- return line with one-way-valve or emergency off-selector .
I have talked to Andy Draper on this topic. My analysis is as follows:-
Ideally the return pipe should be a single piece from end to end. So the
high risk of leakage is at the end connections (the pipe being severed mid
cockpit is, even in an accident, possible but very unlikely if properly
routed).
By fitting a one way valve, this suggests that the unwanted flow is coming
---From the tank. The engine end (with the restrictor in it) is higher than the
tank so fuel would not flow from the line if disconnected. If the aircraft
is inverted then fuel will not flow from the tank.
So the only failure mode of concern is disconnection at the tank end. If
the valve is there it is at least 50% likely that the disconnection would be
between tank and valve, so the valve does not really make things much safer.
So I conclude that fitting a valve is superficially a good idea, but when
you analyse it I can't see a case for fitting a one-way valve.
Having an emergency hammer and the fuel vent(s) at the bottom of the
aircraft are good ideas I have implemented.
Ian Rickard G-IANI XS Trigear, 280 hours
Europa Club Mods Rep (Trigear)
e-mail g-iani@ntlworld.com
$B!!(B
_____
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of Brian Davies
Sent: 18 November 2009 15:28
Subject: RE: Europa-List: Safety improvement list
In the UK, homebuilts are daylight VFR only. I have never spotted an
aircraft in daylight by seeing its strobes. I dont think they are an
essential safety feature.
Regarding the check valve in the fuel return line, has there ever been an
incident/accident where the lack of one has caused a fire?
It is very easy to add a long list of additional safety items (and weight)
using a "what if" method. If you are carrying out a proper risk assessment
you should always balance this with probability and the consequences of the
risk materialising.
The reason everyone in the UK has to wear hard hats, high vis jackets,
safety boots and safety glasses to change a light bulb is because of
defective risk assessment.
Brian Davies
_____
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of G-IANI
Sent: 18 November 2009 11:56
Subject: RE: Europa-List: Safety improvement list
Frans and all,
Some comments on your safety improvement list
1) Safety belts.
Do not use types which formulate loops - Agreed
Make modified upper fixing points - Agreed
I am not sure you need the "lengthened and foldable headrest".
2) Fuel systems
- routing outside the cabin (weight penalty none or some) - Agreed in
principal. G-IANI is a Trigear so all the fuel system is in the centre
tunnel
- return line with one-way-valve or emergency off-selector - Sounds a good
idea, I will talk to LAA about this
- do not use original glass fuel filters - They have there limitation but
are acceptable if they are accessible and can be monitored and cleaned. Has
anyone found a reasonably priced substitute we could standardise on.
- consider the safety of sight gauge and it$B!-(Bs location. - What the manual
recommends is not good. Of the variations that builders have done which is
the best compromise in terms of safety and functionality?
- have a fuel warning /gauge/pressure gauge /computer - Agreed I would not
fly G-IANI without it
3) Doors
- use unintentioned opening guards and secure them with pip-pins to levers
- In the UK the LAA do not approve this. It is a value judgement on the
risks involved.
- install serial connected micro switches w warning lights behind shoot
bolts. - OK but, as Karl said, they can lead to a false sense of security.
A manual check is essential
4) Cowlings
- do not make those little oil/water check doors - so you have to take whole
upper cowling away and see and check same time much much more (weight
penalty none, use cam locks or equal - so it is pleasure to open so often
you like - I do it every 5 flight hrs)
I have Southco fasteners on my cowl. They are a lot of work to fit but do
make removing the cowl a lot easier. I still think you need the oil/water
check doors for doing the daily $B!H(BA$B!I(B check.
5) Electrics
- use two serial connected master switches; so called panel mstr leaves
juice for trim, stall warner, charging for emergency batteries, clocks,
burglar alarms, horns, convenience lights AND an engine starter - total
master cuts everything (weight penalty none, normally my total master is
always on, I close it only during longs stays over two weeks or just before
possible crash I wish, panel mstr switch uses light weight 40A relay which
uses only few milliamperes, total mstr switch is mechanical with "a key" and
uses 0 amperes)
That is essentially how G-IANI is set up1. Both my switches are mechanical
6) Cockpit equipments
- have a carbon monoxide detector - Agreed
- have a Halon fire extinguisher - Agreed it is a requirement in the UK
- have a personal locater beacon with gps - Agreed
- have a stall warner or AoA indicator - Agreed
7) Outside equipments
- have at least strobes - Agreed. This is something that should be in the
manual
Ian Rickard G-IANI XS Trigear, 280 hours
Europa Club Mods Rep (Trigear)
e-mail g-iani@ntlworld.com
href="http://www.aeroelectric.com";>www.aeroelectric.com
href="http://www.buildersbooks.com";>www.buildersbooks.com
href="http://www.homebuilthelp.com";>www.homebuilthelp.com
href="http://www.matronics.com/contribution";>http://www.matronics.com/chref
"http://www.matronics.com/Navigator?Europa-List";>http://www.matronhref="http
://forums.matronics.com">http://forums.matronics.com
270.14.69/2508 - Release Date: 11/18/09 07:50:00
|