First Emergency: Electrical Failure at Night

tlglenn

tlglenn

Line Up and Wait
Joined
Jul 5, 2007
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976
Location
Tucson, Arizona, United States
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Display name:
Ted
After over eight years of flying I suppose I was due for an emergency.

Wednesday night I was flying from Fort Smith, Arkansas to Austin, Texas in a Cessna 182RG. I was near McKinney, Texas when my second nav/com unit started acting weird (lights flickering, digits changing) after I tried to transmit on it. I shut it off. Other lights started flickering and then I noticed that the amperes needle indicated a slight discharge. I started shutting down items to save juice. Then the transponder stops working and I hear Ft. Worth Center trying to contact me to confirm position.

I manage to transmit that I have electrical issues and will divert to McKinney. He hands me off to regional approach. I can't get a message to regional approach because the first nav/com unit (Garmin 430) starts shutting off and powering back on (in hindsight I probably should've shut off that unit and turned the second unit back on). I've tried cycling the alternator switch by itself and the master switch (alternator and battery switches together) to see if that helps, but it doesn't.

I aim right for the rotating beacon on the control tower and duck under the floor of the DFW class B. I circle the tower at the top of the class D airspace and switch to the tower frequency. I manage to squeeze out a few 1-3 word messages (each transmission causes the Garmin 430 to power cycle, but receiving is okay) to declare that I was an emergency aircraft circling the tower. The controller eventually pieces together my transmissions and clears me to land while redirecting everyone else.

The landing gear switch did nothing so I pump down the gear manually (I automatically did that by habit thanks to my CFIs once I noted no sound from the gear deploying) and land the airplane. I have no recollection if the flaps were deployed (I do know I actuated the flap switch by habit), but they probably weren't since the airspeed was higher than usual and the approach angle wasn't as steep as usual.

On the ground I call my club mechanic and he has me check the alternator belt and we discuss the other things I did during the flight. A few minutes later two other pilots come over (they had been in the air when I declared the emergency) and one of them also checked the belt. No problems with the belt.

The next day the mechanics at Air-O (Charles is a stand-up owner) looked over the electrical system. They couldn't find a definite cause. They noted that the alternator is made by Plane Power and the voltage regulator is made by Zeftronics. Perhaps they miscommunicated (apparently it's a good idea if both are made by the same manufacturer). The battery is two years old and still good. There was some corrosion with some connections that was cleaned off.

The next day I flew to Austin during daylight and had no issues.
 
When that almost identical event happened on my 210 it was due to intermittant connection on the big plastic connector on the alternator. They can't see or feel the problem on the ground, and duplicating it is difficult. You might have somebody check all of the connections.
 
I once had the wire for the field wire connector on the back of the alternator break off inside the ring terminal crimp connection insulation that could not be detected visually. A gentle tug on the wire eventually revealed the break. It manifested itself only in cruise flight by illumination the alternator light. On the ground the charging system appeared to operate normally.
 
Nice Job. Sounds like you handled it well.

The one time I lost electrical power I was in severe clear 30 mins from my home airport so I was able to get home on the power remaining in the battery after I shed all non essential electrical equipment.
 
Yeah, I had a flashlight around my neck (plus two more next to me). It's somewhat flat so it's easy to hold between my teeth. Came in handy.
 
When I first bought my Tiger almost ten years ago I had electrical gremlins. I had two total electrical failure both during the day. I replaced an alternator, Voltage Regulator and still had problems. I'd take it in to my mech who would scratch his head as the problem was intermittant, and of course would not occur for him. He bench tested the battery. It worked fine. Then he reinstalled it and the darn thing boiled over. He removed it again and found it had an internal, intermittant short. Replace battery and it was fine. Since, I have replaced a lot of old wiring also and the electrical system has been very reliable.

Electrical problems can be very hard to diagnose and repair. Watch it closely.
 
Well done! :smile:

The possibility of such an emergency is the reason why I always carry two headlamps with a set of spare batteries, as well as a handheld radio with me. :yesnod:

Just the imagination of everything going dark during a night flight, over a dark area, at a dark night, with no possibility to read the instruments causes me sheer terror. :yikes:
 
Anthony said:
Intermittent electrical problems can be very hard to diagnose [del]or repair[/del]. Watch it closely.
Click to expand...
Fixed it for ya...

Solid failures are generally fairly easy to diagnose if one uses the proper tools and techniques. Even many intermittent problems can be diagnosed, either by finding a way to precipitate the failure or by setting up traps that offer clues each time a failure occurs. The real problem IME is that most good wrenches are nearly clueless when it comes to debugging electrical issues and they trend to resort to replacing (expensive) components until the problem goes away (or in all too many cases, gets worse).

BWT, how does one code strikethrough in a post anyway?
 
gismo said:
Fixed it for ya...

Solid failures are generally fairly easy to diagnose if one uses the proper tools and techniques. Even many intermittent problems can be diagnosed, either by finding a way to precipitate the failure or by setting up traps that offer clues each time a failure occurs. The real problem IME is that most good wrenches are nearly clueless when it comes to debugging electrical issues and they trend to resort to replacing (expensive) components until the problem goes away (or in all too many cases, gets worse).

BWT, how does one code strikethrough in a post anyway?
Click to expand...


Yep. Spot on. Its the intermittant ones that are a royal PITA!
 
Alternator field brushes wear out, and many alternators are never opened up to get those brushes and slip rings checked. The owners run them until they quit or get weak, and that weakness often shows up at night when the loads are more than the alternator can produce. In the 12-volt systems I find the brushes about a third gone at the first 500 hours and they get replaced at the second 500. The 24-volt systems eat them even faster. Brushes are rather inexpensive; it's the labor to do the job that costs. And we've also had some hassles with Kelly's alternators, with too much grease in the rear bearing that get ends up on the slip rings and gums them up. Makes the alternator very weak.

The same run-it-until-it-fails mentality often applies to vacuum pumps (sad, because there are pumps now that have vane wear inspection ports) and magnetos. No need for it. A breakdown in some really inconvenient spot or in nasty weather could cost a lot more than regular checks.

Dan
 
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