[pierre smith]

After yesterday's devastating Cessna 310 crash into two homes near Orlando, Brian (RV4 building buddy) and I started discussing options when/if smoke or fire enters the cockpit. I never realized that if the master and alternator is turned off, the buss is still being fed by the alternator and the source of smoke would not be stopped if it's an electrical problem. (The 310 pilot had reported smoke in the cockpit). You have to have a circuit breaker that you can pull to disengage the alternator as well as turning the master and alt off.

If there ever is an engine fire and it starts into the cockpit, you have to shut the fuel off immediately and also turn off the mags. The reasoning is:
a) You don't know whether or not it is an oil or fuel fire, so shutting off fuel is a must.

b) If the engine continues to run for a while, it can still pump oil, fueling the fire if it's an oil fire. The reason for turning off the mags and leaning the mixture.

Obviously your next concern will be finding a suitable forced landing site since you now have no other choice.

If any of you guys have experienced either of these scenarios, I'd like to hear how you dealt with it. There are many first flights reported here and I'll shortly be the test pilot of the -4 in my hangar. I figure that we can all learn from bad experiences and help one another to better cope with them in the future.

Regards,
Pierre

 

[kentb]

If the smoke is obscuring vision?

Would you, should you, try to break the canopy? Besides what Pierre said above does anyone have a plan for seeing if there is to much smoke?

[edit]On second though instead of breaking, probably just open it a bit. This should work for the tipup, I don't know about the slider.

Kent

 

[Kevin Horton]

I never realized that if the master and alternator is turned off, the buss is still being fed by the alternator and the source of smoke would not be stopped if it's an electrical problem.

This depends on how your electrical system is designed. On my RV-8, if I select the alternator OFF, this removes power to the external regulator, which removes power from the alternator field, which will kill the ability of the alternator to produce power.

Some internally regulated alternators may be designed so the alternator field cannot be selected off once the alternator is running, as the field power is provided directly by the alternator itself. I would not want such an alternator in an aircraft. I believe that it is important to be able to stop the alternator from producing power, so that it can be shut down in the event of an engine compartment fire, or alternator overvoltage.

 

[Jim Percy]

I never realized that if the master and alternator is turned off, the buss is still being fed by the alternator and the source of smoke would not be stopped if it's an electrical problem.

If you're using a master solenoid, power to the bus would be cut off as soon as you turn the master switch off. My solenoid (as are most, I think) is forward of the firewall so the only "hot" wire in the cockpit would be the E-bus feed, and that would only be hot up TO the switch (assuming the switch gets turned off).

Yes, my IR alternator would still be producing power but only to the battery, also forward of the firewall.

 

[rv7boy]

Smoke in the cockpit

Interesting, Pierre. I do appreciate you starting this thread. The last time I flew (my 172) I smelled a burning odor. Fortunately, I had just landed at my home airport. It was dusk and I had previously turned on my position lights, landing lights and interior lights just as a precaution, even though it wasn't 30 minutes after sundown.
I switched off all radios, lights, and then the master and taxied back to my hangar, but gave serious consideration to parking near the FBO fire truck.
As it turns out, two wires had gotten together in the overhead module where the dimming rheostats are located. There was some charred headliner material. So even though this was not as bad as it could have been, it definitely raised my blood pressure...and gave me time to think about what could happen.
The amazing thing is not once did I remember that I had a small fire extinguisher available between my seats!

Several years ago there was an RV-8 pilot flying near Seattle or Portland who had an engine compartment fire. He perished after jumping from his burning airplane. It was tragic. IIRC a connecting rod broke the engine case and the fire originated near the gascolator. I'm not sure they ever determined the sequence of events but it must have happened fast. Apparently when he opened the canopy, flames burned his eyebrows and hair. I remember seeing photos of his RV-8 prior to the accident. I've thought about that accident often and wondered if he could have done anything to save his life. It would be easy now to be a Monday morning quarterback and say a parachute or a BRS would have saved him, but I'm not sure what he could have done in his situation. The NTSB report has more details than I can remember. It can be found at this NTSB link.

Don

 

[SteinAir]

How are you guys wiring your planes to have the main alternator lead hot all the time?

I don't mean this as a flame, but standard practice is to put that feed line on the downstream side of the master relay so that when you shut it off, all power is removed (battery and alternator)!

Depending on what you do you might have an EBuss feed, etc... This is one of the reasons I'm personally not a huge fan of Hot Buss's. For me personally, I want to be able to shut off ALL the power being fed into my panel - completely....but that's just my personal opinion. Lord knows we've built panels with just about every imaginable architecture out there - and for differing missions different designes make sense.

Just my 2 cents as usual.

Cheers,
Stein.

 

[L.Adamson]

A few years back I installed an over voltage protection system for internally regulated alternators that was on Bob N????'s (can't remember the spelling) website.

Then we found out that nusance tripping was killing a few alternators, and the diagram was pulled from the website.

However, I disconnected the over voltage tripping circuit, but left the firewall mounted relay in, that breaks the B-lead from the alternator at the firewall. This relay is still controlled from the alt switch & circuit breaker.

Since my master relay is just a few inches from the battery on the cockpit side of the firewall(RV6A), I still have the option of disconnecting the two major wires in the airplane. I will leave this alternator relay connected, and put up with the slight amount of extra weight.

L.Adamson

 

[steveciha]

I had read on these forums that an internally regulated alternator would continue to charge even once field current was turned off. So I tried it one day after i landed. Noting that the alternator was putting out 22 amps, i turned off the field side of the master switch. The alternator ramped down in about 5 seconds to where it was producing no current. Some alternators may continue to charge, but mine did not

steve ciha

 

[srv]

Opening canopy may be bad

From that NTSB report:

The aircraft's canopy is airfoil shaped and during flight conditions would tend to create an aerodynamic low pressure condition near the top of the canopy. If the canopy were opened in flight with fire conditions existing along its forward exterior surface, the entrainment of hot air and fire within the upper cockpit interior environment may have become intolerable ​

Fire/smoke on the outside, and it would just get sucked in. Where would you break the canopy to suck smoke out and bring air in if it was mostly external? Would that be the same for smoke for an internal fire?

 

[joeboisselle]

Fire/smoke on the outside, and it would just get sucked in. Where would you break the canopy to suck smoke out and bring air in if it was mostly external? Would that be the same for smoke for an internal fire?

I agree, you'd just be creating a vacuum in your cockpit. If you busted a hole in the front of your canopy, ram air should create a high pressure to keep smoke/flames out. In theory. Bigger the hole, larger the pressure... if it's an engine fire, your competing against the air pressure inside the cowling.

I have a internally regulated, single wire alternator on my -4. The wire runs from the hot side of the master solenoid, to a switch on the panel, down to the alternator. There is no e-bus. There is nothing "always hot"

 

[Transporter]

Panel Fire

Experienced a panel fire several years ago in a Cessna 206; flight was actual IFR and my friend John (CFII) was PIC. Preflight was uneventful and included a thorough review of aircraft systems and emergency procedures, to include what my role would be during an emergency. I should state at this point that this was my first flight in a 206; although this was not a lesson John allowed extra time to go over all the aircraft systems and procedures with me. I can't overemphasize how much this paid off when we had the fire since John and I had discussed the cockpit fire checklist and talked about what each of us was going to do.

The flight was going well with no system glitches until about 30 minutes after takeoff. We both smelled hot wiring at about the same time (I turned to John to say "do you smell something?" when he said the same to me) and then the cockpit filled with smoke (lots of it) with sparks and flame (small but scary) from under the panel. Not much reaction time.

Conditions were solid IFR (stratus with light rain and we were in a thick layer of cloud). As agreed during the preflight, John flew the plane (on an increasingly partial panel) as I killed everything electrical (except the mags), shut air vents and hit the fire with the extinguisher. Hot wiring insulation/panel plastic continued to flare up and it took a total of three shots with the BC fire extinguisher (almost all of it) to get the fire out.

Once the fire was out (probably less than a minute, but seemed much longer!) we opened a window and the air vents. IMHO opening the window/leaving the vents open before the fire was out would have given the fire a chance to spread.

Since the air was smooth I slid my seat back and looked under the panel (as best I could with my flashlight-an inspection mirror would have helped) and used the POH to carefully work through the electrical system (one switch at a time, checking for signs of smoke, sparks, odor etc.) to see if I could find the bad circuit and restore at least one radio/some of the electrical instruments. Started with the master and was able to get one navcom (with localizer) and the DG working; nothing else worked on battery only. Switching the alternator on got scary again (sparks but no fire). I shut everything off again and discussed status with John; we agreed we would save the battery for approach. I should add at this point that the one working radio was extremely weak and our one attempt at comms with center while the battery switch was on failed. We later learned that the antenna lead was melted and the wiring to all other instruments and avionics were fried. John flew a "lost comms" pattern and we continued to our destination on partial panel. This was before GPS...and we got lucky-broke out of the soup into clear weather about ten miles before our destination to find we were still on course! John made an exceptionally smooth landing and we called center to let them know we were down safely. The post-incident report writing took longer than the flight. What worked: (1) John's thorough review of systems and emergency procedures with me-I was new to this model and John was an exceptionally good teacher as he did the preflight and walked me through the POH. (2) Cockpit management worked-John flew the plane and I handled switches and extinguisher as agreed. (3) Extinguisher worked (barely). (4) POH checklists. (5) IFR procedures. (6) Great partial panel flying and landing by John!

What didn't work? (1) Don't expect breakers to protect from every eventuality; we only had one breaker pop. (2) BC extinguishers make a heck of a mess. Powder in the cockpit was almost as bad as the smoke. (3) Once you've had a panel fire, don't count on anything electrical. This was a very well equipped plane (all the avionics available in the day) and nothing worked well after the fire. We were lucky we didn't have to shoot an approach.

What would I do today? (1) Buy the best extinguisher(s) that will reasonably fit in the plane-given all must be within easy reach. Two are better than one, etc. (2) Carry a handheld comm radio with nav function with spare battery (3) Carry a handheld GPS (or removable panel mount unit) with spare battery (4) Give serious consideration to panel design and wiring with emergency procedures in mind (as others have/are discussing on this thread). (5) Carry an inspection mirror in my flight bag (6) Try not to get complacent-review the POH and perform a thorough preflight (including use of the mirror to check firewall forward and panel wiring for signs of chafing, loose connections, etc.) before each flight.

Apologies for the lengthy post but there may be some lessons here that will help someone when they need it most.

Stay safe and have fun!

Mike
________
Setting up shop in KC

 

[w1curtis]

How are you guys wiring your planes to have the main alternator lead hot all the time?

I don't mean this as a flame, but standard practice is to put that feed line on the downstream side of the master relay so that when you shut it off, all power is removed (battery and alternator)!

Hmm, I thought standard practice was to have the alternator feed go to a 60 Amp alternator circuit breaker, then the bus. That way if you turn off the master/alternator and you still smell smoke, you pull the 60 Amp alternator breaker. This is the way it is on my Cardinal and is the way I plan to wire it on my -10.

http://wcurtis.nerv10.com/90Electrical/RV10Electrical_v3a.pdf

I see these installations where some are attaching the alternator feed to the battery side of the starter relay providing no way to "truly" disengage the alternator from the bus other than the field circuit. This makes for simpler wiring and one less hole in the firewall but internally or externally regulated, this is poor practice.

If I understand your approach correctly, in the rear mounted battery installation, you would have to run a wire from the alternator, all the way back to the master relay by the battery. Seems counterproductive to me.

I agree with you in that the main alternator lead, should NOT be attached to the bus without a circuit protection device and a way to disengage it from the bus. But I disagree that it should be attached to "the downstream side of the master relay."

 

[SteinAir]

Excellent point that I completely forgot to mention...putting the fuse/circuit breaker somewhere in that chain. I often forget about the rear mounted battery guys because of my -6 having the batt up front. I guess my thoughts are that if one of your fat wires is causing the problem and hasn't blown the fuse or breaker in the panel, then pulling the breaker is unlikely to solve that problem...because it's likely something else - like a short ahead of the breaker, etc... If the problem is downstream from that big breaker and it hasn't blown that fuse/breaker or any others, you're still in pretty deep doo-doo...because it means something pretty bad has happened that we/you didn't plane for when installing wires/breakers/fuses - and at that point we're almost a slave to our own designs because you won't know where to start. As you well know it's impossible to protect every inch of every wire in the plane, so we design around that the best way we can. I just figure in my plane that if something huge like that happens I reach over and turn off my master switch. I still have 1 mag on the engine, and internal batter in my GPS, backup instruments, and an internal battery on my EFIS. Pull out my handheld radio and I'm in OK shape (or at least I an still keep the airplane upright and hopefully find my way to somewhere safe).

I'm still a fan of keeping the fat alternator wire off of the panel and off the actual busses (because they are likely to be the some of the noisiest electrical wires in your plane). For the most part I like your electrical layout, but just as a bit of personal taste I think 3 batteries + an external power source, 6 electrical busses and 6 relays may be a tad overkill for my own taste (not that it won't work for you just fine, because it will).

I'd like to take this opportunity to repeat my own personal thoughts....less is more and simple is better - and nope - I wasn't creative enough to think of that on my own; I've plagarized it from Bob Nuckolls Where we differ is that I'm not a fan of designing and airplane for continuing a flight after some sort of electrical failure. I'm a proponent of designing the plane to keep you safe until you can get on the ground and fix something.

I'm not belittling Bill's design because it's pretty decent (and your drawings are among the best I've seen). It's just that every time you add more relays and more busses you add more complexity, which has the exact effect of reducing reliabitliy of each system those components are connected to. I'm not saying redundancy is a bad thing, because it's not. It's just that many times too much redundancy actually reduces the overall reliability of the entire plane. In the end, there is still one HUGE single point of failure in these RV's we're building. You only have 1 fan in front.

Just my 2 cents as usual.

Cheers,
Stein.

 

[MCA]

If I understand your approach correctly, in the rear mounted battery installation, you would have to run a wire from the alternator, all the way back to the master relay by the battery.

William,

In this type of installation, you can run the alternator b-lead to the battery contactor side of the starter contactor, which is located on firewall. This is electrically equivalent to what you say above. So... you don't need to run a separate wire back. You can then place an in-line fuse on the b-lead before it connects to the starter contactor.

If you have an externally regulated alternator, and turn off the field wire, the alternator will quit alternating and therefore eliminates the need to "pull the alternator breaker".

Another 2 cents for ya...

 

[MCA]

I had read on these forums that an internally regulated alternator would continue to charge even once field current was turned off. So I tried it one day after i landed. Noting that the alternator was putting out 22 amps, i turned off the field side of the master switch. The alternator ramped down in about 5 seconds to where it was producing no current. Some alternators may continue to charge, but mine did not

steve ciha

Steve,

Under normal operating conditions, turning the field circuit off on an internally regulated alternator will cause the alternator to stop charging, as you describe above. I think what you read about is a certain failure mode for internally regulated alternators that causes them to continue charging even when the field is turned off. I am not aware of any hard data that demonstrates how common this is, but it is something that can be solved if it is of concern to you. Either install an externally regulated alternator, or install a Plane Power internally regulated alternator which (the guys at PP tell me this) does not have this failure mode.

Our installation manual has a section on alternator and voltage regulator considerations that you might find useful. It's on the web at http://www.verticalpower.com/documents.html

 

[pierre smith]

Thank you

Mike, Stein and others,
Thanks so much for your great advice on this subject. I tried turning my master off in flight and the alternator still puts out and everything still works. So I'd have to pull my 60 amp alternator breaker to truly disengage it. That is what I wanted evryone to know. We can go back and do some rewiring if we don't like it like mine.

Hopefully this very productive thread will prevent other disasters and/or help to better cope. It also points out the need to cooperate in the cockpit. My wife/passenger will now be the fuse/circuit breaker techie while I fly.....great advice from Mike.

Thanks again,
Pierre

 

[w1curtis]

William,

In this type of installation, you can run the alternator b-lead to the battery contactor side of the starter contactor, which is located on firewall. This is electrically equivalent to what you say above. So... you don't need to run a separate wire back. You can then place an in-line fuse on the b-lead before it connects to the starter contactor.

If you have an externally regulated alternator, and turn off the field wire, the alternator will quit alternating and therefore eliminates the need to "pull the alternator breaker".

Another 2 cents for ya...

Marc,

Take a look at the paragraph directly above the one you quoted. Here it is again:

I see these installations where some are attaching the alternator feed to the battery side of the starter relay providing no way to "truly" disengage the alternator from the bus other than the field circuit. This makes for simpler wiring and one less hole in the firewall but internally or externally regulated, this is poor practice.

 

[MCA]

Yep, saw that.

Not sure I agree with your statement that that is poor practice. In fact, there are those who argue that bringing another high-current wire into the cockpit is poor practice. And, turning off the field wire on an externally regulated alternator will turn off the alternator. You do do not need another high-current switch in line, IMO. If you're using an IR alternator where a "runaway" alternator is possible, then another switch/breaker in line is helpful, but adds complexity where it is not needed becuase that failure mode can be eliminated by using an ext reg alternator.

Using a certified aircraft as the standard has also been questioned. Some will say that certified aircraft have made very little progress in advancing the "state of the art" in electrical architectures. Just food for thought.

Bottom line is, it's your plane and you have to build it in a way that makes you comfortable as pilot in command, right?

 

[MCA]

I tried turning my master off in flight and the alternator still puts out and everything still works.

Hi Pierre,

Can you elaborate? I'm not sure how you can tell that everything works when you turn off the master. Everything should shut off, unless you have a backup bus which powers the field and other equipment. I may have been working too many hours lately and unable to see through the haze..

 

[Jetj01]

What would you do...?

Don,

It brought back painful memories your mentioning that RV-8 accident in the NorthEast. Most may not know this but this gentleman was selling his RV-8 at the time and I had a Mooney he was interested in trading with. We had got down to the actual figures and I was waiting for him to call back with what the deal would be, back in July 1999. The call never happened...

Guys, how bad does it have to be before one decides to JUMP FROM THE AIRPLANE HE MADE rather than perish a painful death in the plane burning up around you. This guy did indeed have his engine case split (Aerosport I think???) which then ignited the hot oil now spewing from the engine compartment that then spread into the cockpit area. Eye witnesses saw him trying to decsend to make it to an emergency landing but at about 300-500 feet he decided he had had enough and jumped to his death...much like many chose to do in the towers of 9-11 rather than the torture of burning.

OK, enough yuck. This is a GREAT discussion item for all of us who fly any aircraft, especially as we cram as much electronics into the panel as we can, and sometimes none mil-spec, experiemtal electronics that were never meant for 6 Gs, un cooled cockpits and many off/on cycles. Most of us don't even have cooling avionics fans.

As a military pilot I have experience two cockpit fires, both associated with electrical wires/filaments burning. Yes, ONE BULB burning can be catastrophic for cockpit oxygen and the accompanying toxic fumes. Long story short, if it wasn't for an oxygen mask, I would be either dead or an experienced ejection seat user, neither of which happened but I remember my eyes feeling like they would rather die than have another second exposure to that acrid smoke.

Believe it or not, those electrical wires that are rampant behind our panels are NOT user friendly if they deside to start cooking. And having a plan if and when that happens is important, even if it is not an ideal perfect plan.

So I encourage ALL OF US to to take the time and do 'what if' scenarios NOW and think, what will I do if: I have a fuel fire in the left wing, right wing, a blown oil line, a blown primer fuel line, smoke in the cockpit, oil on the canopy hampering forward vision, etc etc etc.

In the military every day, every mission we have to cover in EVERY BRIEF what are we going to do in an electrical fire, gas fire, overheat etc situation. Not a bad plan for all of us.

When I think back of that RV-8 that I almost owned, I wonder what I would have done different...would I have jumped???

Yah, those are the hairs standing on the back of your neck!

 

[Kevin Horton]

This guy did indeed have his engine case split

Are you sure the engine case split? Where did that info come from? The automotive oil cooler that he used is a more like candidate for the initial failure, I believe (evidence of Setrab oil cooler from his postings on the RV-List).

 

[s_tones]

smoke

I had a minor smoking panel incident while still in training for my PPL.
I was flying an Archer when the panel began to emit an electrical burning smell. Very exciting for a new pilot! Did the drill shutting off all electrical after calling SBA tower for possible emergency landing. Fortunately I had a clue as to the source in that the Garmin GPS was misbehaving just prior.
The smell quickly abated and I flipped the radio back on and flew home without further problem. No fire extinguisher in there BTW.

I hope that's my last encounter with toasted airplane components.

Steve

 

[rv7boy]

Are you sure the engine case split? Where did that info come from? The automotive oil cooler that he used is a more like candidate for the initial failure, I believe (evidence of Setrab oil cooler from his postings on the RV-List).

Kevin,

From the NTSB link provided in my previous post, "Holes in the upper engine case halves in the vicinity of cylinders one and two (both forward cylinders) were noted..."

Technically, the engine case didn't split, but rather had two holes in it. Cylinder One piston and connecting rod failed. The fire apparently was fed from the gascolator area. It must have happened awfully fast.

Ironically, the report says during the first 25 hours of the airplane's flyoff period, the pilot wore a parachute.

It's just a sad, sad narrative.

We all can learn from this. I know I need to have more discipline in my what-if scenarios before I take off.

Have a good weekend,

Don

 

[Jetj01]

Thanks Don!

Well said Don!

 

[kentb]

Time to shut off fuel flow.

This weekend I was finishing up my first conditional inspection. One of the last items on my checklist is to shutdown the engine with the fuel selector control. I was running the engine at 1000 rpm and after placing the control in OFF position, it took 87 seconds before the engine shutdown.
I was very surprised at the length of time. I know that if the engine were running faster it would take less time, but if I had an engine fire I think that this would be a very long time.

So if I had a engine fire I think that the correct thing to do would not to kill the engine with the mixture and throttle, but the leave it running at it's current setting and switch off the fuel in the cockpit. I just hope that the time it takes to use the fuel will be short enough that the firewall will last.

I will be doing the shutdown test with the engine at a higher speed to see how fast it quits soon.

Kent

 

[airguy]

Except that in the case of an oil-fed fire, every second the engine is running adds the turning oil pump to the equation.

 

[WSBuilder]

Rather be down there wishin I was up there...

What's the merit is AGGRESSIVELY seeking lower altitude at the first sign of trouble instead of cruising along trying to diagnose the problem - especially if sole occupant? I'd like the option of putting it down, even hard, rather than sky walking because I took too long.

 

[Kevin Horton]

What's the merit is AGGRESSIVELY seeking lower altitude at the first sign of trouble instead of cruising along trying to diagnose the problem - especially if sole occupant? I'd like the option of putting it down, even hard, rather than sky walking because I took too long.

Leo, a recently retired coworker was doing a test flight on a modified DHC-2 Beaver many years ago, with the aircraft owner in the right seat. The aircraft was fitted with straight (i.e. not amphibious) floats. The aircraft developed elevator flutter for a reason that I do not know. They slowed down, and the flutter stopped. But Leo didn't like the way the pitch control felt, so he put the aircraft down in a field, rather than try to make it to some water. The aircraft was not damaged in the landing, other than some grass stains on the floats, and they were not injured Subsequent inspection showed that the elevator control had almost failed. A few more minutes flying, and control would have been lost.

Moral of the story - if the aircraft is telling you it is time to land, land the aircraft. Don't pass up an airport just so you can get to your home field. Land in a field if need be. Far better to land too early than too late.

 

[WSBuilderHM]

Yikes!

Are you familiar with TFOA = Things Falling Off Aircraft? I hate it when elevators depart! I guess if I suspected a control surface problem I'd EASE it on down, but smoke or fire and I'm DUMPING altitude to get lower, then figure out the problem after I'm on the ground.
Just today an employee showed me a picture of him standing in front of the amphib Beaver in which he bought a ride that lost hydraulics with one nose wheel down. They grass landed!
I was flying my C140 and felt a hard bump followed by a continuous left ball. I slowed down, fearing a rudder failure of some sort and gently checked pedal response. Good, but still left ball. I eased back to Earth and checked everything but found nothing! I even removed the rudder to replace the hinge bolts. To this day I can only assume a bird strike without telltale gore.