Emergency Exercise

sixpack

sixpack

New Member
I have described two emergency scenarios below, in an attempt to solicit ideas and opinions about handling emergencies. Consider what you might do if you were in each of the situations described. Might lead to some useful discussions.

1. Total Electrical Failure on ILS
You're on the ILS at 2000' AGL just before FAF.
Weather is IMC down to ILS minimums.
Voltage drops from 12V to about 3V and your avionics are failing.
There's 50 amps indicated on both alternators of your small twin.
You can hear tower calling you as your COM2 goes in and out, but every time you key the mike the radio goes black. Nothing electrical is working.
You pulled every breaker, but you're still showing 50A each side.
What do you do?


2. IMC ENGINE FAILURE over MOUNTAINS
You're over the mountains, IMC, and your left engine goes out.
Troubleshooting failed, so you secure the dead engine.
You're call ATC, declare an emergency.
You cannot maintain altitude.
The second engine starts to fail.
What do you do?
 
Scenario 1:

I would discontinue the approach if nothing electrical was working (no nav radios). Next I'd do whatever it took to find VMC, then land in it. With no comms and no navs in IMC, what other choice do you have? This all seems pretty unlikely, as you would should have at least 15-20 mins of power on your battery after your alternators quit. With a 45 minute reserve, you should be able to fly at least 100 NM in most light twins.....there's almost always going to be VMC somewhere within a 100 NM radius of your location. Hope you did a thorough check of the wx before you left.


Scenario 2:

Turn immediatly toward the most favorable terrain within glding distance. Advise ATC of your location and situation. Prepare for a forced landing. Hope you break out of the clouds with enough room to see what's going on. Try to land upslope if possible.
 
Funny. I actually GOT that first scenerio during my IR oral exam. Being in FL, it's a little easier, though. Terminate the approach and climb to the obstacle clearance altitude. Using your charts, determine approximately how far you are from the ocean. In the scenario the DE said the ceilings were 200 feet statewide. Using your stopwatch (or the expensive thing on your wrist) figure our how long it will take to get to the coast. When you are out over the coast, descend until you are below the clouds. Put it down on the beach. Odds are with weather that crappy, no one will be there.
 
RE: Total Electrical Failure on ILS
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This all seems pretty unlikely, as you would should have at least 15-20 mins of power on your battery after your alternators quit

[/ QUOTE ] Ammeters both indicating 50 or more amps.
The GPS and radios failed all at once (in about 5 seconds).

Note: The situation is actually real experience (except for the weather).
 
Even so, a 35 amp hour battery should be able to sustain the 100 amp current draw for 20 minutes or more, if I'm not mistaken. When the alternators quit (the big red low voltage lights should come on and alert you), I don't see how everything is going to fail within 5 seconds unless the battery explodes or all the electrical wiring in the aircraft suddenly gets burnt to a crisp.

Since this really did happen to you, I'm curious about what went wrong with your electrical system. Did the mechanic give you an explanation?
 
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Even so, a 35 amp hour battery should be able to sustain the 100 amp current draw for 20 minutes or more, if I'm not mistaken. When the alternators quit (the big red low voltage lights should come on and alert you), I don't see how everything is going to fail within 5 seconds unless the battery explodes or all the electrical wiring in the aircraft suddenly gets burnt to a crisp.

Since this really did happen to you, I'm curious about what went wrong with your electrical system. Did the mechanic give you an explanation?

[/ QUOTE ] I'll send you a PM.
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Want others to think about it a bit longer.
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there's almost always going to be VMC somewhere within a 100 NM radius of your location.

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You must not live in the Northwest.
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Sixpack will hopefully excuse me for not answering #1 :-)

#2: Probably land in the best place I could find while I still had some power. If ATC has decent radar coverage, they could vector you down pretty close to the ground.
 
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I'll send you a PM.
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Want others to think about it a bit longer.
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I am curious as well as what the mechanic said, maybe you could share it with all of us here.
 
This really happened, PM me the reason if u can, I got no idea since im only gonna start lessons soon, but im interested in what was wrong with ur aircraft.
 
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This really happened, PM me the reason if u can, I got no idea since im only gonna start lessons soon, but im interested in what was wrong with ur aircraft.

[/ QUOTE ]

ANSWER: The battery has an internal short.

Apparently, sediment from the cells can flake off (the lead I think) and collect at the bottom of the battery. This sediment can short out the lead plates. The short was strong enough to pull about 100 amps. Perhaps 500 to 1000 watts depending on what the resultant voltage was (make for a warm battery
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).

Anyway, the Wx during the actually occurrence was not IFR, so I was able to land. By the time I got to short final, all the breakers were pulled, and the alternators and battery were switched off, so I grabbed my handheld COM out of my bag and told the tower I was landing (I didn't ask for permission).

After taxiing off, before shutdown, we did some more troubleshooting. That's when we discovered that the only time the alternators were putting out 50 A each was when the battery master was on.

So if you ever lose all you electrical suddendly, try switching of the battery. It might give you back you power.
 
Just found this thread, found it interesting since we fly the same equipment.

You could also pull the 60A breaker for the battery on the secondary circuit breaker panel (under the main one) to isolate the battery. The battery master switch would be left on to power the avionics. Not good for the electronics or the alternators, but will get you on the ground.
 
Stupid question here... If you isolate out the battery, won't the alternators fry most of your avionics? The way I understand the generic electrical system is that power is drawn from the battery (in DC) and the battery is recharged from the alternators in AC. So if you remove the battery from the loop then you are sending AC to your avionics which can't be too good. Or do I have it all backwards, in which case it would work out just fine.

Ethan
 
Yep, you've got it backwards.

The alternator generats AC, but converts it to DC before it ever leaves. In most modern light airplanes there is no AC anywhere in the system. The battery keeps the Amps constant when the RPMs are low. The voltage regulator keeps the Volts even. Sudden changes in voltage are what can fry sensitive avionics. If you disable the battery (or even physicaly take it out of the airplane) the lights may dim, but it won't hurt anything.

Also, who cares if it's bad for the radios, as long as you get on the ground in one piece. In an emergency, taking care of the airplane falls a distant second to staying alive.

On older airplanes that only had generators electricty was only generated at full RPM. Also their voltage varried wildly. This is the source of many OWTs regarding electricty. Most of the tales simply don't apply to light aircraft.

On the CH-53 (and C-141 I'm told) there are no batteries anywhere on board. The hydraulic accumalator is used to start the APU, which has a generator. On the CH-53 you get three tries to start the APU before you have to use a hand pump to refill the accumualator. It takes about 150 strokes of the pump to get the pressure back. This is a real pain in the a$$, I know!
 
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On the CH-53 you get three tries to start the APU before you have to use a hand pump to refill the accumualator. It takes about 150 strokes of the pump to get the pressure back. This is a real pain in the a$$, I know!

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Man, you're bringing back some memories!!! Not many that I care to remember, of course....
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Whoopps! I stand corected.
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I did some checking. In order for an alternator to work the battery has to be conected, and have a charge. An alternator will not charge a completely dead battery.

If the battery is completely dead nothing electrical will work. The engine will still run of course since the Mags are a completely diferent system.
 
Actually, I think your first hunch was right.

I believe the alternator will continue to generate voltage if you disconnect the battery. Once you have a field, you can maintain it with your output voltage.

I remember back from school, that a pure (primitive) alternator needs a field to start. However, (again way back in my memory) some alternators can provide their own field current -- a small DC generator incorporated into the alternator.



Note to pscraig... some of the seminoles don't have breakers for ALT and BATT.
 
Scenario # 1: Assuming everything is going to fail in 5 seconds, I would execute a missed approach and sqwauk 7600. I would then proceed to the area of VFR weather that I know is there because my planning demands it is no more than 200 miles away and land. my Handheld GPS would be my primary means of navigation now. I would also use my handheld radio.

Scenario # 2: I would have picked a better route taking into consideration weather and terrain. No other route options, I would remain calm and fly the plane. I would hit the nearest function on the GPS and try like hell to make it. I would do whatever I can to make it to the most friendly terrain. If I don't like what I see when I get low enough to see what the landing light shows me, I will turn the landing light off.
 
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I would have picked a better route taking into consideration weather and terrain.

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This is a good point to discuss. I'm interested in hearing some more thoughts on this. Should a flight be canceled or re-routed because of SE performance vs. terrain? What if you had been in a single-engine airplane? Just some food for discussion.

Personally, I've flown such a flight over mountainous terrain in the weather. A friend and I took a plane up to Aspen, CO in IMC several months back, and had we actually had an engine failure, we would have drifted down enough to where terrain would have been a definite factor.

That said, I don't think this flight was at all unsafe. Plenty of GA aircraft (even normally-aspirated) fly out of this airport on a daily basis. If it was unsafe for these aircraft to fly due to the risk of engine failure, you'd only see G-Vs and Citation Xs operating out of there. Anyways, just my opinion on things.
 
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I would have picked a better route taking into consideration weather and terrain.

[/ QUOTE ]

This is a good point to discuss. I'm interested in hearing some more thoughts on this. Should a flight be canceled or re-routed because of SE performance vs. terrain? What if you had been in a single-engine airplane? Just some food for discussion.

Personally, I've flown such a flight over mountainous terrain in the weather. A friend and I took a plane up to Aspen, CO in IMC several months back, and had we actually had an engine failure, we would have drifted down enough to where terrain would have been a definite factor.

That said, I don't think this flight was at all unsafe. Plenty of GA aircraft (even normally-aspirated) fly out of this airport on a daily basis. If it was unsafe for these aircraft to fly due to the risk of engine failure, you'd only see G-Vs and Citation Xs operating out of there. Anyways, just my opinion on things.

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IMO, it's a myth about this whole "unsafe to fly single-engine aircraft in IFR (IMC)." IF that were true, then we shouldn't fly single-engine planes at night either. Hell, some light multi's shouldn't be flown for the same reasons due to their inadequate S/E performance, if one wants to follow that logic.

There's a risk in any kind of flying.
 
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