrectly. 

Parting Thoughts

Thankfully, this incident ended without incident thanks to a cool-headed approach to the problem; it is obvious that it could have been much worse 

In the end, the pilot descended through the mountains on battery power alone.

With most of the electrical system inoperative, he manually extended the landing gear and completed a safe landing while coordinating with ATC to the best of his abilities with remaining battery power and then with his handheld unit. 

The outcome was not determined by luck or happenstance. It was determined that the pilot being prepared before he ever took off. 

He:

• Understood the aircraft’s systems
• Made sound decisions under pressure
• Maintained situational awareness despite failing instruments and failed electrical power. 

None of these are out of reach for the typical Cessna owner/pilot. We strongly suggest taking one of our courses for your aircraft model. In-person is the best option, since you will get face time with our cadre of instructors and be able to put the pieces together on a real aircraft. However, this isn’t always an option for everyone, so we also offer courses online. These have access to the exact same materials as the in-person events, along with video, and are self-paced, so you can do them anytime. 

These courses put you in the highest echelon of knowledge among Cessna owners and pilots, and anything that isn’t covered in them is probably covered in our forum archives.