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Jay, et al,
The problem with low wing only fuel systems is that they are seldom tested
before the first flight for usable fuel at different attitudes. These
tests are easy to perform before the wings are mounted (or even painted if using
a wing spit). Depending on the pickup location, fuel available in level
flight may not be the same as in a dive, climb, at a higher angle of attack
during slow flight or in an uncoordinated turn or slip, slosh chamber
notwithstanding. Fuel availability may be slightly different from side to
side.
Grayhawk
In a message dated 5/15/2011 7:15:41 A.M. Central Daylight Time,
jayph@fastairplane.net writes:
Lancair
lists the Legacy’s (RG) fuel capacity at either 64 or 65 gallons depending on
where you look. My Legacy is marked as 66 gallons. I recently emptied the fuel
tanks to weight the aircraft. I emptied them by discconecting the output line
from the gascolator and running a temp line into fuel cans. Then I used the
boost pump until it sucked air. That should have left only unusable fuel in
the system. After weighing the aircraft I had the fuel truck come out and fill
me up. I took 33 gallons in each tank. Of course, since every Lancair is
custom built and therefore serial number 1, the capacity can very by
aircraft.
Jay
Phillips
L2K-254
N92SX
From: Lancair Mailing
List [mailto:lml@lancaironline.net] On Behalf Of Colyn
Case
Sent: Friday, May 13, 2011 3:14 PM
To:
lml@lancaironline.net
Subject: [LML] Re: N23PH Flight
time
Thanks Paul. Are those cruise numbers
WOT?
Also - I'm confused about standard capacity of Legacy
tanks. Is it 60 or 66 and how much is normally
usable?
On May 13, 2011, at 3:43 PM, Paul Bricker
wrote:
I
had an IO-550 in my Lancair ES, which I ran per APS guideline. During takeoff
at sea level fuel flow was ~ 30gph, and above ~3000' I would start leaning to
match takeoff EGTs during climb. This improved performance but still
maintained detonation margin.This engine sucks fuel at high rpms and rich. I
used 26 gph average (reducing to 2500 rpms at 500 AGL), even when leaning
during climb.
I
would go LOP when in cruise. At 8000'DA and ~ 70 deg LOP I'd see around 13.5
gph, going to ~11.5 gph at 11000'.
I
generated a duration spread sheet to verify fuel for long trips. Tested
against actual flights I had about 3 gal more at the end of a long trip then
it would estimate. I'm pretty comfortable with the assumptions that when into
my calculations.
I
ran my range calculations for a 60 gal usable AC, leaning during the climb to
8000' LOP after that. I assumed a leisurely cruise climb to 8000' averaging
700 fpm. This gives a time to exhaustion of 4 hrs, 16
mins.
There
are several factors which will radically shorten this. First, was his 60 gal
usable? I found I had 4 gals unusable in my ES, but I ran each tank dry (one
at a time over an airport at altitude) to determine that. Had he verified
usable fuel? This alone shortens TTE to 3 hr 58
mins
Also,
if he ran ROP the fuel flow would probably be about 18 gph. TTE is now 3 hs 15
mins w/ 60 usable. At 56 usable his TTE is 3 hrs, 2
mins.
The
bottom line is his time to exhaustion is greatly influenced by how he ran his
engine, and he could have easily run it dry.
I
don't have definitive information.
As
far as I know, never took HPAT or equivalent.
As
far as I know, total time in last 6 months was the 5 hours engine breakin
time.
There
were conflicting reports about whether the "pressure" problem was oil pressure
or fuel pressure.
I
believe he was intending to operate LOP on this
trip.
Anyone
have LOP numbers for an IO-550 at 8000?
Again
the log records 3:17 of flight but does not include the climb (7
minutes?)
nor
the descent ( 12 minutes? but was that power on or power off? one thing very
peculiar about the track log is that there is no
descent.)
If
you add 3 gallons for climb and take off, the total burns come out like
this:
If
he were really at 17 and knew it I think he would have done something about
it.
I
suspect there were other contributing factors. ...like faulty fuel flow
reporting, faulty fuel level gauging, max usable fuel less than thought,
or maybe it really was oil pressure.
I
looked at the google earth view for the general area. I'm not sure which
field he landed in but they all looked smallish and maybe intimidating at
speed.
It's
hard to know what happened in the final moments but the wreckage doesn't look
consistent with forward progress once on the
ground.
Do we
know this was fuel exhaustion? I know I ran my IO-550 150+ degrees ROP
throughout the break-in process. I also flew low to keep 75% power.
That's at or above 15 GPH.
I
thought I read something about oil pressure. I guess we'll find out more in
time. Only 5 hours on a newly rebuilt engine seems minimal before a long
cross country. A rebuilt engine doesn't constitute a major modification,
so there's really no need to re-enter Phase 1 flight testing for a minimum of
5 hours, unless there was more work done that just an
R&R.
Losing
an engine shouldn't be fatal. What do we know about the pilot and his
training, time in type, etc.? Maybe Colyn can give us a bit more about
the pilot's experience.
Just
sorting through the scenario like I do with every Lancair
accident.
In a
message dated 5/11/2011 1:17:19 P.M. Mountain Daylight Time, edmartintx@aol.com
writes:
At high altitude, a stock Legacy with IO-550 should burn approximately 10.5
gallons/hour using "lean-of-peak" technique. In this
example, actual flight time was over four hours with 21 gallons remaining
(66-gallon capacity). Please see: http://flightaware.com/live/flight/N767EM
-----Original
Message-----
From: Karen Farnsworth <farnsworth@charter.net>
To: lml
<lml@lancaironline.net>
Sent: Tue,
May 10, 2011 11:22 am
Subject: [LML] Re: N23PH
Crash
Flight Aware shows 3 hours
50 min, not 3 hours 15 min. That is a long way on 60
gallons..
If,
as has been reported, the engine was new, I would think that it was still
being broken in. This would lead me to thing that fuel flow would be on the
high side; thus reducing range.
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