REFLECTOR: Grounding Point

Jim Sower canarder at frontiernet.net
Fri Oct 29 00:27:28 CDT 2004 

Scott,
<... All OK now? ...>
No. 
Had a rough runner and power loss coming out of SPI bound for IJX.  Made 
it 15 mi or so to IJX and found the head was separating from #3 
cylinder.  Got a new jug installed.  Everyone agreed that that explained 
the whole deal as well as an oil pressure fluctuation I'd had a couple 
of weeks ago. 

Launched for home and it started running rouge climbing through 1500'.  
Another precautionary approach.  Messed around with plug wires, replaced 
a couple of plugs, compression check etc. etc. (nothing particularly 
convincing) and tried again.  Another failure.  Mechanic insisted it was 
the cam.  Checked finger screen.  Not making metal.  Replaced scat tube 
to throttle body and tried again.  Same shit.  Now I'm 5 for 5.  The 
last two tries, I was able to circle the field for a while (the last one 
for 45 min or so) while it was belchin' and fartin', trying different 
things (mag checks, mixture adjustments, boost pump on or off, etc. 
etc.) checking pressures, temps (CHT, EGT, Oil, etc.) at different 
throttle, mixture, boost pump, etc.settings..  Nothing to hang anything 
on.  Sounds and feels like fuel delivery problem.  I'm going back again 
this weekend and replace the fuel filter, replumb part of the fuel 
system downstream of the sump and head for home. 

I'm pretty sure I can keep it up for the better part of an hour, and 
from IJX to CSV is around 350 - 400 nm so I could limp home in 3 legs or 
so, never more than 15-20 mi from a 4000' runway.  I need the resources 
I've got at home and perhaps and the opportunity to talk to a mechanic 
who doesn't declare what the problem is and then systematically amend 
the laws of physics to support his contention (... if your onliest 
solution is a hammer, the problems all start looking like a nail...).

I'll let you know how it all comes out whenever it does ... Jim S.
... Destiny's Plaything ...

Scott Derrick wrote:

> Jim, heard you had an unfortunate cylinder failure?
>
> All OK now?
>
> Scott
>
> At 03:49 PM 10/28/2004, you wrote:
>
>> My fuel caps are fastened by a 6"-8" chain to the apex of a 3" x 1.5" 
>> triangular piece of Al to prevent the cap from departing the airplane 
>> (through the prop :o).  I fastened another 12" piece of chain to the 
>> center of the base of the cap retainer so it dangles to the bottom of 
>> the fuel tank.  The retention mechanism cannot but be in contact with 
>> the metal filler neck, nor can the fueling nozzle.  I just clip the 
>> ground cable to the chain.
>> Added a little hunk of chain to the mandatory cap retention mechanism 
>> .... Jim S.
>>
>> Gilles Gratton wrote:
>>
>>>
>>> We are talking retrofit here.  My plane has been flying (and 
>>> refueling) for
>>> 4 years and I only clip the grounding cable to the nozzle for lack of a
>>> better grounding point.  However I like the screen bit.  Would it 
>>> work if
>>> one was to shape a cylindrical screen that could be inserted in the 
>>> fuel cap
>>> opening at every fuel stop.  This cylinder could reach the bottom of 
>>> the
>>> tank and have a flange that would barely touch the top strake around 
>>> the
>>> fuel tank opening. The fuel nozzle would then  flow through that 
>>> screen.
>>> The only draw back would be to carry (and store ) this contraption 
>>> to have
>>> it on hand at every refueling stop.
>>> Gilles
>>>
>>> -----Original Message-----
>>> From: <mailto:reflector-bounces at tvbf.org>reflector-bounces at tvbf.org 
>>> [mailto:reflector-bounces at tvbf.org]On
>>> Behalf Of Jim Agnew
>>> Sent: 24 octobre 2004 14:43
>>> To: Velocity Aircraft Owners and Builders list
>>> Subject: RE: REFLECTOR: Grounding Point
>>>
>>>
>>> The concept of a fire screen has been proven for many years in 
>>> miners lamps.
>>> A
>>> fine mesh screen tube surrounding the filler inlet that goes to the 
>>> bottom
>>> of
>>> the tank will prevent the passage of the flame front into the fuel 
>>> tank even
>>> if
>>> the fuel vapors inside the fire screen tube ignite.  This screen 
>>> does not
>>> depend on grounding.
>>>
>>> Jim
>>>
>>>
>>> --- Chuck Jensen <mailto:cjensen at dts9000.com><cjensen at dts9000.com> 
>>> wrote:
>>>
>>>
>>>>
>>>> Mmmmmm. Alex's idea of first checking for continuity between the 
>>>> fueler
>>>>
>>>
>>> ring
>>>
>>>>
>>>> and the exhaust pipe is a good one.  If there is continuity, then
>>>>
>>>
>>> executing
>>>
>>>>
>>>> Al's idea of a drooping chain from the cap down into the fuel seems to
>>>> assure there is a fuel-chain-exhaust-refueling stating ground (all 
>>>> this
>>>> assuming there is fuel ring to exhaust continuity).  Richard's method,
>>>>
>>>
>>> from
>>>
>>>>
>>>> a Very Large Aerospace Company, appears to do the same thing, just 
>>>> better
>>>> and with a higher degree of certainty.  Of course, if there's not
>>>> continuity, then its back to the drawing board.  It's somewhat 
>>>> comforting
>>>>
>>>
>>> to
>>>
>>>>
>>>> know that the incidence of Velos going off like Roman Candles is 
>>>> rare, but
>>>> I'd hate to be the first data point.
>>>>
>>>> Chuck
>>>>
>>>> -----Original Message-----
>>>> From: <mailto:reflector-bounces at tvbf.org>reflector-bounces at tvbf.org 
>>>> [mailto:reflector-bounces at tvbf.org]On
>>>> Behalf Of Richard Riley
>>>> Sent: Sunday, October 24, 2004 11:44 AM
>>>> To: Velocity Aircraft Owners and Builders list
>>>> Subject: RE: REFLECTOR: Grounding Point
>>>>
>>>>
>>>> We went around and round on this topic on one of the canard mailing 
>>>> lists
>>>>
>>>
>>> a
>>>
>>>>
>>>> few months ago.  Following all the suggestions, I talked with a fuel
>>>>
>>>
>>> system
>>>
>>>>
>>>> designer at the Very Large Aerospace Company where I work and came 
>>>> up with
>>>> the following for my plane...
>>>>
>>>> The fuel cap ring is attached to a coarse brass screen, shaped in a 
>>>> tube,
>>>> that goes from the fuel cap ring to bottom of the tank.  It is 
>>>> attached by
>>>> a brass ball chain to the fuel drain, and to a brass bolt in the 
>>>> outboard
>>>> fuel bulkhead.  That bolt is then attached by a wire to the engine, 
>>>> and
>>>> therefor to the exhaust pipes.
>>>>
>>>> Most of the static charge in refueling is created by the fuel 
>>>> falling from
>>>> the nozzle to the surface of fuel in the tank.  The brass screens 
>>>> strips
>>>> that away.  No matter what the level of the fuel, it's pierced by the
>>>>
>>>
>>> chain
>>>
>>>>
>>>> going to the fuel drain.  And then the whole thing is electrically 
>>>> bonded
>>>> to the engine block.  If the fuel truck attaches the ground strap 
>>>> to the
>>>> exhaust pipe, all the potential is equalized.
>>>>
>>>>
>>>> At 09:21 AM 10/24/04, Al Gietzen wrote:
>>>>
>>>>>
>>>>> I guess there are different views on this, but I see little 
>>>>> relation (as
>>>>> in maybe "none") between grounding the exhaust pipe, and refueling
>>>>> safety.  The static charge buildup is between the nozzle and the fuel
>>>>> (surface); or the nozzle and the potential existing static charge 
>>>>> on the
>>>>> surface of the strake due air friction.  So have a metal chain or 
>>>>> cable
>>>>>
>>>>
>>>> >from the cap ring hanging into the fuel, and keep the nozzle 
>>>> against the
>>>>
>>>>>
>>>>> ring; and, if you have just landed, wipe the surface of the strake 
>>>>> with a
>>>>> damp cloth before contacting the nozzle to the ring.
>>>>>
>>>>> Anyway, that's my take; but I've been wrong once before in my lifeJ.
>>>>>
>>>>> Al
>>>>> Subject: REFLECTOR: Grounding Point
>>>>>
>>>>> I didn't find a direct reference in the archives, so I was still
>>>>>
>>>
>>> wondering
>>>
>>>>>
>>>>> if the exhaust pipes is an adequate grounding point when 
>>>>> refueling?  I
>>>>> always assumed it was but I'd hate this to be a FireBall Falacy.
>>>>>
>>>>> Chuck
>>>>> _
>>>>
>>
>> _______________________________________________
>> To change your email address, visit 
>> http://www.tvbf.org/mailman/listinfo/reflector
>>
>> Visit the gallery!  www.tvbf.org/gallery
>> user:pw = tvbf:jamaicangoose
>> Check new archives: www.tvbf.org/pipermail
>> Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
>
>
>
> "Those who sacrifice freedom to get security, deserve neither."
> - Benjamin Franklin
>

More information about the Reflector mailing list