Bud,
Thank you for your comments. Well thought out and valuable as always.
I was one of the earlier pioneers of the system to route my filling vent
and into the top of the cobra inlet. For the fuel tank / system vent I did
something different again.
I adopted the idea that Robin use and placed my vent in the backside of the
wing root. At the time I thought this was a great idea, but over time
perhaps its only a good idea, maybe not even that. The upside is that it
is unlikely to be plugged by mud, but there are a number of downsides:
- Once in a great while, if I over fill the tank, it will run out of this
vent and out of the wing root over the flap. I inspect the flap regularly
to make sure fuel has not got inside the core and dissolved the foam.
- If I over fill the tank the fumes make there way into the flap drive slot
during flight.
- I have to take the wing off to inspect the vent which doesn't happen
regularly. There is a slight risk on my area that an insect called a "Mud
Dauber" can get in there.
So, in conclusion, while these departures from the original design seem
like a good idea there are often hidden consequences.
Over the years I have become involved in inspecting and
technical counselling for the EAA, and the experience of this community has
taught me that fuel systems and modifications to them feature high on the
list of accident causes.
Cheers, Paul
On Sat, Jan 5, 2013 at 10:40 PM, Bud Yerly <budyerly@msn.com> wrote:
> **
> Jim, and tibits for the rest of us:
> After the tire failure and the subsequent off roading mud and
> dirt experience while cross country, I commend you for your pursuit of the
> problem which cost you much time, and money. You knew you had a mud
> plugged vent, but an experienced guy like you missed the kinked vent line
> cause. So what's a normal guy to do?
>
> I had to ponder that we (really me), are always quick to assume an engine
> related problem is causing the power loss. You told me about finding the
> kink but I still assumed that you had a carb problem. You cleared the
> clogged vent, but who would have thought about the rest of the vent system
> and a possible kinked line when the plane has been flying for years. I am
> anal about fuel system install and operation, but once installed, I rarely
> look beyond making sure there is not chaffing or leaks.
>
> Added for all of us:
> Recently I just finished an extended annual and another fuel tank
> replacement / annual in a couple aircraft that I helped customers build
> back in 2002 and 2004. Interesting to note that on both aircraft,
> that they were past the 5 year hose replacement timeframe (we all dread
> that). In both aircraft I found that the vent line was kinked or
> compromised. In one of the aircraft when the upholsterer forced the fabric
> around the fuel cover he had forced the fuel cover over one of the
> polyurethane vent lines and over time the cover pushed on it nearly flat so
> it barely vented properly, and on the other, the vent line was perfect
> looking, but the hose was horribly brittle because the vent tube was made
> from clear Tygon tubing. Tygon is supposed to be completely impervious to
> fuel related problems. Duh, maybe not...
>
> In my old Europa Operators Manual there was the requirement to pull the
> fuel bosses off and flush the tank annually, which is quite tough, but
> never to check our vent system, and in the new ops manual, it only
> indicates to check and inspect for leaks. The 5 year recommendation for
> changing hoses is still there, but not the vent lines. Vent lines never
> get checked.
>
> As far as I know, you are the first with an underside vent that ever got
> plugged, however, you are the only mono I know of with the vent on the
> bottom and operate off of grass a lot. In the trigear the vent on the
> bottom is always clean, but your point of the oil overflow on the right
> side of the cowl exit and a centrally located vent will be a potential
> problem for oil, grime and dirt. I'll have to admit I will make sure my
> annual checklist is changed to check the vents.
>
> I prefer not to vent out of the top because with the motor glider in turns
> when trying to soar, the fuel sprays out of the vent in right turns. It
> also will vent fuel out if overfilled on a hot day in Florida and let set
> in the sun (especially a mono), which of course can ruining the paint.
>
> Inspecting an aircraft is not an exact science. Manufacturers and
> regulating agencies give only vague guidance. We are the manufacturer as
> the builder, so we set the guidelines for inspections of our aircraft, and
> if the kit manufacturer gives guidance, we the manufacturer of the aircraft
> should be more specific, not less to include info on our added systems,
> changes, modifications, and additional wear areas or time change items due
> to all the above. I'm in the US, and have my A&P use the FAA FAR 43
> Appendix D as well as the engine 100 hour checklist and I insist on him
> using the Kit Manufacturers guidelines such as the Appendix E of the build
> manual and Section 8 of the Ops manual when inspecting an experimental
> aircraft. Now, I have been accused of doing a complete rebuild instead of
> an annual inspection, but I am anal so that is my excuse, but on an
> experimental aircraft (especially one I didn't help build or maintain) I
> have found that there are many non standard items, routing conflicts
> between wiring, fuel lines, brake lines and control cables, as well as poor
> installation of equipment and structural construction mistakes that the
> builder and final FAA inspector missed on the initial Airworthiness
> Inspection. The FAA actually requires us, as US Experimental Aircraft
> Manufacturers, to have established maintenance and operations procedures.
>
> I am attaching my personal annual inspection checklist out in the open to
> show what we the builder can do to improve the inspections on our
> aircraft. I only just added an item to inspect the fuel vents since you
> called me about the problem weeks ago. I developed this checklist long
> ago, before becoming a Europa owner and just tailored it to include items
> in the Europa Section 8 inspection, the FAA and LAA recommended guidelines
> etc. I am preparing to submit some of this info in a condensed fashion in
> an updated Tech Support section of Europa's Website as well as some other
> notes we all should know when maintaining the Europa. Now this is my
> personal checklist, not for general dissemination as a Europa Directive,
> but provided for others to see that an annual inspection is not a walk
> around. But then again, it is not an IRAN (Inspect and Repair as
> Necessary) like the military does by completely disassembling every panel,
> inside and out, instruments, wings, engine, etc. and inspect, refurbish,
> service and repair all the above, it is however, more than a quick check
> for wrinkles in the skin, change the oil and sign it off.
>
> Great job of troubleshooting and thanks for the report Jim. Your findings
> and my recent observations have changed my annual checklist for sure...
>
> Regards,
> Bud Yerly
>
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