PA-31 down at TCL

ronnieh said:
I only used the boost pumps to prime (or purge vapor on a hot engine) then turned off pumps for the actual start. Boost pumps back on for take off. Boost pumps were to be used during switching tanks and landing.

Edit: Just to clarify the boost pumps I am referring to are not to be confused with the low pressure pumps that come on when the master is on. The high pressure pumps are pilot controlled and what I refer as boost pumps. they will take the place of the engine driven pumps but, you may be power limited due to altitude.
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My understanding is that the system was really designed for the fuel flows necessary to feed 310hp and that rather than increase all the size of the lines, valves, etc, when they went to higher HP, they added header pump instead. With the header pump inop, the lower pressure due to the restrictions in the lines can lead to vapor formation at altitude.
 
Fearless Tower said:
Be interesting to know the pilot's experience before getting the Navajo.
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There is a 1975 Seneca, N1467X, registered to a similarly named LLC with the same address as the LLC for the accident airplane. I would assume it was his. The plane was only registered in May, but since 2006 had been in a similarly named LLC with an Ashland address which I think I recall being the pilot's hometown. I know this is a lot of assumptions, but for what it's worth....
 
ronnieh said:
Engine driven pump and electric pump for both engines. Concerning air in the line it is normal to run the outboards empty then switch to mains. If you are good you can watch for flow fluctuations and switch before the engine even hic cups. A popular way to manage fuel is to take off (required to be on mains) and climb to altitude. Switch to outboards and empty them then switch back to mains. On mains required for landing. IMO it is highly unlikely to have lost two engine and two boost pumps at the same time. If the tanks (all four) were topped off and he had six adults and luggage that was one heavy plane. I have never seen a CR with a useful load above 800 pounds with full fuel. If it had the Colemill conversion it would have had even less useful load since the crankshaft extensions and the winglets add weight. Not all Colemill conversions of the CR had the 350 HP engines. It will be interesting to see if there was any fuel in the plane when it crashed.
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A lot of the Navajos have the VG installation that bumps the useful load by a couple of hundred lbs. I haven't flown one of those on one engine, but I have my doubts that it has much performance at the higher gross. I am sure that it was pretty heavy. Given the length of the flight and the temperature, the decision to top the tanks was probably iffy.
 
Kristin said:
My understanding is that the system was really designed for the fuel flows necessary to feed 310hp and that rather than increase all the size of the lines, valves, etc, when they went to higher HP, they added header pump instead. With the header pump inop, the lower pressure due to the restrictions in the lines can lead to vapor formation at altitude.
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So that could make it difficult/impossible to restart the one that failed at 12,000 feet. But 10 miles out when the second failed it might not have been a factor for the second engine, as I would imagine him not having much altitude left. In any case, it seems your theory about running an aux dry and just assuming the fuel pump failed because a fuel pump light came on seems more plausible than both pumps failing within 10 minutes of each other. What a heartbreaking tragedy. Perhaps a few days of simulator training should be a high priority for drivers of high performance twins.

Any idea why the props wouldn't have been feathered?
 
Chester Clark III said:
There is a 1975 Seneca, N1467X, registered to a similarly named LLC with the same address as the LLC for the accident airplane. I would assume it was his. The plane was only registered in May, but since 2006 had been in a similarly named LLC with an Ashland address which I think I recall being the pilot's hometown. I know this is a lot of assumptions, but for what it's worth....
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Good detective work. We don't know what kind of a check out he got in the Navajo, but the fuel system is completely different. The Seneca is ON/OFF/CROSSFEED. Aux tanks could have been an entirely new concept. I feel sorry for the check out instructor, if there was one, as he/she could get caught up when the lawsuits start to fly.
 
Chester Clark III said:
So that could make it difficult/impossible to restart the one that failed at 12,000 feet. But 10 miles out when the second failed it might not have been a factor for the second engine, as I would imagine him not having much altitude left. In any case, it seems your theory about running an aux dry and just assuming the fuel pump failed because a fuel pump light came on seems more plausible than both pumps failing within 10 minutes of each other. What a heartbreaking tragedy. Perhaps a few days of simulator training should be a high priority for drivers of high performance twins.

Any idea why the props wouldn't have been feathered?
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Chester,

If he had switched tanks and hit the boost pump, the engine would likely have restarted. In my hypothetical, a pilot may not have realized that he had an engine failure initially. After the second pump failure light comes on, he is still thinking pump failure and doesn't realize for a few seconds that he has a huge sink rate. Assuming he then realizes that he has a double engine failure, does he have time to hit both boost pumps, switch to mains and get a relight? Who knows? Maybe not! At that point, he needs a relight and it probably doesn't occur to feather both and try to make the field. A pilot in such a circumstance would already have dug himself a deep hole.
 
Kristin said:
Chester,

If he had switched tanks and hit the boost pump, the engine would likely have restarted. In my hypothetical, a pilot may not have realized that he had an engine failure initially. After the second pump failure light comes on, he is still thinking pump failure and doesn't realize for a few seconds that he has a huge sink rate. Assuming he then realizes that he has a double engine failure, does he have time to hit both boost pumps, switch to mains and get a relight? Who knows? Maybe not! At that point, he needs a relight and it probably doesn't occur to feather both and try to make the field. A pilot in such a circumstance would already have dug himself a deep hole.
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I see. That makes sense. He actually may have not feathered the first engine thinking it was still producing some thrust. And you're right, if he was low and slow when the second quit there wouldn't be much time. I noticed when I listened to the one-sided recording that the controller went so far as to suggest the interstates on either side of him, which made me think he had lost both and was gliding. Lots of lessons to be learned from this one, or at least from our hypotheticals anyway. Thanks for your patience in answering/explaining.
 
For Chester and Kristan.
Kristan, I have not heard that but, it could be. I don't think the 310 had low pressure boost pumps. The 325 I just don't know. In reality the low pressure pumps were more to prevent cavitation in the engine driven pump during take off and initial climb during high fuel flows. Most pilots turn off the high pressure pump after a thousand feet or so which could lead to cavitation during the climb without the low pressure pumps. I personally never got in a hurry to turn them off. I would be surprised if the low pressure pump would make much difference in cruise. The flow in cruise is a little over 1/3 that of take off. Even with a low pressure pump inop and running an outboard tank dry I doubt it would be a problem to re light the engine at the altitude he was at. Switch tank, hit high pressure boost and you will have power in a 2-3 seconds.
Even though the fuel system is different than a Seneca it is still quite simple. If you run an outboard dry just switch to inboard and go about your business. I only ran an outboard dry one time by mistake. Switch tanks and before you can get the high pressure pump on you already have power. As I said above it is common to run the outboard until you get fuel pressure fluctuation. Keep a close eye on it and you will get 5-10 seconds of fluctuation before the engine will even stumble. It is just not a big deal.
I suppose it might be possible to run both outboards dry a few minutes apart and mistake that for a failed engine driven pump in both engines. If that is what happened and the pilot did not understand what was seeing then all I can say is wow. Even if you did indeed lose the engine driven pump basic and I mean basic Navajo 101 is turn on high pressure pumps and select the other tank. I do hope that is not what happened but, if it did then this pilot was sorely undertrained. One other thing, the fuel gauge shows fuel quantity of selected tank. If he ran the outboard dry the fuel gauge would have shown that tank empty. I just don't understand how that big of a mistake could have been made. But, I emphasize I like everyone one else here do not know what happened. I am not ready to throw the pilot under the bus just yet. Very sad.
 
Kristan, respectfully I do not think there is anyway to not recognize a failed engine in cruise. The plane trying to swap ends is kind of a dead give away. Again if he ran both outboard tanks dry a few minutes apart and did not even try switching tanks is just about too much for me to accept.
 
Kristin said:
Chester,

If he had switched tanks and hit the boost pump, the engine would likely have restarted. In my hypothetical, a pilot may not have realized that he had an engine failure initially. After the second pump failure light comes on, he is still thinking pump failure and doesn't realize for a few seconds that he has a huge sink rate. Assuming he then realizes that he has a double engine failure, does he have time to hit both boost pumps, switch to mains and get a relight? Who knows? Maybe not! At that point, he needs a relight and it probably doesn't occur to feather both and try to make the field. A pilot in such a circumstance would already have dug himself a deep hole.
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Took me 1800' of altitude to get a relight on the Seminole the other day after caging one on purpose at our high DAs, and that was a 75F day and purposely accelerating to 120 to help the start. Surprising what a cranky pain in the ass the engine was about firing off again after it cooled down in flight.

A double failure due to fuel starvation would be hard to figure out. Similar to a partial failure. Not knowing that fuel system could really bite you in the ass.
 
ronnieh said:
Kristan, respectfully I do not think there is anyway to not recognize a failed engine in cruise. The plane trying to swap ends is kind of a dead give away. Again if he ran both outboard tanks dry a few minutes apart and did not even try switching tanks is just about too much for me to accept.
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I certainly don't know what happened. I am only hypothesizing a possibility based on 1000 hours in "Joes" and 4,000 of dual given. That light can come on a few seconds before the engine quits. It is possible he started to reduce power and didn't recognize it. I have seen pilots do some strange things under pressure. Keep in mind, this airplane was new to him and he had all these passengers. Likely someone was in the right seat yakking at him. In a similar situation, so weird stuff can happen. This hypothetical may be way off bat as we don't have much factual information, like where the fuel was, what the setting on the fuel selectors where, etc. All of those things are key, and could easily change the scenario completely.
 
Even the setting of the fuel selector may not tell much, if he eventually set it right and was attempting a relight... In this hypothetical.
 
denverpilot said:
Even the setting of the fuel selector may not tell much, if he eventually set it right and was attempting a relight... In this hypothetical.
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That is true, but in combination with other engine indications and condition of spark plugs, etc, they may be able to tell if the engine was firing. One picture showed the left prop and it wasn't feathered and it did not appear to have been developing power, and perhaps was even stopped at impact. It is amazing what they investigators can figure out, but often there is still a guess factor.
 
Yep. If there's one thing I've figured out in my twin training, so far, it's that twins have even more interesting and subtle ways to try to kill you than singles. Heh.
 
Kristan, I certainly do not mean any disrespect, your ideas are at least as valid as anyone else at the keyboard. I just find it incredible that any pilot could run both outboard tanks dry and not know what happened. I think there are a few things we can all agree on. The likelihood of dual engine driven pumps failing within minutes of each other is very, very slim. In fact while we are speculating let's just assume that did not happen. Also the fuel quantity gauges show the fuel in the selected tank.
Again assuming he is setting up there fat, dumb and happy and he gets a low fuel pressure warning, why would it even occur to a pilot to reduce power? Seems to me the first thing would be to turn on the high pressure boost pump followed by a glance up at the fuel gauges. This would have been the same procedure as in the PA34. Even if for some weird reason he did reduce power, a few seconds after the warning light the engine is going to run rough for a couple of seconds before quitting. I just can't imagine a pilot not recognizing the loss of an engine. JMO. Also if the above scenario did happen and he switched tanks then the engine would have been up and running in a couple or three seconds at most. He was at 12K and he never once glanced at a fuel gauge all the way down? I just can't wrap my mind around losing an engine at 12K due to running a tank dry and not recognize what happen in a matter of seconds. Then add to this losing the second engine a few minutes later for the same reason, never knowing what happened. He had to be aware that he had been in the air close to 2 hours and he had no awareness of his fuel situation? I just can't can't make what happened fit with what little we know. If and I repeat if he did indeed run both outboard tanks dry and did not know what had happened it has got to go down as some of the worse piloting I have ever heard of. At some point we will likely know what happened but, may never know why.
Also, excuse my ignorance but what is a Joe?
 
ronnieh said:
Kristan, I certainly do not mean any disrespect, your ideas are at least as valid as anyone else at the keyboard. I just find it incredible that any pilot could run both outboard tanks dry and not know what happened. I think there are a few things we can all agree on. The likelihood of dual engine driven pumps failing within minutes of each other is very, very slim. In fact while we are speculating let's just assume that did not happen. Also the fuel quantity gauges show the fuel in the selected tank.
Again assuming he is setting up there fat, dumb and happy and he gets a low fuel pressure warning, why would it even occur to a pilot to reduce power? Seems to me the first thing would be to turn on the high pressure boost pump followed by a glance up at the fuel gauges. This would have been the same procedure as in the PA34. Even if for some weird reason he did reduce power, a few seconds after the warning light the engine is going to run rough for a couple of seconds before quitting. I just can't imagine a pilot not recognizing the loss of an engine. JMO. Also if the above scenario did happen and he switched tanks then the engine would have been up and running in a couple or three seconds at most. He was at 12K and he never once glanced at a fuel gauge all the way down? I just can't wrap my mind around losing an engine at 12K due to running a tank dry and not recognize what happen in a matter of seconds. Then add to this losing the second engine a few minutes later for the same reason, never knowing what happened. He had to be aware that he had been in the air close to 2 hours and he had no awareness of his fuel situation? I just can't can't make what happened fit with what little we know. If and I repeat if he did indeed run both outboard tanks dry and did not know what had happened it has got to go down as some of the worse piloting I have ever heard of. At some point we will likely know what happened but, may never know why.
Also, excuse my ignorance but what is a Joe?
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It is one possible scenario. I am not emotionally attached to it being correct. Not much makes sense about an engine failure at 12,000 feet killing six people in a aircraft that should fly on one. I base much of my hypothetical on the fact that he reported to ATC that he had a fuel pump failure. In fact, he was so focused on that, he reported that the other pump failed. This suggests to me a misdiagnosis at the first report, and fixation based on the second.

As for why he might not have noticed the fuel gauges, that too is hard to fathom, but he may never have flown a plane with the gauges overhead like they are in the Navajo.

The fuel pump use in the Seneca, if it was a Seneca II or later, is a bit different as it is the Continental fuel injection system. You don't routinely use the boost pump so it is not necessarily ingrained to turn on the boost pump. The boost pump in the Continentals are only for use if the engine driven pump has failed. Also, in that model Navajo, the fuel selectors are behind the pilot, between the pilot and copilot seats, against the spar. So even that is not in his scan. Obviously he knew it was there, but add surprise, perhaps a touch of panic, and maybe even a screaming passenger, and an inexperienced pilot can get overloaded.

"Joe" is slang for a Navajo.
 
Never heard that one before. I have 1800+ in the 31-350 and another 400 or so in a Colemill 31-350. I also have about 500 hours in the Seneca III mostly 135 stuff. For sure the boost pumps are used differently but standard training in the PA34 would be to activate boost pump if an engine is lost. Yes the fuel gauges are in a different place but, really never glance up at them all the way down? And yes the fuel selector is a little more aft but really? As you point out, he for sure thought he had lost a fuel pump(s). But, your statement "not much makes sense about an engine failure..." I think pretty much sums up the situation.
 
ronnieh said:
For Chester and Kristan.
Kristan, I have not heard that but, it could be. I don't think the 310 had low pressure boost pumps. The 325 I just don't know. In reality the low pressure pumps were more to prevent cavitation in the engine driven pump during take off and initial climb during high fuel flows. Most pilots turn off the high pressure pump after a thousand feet or so which could lead to cavitation during the climb without the low pressure pumps. I personally never got in a hurry to turn them off. I would be surprised if the low pressure pump would make much difference in cruise. The flow in cruise is a little over 1/3 that of take off. Even with a low pressure pump inop and running an outboard tank dry I doubt it would be a problem to re light the engine at the altitude he was at. Switch tank, hit high pressure boost and you will have power in a 2-3 seconds.
Even though the fuel system is different than a Seneca it is still quite simple. If you run an outboard dry just switch to inboard and go about your business. I only ran an outboard dry one time by mistake. Switch tanks and before you can get the high pressure pump on you already have power. As I said above it is common to run the outboard until you get fuel pressure fluctuation. Keep a close eye on it and you will get 5-10 seconds of fluctuation before the engine will even stumble. It is just not a big deal.
I suppose it might be possible to run both outboards dry a few minutes apart and mistake that for a failed engine driven pump in both engines. If that is what happened and the pilot did not understand what was seeing then all I can say is wow. Even if you did indeed lose the engine driven pump basic and I mean basic Navajo 101 is turn on high pressure pumps and select the other tank. I do hope that is not what happened but, if it did then this pilot was sorely undertrained. One other thing, the fuel gauge shows fuel quantity of selected tank. If he ran the outboard dry the fuel gauge would have shown that tank empty. I just don't understand how that big of a mistake could have been made. But, I emphasize I like everyone one else here do not know what happened. I am not ready to throw the pilot under the bus just yet. Very sad.
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Thanks for your message Ronnie, I hear what you're saying. I'm not trying to rush to judgment on this, or be critical of the pilot. Perhaps I am too preoccupied with initial reports, but I find that except in unusual cases (this will probably be one of them) I might not be very timely in my reading of the final report with probable cause, should one even be found. Because I'm also a non-professional twin pilot (I have a commercial rating for multi- and single-engine but do not fly for a living) I am always anxious to learn what I can from accidents such as this one. From what I have learned from NTSB reports most crashes occur while planes are doing exactly what they ought to be expected to do, and reassuring or not, it's the decisions or actions of the operators that usually are at fault. I don't know if this was the case here, but my approach is to explore with someone who knows a lot more about aviation in general or a specific plane in particular what the various possibilities MAY be, and see what can be learned from each hypothetical scenario. I've seen a lot of hypotheticals proven wrong; but I'd like to think I've learned from even those that could have been the cause but eventually were proven not to be.

Ultimately, I'm not only taking my well-being into my own hands when I launch in a GA aircraft, but the lives of all who trust me to be a safe and competent pilot who is confident of a positive outcome. Crashes like these make me, I believe justifiably, continually reassess that proposition on the basis of my training and abilities, and the reliability of my aircraft. We spend significant resources for the redundancy of a twin, and the confidence it gives (at least in cruise at altitude!). If a late model (for twins) well equipped plane with redundancy, such as this Colemill Panther Navajo had, should have a mechanical failure or cascading failures that were difficult to manage, I'd like to learn from them. If there was nothing the best trained pilot could do to save the situation from FL 120 cruise, I might be consider myself fortunate to have survived my 1000+ hours of flight and rethink this GA proposition. I take this very seriously.

It's an extremely sad situation, and I feel for each of those children and family and employees involved. I would hope and pray that my setting aside the emotions of the tragedy to attempt an analysis of what could be learned would not be interpreted as judgmental or uncaring.
 
Nothing I can add to that. As I said we will likely know what happened in time but, we may never know the why.
 
denverpilot said:
Took me 1800' of altitude to get a relight on the Seminole the other day after caging one on purpose at our high DAs, and that was a 75F day and purposely accelerating to 120 to help the start. Surprising what a cranky pain in the ass the engine was about firing off again after it cooled down in flight.

A double failure due to fuel starvation would be hard to figure out. Similar to a partial failure. Not knowing that fuel system could really bite you in the ass.
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I don't think you had trouble with that engine because it cooled down, it was the incomplete unfeathering that created problems. The engine was likely firing, but lugged down by the impartially unfeathered prop, thus the attempt to coax it into fine pitch windmill by increasing the indicated airspeed (dyn pressure). The NA Seminoles without accumulators behave the same way. I almost didn't get my ATP (last week of my old rules written, so a discontinuance would have cost me an automatic 5AMU for the CTP) because of these stupid props not unfeathering easily during the ride. The semionle I flew was the non-accumulator type. The accumulators in theory would solve this, but this is a rental fleet we're talking about, they don't perform as advertised after so much abuse.



--break break--

The accident airplane would have no problem re-firing on engines that were never feathered in the first place. They just needed gas and fuel pressure, assuming the mags were fine. It appears the accident pilot may have mistaken the full time electric pumps lighting off the low px lights as indicative of a fuel pump failure, when in reality it's merely indicative of the px going out because the tank is dry. In that mode, these pump lights are effectively "dummy lights" for check your tanks dummy. Even a "normal Piper" recreational driver would instinctively hit the auxiliary electric boost pump and check the fuel selector for the engine in question (or the only engine in the case of piper singles). I believe we call that troubleshooting. It is only after that not fixing it that you would then feather the thing.

BTW, what does the light say when it goes off? Does it say "PX low", or does it actually read "pump fail". Because if it's the latter, ruh roh. That's a human factors design boo boo.

The position of the fuel selectors by the NTSB will be an important inflection point in this investigation for sure.
 
Kristin said:
..."Joe" is slang for a Navajo.
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Thanks. Where I come from we call them "Hoes". (like whores but without the r);)

For take off in the Chieftain, I don't turn off the electric emergency pumps until after the first power reduction. I don't get in a big hurry to turn them off. And I turn off one at a time, watching the fuel pressure gauge. And yes, the electric low boost pumps are primarily to keep a constant pressure fuel flow, (approx. 10 PSI) to the engine driven high boost pumps to prevent cavitation.

Our company operations manual states to use full power for take off, then at 500 agl (as long as everything is normal) for climb settings, MP back to 38 inches, rpm to 2400, mixture back to 32 GPH. Then I turn off the emergency pumps. By this time I am usually over 1000 AGL. Normal cruise is MP 31 inches, 2200 RPM and mixture back to around 18 to 20 GPH to set the EGT at 1425F. This is what the company wants us to do. I do not know if the Colemill conversion is different, probably is but still close to the same.

The plane I fly has standard fuel tanks, which holds 35 usable in the outboards. That will give me about 1.75 hours at the above cruise settings. Again, the Colemill conversion is probably different.

The plane I fly has the vortex generator kit that increases the TO weight to 7368. With 2.5 hours of fuel on board, (inboards full) plus myself, I can take a 1917 pound pay load. With 8 seats up. With full fuel@ 1056 pounds, that decreases the pay load to 1497. With full fuel and 6 people, each person would have to have an average weight, including luggage, of about 250 pounds to achieve max gross TO weight.

A thought woke me up in the middle of the night last night. Since the low boost pumps and the emergency pumps are electric, could there be a possibility that if the engine driven high pressure pump(s) fail, and then an electrical failure stopped the low boost and the emergency pumps, would the engine(s) quit running in this highly unlikely situation?
 
Zeldman said:
A thought woke me up in the middle of the night last night. Since the low boost pumps and the emergency pumps are electric, could there be a possibility that if the engine driven high pressure pump(s) fail, and then an electrical failure stopped the low boost and the emergency pumps, would the engine(s) quit running in this highly unlikely situation?
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Along a similar thought process, if some or all the electric fuel pumps were on the same electrical circuit and the circuit breaker popped, that would possibly explain the incident as well, if it went undetected. That was one of the other things I've been wondering about too.
 
I wouldn't think all the electric pumps would be on the same bus. But stranger things have happened before. As old as the Navajo is I would guess it would've been corrected by now, IF there ever was a problem to begin with.
 
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The Navajos I have flown didn't have split buses so as long as the other engine was working or you had some juice in the battery, that wouldn't keep you from getting a relight if fuel was flowing. This was one of the very last Navajos so I can't say for sure that there were not any changes, but I would expect those kinds of circuits to be on an essential bus so would not be affected by the failure of the engine due to lack of fuel.
 
Not sure which pumps you are talking about. I am not positive (been too many years) but, I am pretty sure both the left and right high pressure boost pumps are on different busses. Also the annunciator lights say low fuel pressure or flow (not sure which word is used pressure or flow) if I remember correctly. There is also annunciator lights for "fuel boost inop" for the low pressure pumps.
Zeldman, let's look at your question. Did both engine driven fuel pumps fail followed by such a catastrophic electrical failure as to take out both high pressure pumps and yet is is still communicating with ATC about fuel pump failure? Yes, I guess it is possible to have lost both busses operating the high pressure pumps and still have at least one of the avionics busses still energised. I think we are getting into the realm of hearing hoof beats and looking for zebras. Also you must operate the lightest Chieftain in the whole country if my math is correct. I am absolutely not saying your numbers are wrong but, that puts you right at 4225 pounds empty weight. The published factory empty weight is around 4220. I have only been around a hand full of Chieftains but none of them were under 4550 - 4600 pounds empty. The one Colemill I flew was right at 4700 pounds empty. The Colemill does add weight. The four blade props, crankshaft extensions, winglets and cowl mods add about 70 pounds if I recall correctly.
I guess I just don't want to accept the possibility that six people lost there life when a perfectly functioning aircraft with adequate fuel in VFR hit the ground because a pilot did not know that the outboard tanks were empty. I do hope this is not what happened.
 
Kristan, check that again. Is there not a buss tie breaker that ties the left and right buss together? If a catastrophic electrical event happened to one buss that tie buss could open leaving one buss hot but not the other or am I remembering incorrectly?
While setting here typing this it just occurred to me it has been 8 years since sim school on the Navajo. No wonder my memory is so foggy.
 
ronnieh said:
Kristan, check that again. Is there not a buss tie breaker that ties the left and right buss together? If a catastrophic electrical event happened to one buss that tie buss could open leaving one buss hot but not the other or am I remembering incorrectly?
While setting here typing this it just occurred to me it has been 8 years since sim school on the Navajo. No wonder my memory is so foggy.
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I just looked at the Chieftain Service Manual and it shows both alternators feeding the same bus. Each alternator can be turned off separately, but there do not appear to be separate right and left buss's and no suggestion of bus ties.
 
Hmmm, no bus tie between right and left? I may be getting the Cheyenne and Navajo systems crossed up. Been 4 years since Cheyenne sim school. Been retired 4 years. This is making my brain hurt.You young'uns continue on.
 
ronnieh said:
Hmmm, no bus tie between right and left? I may be getting the Cheyenne and Navajo systems crossed up. Been 4 years since Cheyenne sim school. Been retired 4 years. This is making my brain hurt.You young'uns continue on.
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Not even a right and left. I think you may be thinking of the Cheyenne.
 
ronnieh, the Chieftain I fly weighs in at 4605.4 with 8 seats on it before fuel, with the VG add on to bring total take off weight of 7368.

And I am not saying this happened in this accident, but I was looking at the possibility of both high pressure pumps (engine driven) stop working for some reason, then an electrical failure occurs. Would that stop the fuel flow through the electric low boost pumps and emergency pumps?

Yes, I do lay awake at night and come up with these possible problems..... never know when that knowledge might come to good use...:fcross:

I feel the same and I do not want to think that this accident happened because the fuel system was not fully understood.

Kristin said:
I just looked at the Chieftain Service Manual and it shows both alternators feeding the same bus. Each alternator can be turned off separately, but there do not appear to be separate right and left buss's and no suggestion of bus ties.
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Thanks Kristin, I am looking at my generic POH and while it isn't really clear, that is how it appears to me.

I
 
overdrive148 said:
Surprisingly constructive discussion on an aircraft accident. What forum did I log into??
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People knowledgeable about twins, and this model particularly (Kristin, Ronnien, Zeldman) ), and the importance of knowing the systems (any plane actually) and how to operate them so they don't kill you. I think, and hate to say this, that the pilot screwed up on this one due to not being familiar enough with the fuel system and what warning lights actually mean. There was a pretty intense fire post impact (on TV here in BHM) which indicates a lot of fuel still onboard. Fuel mismanagement, yeah I think that will likely be the cause, IMO. Three families, eleven children without their parents now, so sad and unnecessary.
 
mscard88 said:
People knowledgeable about twins, and this model particularly (Kristin, Ronnien, Zeldman) ), and the importance of knowing the systems (any plane actually) and how to operate them so they don't kill you. I think, and hate to say this, that the pilot screwed up on this one due to not being familiar enough with the fuel system and what warning lights actually mean. There was a pretty intense fire post impact (on TV here in BHM) which indicates a lot of fuel still onboard. Fuel mismanagement, yeah I think that will likely be the cause, IMO. Three families, eleven children without their parents now, so sad and unnecessary.
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The registration shows a change in July 2016, a month before the accident. Any chance that since it was a "new" airplane, the pilot hadn't gotten used to the differences from the Senaca he had previously flown? Maybe a few hours with a CFI for the transition and you're good to go.
 
Possibly. Wasn't it a charter Co that the pilot owned and the plane assigned to? Seems I read that somewhere, maybe not. If so that would be under Part 135 wouldn't it? Operating Certificate and FAA check ride?
 
The plane was apparently "owned or operated" by an air taxi company but, I think the dentist (pilot) owned the air taxi company. That does not mean he was 135 compliant. He may have had other pilot(s) that did the 135 work. I suspect though I certainly don't know that the particular trip was being operated part 91. To your question, yes if the pilot was 135 compliant it should have taken at least a check ride after the required training per the op spec for the 135 operation. I of course do not know if the plane had even been placed on the certificate yet.
 
I am sure many are aware it is getting more common for the insurance to require more than a check out by an instructor. The last to Navajo I flew actually required yearly sim school. I suspect it may have been due to the very high liability coverage the owners carried. My personal opinion is nothing can take the place of a good sim school that incorporates thoroughly understanding systems. It is possible, as some have alluded to, that he may have been able to mechanically fly the plane however, he may not have had sufficient understanding of the plane's systems. The Navajo is a relatively simple aircraft with simple systems but....
 
mscard88 said:
Possibly. Wasn't it a charter Co that the pilot owned and the plane assigned to? Seems I read that somewhere, maybe not. If so that would be under Part 135 wouldn't it? Operating Certificate and FAA check ride?
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A lot of people have LLC's that say charter or something similar to avoid sales tax, if it's a "rental" you pay the sales tax per hour rather than upfront, at least it's that way in Georgia. I'd be surprised to see a fairly young dentist with kids flying on a 135 certificate, when would he have time?
With him owning the plane for a month, I'm going with the theory that he ran the aux tanks dry, thought and fixated on having pump failures, crashed with plenty of fuel in the mains.
 
mscard88 said:
Possibly. Wasn't it a charter Co that the pilot owned and the plane assigned to? Seems I read that somewhere, maybe not. If so that would be under Part 135 wouldn't it? Operating Certificate and FAA check ride?
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I could be wrong, but I don't think that having the word "Charter" in an LLC that "owned" a single aircraft would necessarily require it to be operated as a charter company. According to the records I've seen the dentist/pilot was not commercially rated. News reports gave conflicting information about it being affiliated with the University, or the plane often chartered by the University, but these reports also seem to be assumptions made by reporters due to the word "University" being a part of the LLC name when apparently there was no such connection to the University of Mississippi. I suspect that the LLC name doesn't portray the manner in which this plane was being utilized.
 
Chester Clark III said:
I suspect that the LLC name doesn't portray the manner in which this plane was being utilized.
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You're probably right Chester. Could just be a way for a tax write off, income shelter type deal. It will all come out in the final NTSB report anyway. I guess the 'charter' in the name had me wondering if the Doc leased it to a 135 operation using their pilots who would be certified under 135 and of the plane itself. Leaseback type arrangement, just guessing. Just can't get over those 11 kids left parentless. So sad.
 
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