X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 30 Jan 2012 07:51:10 -0500 Message-ID: X-Original-Return-Path: Received: from mail-lpp01m010-f52.google.com ([209.85.215.52] verified) by logan.com (CommuniGate Pro SMTP 5.4.3) with ESMTPS id 5369735 for lml@lancaironline.net; Mon, 30 Jan 2012 06:33:34 -0500 Received-SPF: pass receiver=logan.com; client-ip=209.85.215.52; envelope-from=indigoaviation@gmail.com Received: by lagy4 with SMTP id y4so1188868lag.25 for ; Mon, 30 Jan 2012 03:32:58 -0800 (PST) MIME-Version: 1.0 Received: by 10.152.147.38 with SMTP id th6mr8622395lab.47.1327923178163; Mon, 30 Jan 2012 03:32:58 -0800 (PST) Received: by 10.112.45.33 with HTTP; Mon, 30 Jan 2012 03:32:58 -0800 (PST) In-Reply-To: References: X-Original-Date: Mon, 30 Jan 2012 06:32:58 -0500 X-Original-Message-ID: Subject: Re: [LML] Re: Lycoming exhaust valve questions From: swaid rahn X-Original-To: Lancair Mailing List Content-Type: multipart/alternative; boundary=e89a8f22bdc552cc1d04b7bd35bb --e89a8f22bdc552cc1d04b7bd35bb Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable Hello Gary and LML, I want to apologize for the harsh response I wrote. I feel bad that my response may have had a negative effect on you or anyone else. I did not write it to be mean spirited or rude to you or anyone else. Please accept my apology as I don't want to appear to be that type of person. I am service oriented and I am trying to help others maintain safe aircraft. I do much better talking to people in person than writing letters. I did not realise that the wording sounded that strong on paper. Thank you, Swaid Rahn On Fri, Jan 27, 2012 at 4:22 PM, swaid rahn wrote= : > Gary, > My name is Swaid not Swain. > You have some interesting procedures for the care and feeding of your > engine. What data do you have to back up extending your oil change > intervals? Is it that you just don't want to spend the money? > Also all contaminates in oil are not black. There is also a calendar > interval for oil change regardless of operating hours, it's to prevent > corrosion inside the engine due to condensation. > Also there is more to a compression test than just the number. There is = a > real neat place to get the right information on operating and maintenance > of your engine. It's called the manufacturer. They have a vested interest > in helping you get the best service from their product. Believe it or not > they really know what they are talking about. > Best of luck with your TBO, > Swaid Rahn > > On Fri, Jan 27, 2012 at 1:40 PM, wrote: > >> ** >> Grayhawks says high readings on a Lyc 320,360 may be OK based on the >> tester orifice. Here's a bit of additional info: >> >> >> >> *FAASTeam Maintenance Safety Tip * >> *November 2011* >> >> *Differential Compression Test (AC 43.13-1B)* >> >> The differential pressure tester is designed to check the compression of >> aircraft engines by measuring the leakage through the cylinders caused b= y >> worn or damaged components. >> >> The operation of the compression tester is based on the principle that, >> for any given airflow through a fixed orifice, a constant pressure drop >> across that orifice will result. The restrictor orifice dimensions in th= e >> differential pressure tester should be sized for the particular engine a= s >> follows: >> >> *(Although AC 43.13-1B was revised in 1998, the following information >> was revised in Chg. 1 in September 2001. The identification criteria was >> revised from using =93engines with a certain cubic inch displacement=94 = to >> cylinder bore)* >> >> *(1) *For an engine cylinder having less than a 5.00-inch bore; >> 0.040-inch orifice diameter; >> .250 inch long; and a 60-degree approach angle. >> *(2) *For an engine cylinder with 5.00 inch bore and over: 0.060 inch >> orifice diameter, .250 inch long, and a 60 degree approach angle. >> >> Remember, some of the smaller production engines have 5 inch or larger >> cylinder bores (e.g. Lycoming O-320-A1A has a cylinder bore of 5.125 >> inches). Therefore, an orifice of 0.060 diameter should be used to perfo= rm >> the compression test. >> >> See AC 43.13-1B, >> Chapter 8, paragraph 8-14 for more information. >> ALSO at Sacramento Sky Ranch note that Lyc's are expected to result in >> higher pressure readings - BUT orifice is not mentioned....... >> >> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D >> In a message dated 1/27/2012 10:24:58 A.M. Central Standard Time, >> casey.gary@yahoo.com writes: >> >> Okay, I'll take the dare from Swain and post what might be the more >> "normal" reply :-). I think he is being a little of a perfectionist. I >> don't have his credentials, but from what I have seen, a compression >> leakage of 74 to 76 is the most common. A compression number up to 78 >> suggests that the engine is pumping excess oil past the rings and the oi= l >> is sealing that leak path. So I would worry more about the ones that >> measure 78 than I would about the one that is at 75. Assuming you check >> the compression every 100 hours or so, I would wait until you have more >> than 2 compression tests with ever-dropping values before I would even >> start to worry. That will take another 200 hours of operation. I would= n't >> worry until the compression dropped below 70. And like Dan said, it is >> always a good idea to warm the engine and then do the compression test a= s >> soon as possible afterward. I've gone as far as to warm the engine with >> the cowl off so I could do it faster, but to just idle on the ground is = not >> a good thing just before a compression test. If I were really into the >> diagnostics I would warm the engine (cowl off) at the normal runup rpm a= nd >> then run it at full power for maybe 15 seconds, pulling the mixture whil= e >> at full power to get a "clean" shut-off. Then you'll get as good a test= as >> possible. >> >> And why do you change oil every 25-35 hours? With a modern engine and >> modern oil, I don't see any reason to change oil that often. I would ru= n >> it at least 50 hours and try to change it before 75. If the engine is r= un >> often, even 100 hours isn't out of line. What does the oil look like at >> the oil change? Can you see the dipstick through the oil? If so, it >> probably doesn't need to be changed yet. >> Gary >> >> Previously, from Swain: >> Hi Dan, >> My opinion will differ from most here. It is based on 28 years as a >> professional aircraft mechanic and a cylinder overhaul shop owner for 17 >> years. Lycoming says that NO static leakage is allowed during a compress= ion >> test and I agree. What will happen is that if your ex. valve continues t= o >> leak past it's seat it will errode a gas path in the seat and valve face= . >> This will cause a "hot spot" in that area that can eventually lead to >> valve face breakage which might do major damage to one or more cyl. I sa= y >> more than one because I have personally seen a piece of ex. valve leave >> it's cyl. through it's intake port and enter the next cyl. beside it and >> lodge itself into the face of that piston while bending the other cyl. >> intake valve. (BTW I keep that piece of valve in my desk drawer as a >> reminder of what can happen). The only way a valve can cool itself is >> through the time it sits on it's valve seat to transfer heat from the va= lve >> to the head and also through the valve stem. That's why when guides get >> worn and seats leak you wear out valve stems and guides much quicker, th= ere >> is not as much metal contact for cooling and the psi of force on the wea= r >> surfaces increases (same force less wear surface). >> Remember one compression test is only a snapshot of what is happening i= n >> your engine. You need more than one and other information to develope a >> trend on what your engine is really doing. >> I would go fly your airplane at high power settings for one hour and >> come back and take another compression test. Then you might try some of = the >> tricks mentioned here ( I have never had much luck with short cuts). If = it >> was my airplane I would pull the cyl. and fix the problem and not screw >> around with wobble test, staking the valve, or trying to lap a valve >> without pulling the cyl. A gasket set is less than $20 bucks and you don= 't >> have to replace the rings if there are serviceable and you don't hone th= e >> cyl.. >> I have repaired/overhauled over a 1000 Continental and Lycoming >> cylinders and it does not take very long to R&R a cyl. >> Swaid Rahn >> A&P,I.A.,ATP >> LIVP-T(Walter) >> LIVP-T(Garrett under construction) >> >> >> >> On Tue, Jan 24, 2012 at 11:06 AM, Dan & Kari Olsen >> wrote: >> >> LML Gang,**** >> **** >> Doing the annual on my 320 this week. Compression check shows 77-78 on >> cylinders 1, 2, 4. #3 is 75 and I hear pretty good leakage through the >> exhaust, indicating a leaking exhaust valve. I=92ve had no indication o= f >> sticking valves or morning sickness. I pulled the rocker cover and ther= e >> is no abnormality there. This engine is typically run lean of peak at >> power settings of 55-65% power. Oil changes every 25-35hrs. Engine has >> 623hrs since new.**** >> **** >> My question to those of you who are much more experienced with the >> Lycoming 4-cylinder engines, is what should be my next course of action?= * >> *** >> **=B7 **Do the valve lapping procedure per the Lyc service >> instruction?**** >> **=B7 **Start using TCP and re-check in a few hours?**** >> **=B7 **Go run the engine hard and re-check the compression?**** >> **=B7 **Something else?**** >> **** >> I really want to nip this in the bud and not end up with a burned exhaus= t >> valve, requiring pulling a jug.**** >> **** >> Appreciate your thoughts and responses.**** >> **** >> Cheers!**** >> **** >> Dan Olsen >> >> > > > -- > Swaid L. Rahn > Indigo Aviation, Inc. > 940 Mock Road > Springfield, Ga. 31329 > Cell 912.655.0966 > > > --=20 Swaid L. Rahn Indigo Aviation, Inc. 940 Mock Road Springfield, Ga. 31329 Cell 912.655.0966 --e89a8f22bdc552cc1d04b7bd35bb Content-Type: text/html; charset=windows-1252 Content-Transfer-Encoding: quoted-printable
Hello Gary and LML,
I want to apologize for the harsh re= sponse I wrote. I feel bad that my response may have had a negative effect = on you or anyone else. I did not write it to be mean spirited or rude to yo= u or anyone else. Please accept my apology as I don't want to appear to= be that type of person. I am service oriented and I am trying to help othe= rs maintain safe aircraft. I do much better talking to people in person tha= n writing letters. I did not realise that the wording sounded that strong o= n paper.
Thank you,
Swaid Rahn

On Fri, Jan 27, 2012 at 4:22 PM, swaid rahn <indigoaviation@gmail.com> wrote:
Gary,
My name is=A0=A0=A0=A0=A0=A0=A0 Swaid=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0= =A0 not=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0Swain.=A0=A0=A0=A0= =A0=A0=A0=A0=A0=A0 You have some interesting procedures for the care and fe= eding of your engine. What data do you have to back up extending your oil c= hange intervals? Is it that you just don't want to spend the money?
Also all contaminates in oil=A0are not black. There is also a calendar= interval for oil change regardless of operating hours, it's to prevent= corrosion inside the engine due to condensation.
=A0Also there is more to a compression test than just the number. Ther= e is a real neat place to get the right information on operating and mainte= nance of your engine. It's called the manufacturer. They have a vested = interest in helping you get the best service from=A0their product. Believe = it or not they really know what they are talking about.
=A0Best of luck with your TBO,
Swaid Rahn

On Fri, Jan 27, 2012 at 1:40 PM, <Sky2high@aol.c= om> wrote:
Grayhawks says high readings on a Lyc 320,360 may be OK based on the t= ester orifice.=A0Here's a bit of additional info:
=A0
=A0=20

FAASTeam Ma= intenance Safety Tip
November 2011

Differential Compression Test (AC 43.13-1B)

The different= ial pressure tester is designed to check the compression of aircraft engine= s by measuring the leakage through the cylinders caused by worn or damaged = components.

The operation of the compression tester is based on the principle that, = for any given airflow through a fixed orifice, a constant pressure drop acr= oss that orifice will result. The restrictor orifice dimensions in the diff= erential pressure tester should be sized for the particular engine as follo= ws:

(Although AC 43.13-1B was revised in 1998, the following informa= tion was revised in Chg. 1 in September 2001. The identification criteria w= as revised from using =93engines with a certain cubic inch displacement=94 = to cylinder bore)

(1) For an engine cylinder having less than a 5.00-inch bore; 0.= 040-inch orifice diameter;
.250 inch long; and a 60-degree approach ang= le.
(2) For an engine cylinder with 5.00 inch bore and over: 0.0= 60 inch orifice diameter, .250 inch long, and a 60 degree approach angle. <= br>
Remember, some of the smaller production engines have 5 inch or larger = cylinder bores (e.g. Lycoming O-320-A1A has a cylinder bore of 5.125 inches= ). Therefore, an orifice of 0.060 diameter should be used to perform the co= mpression test.

See AC 43.13-1B, Chapter 8, paragraph 8-14 for more info= rmation.

ALSO at Sacramento Sky Ranch note that Lyc's are expected to resul= t in higher pressure readings - BUT orifice is not mentioned.......
=A0
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
In a message dated 1/27/2012 10:24:58 A.M. Central Standard Time, casey.gary@yahoo.com<= /a> writes:
Okay, I'll take the dare from Swain and post what might be the mor= e "normal" reply :-). =A0I think he is being a little of a perfec= tionist. =A0I don't have his credentials, but from what I have seen, a = compression leakage of 74 to 76 is the most common. =A0A compression number= up to 78 suggests that the engine is pumping excess oil past the rings and= the oil is sealing that leak path. =A0So I would worry more about the ones= that measure 78 than I would about the one that is at 75. =A0Assuming you = check the compression every 100 hours or so, I would wait until you have mo= re than 2 compression tests with ever-dropping values before I would even s= tart to worry. =A0That will take another 200 hours of operation. =A0I would= n't worry until the compression dropped below 70. =A0And like Dan said,= it is always a good idea to warm the engine and then do the compression te= st as soon as possible afterward. =A0I've gone as far as to warm the en= gine with the cowl off so I could do it faster, but to just idle on the gro= und is not a good thing just before a compression test. =A0If I were really= into the diagnostics I would warm the engine (cowl off) at the normal runu= p rpm and then run it at full power for maybe 15 seconds, pulling the mixtu= re while at full power to get a "clean" shut-off. =A0Then you'= ;ll get as good a test as possible.

And why do you change oil every 25-35 hours? =A0With a modern engine a= nd modern oil, I don't see any reason to change oil that often. =A0I wo= uld run it at least 50 hours and try to change it before 75. =A0If the engi= ne is run often, even 100 hours isn't out of line. =A0What does the oil= look like at the oil change? =A0Can you see the dipstick through the oil? = =A0If so, it probably doesn't need to be changed yet.
Gary

Previously, from Swain:=A0
Hi Dan,
=A0My opinion will differ from most here. It is based on 28 years as a= professional aircraft mechanic and a cylinder overhaul shop owner for 17 y= ears. Lycoming says that NO static leakage is allowed during a compression = test and I agree. What will happen is that if your ex. valve continues to l= eak past it's seat it will errode a gas path in the seat and valve face= . This will cause a "hot spot" in that area that can eventually l= ead to=A0 valve face breakage which might do major damage to one or more cy= l. I say more than one because I have personally seen a piece of ex. valve = leave it's cyl. through it's intake port and enter the next cyl. be= side it and lodge itself into the face of that piston while bending the oth= er cyl. intake valve. (BTW I keep that piece of valve in my desk drawer as = a reminder of what can happen). The only way a valve can cool itself is thr= ough the time it sits on it's valve seat to transfer heat from the valv= e to the head and also through the valve stem. That's why when guides g= et worn and seats leak you wear out valve stems and guides much=A0quicker, = there is not as much metal contact for cooling and the psi of force on the = wear surfaces increases (same force less wear surface).
=A0Remember one compression test is only a snapshot of what is happeni= ng in your engine. You need more than one and other information to develope= a trend on what your engine is really=A0doing.
=A0I would go fly your airplane at high power settings for one hour an= d come back and take another compression test. Then=A0you might=A0try some = of the tricks mentioned here ( I have never had much luck with short cuts).= If it was my airplane I would pull the cyl. and fix the problem and not sc= rew around with wobble test, staking the valve, or trying to lap a valve wi= thout pulling the cyl. A gasket set is less than $20 bucks and you don'= t have to replace the rings if there are serviceable and you don't hone= the cyl..
=A0I have repaired/overhauled over a 1000 Continental and Lycoming cyl= inders and it does not take very long to R&R a cyl.
Swaid Rahn
A&P,I.A.,ATP
LIVP-T(Walter)
LIVP-T(Garrett under construction)


=A0
On Tue, Jan 24, 2012 at 11:06 AM, Dan & Kari Olsen=A0<olsen25@comcast.net>=A0wrote:
LML = Gang,
<= /u>=A0
Doin= g the annual on my 320 this week.=A0 Compression check shows 77-78 on cylin= ders 1, 2, 4.=A0 #3 is 75 and I hear pretty good leakage through the exhaus= t, indicating a leaking exhaust valve.=A0 I=92ve had no indication of stick= ing valves or morning sickness.=A0 I pulled the rocker cover and there is n= o abnormality there.=A0 This engine is typically run lean of peak at power = settings of 55-65% power.=A0 Oil changes every 25-35hrs.=A0 Engine has 623h= rs since new.
<= /u>=A0
My q= uestion to those of you who are much more experienced with the Lycoming 4-c= ylinder engines, is what should be my next course of action?<= /div>
<= /u>=B7=A0=A0=A0=A0=A0=A0=A0= =A0=A0Do the valve lapping procedure per the Ly= c service instruction?
<= /u>=B7=A0=A0=A0=A0=A0=A0=A0= =A0=A0Start using TCP and re-check in a few hou= rs?
<= /u>=B7=A0=A0=A0=A0=A0=A0=A0= =A0=A0Go run the engine hard and re-check the c= ompression?
<= /u>=B7=A0=A0=A0=A0=A0=A0=A0= =A0=A0Something else?
<= /u>=A0
I re= ally want to nip this in the bud and not end up with a burned exhaust valve= , requiring pulling a jug.
<= /u>=A0
Appr= eciate your thoughts and responses.
<= /u>=A0
Chee= rs!
<= /u>=A0
Dan = Olsen


--
Swaid L. RahnIndigo Aviation, Inc.
940 Mock Road
Springfield, Ga. 31329
Cell = 912.6= 55.0966





--
Swaid L. Ra= hn
Indigo Aviation, Inc.
940 Mock Road
Springfield, Ga. 31329
C= ell 912.655.0966


--e89a8f22bdc552cc1d04b7bd35bb--