X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Fri, 19 Jun 2009 12:21:57 -0400 Message-ID: X-Original-Return-Path: Received: from web81202.mail.mud.yahoo.com ([68.142.199.106] verified) by logan.com (CommuniGate Pro SMTP 5.2.14) with SMTP id 3688216 for lml@lancaironline.net; Fri, 19 Jun 2009 10:11:15 -0400 Received-SPF: none receiver=logan.com; client-ip=68.142.199.106; envelope-from=cwfmd@yahoo.com Received: (qmail 27662 invoked by uid 60001); 19 Jun 2009 14:10:35 -0000 DomainKey-Signature:a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=Message-ID:X-YMail-OSG:Received:X-Mailer:Date:From:Subject:To:MIME-Version:Content-Type; b=X0XAZGVtoQ8NZR+aTfN8eFu49JR9BhNEKvZM16rrYOvS+p3z528d69o/M9J91IcFaoKecVfRgj3ZqH5ba53u8CXDXz1R2pJ0xoqoovfoi0dMpvGGqzLPOzeJINgdensqM0ronwlwlcLe8Hzib/xKog3gdgAgMnU/05bu6M53afE=; X-Original-Message-ID: <484460.12605.qm@web81202.mail.mud.yahoo.com> X-YMail-OSG: Vc3lMb4VM1km_UaxvkiQle0Mbw2dkrDReLZw3x_8qnoUqLi1JTCbaf4xMY5d_3Xo2xH33ir5TvoMXXtJZ.e_zgx0dfI_334ohyK7WvqIAioQ.vzB_OFMJWZuyHGUg596zCqt2SSfOqnRvybi9b86LNMALbSL3sW9pCnlFLpNnV3DZxusqarw3YvYAwfgmdySDIcuwlp53Pi4f.Ys8T1y3QT2TJ7NsCYMghJUy9JAgCMn5xnSIrp.CeINiZjoc0bbjFCNGNJnsCklGLJm2lgsm7Qg49kDbUxjV8G4Bm8QzqzcX2X3Qes.6Ks- Received: from [98.201.146.11] by web81202.mail.mud.yahoo.com via HTTP; Fri, 19 Jun 2009 07:10:35 PDT X-Mailer: YahooMailClassic/5.4.17 YahooMailWebService/0.7.289.10 X-Original-Date: Fri, 19 Jun 2009 07:10:35 -0700 (PDT) From: William Miller Subject: Boost Pump Question and FL220 flameout X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-1256657483-1245420635=:12605" --0-1256657483-1245420635=:12605 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable =0A=0AMy=0Awondrously performing 300KTAS(FL250, ISA+0, 75%) Lancair IV-P ha= s two separate=0Aswitches labeled high boost and low boost.=C2=A0 Before my= recent adventures on hot=0Adays, enroute to high key, I only turned on the= low boost on climb out, passing=0A10k. During the last month's shakedown o= f the fuel system, I discovered that=0Ahigh boost will consistently kill th= e engine, probably by flooding it. Low=0Aboost seems to offer some buffer a= gainst vapor, and I have begun selecting it=0Aat lower altitudes when the w= eather is hot. (Joe discussed this in the archives=0A1/31/07) =0A=C2=A0I also was surprised to find that selecting high boost, after low = boost=0Ais on, has no effect in my existing installation, because of wiring= .=C2=A0=0AContrary to what you might expect, you must turn OFF the low boos= t switch to=0Aactually get high boost pressure. This probably also occurs w= hen with "low=0Aboost" ON similarly blocks the "prime" pushbutton, which I = will=0Atest on my next trip to the airport. I am considering rewiring this = so that=0Aboth high and low on will command HIGH, rather than low, and puls= ing the prime=0Abutton will pulses high at all times! (anybody know a reaso= n to justify the=0Acurrent setup?) =0A=C2=A0 I am still not certain that we found the cause of the fuel flow= =0Ainterruption which has now occurred at FL220, on deck after multiple hot= day run-ups,=0Aand after calibrating the AOA at zero G. Recall what the re= minder is, if you=0Aever forgot to select low boost passing 10k. I confess = that I have missed this=0Achecklist item before, and I think the rough engi= ne sounds are caused by vapor=0Ain the fuel system, but I don't have any da= ta to tell me where. My best guesses=0Aare the hot low pressure lines feedi= ng the engine driven fuel pump(EDFP) or the=0Aeven lower pressure (but cool= er) lines leading from the tank through the selector=0Ato the boost pump by= the copilot's right foot.=0A=0A=C2=A0=0AMy list when the engine goes silen= t these days is mostly the SEVEN=C2=A0 V's: =0A1. Fuel tank Vent blocked creating vacuum in the tank=20 =0A(Why is there no "crossfeed vent" between upper tanks? or=0Avalve betwee= n vapor return lines? Or is there?) =0A2. Negative/zero G's exposing the tank gravity feed outlet to air (okay = mostly=0AN2, but still N2 Vapor).=0A=0A3.=0AVapor in the lines before the s= elector Valve =0A4. Vapor leaking past the fuel selector Valve O-rings from the=0Apressur= ized cabin =0A5. Vapor in the line feeding the EDFP around the accessory case=0Aespeci= ally in a hot climb =0A6. Vapor anywhere else the fuel line runs next to a heat source, though= =0Aless likely in the higher pressure areas. ( Anybody have a triple point = chart=0Afor 100LL? Marv has a nice graph on 2/2/07=0A-- but no pressure axi= s or contour/family of curves... yet )=0A=0A=C2=A0=0A=0A7.=0AALL OF THE ABO= VE: My recent experience indicates anything can start the bubbles=0Aanywher= e back in the system. And as they propagate forward, you can actually=0Aagg= ravate cavitations of pumps by your countermeasures. The more suction=0Aapp= lied to a vapor lock, I theorize, the bigger it gets until you have removed= =0Aall the liquid from the system.=0A=0A=C2=A0I=0Ahave managed to kill a ro= ugh engine with both high and low boost. I have not=0Atried pulsing the pri= me pushbutton, but probably need to turn off the low boost=0Aswitch because= of my odd wiring.=0A=0A=C2=A0=0A=0A=C2=A0Procedures=0Aspeculation: =0A =0A=0A=0A=0A=0ASo=0Afar I have not had the engine quit during a critical fl= ight phase, which I=0Adefine as below the low key altitude, on takeoff(abou= t 30 sec after rotation=0Apassing the abort limits). If it does, I have alr= eady been scanning fuel=0Apressure and flow during the abort-option phase a= nd the initial climb. These=0Adays I am climbing to low key over the highwa= y at Vy after liftoff.=0A=0AMy=0Acurrent thinking is to turn on low boost d= uring takeoff as a preemptive measure=0Aon hot days. If the engine roughens= or FF or FP drop (note- set alarm) or=0Aquits(#1-fly), deselect low and bu= mp the prime(&fly). If this doesn=E2=80=99t work=0Afor 5-10 seconds(feels l= ike 2 minutes here), switch tanks(&fly). Then=0Aselect high boost, then low= , then land on the highway.=20 =0AThis all happens in 20 seconds so I am "chair flying" it for=0Aproficien= cy.=0A=0A=C2=A0=C2=A0=0AYeah=E2=80=A6 mags and mixture, air, fuel and all t= hat, but why did I not already abort=0Athe takeoff for low fuel flow when t= he mixture was set wrong.... and who=0Arotated the mag switch down by my le= ft knee after the runup mag check? There is=0Anot much time here so I have = reordered priorities for survival. Also pay the=0Ainsurance, so the decisio= n is similar to the military ejection decision: OPM!=0A=0A=C2=A0=0A=0ADiscl= aimer:=0Athis is a proposed experimental flight test procedure on an airpla= ne=0Awhich has demonstrated probable vapor lock problems on hot days. We ha= ve not=0Afound a "smoking gun" after a complete (one month) search of the f= uel=0Asystem including EDFP overhaul, recalibration, purge, and test of all= =0Acomponents. The conservative approach is also to avoid very hot takeoffs= until=0Athe problem is resolved (I am getting up at 4-5am=0Athese days). L= ong runways and a very=0Alow abort decision threshold are also good. You ma= y not have the same odd boost=0Apump wiring or you may have a kid or dog wh= o stealthily twists mag switches and=0Amixture undetected, so your performa= nce and procedures may vary.=0A=0AThanks=0A=0ABill=0AMiller=0A=0A=C2=A0=0A= =0A=C2=A0=0A=0APS:=0ASomehow in 16 months and 200 hrs, through all my due d= iligence, prepurchase=0Ainspection, initial training, condition inspections= , insurance inspections,=0Arecurrent training, and a month's safety standdo= wn accompanied by excellent=0Aconsultation with superb experts, I only lear= ned about Lancair SBs 020 and=0A033 yesterday. It was probably because ever= ybody assumed they had already=0Abeen covered, but there is no record of it= .=C2=A0 If you are new to this stuff,=0Aread those SBs.=0A=0A --0-1256657483-1245420635=:12605 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable
=0A=0A

My=0A= wondrously performing 300KTAS(FL250, ISA+0, 75%) Lancair IV-P has two separ= ate=0Aswitches labeled high boost and low boost.  Before my recent adv= entures on hot=0Adays, enroute to high key, I only turned on the low boost = on climb out, passing=0A10k. During the last month's shakedown of the fuel = system, I discovered that=0Ahigh boost will consistently kill the engine, p= robably by flooding it. Low=0Aboost seems to offer some buffer against vapo= r, and I have begun selecting it=0Aat lower altitudes when the weather is h= ot. (Joe discussed this in the archives=0A1/31/07)
=0A I also was surprised to find = that selecting high boost, after low boost=0Ais on, has no effect in my exi= sting installation, because of wiring. =0AContrary to what you might e= xpect, you must turn OFF the low boost switch to=0Aactually get high boost = pressure. This probably also occurs when with "low=0Aboost" ON similarly bl= ocks the "prime" pushbutton, which I will=0Atest on my next trip to the air= port. I am considering rewiring this so that=0Aboth high and low on will co= mmand HIGH, rather than low, and pulsing the prime=0Abutton will pulses hig= h at all times! (anybody know a reason to justify the=0Acurrent setup?)
= =0A  I am still not certain that we found the cause of the fuel flow= =0Ainterruption which has now occurred at FL220, on deck after multiple hot= day run-ups,=0Aand after calibrating the AOA at zero G. Recall what the re= minder is, if you=0Aever forgot to select low boost passing 10k. I confess = that I have missed this=0Achecklist item before, and I think the rough engi= ne sounds are caused by vapor=0Ain the fuel system, but I don't have any da= ta to tell me where. My best guesses=0Aare the hot low pressure lines feedi= ng the engine driven fuel pump(EDFP) or the=0Aeven lower pressure (but cool= er) lines leading from the tank through the selector=0Ato the boost pump by= the copilot's right foot.

=0A=0A

 =0AMy list when the engine goes silent these days is mostly the= SEVEN  V's:
=0A1. Fuel tank Vent blocked creating vacuum in the tank
=0A(Why is there no "crossfeed vent" bet= ween upper tanks? or=0Avalve between vapor return lines? Or is there= ?)
=0A2. Negative/zero G's exposing the tank gravity feed outlet to air = (okay mostly=0AN2, but still N2 Vapor).

=0A=0A

3.=0AVapor in the lines before the selecto= r Valve
=0A4. Vapor leaking past the fuel selector Valve O-rings from the=0Apressurized cabin
=0A5. Vapor in the lin= e feeding the EDFP around the accessory case=0Aespecially in a hot climb=0A6. Vapor anywhere else the fuel line runs next to a heat source,= though=0Aless likely in the higher pressure areas. ( Anybody have a triple= point chart=0Afor 100LL? Marv has a nice graph on 2/2/07=0A-- but no pressure axis or contou= r/family of curves... yet )

=0A=0A

 

=0A=0A

7.=0AALL OF THE ABOVE: My recent experience indicates anything can st= art the bubbles=0Aanywhere back in the system. And as they propagate forwar= d, you can actually=0Aaggravate cavitations of pumps by your countermeasure= s. The more suction=0Aapplied to a vapor lock, I theorize, the bigger it ge= ts until you have removed=0Aall the liquid from the system.

= =0A=0A

 I=0Ahave managed to kill a ro= ugh engine with both high and low boost. I have not=0Atried pulsing the pri= me pushbutton, but probably need to turn off the low boost=0Aswitch because= of my odd wiring.

=0A=0A

 

=0A=0A

 Proc= edures=0Aspeculation:
=0A=
=0A

=0A=0A=0A=0A

So=0Afar I have not had the engine quit during a = critical flight phase, which I=0Adefine as below the low key altitude, on t= akeoff(about 30 sec after rotation=0Apassing the abort limits). If it does,= I have already been scanning fuel=0Apressure and flow during the abort-opt= ion phase and the initial climb. These=0Adays I am climbing to low key over= the highway at Vy after liftoff.

=0A=0A

My=0Acurrent thinking is to turn on low boost during takeoff a= s a preemptive measure=0Aon hot days. If the engine roughens or FF or FP dr= op (note- set alarm) or=0Aquits(#1-fly), deselect low and bump the prime(&a= mp;fly). If this doesn=E2=80=99t work=0Afor 5-10 seconds(feels like 2 minut= es here), switch tanks(&fly). Then=0Aselect high boost, then low, then = land on the highway.
=0AThis all happens in 20 seconds so I am "chair f= lying" it for=0Aproficiency.

=0A=0A

  =0AYeah=E2=80=A6 mags and mixture, air, fuel and all th= at, but why did I not already abort=0Athe takeoff for low fuel flow when th= e mixture was set wrong.... and who=0Arotated the mag switch down by my lef= t knee after the runup mag check? There is=0Anot much time here so I have r= eordered priorities for survival. Also pay the=0Ainsurance, so the decision= is similar to the military ejection decision: OPM!

=0A=0A

 

=0A=0A

Disclaimer:=0Athis is a proposed experimen= tal flight test procedure on an airplane=0Awhich has demonstrated proba= ble vapor lock problems on hot days. We have not=0Afound a "smoking gun" af= ter a complete (one month) search of the fuel=0Asystem including EDFP overh= aul, recalibration, purge, and test of all=0Acomponents. The conservative a= pproach is also to avoid very hot takeoffs until=0Athe problem is resolved = (I am getting up at 4-5am=0Athese days). Long runways and a very=0Alow abort decision th= reshold are also good. You may not have the same odd boost=0Apump wiring or= you may have a kid or dog who stealthily twists mag switches and=0Amixture= undetected, so your performance and procedures may vary.

=0A= =0A

Thanks

=0A=0A

Bill=0AMiller

=0A=0A

 

=0A=0A

&nbs= p;

=0A=0A

PS:=0ASomehow in 16 mon= ths and 200 hrs, through all my due diligence, prepurchase=0Ainspection, in= itial training, condition inspections, insurance inspections,=0Arecurrent t= raining, and a month's safety standdown accompanied by excellent=0Aconsulta= tion with superb experts, I only learned about Lancair SBs 020 and=0A033= yesterday. It was probably because everybody assumed they had already= =0Abeen covered, but there is no record of it.  If you are new to this= stuff,=0Aread those SBs.

=0A=0A
--0-1256657483-1245420635=:12605--