russ

Have found meself pondering at times............safety

We've got these flying machines, we "sit" on fuel, and we've got 12v wiring going everywhere.

Ok...........heaven forbid, mishap......tank spews fuels everywhere, our little 12v wires get torn, we get sparks..........."BOOF"........we got fire.

Should we all have a dedicated fuse.............right at the battery, [ fuseable link ]. Shut the 12v off at the battery.

just pondering here................

__________________
State of origin..........go the maroons

I intend living forever...........so far so good.

ken watson

g'day Russ. Hot exhaust and motor is the problem, and an electric fuel pump that just keeps pumping. Yamaha fzr's had the problem that when they fell over they would burn as the pump just kept pumping through the carbies as the floats cant work when sideways. On race machines we used a pump that stopped when on its side. I wonder if the foam type stuff they put in race car tanks would help. It slows down that rapid deluge in a rupture. I know that in my crash the pump was pumping flat out and fuel was going everywhere. I got that belt off real fast. I also think it must be difficult to get out of a cab when on its side as one opening is blocked. A lot of complex circumstances with sad consequences. It's sad when fun leads to the unhappiness of many. I hope the pain is recoverable and I wish we could turn back time to stop these occurences.But unfortunately this is part of life. We can never really make anything completely safe.Best wishes to all involved. Ken

ken watson

By the way, my flight suit is flame proof, but now I'm going to go a step further and where my race car suit and underwear,boots,gloves, . The jacket I wear is a kleenheat gas jacket which is also fire resistant. Didn't realize till I checked the label. Race suits are about $300 with undies and boots and gloves.Ken

Gyrodes

Well posted Ken, This is a classic case for a mechanical pump on the motor. High pressure pumps for the fuel injected motors can be mechanical as well. In my personal opinion electical should only be used for priming. If electrical is the choice, a pressure control switch is required in the circuit so that the engine stops then the fuel pump stops. Fuel will leak from ruptured tanks but at least it will not be under pressure atermising.(sp)
There is pressure switchs available to do this as a lot of hire comressors, welders, gensets have them in the murphy shut down system. How they operate is that a bypass switch is held down till the oil pressure builds to a designated pressure then the system remains operational.
May be Saml could tell us what is available as it is auto sparky stuff.
Des Garvin

__________________
What you focus on grows. Des Garvin

niquenaque

Ken,

Where did you get them from for the benefit of everyone??

Ross Bannerman rang me today about this issue, his concerns were the same as Ken has nominated. He wanted to know if there was a fire protection / detection mechanism that might take care of this sort of issue.

There are a couple of ideas::

Detection -

Ross asked if there were any detection systems like fusible cable - yes, there are cables made with a 67 degree melt point where twisted pair cable with an insulator that melts at 67 degrees. The insulation melts, the wires touch and form a circuit and the alarm is triggered, though 67 degrees is a low temp in an engine bay. I am sure they have higher temperature cable and will confirm once I have dug up my catalogue. [Reservation about this = short circuits in cable may mean sparks in a bad situation, it would have to go through a limiting resistor.]

There are dedicated electrical detectors we use in cooking exhaust hoods and the like, they have a higher temp setting and merely short circuit at the appropriate temperature.

There is a system of electro-pneumatic detection that can be cooked up out of some stainless steel or copper capilliary tube, what happens with this is that you have a series of canisters in the engine bay that are located near heat and ignition sources, they are inteconnected with the capilliary tubing which in turn is connected to a pressure switch, which is calibrated for a temperature in the engine bay = normal climb out temp + 10 degrees C. When the temp is exceeded the pressure switch can sound an alarm, fire an extinguisher and all the rest of what you want it to do, like they have in the FA-18 hornets.

Protection -

Options here are pretty limited as most engine bays on gyros are usually flowing a large amount of air. Unless you have a cowling [as they do in the jets] that can close off at the infeed you may have some issues. Ross suggested pulling up the nose and doing a vertical down - then firing the extinguisher. Ross has a gyro with a fully enclosed engine.

You could potentially use one of two types of extinguisher - Dry Chemical Powder or AFFF / Flouroprotein foam

There are others but they are typically gas based and would suffer from inefficiency due to the venting of the engine bay.

The solution of sorts is to have an over capacity extinguisher and to vent it manually via an extended hose into the engine bay - a little difficult on a gyro with an exposed motor as most of them are. So the fact of an extinguisher requires a closing cowling to effect the job.. it is all starting to look like too much trouble, maybe not for some but everything that we add on means we have to sacrifice elsewhere, we´ll end up sacrificing flying if we go all out on this issue.

The RAAF run their ops with what they call ´acceptable risk´. I guess it is a question as to where you want to draw the line.

I´ve seen three crashes and read of a few more, the percentage of then that end with the gyro bursting into flame has been pretty low, but by the same token there is no way I would like to be burnt, it happens too much at work these days to have it happen when you´re supposed to be out there having fun.

Cheers,

Nick.

SamL

Sorry Des, but I have an Industrial Electrical back ground, not Auto Elect !!!
An easy and very cheap solution, would be to use a mercury switch in your control wiring, possibly switching your pump off during a roll over. :
The other consideration is a supply isolator (Solenoid) in line with your electrical pre-rotator (should be fitted as close to your battery as possible). This isolates the normally live cable that runs up your mast. This is very important, as its your mast which normally twists, bends, or breaks, during a roll-over, potentially cutting and shorting this live cable.
Regards Sam.......

__________________
-- Leonardo da Vinci --

mceagle

Fuel injection pumps are positive displacement and shut down as soon as the ignition is cut or the crankshaft stops turning.
On all engines the primary circuit should be fused as close to the battery as possible, but it must be done correctly. There have been many instances where the installed fuse itself has caused problems.

Sam's suggestion for a battery isolater (near the battery) is a good idea. It could be activated by either the electric prerotator or the starter motor, such that the wires are dead except when in use (starting or prerotating).

__________________
Tim McClure

Adrian S

Guys,

This is a good thread to raise safety awareness of fire risk from electrical/fuel systems.

When ever a gyro is presented to me I always strongly recommend the instalation of a "master power soleniod" so that the pilot can isolate the electrical system at the flick of a switch. Note this should be a guarded switch so that it is not accidently switched off.

With such a system you can then implement a basic safety drill that would see the master switched off just before contact with the ground- effectively isolating the fuel pumps and other electrical sources.
This is basicaly the way most other aircraft are wired so that fires can be minimised from uncontroled(crash!)landings .

Adrian

Brian

Aim number 1 is not to crash.
Aim 2 is to, in the event of a problem, fly it untill it all stops.[or at least try every possible thing to retain /regain controll]

At the end of the day, the impact it takes to split say a Gerry 60 litre tank, is [most times] going to cause a fairly big problem in the pilots health.

__________________
Brian Reid
Pooncarie
NSW

russ

True................but if we could eliminate one of his health problems [ ie.......burning ] then he could concentrate on other health problems...........

__________________
State of origin..........go the maroons

I intend living forever...........so far so good.