---------------------------------------------------------- RV-List Digest Archive --- Total Messages Posted Thu 06/26/14: 8 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 07:47 AM - Re: 70 psi compression (Thomas Sargent) 2. 08:28 AM - Re: 70 psi compression (Bill Boyd) 3. 12:27 PM - Re: 70 psi compression (Kelly McMullen) 4. 02:33 PM - Re: leaking nylo -seal fittings (Thomas Sargent) 5. 03:25 PM - Re: 70 psi compression (Jeff Luckey) 6. 03:28 PM - Re: 70 psi compression (Charlie England) 7. 06:26 PM - Re: leaking nylo -seal fittings (Dave Saylor) 8. 08:06 PM - Re: 70 psi compression (vanremog@aol.com) ________________________________ Message 1 _____________________________________ Time: 07:47:45 AM PST US Subject: Re: RV-List: 70 psi compression From: Thomas Sargent Well 88 may well be a mistake, but that's what the A&P said. He seemed a bit baffled. I have my own compression tester now. I will do it myself next time. On Wed, Jun 25, 2014 at 8:11 PM, Linn Walters wrote: > On 6/25/2014 9:44 PM, vanremog@aol.com wrote: > > Just a wild question since no one has asked it...How can one get an 88 > psig aircraft bleed down type compression reading with 80 psig supplied air? > > You can't if you use the differential gauge properly. I can only > surmise that 88 was a typo. > Linn > > > -----Original Message----- > From: William Greenley > To: rv-list > Sent: Wed, Jun 25, 2014 4:26 pm > Subject: RE: RV-List: 70 psi compression > > An 88 means something is wrong with the equipment or the methodology. > The max is 80 with the standardized orifice. > > *From:* owner-rv-list-server@matronics.com [ > mailto:owner-rv-list-server@matronics.com > ] *On Behalf Of *Thomas Sargent > *Sent:* Wednesday, June 25, 2014 7:11 PM > *To:* rv-list > *Subject:* Re: RV-List: 70 psi compression > > > Thanks for all the good information. > > Reading the Lycoming Service instructions, I should note that cyl#1 showed > 88psi. I was doing the test as part of the annual inspection. Last year > they were all in the 72 - 78 range I think. What does an anomalously high > reading indicate? Off hand I would have guessed that the higher the > better, but apparently not. Lyc. says more than 15psi difference is trouble. > > I think I need to repeat this whole test soon after actually flying the > plane. > > I'm still finishing the annual, I haven't flown it for a couple weeks. > > > -- > Tom Sargent > > > *http://www.matronics.com/Navigator?RV-List * > > *http://forums.matronics.com * > > *http://www.matronics.com/contribution * > > > * > > t="_blank">http://www.matronics.com/Navigator?RV-List > tp://forums.matronics.com > _blank">http://www.matronics.com/contribution > > * > > > * > > > * > > -- Tom Sargent ________________________________ Message 2 _____________________________________ Time: 08:28:01 AM PST US Subject: Re: RV-List: 70 psi compression From: Bill Boyd Be careful. Two-man job to do safely... 80 psi into one jug can be deadly if the prop gets away from you and your noggin is in the way. IIRC, the trend in the "literature" is away from compression testing altogether and toward boroscopy as a means of assessing engine health. --kind of like internal like medicine... the old standards of screening are giving way to the $$ passing-of-scopes $$ into various body cavities. -Stormy On Thu, Jun 26, 2014 at 10:46 AM, Thomas Sargent wrote: > Well 88 may well be a mistake, but that's what the A&P said. He seemed a > bit baffled. I have my own compression tester now. I will do it myself > next time. > > > On Wed, Jun 25, 2014 at 8:11 PM, Linn Walters > wrote: > >> On 6/25/2014 9:44 PM, vanremog@aol.com wrote: >> >> Just a wild question since no one has asked it...How can one get an 88 >> psig aircraft bleed down type compression reading with 80 psig supplied air? >> >> You can't if you use the differential gauge properly. I can only >> surmise that 88 was a typo. >> Linn >> >> >> >> -----Original Message----- >> From: William Greenley >> To: rv-list >> Sent: Wed, Jun 25, 2014 4:26 pm >> Subject: RE: RV-List: 70 psi compression >> >> An 88 means something is wrong with the equipment or the methodology. >> The max is 80 with the standardized orifice. >> >> *From:* owner-rv-list-server@matronics.com [ >> mailto:owner-rv-list-server@matronics.com >> ] *On Behalf Of *Thomas Sargent >> *Sent:* Wednesday, June 25, 2014 7:11 PM >> *To:* rv-list >> *Subject:* Re: RV-List: 70 psi compression >> >> >> Thanks for all the good information. >> >> Reading the Lycoming Service instructions, I should note that cyl#1 >> showed 88psi. I was doing the test as part of the annual inspection. Last >> year they were all in the 72 - 78 range I think. What does an anomalously >> high reading indicate? Off hand I would have guessed that the higher the >> better, but apparently not. Lyc. says more than 15psi difference is trouble. >> >> I think I need to repeat this whole test soon after actually flying the >> plane. >> >> I'm still finishing the annual, I haven't flown it for a couple weeks. >> >> >> >> >> >> >> -- >> Tom Sargent >> >> >> >> >> >> *http://www.matronics.com/Navigator?RV-List * >> >> *http://forums.matronics.com * >> >> *http://www.matronics.com/contribution * >> >> >> >> * >> >> t="_blank">http://www.matronics.com/Navigator?RV-List >> tp://forums.matronics.com >> _blank">http://www.matronics.com/contribution >> >> * >> >> >> >> >> * >> >> t="_blank">http://www.matronics.com/Navigator?RV-List >> tp://forums.matronics.com >> _blank">http://www.matronics.com/contribution >> >> * >> >> > > > -- > Tom Sargent > > * > > > * > > ________________________________ Message 3 _____________________________________ Time: 12:27:46 PM PST US From: Kelly McMullen Subject: Re: RV-List: 70 psi compression Not really. Until Appendix D of Part 43 gets re-written, compression tests are mandatory for both certified and experimental aircraft. Item (d) (3) of the appendix requires compression test, and AFAIK most all experimental operating limitations require condition inspect that meets requirements of Appendix D as a minimum. Yes, borescope is good addition to checking cylinder health, but FAA does not recognize it as a complete substitute. IF one gains the experience to get a cylinder to TDC there will be no force on the prop. But allowing it to go very many degrees either side of TDC generates a dangerous force in the prop. I position prop near TDC, dial up about 20psi while adjusting prop for minimum to no force at the prop, then bring the pressure on up to 80. I also make sure to hold prop such that if it got away from me it would hurt nothing. Especially keep rest of body besides hand outside the prop arc.I don't even pick up compression tester until I have prop in safe position. On 6/26/2014 8:27 AM, Bill Boyd wrote: > Be careful. Two-man job to do safely... 80 psi into one jug can be > deadly if the prop gets away from you and your noggin is in the way. > > IIRC, the trend in the "literature" is away from compression testing > altogether and toward boroscopy as a means of assessing engine health. > --kind of like internal like medicine... the old standards of > screening are giving way to the $$ passing-of-scopes $$ into various > body cavities. > > -Stormy > > > On Thu, Jun 26, 2014 at 10:46 AM, Thomas Sargent > wrote: > > Well 88 may well be a mistake, but that's what the A&P said. He > seemed a bit baffled. I have my own compression tester now. I > will do it myself next time. > > > On Wed, Jun 25, 2014 at 8:11 PM, Linn Walters > > wrote: > > On 6/25/2014 9:44 PM, vanremog@aol.com > wrote: >> Just a wild question since no one has asked it...How can one >> get an 88 psig aircraft bleed down type compression reading >> with 80 psig supplied air? > You can't if you use the differential gauge properly. I can > only surmise that 88 was a typo. > Linn >> -----Original Message----- >> From: William Greenley >> >> To: rv-list >> >> Sent: Wed, Jun 25, 2014 4:26 pm >> Subject: RE: RV-List: 70 psi compression >> >> An 88 means something is wrong with the equipment or the >> methodology. The max is 80 with the standardized orifice. >> *From:*owner-rv-list-server@matronics.com >> >> [mailto:owner-rv-list-server@matronics.com >> ] *On Behalf Of >> *Thomas Sargent >> *Sent:* Wednesday, June 25, 2014 7:11 PM >> *To:* rv-list >> *Subject:* Re: RV-List: 70 psi compression >> Thanks for all the good information. >> >> Reading the Lycoming Service instructions, I should note that >> cyl#1 showed 88psi. I was doing the test as part of the >> annual inspection. Last year they were all in the 72 - 78 >> range I think. What does an anomalously high reading >> indicate? Off hand I would have guessed that the higher the >> better, but apparently not. Lyc. says more than 15psi >> difference is trouble. >> >> I think I need to repeat this whole test soon after actually >> flying the plane. >> >> I'm still finishing the annual, I haven't flown it for a >> couple weeks. >> >> >> >> >> -- >> Tom Sargent >> * * >> * * >> ** >> ** >> ** >> ** >> ** >> *http://www.matronics.com/Navigator?RV-List* >> ** >> ** >> *http://forums.matronics.com* >> ** >> ** >> ** >> ** >> *http://www.matronics.com/contribution* >> ** >> * * >> * >> >> t="_blank">http://www.matronics.com/Navigator?RV-List >> tp://forums.matronics.com >> _blank">http://www.matronics.com/contribution >> >> * >> * >> >> >> * > > * > > t="_blank">http://www.matronics.com/Navigator?RV-List > tp://forums.matronics.com > _blank">http://www.matronics.com/contribution > > * > > > -- > Tom Sargent > > * > > t="_blank">http://www.matronics.com/Navigator?RV-List > tp://forums.matronics.com > _blank">http://www.matronics.com/contribution > > * > > > * > > > * ________________________________ Message 4 _____________________________________ Time: 02:33:37 PM PST US Subject: Re: RV-List: leaking nylo -seal fittings From: Thomas Sargent Dave: Yes, that was my main problem. A few of the fittings didn't have the "tube support". That and some teflon tape on the T's that screwed into the instruments fixed the problem. On Mon, Jun 23, 2014 at 9:41 AM, Dave Saylor < dave.saylor.aircrafters@gmail.com> wrote: > Tom, > > I said insert but I should have said "tube support". They look like this : > > [image: Inline image 1] > > =8BThey fit inside the end of the tube. > > You're right, according to a note from McMaster-Carr, they aren't needed > for harder tubing=8B: > > "Tube supports are recommended for polypropylene, polyethylene, and nylon > tubing with a hardness of Shore A70 or less". > > I tubing I prefer is pretty soft, almost rubbery. I use tube supports > anywhere there's a B-nut. > > If you have some smooth-jawed vice grips or some other clamp, you can > clamp pinch the tubing to isolate various sections as you chase down the > leak. > > --Dave > > > On Mon, Jun 23, 2014 at 9:07 AM, Thomas Sargent wrote : > >> >> >> I am using the insert on th 1/4" poly tubing. By "insert" I mean the >> little "sleeve that fits over the tubing, not the other free floating pi ece >> that goes inside the fitting. However, that's not the part that's leaki ng >> (I think). The "nut" isn't leaking. it's the NPT part that screws into t he >> instrument. I'm pretty sure about this. I should devise an experiment to >> prove my thinking. >> >> It was my understanding that the free-floating inserts are not necessary >> except with certain kinds of tubing. Maybe I misunderstand that. Do you >> always have to use the insert? >> >> >> -- >> Tom Sargent >> >> * >> >> t="_blank">http://www.matronics.com/Navigator?RV-List >> tp://forums.matronics.com >> _blank">http://www.matronics.com/contribution >> >> * >> >> > -- Tom Sargent ________________________________ Message 5 _____________________________________ Time: 03:25:25 PM PST US From: Jeff Luckey Subject: Re: RV-List: 70 psi compression In addition to the regs - I can't see how a visual inspection w/ a bore sco pe/camera would be a good substitute for actually testing seals by putting actual air pressure on them.- I don't think the Compression Test is going to disappear anytime soon - it's such a great diagnostic.=0A=0A-Jeff=0A=0A =0A=0AOn Thursday, June 26, 2014 12:36 PM, Kelly McMullen =0A=0ANot really. Until Appendix D of Part 43 gets re-writt en, compression =0Atests are mandatory for both certified and experimental aircraft. Item =0A(d) (3) of the appendix requires compression test, and AF AIK most all =0Aexperimental operating limitations require condition inspec t that meets =0Arequirements of Appendix D as a minimum. Yes, borescope is good addition =0Ato checking cylinder health, but FAA does not recognize it as a complete =0Asubstitute.=0AIF one gains the experience to get a cylind er to TDC there will be no =0Aforce on the prop. But allowing it to go very many degrees either side =0Aof TDC generates a dangerous force in the prop . I position prop near =0ATDC, dial up about 20psi while adjusting prop for minimum- to no force =0Aat the prop, then bring the pressure on up to 80 . I also make sure to =0Ahold prop such that if it got away from me it woul d hurt nothing. =0AEspecially keep rest of body besides hand outside the pr op arc.I don't =0Aeven pick up compression tester until I have prop in safe position.=0A=0AOn 6/26/2014 8:27 AM, Bill Boyd wrote:=0A> Be careful.- T wo-man job to do safely... 80 psi into one jug can be =0A> deadly if the pr op gets away from you and your noggin is in the way.=0A>=0A> IIRC, the tren d in the "literature" is away from compression testing =0A> altogether and toward boroscopy as a means of assessing engine health.=0A> --kind of like internal like medicine... the old standards of =0A> screening are giving wa y to the $$ passing-of-scopes $$ into various =0A> body cavities.=0A>=0A> - Stormy=0A>=0A>=0A> On Thu, Jun 26, 2014 at 10:46 AM, Thomas Sargent > wrote:=0A>=0A>- - Well 88 may well be a mistake, but that's what the A&P said.- He=0A>- - see med a bit baffled.- I have my own compression tester now.- I=0A>- - will do it myself next time.=0A>=0A>=0A>- - On Wed, Jun 25, 2014 at 8:11 PM, Linn Walters=0A>- - > wrote:=0A>=0A>- - - - On 6/25/2014 9:44 PM, vanremog @aol.com=0A>- - - - wrote:=0A>>- - - - Just a wild question since no one has asked it...How can one=0A>> - - - - get an 88 psig aircraft bleed down type compression readin g=0A>>- - - - with 80 psig supplied air?=0A>- - - - You c an't if you use the differential gauge properly. I can=0A>- - - - only surmise that 88 was a typo.=0A>- - - - Linn=0A>>- - - - -----Original Message-----=0A>>- - - - From: William Greenley =0A>>- - - - =0A >>- - - - To: rv-list =0A>>- - - - =0A>>- - - - Sent: Wed, Jun 25, 201 4 4:26 pm=0A>>- - - - Subject: RE: RV-List: 70 psi compression=0A> >=0A>>- - - - An 88 means something is wrong with the equipment or the=0A>>- - - - methodology. The max is 80 with the standardized orifice.=0A>>- - - - *From:*owner-rv-list-server@matronics.com=0A> >- - - - =0A>>- - - - [mailto:owner-rv-list-server@matronics.com=0A>>- - - - ] *On Behalf Of=0A>>- - - - *Thomas Sargent=0A>>- - - - *Sent:* Wednesday, June 25, 2014 7:11 PM=0A>>- - - - *To:* rv-list=0A>>- - - - *Subject:* Re: RV-List: 70 psi compression=0A>>- - - - Thanks for all the goo d information.=0A>>=0A>>- - - - Reading the Lycoming Service instr uctions, I should note that=0A>>- - - - cyl#1 showed 88psi.- I w as doing the test as part of the=0A>>- - - - annual inspection. La st year they were all in the 72 - 78=0A>>- - - - range I think. Wh at does an anomalously high reading=0A>>- - - - indicate?- Off h and I would have guessed that the higher the=0A>>- - - - better, b ut apparently not. Lyc. says more than 15psi=0A>>- - - - differenc e is trouble.=0A>>=0A>>- - - - I think I need to repeat this whole test soon after actually=0A>>- - - - flying the plane.=0A>>=0A>> - - - - I'm still finishing the annual, I haven't flown it for a =0A>>- - - - couple weeks.=0A>>=0A>>=0A>>=0A>>=0A>>- - - - -- =0A>>- - - - Tom Sargent=0A>>- - - - *- *=0A>>- - - - *- *=0A>>- - - - **=0A>>- - - - **=0A>>- - - - **=0A>>- - - - **=0A>>- - - - **=0A>>- - - - *http://www.matronics.com/Navigator?RV-List*=0A>>- - - - **=0A>>- - - - **=0A>>- - - - *http://forums.matroni cs.com*=0A>>- - - - **=0A>>- - - - **=0A>>- - - - **=0A>>- - - - **=0A>>- - - - *http://www.matronics.com /contribution*=0A>>- - - - **=0A>>- - - - *- *=0A>>- - - - *=0A>>=0A>>- - - - t="_blank">http://www.matronics. com/Navigator?RV-List=0A>>- - - - tp://forums.matronics.com- =0A>>- - - - _blank">http://www.matronic s.com/contribution=0A>>=0A>>- - - - *=0A>>- - - - *=0A>> =0A>>=0A>>- - - - *=0A>=0A>- - - - *=0A>=0A>- - - - t="_blank">http://www.matronics.com/Navigator?RV-List=0A>- - - - tp://forums.matronics.com- =0A>- - - - _blank">http://www.matronics.com/contribution=0A>=0A>- - - - *=0A>=0A>=0A>=0A>=0A>- - -- =0A>- - Tom Sargent=0A>=0A>- - *=0A>=0A>- - t="_blank">http://www.matronics.com/Navigator?RV-L ist=0A>- - tp://forums.matronics.com=0A>- - _blank">http://www.ma tronics.com/contribution=0A>=0A>- - *=0A>=0A>=0A> *=0A>=0A>=0A> *=0A ============= ________________________________ Message 6 _____________________________________ Time: 03:28:52 PM PST US From: Charlie England Subject: Re: RV-List: 70 psi compression Even if you buy into the idea that a compression test is required during the condition inspection, it doesn't mean you have to give it any weight in your appraisal of the engine's health. :-) I suspect that Bill was saying that more recent research has shown the traditional compression test to be a very poor indicator of a cylinder's condition (unless, of course, it's very very low and you can hear a 'breeze' blowing out the exhaust or intake...). I've gotten a 75+ reading on a cylinder that had a broken ring, and a low-70s reading followed the next year by a high-70s reading on the same cylinder, when checked 'cold'. If you haven't done it already, I'd suggest reading everything you can find by Mike Busch (writes for Sport Aviation, in addition to seminars, webinars, etc). Charlie (If your mechanic insists that he got an 88/80 reading, then in the immortal words of Monty Python, 'Run away! Run away!' (from that mechanic). On 6/26/2014 2:26 PM, Kelly McMullen wrote: > > Not really. Until Appendix D of Part 43 gets re-written, compression > tests are mandatory for both certified and experimental aircraft. Item > (d) (3) of the appendix requires compression test, and AFAIK most all > experimental operating limitations require condition inspect that > meets requirements of Appendix D as a minimum. Yes, borescope is good > addition to checking cylinder health, but FAA does not recognize it as > a complete substitute. > IF one gains the experience to get a cylinder to TDC there will be no > force on the prop. But allowing it to go very many degrees either side > of TDC generates a dangerous force in the prop. I position prop near > TDC, dial up about 20psi while adjusting prop for minimum to no force > at the prop, then bring the pressure on up to 80. I also make sure to > hold prop such that if it got away from me it would hurt nothing. > Especially keep rest of body besides hand outside the prop arc.I don't > even pick up compression tester until I have prop in safe position. > > On 6/26/2014 8:27 AM, Bill Boyd wrote: >> Be careful. Two-man job to do safely... 80 psi into one jug can be >> deadly if the prop gets away from you and your noggin is in the way. >> >> IIRC, the trend in the "literature" is away from compression testing >> altogether and toward boroscopy as a means of assessing engine health. >> --kind of like internal like medicine... the old standards of >> screening are giving way to the $$ passing-of-scopes $$ into various >> body cavities. >> >> -Stormy >> >> >> On Thu, Jun 26, 2014 at 10:46 AM, Thomas Sargent > > wrote: >> >> Well 88 may well be a mistake, but that's what the A&P said. He >> seemed a bit baffled. I have my own compression tester now. I >> will do it myself next time. >> >> >> On Wed, Jun 25, 2014 at 8:11 PM, Linn Walters >> > wrote: >> >> On 6/25/2014 9:44 PM, vanremog@aol.com >> wrote: >>> Just a wild question since no one has asked it...How can one >>> get an 88 psig aircraft bleed down type compression reading >>> with 80 psig supplied air? >> You can't if you use the differential gauge properly. I can >> only surmise that 88 was a typo. >> Linn >>> -----Original Message----- >>> From: William Greenley >>> >>> To: rv-list >>> >>> Sent: Wed, Jun 25, 2014 4:26 pm >>> Subject: RE: RV-List: 70 psi compression >>> >>> An 88 means something is wrong with the equipment or the >>> methodology. The max is 80 with the standardized orifice. >>> *From:*owner-rv-list-server@matronics.com >>> >>> [mailto:owner-rv-list-server@matronics.com >>> ] *On Behalf Of >>> *Thomas Sargent >>> *Sent:* Wednesday, June 25, 2014 7:11 PM >>> *To:* rv-list >>> *Subject:* Re: RV-List: 70 psi compression >>> Thanks for all the good information. >>> >>> Reading the Lycoming Service instructions, I should note that >>> cyl#1 showed 88psi. I was doing the test as part of the >>> annual inspection. Last year they were all in the 72 - 78 >>> range I think. What does an anomalously high reading >>> indicate? Off hand I would have guessed that the higher the >>> better, but apparently not. Lyc. says more than 15psi >>> difference is trouble. >>> >>> I think I need to repeat this whole test soon after actually >>> flying the plane. >>> >>> I'm still finishing the annual, I haven't flown it for a >>> couple weeks. >>> >>> ________________________________ Message 7 _____________________________________ Time: 06:26:43 PM PST US From: Dave Saylor Subject: Re: RV-List: leaking nylo -seal fittings Yeah, those things seem kind of optional until you spend enough hours with the fuel valve digging into your back, looking for leaks behind the panel. I'm glad that helped. --Dave do not archive --Dave On Thu, Jun 26, 2014 at 2:30 PM, Thomas Sargent wrote: > Dave: > Yes, that was my main problem. A few of the fittings didn't have the "tub e > support". That and some teflon tape on the T's that screwed into the > instruments fixed the problem. > > > On Mon, Jun 23, 2014 at 9:41 AM, Dave Saylor < > dave.saylor.aircrafters@gmail.com> wrote: > >> Tom, >> >> I said insert but I should have said "tube support". They look like thi s: >> >> [image: Inline image 1] >> >> =8BThey fit inside the end of the tube. >> >> You're right, according to a note from McMaster-Carr, they aren't needed >> for harder tubing=8B: >> >> "Tube supports are recommended for polypropylene, polyethylene, and >> nylon tubing with a hardness of Shore A70 or less". >> >> I tubing I prefer is pretty soft, almost rubbery. I use tube supports >> anywhere there's a B-nut. >> >> If you have some smooth-jawed vice grips or some other clamp, you can >> clamp pinch the tubing to isolate various sections as you chase down the >> leak. >> >> --Dave >> >> >> On Mon, Jun 23, 2014 at 9:07 AM, Thomas Sargent >> wrote: >> >>> >>> >>> I am using the insert on th 1/4" poly tubing. By "insert" I mean the >>> little "sleeve that fits over the tubing, not the other free floating p iece >>> that goes inside the fitting. However, that's not the part that's leak ing >>> (I think). The "nut" isn't leaking. it's the NPT part that screws into the >>> instrument. I'm pretty sure about this. I should devise an experiment to >>> prove my thinking. >>> >>> It was my understanding that the free-floating inserts are not necessar y >>> except with certain kinds of tubing. Maybe I misunderstand that. Do yo u >>> always have to use the insert? >>> >>> >>> -- >>> Tom Sargent >>> >>> * >>> >>> t="_blank">http://www.matronics.com/Navigator?RV-List >>> tp://forums.matronics.com >>> _blank">http://www.matronics.com/contribution >>> >>> * >>> >>> >> > > > -- > Tom Sargent > ________________________________ Message 8 _____________________________________ Time: 08:06:51 PM PST US Subject: Re: RV-List: 70 psi compression From: vanremog@aol.com baffled is not the word I was thinking of... -GV -----Original Message----- From: Thomas Sargent Sent: Thu, Jun 26, 2014 8:17 am Subject: Re: RV-List: 70 psi compression Well 88 may well be a mistake, but that's what the A&P said. He seemed a b it baffled. I have my own compression tester now. I will do it myself nex t time. On Wed, Jun 25, 2014 at 8:11 PM, Linn Walters wrote : On 6/25/2014 9:44 PM, vanremog@aol.com wrote: Just a wild question since no one has asked it...How can one get an 88 psig aircraft bleed down type compression reading with 80 psig supplied air? You can't if you use the differential gauge properly. I can only surmise that 88 was a typo. Linn -----Original Message----- From: William Greenley To: rv-list Sent: Wed, Jun 25, 2014 4:26 pm Subject: RE: RV-List: 70 psi compression An 88 means something is wrong with the equipment or the methodology. The max is 80 with the standardized orific e. From: owner-rv-list-server@matronics.com [mailto:owner-r v-list-server@matronics.com] On Behalf Of Thomas Sargent Sent: Wednesday, June 25, 2014 7:11 PM To: rv-list Subject: Re: RV-List: 70 psi compression Thanks for all the good information. Reading the Lycoming Service instructions, I should note that cyl#1 showed 88psi. I was doing the test as part of the annual inspection. Last year they were all in the 72 - 78 range I think. What does an anomalously high reading indicate? Off hand I would h ave guessed that the higher the better, but apparently n ot. Lyc. says more than 15psi difference is trouble. I think I need to repeat this whole test soon after actually flying the plane. I'm still finishing the annual, I haven't flown it for a couple weeks. -- Tom Sargent http://www.matronics.com/Navigator?RV-List http://forums.matronics.com http://www.matronics.com/contribution t="_blank">http://www.matronics.com/Navigator?RV-List tp://forums.matronics.com _blank">http://www.matronics.com/contribution t="_blank">http://www.matronics.com/Navigator?RV-List tp://forums.matronics.com _blank">http://www.matronics.com/contribution -- Tom Sargent ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message rv-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/RV-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/rv-list Browse Digests http://www.matronics.com/digest/rv-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.