|
|
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.
|
|