X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sat, 03 Mar 2012 19:01:48 -0500 Message-ID: X-Original-Return-Path: Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122] verified) by logan.com (CommuniGate Pro SMTP 5.4.4) with ESMTP id 5426719 for lml@lancaironline.net; Sat, 03 Mar 2012 11:45:28 -0500 Received-SPF: none receiver=logan.com; client-ip=71.74.56.122; envelope-from=Wolfgang@MiCom.net X-Original-Return-Path: X-Authority-Analysis: v=2.0 cv=M9vP2lMs c=1 sm=0 a=MHZY6FYWMEQOp7S43i2QIw==:17 a=3Zlka_XeuxsA:10 a=DTcCN-Bu46AA:10 a=ttCsPuSJ-FAA:10 a=Ia-xEzejAAAA:8 a=5FIZSGrRAAAA:8 a=o9ci1NyaTmp0AJJPmMgA:9 a=s-WPAWjsnniSdRQ9zswA:7 a=QEXdDO2ut3YA:10 a=wR8WdYEwGqoA:10 a=EzXvWhQp4_cA:10 a=CjxXgO3LAAAA:8 a=CTJ4oHezixNPQn73SxwA:9 a=mlhsPCyBdfNWg8WSu_EA:7 a=rC2wZJ5BpNYA:10 a=MHZY6FYWMEQOp7S43i2QIw==:117 X-Cloudmark-Score: 0 X-Originating-IP: 74.218.201.50 Received: from [74.218.201.50] ([74.218.201.50:1091] helo=lobo) by hrndva-oedge03.mail.rr.com (envelope-from ) (ecelerity 2.2.3.46 r()) with ESMTP id 35/58-05889-38A425F4; Sat, 03 Mar 2012 16:44:52 +0000 X-Original-Message-ID: <004401ccf95c$f19d0a10$6701a8c0@lobo> From: "Wolfgang" X-Original-To: References: Subject: Re: [LML] Re: 320/360 Hydraulic Pressure Switch X-Original-Date: Sat, 3 Mar 2012 11:44:46 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0041_01CCF933.08973F80" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 This is a multi-part message in MIME format. ------=_NextPart_000_0041_01CCF933.08973F80 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Chris, Life is complicated enough so when I fly, I like to enjoy it. Being a = slave to the system like a cog in a flying machine is not my idea of = "enjoyment". Don't get me wrong, I like getting into technicals up to my = eyebrows, but I prefer to do that at my choosing, not while tending to a = malfunction in flight. That's why I cane up with the gear module.=20 After you detailed the presence of springs in the pump to help center = the spool and popets, I see that my original supposition that the spool = is coming off it's end position is confirmed. It looks like the springs = are in fact, capable of overcoming the friction of the O-rings. You keep = measuring the forces in G's but that does not give us an actual force = measurement that is what the springs are operating against.=20 It remains that some pump installations have the problem of the spool = not maintaining the required position for safe flight operations. You = have come up with many details that go toward esplaining the problem and = a possible fix (take out the springs). I have come up with a module that = WILL fix that problem. Wolfgang ----- Original Message -----=20 From: Chris Zavatson=20 To: lml@lancaironline.net=20 Sent: Friday, March 02, 2012 7:54 AM Subject: [LML] Re: 320/360 Hydraulic Pressure Switch=20 Wolfgang, =20 It is a sad day when removing a pump from the aircraft is too much = effort to investigate an anomaly.=20 =20 Wolfgang wrote:<> =20 As aircraft owners we are responsible for knowing the configuration of = the aircraft systems. If something is out of the ordinary, investigate. = We know a lot about what the configuration should be and how it works = and behaves. We also know of configurations that do not work. You may = very well be holding the key to a new, as of yet, unidentified failure = mode, but we may never know. =20 Wolfgang wrote: <> =20 If my tire has a flat and I see a nail sticking through the side wall, = I am rather confident in assuming the nail was the source of my leak. = Likewise, if I open up a lock-up prone pump and find return springs, I = will have a high degree of confidence I have found the source of the = problem. Could there be a second cause? Possibly, but as of yet, none = have been documented. =20 Wolfgang wrote:<<=E2=80=A6original suspicion of the spool coming off = it's end point (with the help of springs and airframe vibration) is in = fact what's causing the problem.>> =20 Springs definitely - that is what they were designed to do. Oildyne = started adding springs to center the spool to the Legacy pump in ~2003. = Our system will eventually fail if these springs are installed. = Fortunately the vast majority of our pumps do not have them. If you = have springs installed, simply remove them. =20 Vibration - the evidence says otherwise. Measurements of various = spool and pump combinations required from 13 g's (9 year old 'soft' = o-ring) to 70 g's (new 'stiff' o-ring) to move the spool. Aircraft = vibration at the pump was measured to be +/- 0.1 g (flying) to +/-1.3 g = (engine start). Vibration is not nearly sufficient to have any effect on = the spool.=20 =20 Wolfgang wrote:<> The springs are very strong, 26 lb/in. =20 Wolfgang wrote:<> See MIL-STD-810 for expected vibration levels in aircraft = environments. =20 Wolfgang wrote:<> I would still like to know how push buttons can overload anything. = And why would anyone want to override more than one at a time? =20 Wolfgang wrote:< I have never had a thermal lock up, yet I use pressure gauges and the = momentary push buttons on a regular basis. They were originally = installed to deal with sticking VEP switches, but it is like getting a = new tool. After you have it, you can't imagine how you lived without = out it. I have already discussed the benefits of momentary switches not = related to hydraulic lock-up. =20 Wolfgang wrote:<> One should label the push buttons appropriately. =20 Wolfgang wrote:<> Recall that the Legacy pump configuration =E2=80=9CCZZ=E2=80=9D is = proprietary to Lancair. Companies generally don=E2=80=99t post = proprietary materials on-line. =20 <> Not really. I avoid them by thorough examination, no matter what it = requires. Chris Zavatson N91CZ 360std www.N91CZ.net ------=_NextPart_000_0041_01CCF933.08973F80 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable =EF=BB=BF
Chris,
 
Life is complicated enough so when I = fly, I like to=20 enjoy it. Being a slave to the system like a cog in a flying machine is = not my=20 idea of "enjoyment". Don't get me wrong, I like getting into technicals = up to my=20 eyebrows, but I prefer to do that at my choosing, not while tending to a = malfunction in flight. That's why I cane up with the gear module. =
 
After you detailed the presence of = springs in the=20 pump to help center the spool and popets, I see that my original = supposition=20 that the spool is coming off it's end position is confirmed. It looks = like the=20 springs are in fact, capable of overcoming the friction of the O-rings. = You keep=20 measuring the forces in G's but that does not give us an actual force=20 measurement that is what the springs are operating against. =
 
It remains that some pump installations = have the=20 problem of the spool not maintaining the required position for safe = flight=20 operations. You have come up with many details that go toward esplaining = the=20 problem and a possible fix (take out the springs). I have come up with a = module=20 that WILL fix that problem.
 
Wolfgang
 
----- Original Message -----
From:=20 Chris=20 Zavatson
Sent: Friday, March 02, 2012 = 7:54=20 AM
Subject: [LML] Re: 320/360 = Hydraulic=20 Pressure Switch

Wolfgang,
 
It=20 is a sad day when removing a pump from the aircraft is too much effort = to=20 investigate an anomaly.=20
 
Wolfgang=20 wrote:<<We would all like to get at the root cause of the = problem but,=20 as yet, that hasn't happened. Likely because it's too much work to = track down=20 the actual cause and fix it. =E2=80=A6>>
 
As=20 aircraft owners we are responsible for knowing the configuration of = the=20 aircraft systems.  If something is out of the ordinary,=20 investigate.  We know a lot about what the configuration should = be and=20 how it works and behaves.  = We also=20 know of configurations that do not work. =20 You may very well be holding the key to a new, as of = yet,=20 unidentified failure mode, but we may never = know.
 
Wolfgang=20 wrote: = <<So far we=20 only have a good plausible theory missing only demonstratable=20 proof.>>
 
If my = tire has a=20 flat and I see a nail sticking through the side wall, I am rather = confident in=20 assuming the nail was the source of my leak.  Likewise, if I open up a = lock-up prone=20 pump and find return springs, I will have a high degree of confidence = I have=20 found the source of the problem. =20 Could there be a second cause? =20 Possibly, but as of yet, none = have been=20 documented.
 
Wolfgang=20 wrote:<<=E2=80=A6original suspicion of the spool coming off it's = end point (with=20 the help of springs and airframe vibration) is in fact what's causing = the=20 problem.>>
 
Springs=20 definitely - that is what they were designed to do.  Oildyne started adding = springs to=20 center the spool to the Legacy pump in ~2003.  Our system will eventually = fail if=20 these springs are installed. Fortunately the vast majority of our=20 pumps do not have them.  If you have springs installed, = simply=20 remove them.
 
Vibration=20 - the evidence says otherwise.  Measurements of various spool and = pump=20 combinations required from 13 g's (9 year old 'soft' o-ring) = to 70=20 g's (new 'stiff' o-ring) to move the spool.  Aircraft = vibration at=20 the pump was measured to be +/- 0.1 g (flying) to +/-1.3 g (engine = start).=20 Vibration is not nearly sufficient to have any effect on the = spool. 
 
Wolfgang=20 wrote:<<If it takes that much force to move the spindle against = the=20 O-rings then those springs must be pretty darn strong. I find that = dificult to=20 accept.>>
The=20 springs are very strong, 26 lb/in.
 
Wolfgang=20 wrote:<<Vibration=20 levels can exceed 70 G's>>
See=20 MIL-STD-810 for expected vibration levels in aircraft=20 environments.
  
Wolfgang=20 wrote:<<Yes, that would be easy . . . except . . . you can only = override=20 one pressure switch at a time or overload the=20 system>>
I=20 would still like to know how push buttons can overload=20 anything.  And why would anyone want to override more than = one at a=20 time?
 
Wolfgang=20 wrote:<<The items you cited are more a one-of condition=20 ...>
I=20 have never had a thermal lock up, yet I use pressure gauges and the = momentary=20 push buttons on a regular basis.  They were originally installed = to deal=20 with sticking VEP switches, but it is like getting a new tool.  = After you=20 have it, you can't imagine how you lived without out it.  I have = already=20 discussed the benefits of momentary switches not related to hydraulic=20 lock-up.   Wolfgang=20 wrote:<<In the event of a problem you have to make sure you push = the=20 right switch.>>
One=20 should label the push buttons = appropriately.
 
Wolfgang=20 wrote:<<Are you saying that Oildyne is putting springs in the = spool to=20 center it when the pump is not running ?
Springs=20 that are not documented in the Oildyne spec sheet=20 ?>>
Recall=20 that the Legacy pump configuration =E2=80=9CCZZ=E2=80=9D is = proprietary to Lancair.  Companies generally = don=E2=80=99t post=20 proprietary materials on-line.
 
<<You=20 seem to want to be "involved" in the anomalies of=20 flight.>>
Not=20 really.  I avoid them by = thorough=20 examination, no matter what it requires.   Chris=20 Zavatson N91CZ 360std www.N91CZ.net    
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