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RV-10 Inflight Fire and Forced Landing - Pilot Did Great!

pierre smith said:
That's a pretty quick build time for a -10!
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Pierre, in retrospect that might have been a rather prophetic comment you made earlier in this thread (shortly after the first flight) given that the cause of the ensuing fire seems to have been a B-nut on the fuel pump that was not properly torqued.
 
tc1234c said:
I got a few minutes before I have to go out of town. Here is a quick answer.

The first sign was low fuel pressure. I turned on the boost pump. The fuel flow was very high (don't remember the number).

After 10 minutes (I had a 20 nm trip with 32 kts headwind at 2,600' running 23/2300 I was doing 90 kts GS) and 4 nm from my destination I smell the smoke and began the sequence of event I reported before).

My plane landed 1.5 to 2 sm from the end of the runway and the surface wind was reported 4 kts from south. In a dive I estimate that I must be doing 140-150 mph. So it took a little more than 1 minute to travel the 2.2 sm. I must started turning toward the field less than 60 seconds from the time I smelled something.

First has been burning under the tunnel for a few minutes. By the time I noticed it must has burnt through the skin.

Big smoke came out within few seconds after I put off the initial fire along the edge of firewall and tunnel. Now I believe by that time the brake lines have been burnt through.

I am going back to the hangar next week to open the tunnel cover and assess the damage. FAA inspectors want to come and take a look too. I will definitely post pictures.
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Thanks for the report, Ted.

First thing I am going to do as a result of your experience is make sure the EIS fuel flow warning is set to a number just above the normal take off fuel. Also, the low pressure warning will be checked. These are items that will indicate a leak before the fire.....

Excellent job flying the airplane. Very sorry the airplane is such a mess but what's really important is you walked away from it. It will be a while before you stop reliving this one.
 
NOMEX

As a former race car driver I would have NEVER driven a single lap without wearing a NOMEX driver's suit, gloves, balaclava and FULL SET OF UNDERWEAR. When I read Doug's write up last week about his safety missive I had to ask myself why I wasn't doing the same thing in an aircraft? After all, the fuel lines on most aircraft travel through the cockpit.

I do believe adding a pair of NOMEX long johns, long sleeve top and gloves to our "Before Engine Start" checklist should be a serious consideration.

It could literally save your skin...
 
The best solution is??

Dan H- You've obviously researched insulation material options thoroughly. I have a 16yr old RV-4 that I didn't build. This particular incident and thread have made me seriously consider what is installed in my aircraft. I also suspect that better materials may have come to market since mine was built. What insulation did you choose for your RV?
 
RVFlyer said:
Dan H- You've obviously researched insulation material options thoroughly. I have a 16yr old RV-4 that I didn't build. This particular incident and thread have made me seriously consider what is installed in my aircraft. I also suspect that better materials may have come to market since mine was built. What insulation did you choose for your RV?
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I am not Dan but his threads about firewall insulation talk about a ceramic fiber material sandwiched between a stainless steel and aluminum foil mounted on the engine side of the firewall. Here is a picture of my firewall installation of just such a setup. No glue used, just the mechanical fasteners that hold all the various components already on the firewall are what are holding the insulation on the firewall.

firewallinsulation42010.jpg

By steveingraham at 2010-04-05
 
ABC extinguisers BAD

Mike S said:
Ted, the dry chem fire extinguisher residue needs to be cleaned up as soon as you can do so-------depending on what compound was used, it can be bad news for the aluminum :eek:
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Mike, as a former fireman may be able to tell us much more, or recommend an expert to ask, but I have been told in the past that the stuff in ABC-type extinguishers is extremely corrosive to aluminum, and gets into riveted joints and is very bad.
It is worth considering the idea of building a whole new fuselage rather than repairing this one. At least discuss it with an expert before settling the insurance. If you need to replace the whole fuselage because of fire extinguisher powder, then that will be part of the settlement.

For this reason, I made sure that the extinguisher in my hangar is BC-type. And the small one in the airplane is halon. Unfortunately it is hard to influence what the fireman who shows up at the scene uses.
 
scsmith said:
Mike, as a former fireman may be able to tell us much more, or recommend an expert to ask, but I have been told in the past that the stuff in ABC-type extinguishers is extremely corrosive to aluminum, and gets into riveted joints and is very bad.
It is worth considering the idea of building a whole new fuselage rather than repairing this one. At least discuss it with an expert before settling the insurance. If you need to replace the whole fuselage because of fire extinguisher powder, then that will be part of the settlement.

For this reason, I made sure that the extinguisher in my hangar is BC-type. And the small one in the airplane is halon. Unfortunately it is hard to influence what the fireman who shows up at the scene uses.
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Steve, I was always in my told in my training that the stuff was corrosive also, and that is the basis of my comments to Ted.

I did go online to research the MSDS for ABD powder, but could not find any reference to corrosive listing--------but that doesn't mean it aint there.

My fire service tenure was over 8 years ago, so there is a chance the extinguishing agent has been changed-------but better safe than sorry.

There are a lot of fire extinguishers sold that are make of aluminum-----for whatever that is worth in the discussion.
 
Mike S said:
Steve, I was always in my told in my training that the stuff was corrosive also, and that is the basis of my comments to Ted.

I did go online to research the MSDS for ABD powder, but could not find any reference to corrosive listing--------but that doesn't mean it aint there.

My fire service tenure was over 8 years ago, so there is a chance the extinguishing agent has been changed-------but better safe than sorry.

There are a lot of fire extinguishers sold that are make of aluminum-----for whatever that is worth in the discussion.
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My guess Mike - a rural fire department's dry chem extinguishers probably haven't been CHARGED for more than eight years! :p

I doubt that the stuff has changed much, and I know that it makes a heck of a mess - I was told my an insurance guy in our department that if you use a standard size fire department one on an engine compartment, the car is likely totaled these days.

Paul
 
DanH said:
From Ted's Picasa album....

The circled features are the melted/missing sections of the two brake lines. Note their location; well forward of the melted/missing floor section, and above the Ozite insulation. Given the insulation was thus between the hot firewall base and the melted sections, I assume the insulation ignited, then melted the lines.

Ted, did the brake lines melt anywhere else near the bare firewall, perhaps someplace above and forward of the heat duct cross tube?

No matter really....another observation: It is possible that the fire streaming back from the cowling exit was a nice tight narrow stream, but it is unlikely. So, why did it burn through only the tunnel floor and not floor areas in either footwell just outboard of the tunnel walls?

When you heat one surface of a panel, how hot it gets is heavily influenced by how readily it can shed heat from the opposite surface of the panel. In this case the tunnel floor burned through because it was being heated on both sides, unlike the footwell floor areas. There was a fire in the tunnel before the tunnel floor burned through.

2jbpgqt.jpg


4kb2b6.jpg


2s14xmg.jpg
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Dan,

I believe the broke segments are right behind the firewall. The remaining Ozite insulation you see is attached to the firewall. The insulation on the floor are gone. The bottom with nutplates is actually on the bottom cowl that is forward and below the firewall. What you see below the brake line are part of the bottom cowl and left tailpipe. Bottom of the firewall is black band below the Ozite insulation.

Illustration.JPG
 
Ironflight said:
I doubt that the stuff has changed much, and I know that it makes a heck of a mess - I was told my an insurance guy in our department that if you use a standard size fire department one on an engine compartment, the car is likely totaled these days.
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I am afraid that might be the predicament. Well, I am still happy since I am not totaled.
 
I'd just point out that the RV10 has a double floor (outer skin plus floor skin) under your feet and only single skin in the tunnel.
 
What exactly is a "B-nut"? I have been building since 2003 and have never heard that term before ( I don't think :) I hesitate to ask a "stupid" question but I'd rather avoid this same fate.

Thanks!
 
I don't know how I missed this thread, but I am so glad that you are OK Ted. Great job in bringing her down safely, a testament to a great piloting.
 
I was talking with Gus out at Van's one day regarding my plan to use fiberfrax on the firewall and the testing I had done. His comment was the floor under the tunnel will be the first place to go, not the firewall. Not his exact words, but close.

It would seem to me that the area above the exhaust should have a stainless plate with appropriate attaching hardware to withstand the 2000 degrees that is possible with the blown gasoline flames. This would protect the floor and provide an added layer of protection. I seem to recall a post where someone did just that to reduce the heat in the tunnel.

Another lesson learned which would reduce multi point failures is the brake lines. In my opinion, after seeing this, they should run up either side of the fuse and not be enclosed the tunnel nor attached to the firewall. It would have added insult to injury to land on a hard surface and not been able to stop. I am going to change mine when I get back to the fuse assembly to do just that.

This accident, while tragic, presents a great opportunity to analyze what happens when a fire starts in the cowling and to take a look at correcting any design deficiencies in case it happens again.

The tunnel heat issue seems to precipitate a lot of discussion, without a definitive conclusion. How many posts have we had regarding this issue? The fuel pump and associated lines and hardware sitting in this area have always made me feel uncomfortable. Several folks have installed fans, fume detection devices, etc. Just patching the issue. My personal plan is to use only one of the heat valves for heat and use the other to flush unheated outside air down the tunnel. Again, also just a patch.

I for one, would certainly like to see some design changes come out of this tragic event.
 
B-nut

tc1234c said:
I got my airplane back to the hangar and found the cause of the fire. It was a loose b-nut on the mechanical fuel pump. I must not tightened it enough. After 3+ hrs it got loose and leaked fuel. The fuel flow down under the tunnel and burned through. The smoke must be from the brake fluid. It was short lived. If I landed on hard surface I would not have brake!
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First thing, great save. I hope I do as well if put in your situation.
Is this the input to the mechanical fuel pump? If so I am surprised there was a fire problem before the electric fuel pump was turned on. I would have expected the line to suck air into the system not lose fuel.
 
Design changes?

Great job under pressure Ted.
I hope you get to rebuild her soon and without too much delay.

Bill, I am not sure anybody is going to change the design but building in the experimental category you can make your own changes (improvements?).
Here is what I did back when the hot tunnel issue was debated.
A couple of Z brackets and an angle along the side of the tunnel elevate the second floor about 2 inches.
On the bottom a piece of ceramic firewall blanket, followed by brake lines
inside the double floor and room for another piece of heat insulation.
At the time I was trying to keep the heat out of the tunnel but it should help
gain a few precious minutes in case of fire.
The z brackets are strategically placed to accomodate the fuel pump and other accessories and the floor is removable.

IMG_0033.JPG


Photo%20%2035.JPG
 
Posting a picture like this opens the door for constructive criticism and please take my comments as constructive.
The aluminum firewall fittings have been noted and most definitely should be changed to steel. Although this is a very neat and well thought out installation there are at least twice, and maybe, three times as many failure points as you would find in a stock fuel system. I suspect this system allows for a fuel return and thus and extra fuel flow meter to correct for this return flow. If this is an automotive installation those systems may be necessary but if it is for a Lycoming they should be removed. I have lots of time behind a 540 and the standard fuel system, with no return, is simple and provides very accurate fuel use readings with the current engine monitors available. The inaccuracies that occur when you fill the tank will be much greater then any minor imbalances caused during the short times that the boost pump is on.
If this extra plumbing is to account for a fuel return to help with hot starts then again I have found that system to not be required.
Extra fuel plumbing, unless it is absolutely necessary, is a leak waiting to happen.
 
DanH said:
If you want to protect or reduce the temperature of a structure, why do you insulate on the inside of the structure?
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Personally I did not want my fiberfrax getting oil and fuel soaked on the engine side. I want to be able to wipe down the stainless steel surface. It would end up getting damaged from maintenance/repairs.

The smoke produced from Fiberfrax did not seem as toxic as some things I have burned and got a whif of. If I can make it through an inflight fire and back on the ground safely the least of my worries would be breathing in some loose ceramic fibers. I'll try to put on the smoke hood if there is time. If not I will ventilate the cockpit as Ted did with a door departure and breath through my nose. Another reason that I wanted a lightweight interior- paint on visible surfaces only. I also only primed mating surfaces of firewall structure...providing less paint to burn.
 
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Good Job Ted...very glad you are safe.

Keeping your cool under those circumstances, simply amazing.
The value of this post to the community is a testimony to your character also.

This thread has seemed to evolved into design and material choices in the event of an inevitable fire. There has been a lot of discussions and previous posts in this regard and there are some very good take aways posted here. However, the aluminum airboxes did not fail, the aluminum bulkhead fittings did not fail, etc... so, this is a shift back to safety and the events that led to the fire....

A question and an observation;

Your fuel pressure dropped, then you noticed excess fuel flow when you turned on your boost pump. Why did you not abort? (again, I mean no disrespect).

"B" nuts are designed, or have a natural tendency to leak well before they are loose enough to start spewing large quantities of fuel. If this nut was loose, there should have been fuel staining for many hours before the nut became so loose it would present this level of a hazard.

Again, thank you for posting in detail your ill adventure. We can all learn from these situations and it takes a big person to put themselves in the public eye, so to speak.

Best.
 
The morning of the fire I made the 20 nm flight to KEOP to get fuel. All instruments showed normal reading. I even have a picture showing the fuel flow and fuel pressure en-route to KEOP. I was also surprised to find FIS-B weather in my area. On the ground I did not smell any fuel neither burn.

I noticed the low fuel pressure only toward the end of the climb to 2,500' for a 20 nm flight back to my home airport. Since I was still calibrating all my instruments I can only say that I was puzzled by the low fuel pressure and high fuel flow. I did turn boost pump off once and the engine was quiting so I turned it back on. In the hindsight if I turned off the boost pump at that time I would stop the fire yet crash into the mountain. There is no landing options just south of KEOP (see Google map).

At 3 hr hobb time that is before the KEOP flight I did have cowl off to check firewall CO leak using light. At that time I did not see or smell anything out of ordinary. I visually checked everything at 1 hr hobb time and no fuel leak neither. During final inspection inspector and I did not use a wrench but used our hands to turn all the B-nuts. None of them were loose. That was a mistake since the problem is not they are loose but not tight enough. Don't ask me why I did not tighten that B-nut enough to begin with.

From this very expensive experience (I almost die) I learned to be careful with my fuel system. I am not trusting myself by turning all nuts by hand. I want to make sure that they can not be turned further by applying gentle force with a wrench (with a torque wrench whenever I can).
 
Since reading about this accident, I readjusted my Max fuel flow limit on GRT to just above the max fuel flow at full rich & full throttle which came out to be 16 GPH. Since my normal cruise flow is in the neighborhood of 8.5 GPH, I am just wondering what kind (big) of a leak it would take to trip off 16 GPH limit? Chances are that by then, half of the plane is in flame :(

But still a good alarm to set and in conjunction with the fuel pressure alarm, easier to determine a leak in progress.
 
Sounds like you did everything possible considering...

tc1234c said:
The morning of the fire I made the 20 nm flight to KEOP to get fuel. All instruments showed normal reading. I even have a picture showing the fuel flow and fuel pressure en-route to KEOP. I was also surprised to find FIS-B weather in my area. On the ground I did not smell any fuel neither burn.

I noticed the low fuel pressure only toward the end of the climb to 2,500' for a 20 nm flight back to my home airport. Since I was still calibrating all my instruments I can only say that I was puzzled by the low fuel pressure and high fuel flow. I did turn boost pump off once and the engine was quiting so I turned it back on. In the hindsight if I turned off the boost pump at that time I would stop the fire yet crash into the mountain. There is no landing options just south of KEOP (see Google map).

At 3 hr hobb time that is before the KEOP flight I did have cowl off to check firewall CO leak using light. At that time I did not see or smell anything out of ordinary. I visually checked everything at 1 hr hobb time and no fuel leak neither. During final inspection inspector and I did not use a wrench but used our hands to turn all the B-nuts. None of them were loose. That was a mistake since the problem is not they are loose but not tight enough. Don't ask me why I did not tighten that B-nut enough to begin with.

From this very expensive experience (I almost die) I learned to be careful with my fuel system. I am not trusting myself by turning all nuts by hand. I want to make sure that they can not be turned further by applying gentle force with a wrench (with a torque wrench whenever I can).
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...and made sound judgements. We all miss things. My tag line says it all. Anybody who thinks they are too smart to make mistakes.....well, they are just too smart....
Again, the outcome could have been much worse had you not kept your cool.
I still am puzzled about the "B" nut. My experience shows that they leak a bit when loose, then start leaking more, and more, but don't become gushers until they are almost ready to fall off. Perhaps my experience is wrong.

There are several threads going around about safety. One excellent suggestion was that everytime the cowling is off, put a wrench on anything and everything you can. Don't trust anything to be tight by hand.
 
Marking "B" nuts

While we are on this subject, it is very difficult to get a torque wrench on many of the fittings. I follow the method of hand tight then tighten to the appropriate flat as suggested by the fitting suppliers. I mark the fittings with a line that crosses both fittings. I use the line to then indicate how far I turn the fitting. This line is readily visible on any inspection and will allows show you that the fitting has been tightened to the appropriate flat. If it ever loosens, it would be very obvious just by the position of the line. Hope that makes sense.
 
tc1234c said:
At 3 hr hobb time that is before the KEOP flight I did have cowl off to check firewall CO leak using light. At that time I did not see or smell anything out of ordinary. I visually checked everything at 1 hr hobb time and no fuel leak neither. During final inspection inspector and I did not use a wrench but used our hands to turn all the B-nuts. None of them were loose. That was a mistake since the problem is not they are loose but not tight enough. Don't ask me why I did not tighten that B-nut enough to begin with.
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Ted,
Again, I am very happy that there is only physical damage and no personal injury to you, kudos to your handling of the situation.

Just wondering, why do you think that the B-nut was only finger tight? Is it possible that it was tight properly but loosen during the process? I have always wondered about B-nuts and why they are not manufactured so they can easily be safety wired. I think the conversional wisdom is that, they don't loosen as other normal nuts do!!!
 
Great Job!

Ted first off great job on getting that bird down in one piece. I did find there two web pages about the effect of ABC dry chemicals on aluminum. I have always been told that ABC extinguishers should never be used on aluminum aircraft due to corrosion problems it creates not only on the aluminum but also the electronics. Take a look at the links I'm sure there is more info on the web on the subject.

http://www.h3raviation.com/support_faq_2.htm

http://www.finishing.com/61/81.shtml
 
How about an SS plate?

Well done on a flight that went SO wrong!!
Since the first time I saw the stories about the hot tunnel issues, I was wondering about simply pop riveting a SS plate with some insulation, onto the belly aft of the firewall in order to keep heat from the floor. Here I mean some good fire proof material (thin) on top of the SS plate to form a sandwich. Reading through this thread made me think that I should actually do it.
Any thoughts on my idea?
 
Use Torque seal!

JonJay said:
While we are on this subject, it is very difficult to get a torque wrench on many of the fittings. I follow the method of hand tight then tighten to the appropriate flat as suggested by the fitting suppliers. I mark the fittings with a line that crosses both fittings. I use the line to then indicate how far I turn the fitting. This line is readily visible on any inspection and will allows show you that the fitting has been tightened to the appropriate flat. If it ever loosens, it would be very obvious just by the position of the line. Hope that makes sense.
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After torquing or turning one flat past hand tight slap a line of the torqueseal http://www.aircraftspruce.com/catalog/cspages/f9003.php accross both b-nut and fitting. This stuff is brittle and paint like, so if the b-nut loosens, it will crack and be easy to identify upon inspection.

BTW, great job on the forced landing!
 
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