From: "Marvin Kaye" <marv@lancaironline.net>
Subject: Re: Fuel Transfer/ Maximum Fuel Imbalance Tolerances
To: lml
Date: Fri, 21 Apr 2006 00:03:10 -0400
Message-ID: <web-1075218@logan.com>
In-Reply-To: <175557b90604200144p14930485v61ea18aa7ebc5a28@mail.gmail.com>
References: <175557b90604200144p14930485v61ea18aa7ebc5a28@mail.gmail.com>
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Posted for "Clark Baker" <bakercdb@gmail.com>:

>>>>Robert M. Simon writes: Pillar Point just announced that Facet changed
  the design on their pumps,  the controller no longer functions, and they see
  no fix for the  incompatibility.  It works with the transfer pump in my
  GalStar but if that  pump goes then so does the automatic feature of the
  PP.<<<
  
  I just spoke to Dennis at Pillar Point and he stated: "I don't think the
  40105, 40106 or 40108 line of pumps have changed, so those should continue
  to work."
  
  
  The GlaStar uses the 40171 pump, which has both a check valve and an anti
  siphon valve.  The pump in my Lancair 360 is a 40106 (supplied by Kit
  Components) and has no check or anti siphon valves.  Kit Components
  (Lancair) also sells the 40108 pump, which appears to differ only in using
  AN-6 versus 1/8" NPT fittings.
  
  
  1.  Is anyone *successfully* using a *recently manufactured * 40106 or 40108
  pump with the Pillar Point Fuel transfer system?  Below is how to identify
  the *new* series of  *40171* pump (full article from the GlaStar flyer
  attached).
  
  
  It turns out that in February 2004 and until November/December 2004, Facet
  made a change to the 40171 line of pumps.  This change replaced the
  oscillator circuit in the pump with a timer circuit.  This change completely
  neutralizes the auto-shutoff function of the XFR because, with the timer,
  there is virtually *no* change in pump frequency between fuel and air.
  Further,
  the current frequency falls outside the "fuel" range so the XFR shuts the
  pump off.  The pumps that have this change have a date code stamped on the
  mounting tab of B04 through L04 (and maybe some M04).  Another indicator of
  the timer-style pump is the *absence* of a rivet on the underside of the
  pump body.
  
  2.  Has anyone tested or knowledgable with how much fuel imbalance a LNC2
  can be flow with in an emergency so one can calculate "worse case" fuel
  system failure scenarios for those of us without crossfeed systems?  Some
  time ago, I tested (down to approach speeds) flying with a full left tank
  full (21g) and the right tank pumped down to about 1/2 full with an empty
  passenger seat.
  
  Regards,
  Clark Baker
  LNC2 360, 660hrs

An Alert to GlaStar & Sportsman Builders

Dennis Douglas
Pillar Point Avionics

I need to inform the GlaStar & Sportsman builder community about a recently 
identified problem that may affect those who have purchased the Pillar Point 
Avionics XFR-J Fuel Pump Controller who are flying with the XFR, and those who 
are still building their airplanes.

Of particular concern here is the Facet 40171 found in the GlaStar, Sportsman, 
and a fair number of other aircraft.  The 40171 is necessary for the GlaStar 
and Sportsman because it has two-way checking that inhibits the flow of fuel 
unless the pump is running.  Aircraft with both the auxiliary and main tanks 
in the wing need this pump to prevent aux fuel from flowing into the main tank 
and potentially overflowing the main tank.  Here’s the story:

Background.  Since 1998, Pillar Point Avionics has been manufacturing and 
selling the PPAv XFR line of fuel pump controllers.  The XFRs operate a number 
of the Facet solid-state pumps such as the 40171, 40105, 40106, 40108, and 
others.  These pumps operate by means of a magnetically operated piston.  When 
energized, the pump’s piston is pulled forward which “pushes” fuel; when the 
piston reaches the end of its stroke, a switch contact is opened, the pump is 
de-energized, and a spring returns the piston to its resting position which 
closes the contact re-energizing the pump and the process is repeated.  The 
current waveform looks like a real ugly square wave and the frequency, or 
period, of the waveform depends on whether fuel or air is being pumped.

While the XFR line has gone through several improvements over the years, the 
basic operation of the XFR has remained the same: the controller measures the 
period of the current pulses and, through a threshold value stored in the 
microprocessor memory, determines if the measured period corresponds to fuel 
or air.  If a period falling on the “air” side of the threshold is detected, 
the XFR shuts off the pump.  While there was considerable temperature 
variation of both the “fuel’ and “air” pumping periods, it was possible to 
pick threshold values clearly and repeatably separating “air” and “fuel” 
ranges.

The Problem Arises.  Recently, we learned from two customers that the XFR was 
shutting off prematurely.  After going through an extensive series of checks 
and replacements with the first customer, I contacted the engineer at 
Purolator/Facet responsible for the 40171 line of pumps.  It turns out that in 
February 2004 and until November/December 2004, Facet made a change to the 
40171 line of pumps.  This change replaced the oscillator circuit in the pump 
with a timer circuit.  This change completely neutralizes the auto-shutoff 
function of the XFR because, with the timer, there is virtually no change in 
pump frequency between fuel and air.  Further, the current frequency falls 
outside the “fuel” range so the XFR shuts the pump off.  The pumps that have 
this change have a date code stamped on the mounting tab of B04 through L04 
(and maybe some M04).  Another indicator of the timer-style pump is the 
absence of a rivet on the underside of the pump body.

In December 2004 (date code M04), Facet reverted to its oscillator 
configuration but changed the oscillator and (apparently) some of the internal 
mechanisms.  Our tests have shown that these newer pumps have large and 
unstable frequency variability.  So large, in fact, that the XFR’s 
auto-shutoff operating principle cannot be applied to these pumps because the 
fuel and air frequency families have significant overlap.  (The controller 
does, however, retain its pumping capability in the Timed mode.)

Note that we are not implying the changes made by Facet have anything to do 
with the quality of the Facet product; only that the changes affect the way 
our controller operates the pump.  Since Pillar Point Avionics cannot 
influence Facet’s designs, and since the recent changes to the 40171 preclude 
proper auto-shutoff operation of the XFR-J, the Facet changes spell the end of 
the XFR-J product line.  Kaput.  “The End” of a business line.

The Scope of the Problem.  Builders caught with this problem include those who 
recently purchased their kits and were supplied the newer pumps, and those who 
might have an older kit but who are doing the aux tank upgrade and have 
recently purchased the pumps.  If you are in this group, check the date code 
on your pumps.  Look for the model number stamped on one mounting tab and the 
date code on the other tab.  If your pumps have a date code of B04 or later 
(C04, D04…A05, B05…etc.), you are in the affected group.

Also included are the folks flying with the XFR-J…hundreds of us are in this 
group.  One day, one of our 40171s will wear out and the XFR-J won’t operate 
the replacement pump(s).  If you are in this latter group, don’t become 
alarmed.  First of all, the XFR-J will still operate in the Timed mode (a 
5-minute transfer of about 2 to 2.5 gallons of fuel.).  Second, the pumps 
typically have a long life so there is no reason to think that the problem 
will bite you tomorrow or next week, next year or even next decade, so long as 
you avoid losing lubrication by pumping air.

The Solution.  While PPAv has decided to terminate the XFR-J line (and 
eventually the XFR-K line, also), a solution is available.  Two solutions, 
actually, and maybe three, so don’t “get your knickers in a twist”.

The primary solution will replace the XFR-J with the soon-to-be-released 
XFR-SA and installing a soon-to-be-released UFS-T sensor at the input (or 
outlet) to each pump.  The XFR-SA will have exactly the same footprint as the 
XFR-J and –K so panel installation will be simple and direct.  The UFS-T 
sensor will require that 3 wires be brought from each sensor to the XFR-SA and 
connected there.  The XFR-SA will provide the electrical power to the UFS-T so 
no extra power wiring is needed.  The XFR-SA will operate just as the XFR-J, 
with an automatic shutoff mode and a timed mode, and will retain the automatic 
pump fault detection capabilities (no current pulses detected/uncommanded pump 
operation).  The advantage of this configuration is that—even while GlaStar 
and Sportsman builders will still need the 40171 pump—the pump characteristics 
no longer enter into the equation and virtually any pump can be controlled 
with the XFR-SA and UFS-Ts.

The UFS-T is an in-line low fuel sensor similar to our present UFS.  The UFS-T 
will mount at the inlet or outlet of the fuel pump using a (PPAv-supplied) 
stainless steel nipple.

The XFR-SA/UFS-T solution will be particularly attractive to builders who have 
already cut holes in their panel for the XFR, for those wanting to transfer 
fuel in discrete quantities (for lateral load balancing, for example), and for 
those who want the XFR to automatically shut off the fuel pumps upon reaching 
an end-of-fuel condition and thus reduce the dry-running wear and tear on 
their fuel pumps which can accelerate the failure of those pumps.

A second solution is the use of the UFS-T together with the IND 
switch/indicator.  The UFS-T/IND combination will utilize builder-supplied 
toggle switches to start and stop the pumps.  The pilot manually starts the 
transfer pumps.  When the end-of-fuel condition is sensed, the UFS-T signals 
that condition to the pilot via the IND.  The pilot turns off the pumps and 
then acknowledges and clears the “aux tank empty” alarm by pressing the IND 
switch.  We are also considering offering a related alternative wherein the 
IND switch/indicator will be replaced by an identically appearing version with 
a push-on push-off switch, which eliminates the need for additional toggle 
switches.

Either of these two options facilitates the aux fuel transfer independent of 
the pump used for the transfers.

The Cost.  PPAv expects that the XFR-SA-KIT (XFR-SA plus 2 UFS-Ts and 
hardware) will cost $380, while the UFS-T-KIT (2 UFS-Ts, 2 INDs and hardware) 
will cost $270.  We will have a better idea of the actual costs after we’ve 
manufactured the initial quantity and the prices may change.  The XFR-SA-KIT 
and the UFS-T-KIT should be available around the middle of May.  Check our 
website,  HYPERLINK "http://www.ppavioncs.com" www.ppavioncs.com for 
availability.

Replacement Policy.  Builders who are caught in the middle of this problem 
will want to know what PPAv is going to do to help them.  We’ve decided that 
we’ll exchange the XFR-J with the XFR-SA at no cost to the builder, and we’ll 
offer the UFS-T to builders at our cost (estimated now—early March 2006—to be 
around $50 each) plus shipping.  We’ll extend this offer for a period of 
1-year, ending on March 31st, 2007.

Builders in the United States wanting to take advantage of this offer should 
ship us their XFR-J together with a check for $105 (the cost of two UFS-Ts 
plus a nominal $5 shipping charge).  We’ll modify the builder’s controller to 
an –SA type and return it to them along with 2 UFS-Ts, 2 SS nipples, and 
installation hardware and instructions.  Non-US builders should send their 
controllers to us with a check in US Funds for $100 plus the shipping cost to 
their destination.

A Third Option.  PPAv is evaluating the benefit of a fully-integrated fuel 
level and fuel management system.  In this system, up to four capacitance 
probes would be installed, with one probe in each main tank and one probe in 
each aux tank.  The probe wires and the fuel pump power wiring would be 
connected to a fuel gauge controller and display system.  For the GlaStar and 
Sportsman, where the tank configuration and geometry is well-known, the 
controller may be pre-calibrated, with pre-set trip levels.  (The pilot would 
be allowed to change the calibration and trip level pre-sets, if desired.)

In operation, the pilot will have a high-quality display of the fuel quantity 
in each of the four tanks.  When a main tank quantity reaches the low-level 
trip point, the controller will activate the (left or right) transfer pump and 
increase the main tank quantity to the high-level trip point, at which time it 
will turn the transfer pump off.  If the aux tank is empty or if it is emptied 
during a transfer operation, the controller will turn the transfer pump off 
and indicate that condition to the pilot.  Manual operation of the fuel 
transfer pumps would also be available and the controller would have 4, 0 to 
5V outputs for input to an EFIS or engine monitor.  More information about 
this option will be made available if we decide there’s sufficient interest.

I hope Flyer readers understand that Pillar Point Avionics was blind-sided by 
the Facet pump changes and that we are doing all we can to “make it right” 
with our customers.  If you have questions or comments about the above, please 
call me at 541-350-2683 or to email me at sales@ppavionics.com.