---------------------------------------------------------- TeamGrumman-List Digest Archive --- Total Messages Posted Sun 06/26/05: 11 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 01:03 AM - JPI vs EI (TeamGrumman@AOL.COM) 2. 05:57 AM - Aileron Trim (Dave) 3. 06:07 AM - Re: Aileron Trim (flyv35b) 4. 06:19 AM - Re: JPI vs EI (flyv35b) 5. 07:53 AM - Extra seat available to AYA Convention (923te) 6. 09:13 AM - Re: JPI vs EI (Gil Alexander) 7. 10:25 AM - Re: Aileron Trim (TeamGrumman@AOL.COM) 8. 10:36 AM - Re: JPI vs EI (TeamGrumman@AOL.COM) 9. 11:03 AM - Re: JPI vs EI (Gil Alexander) 10. 01:17 PM - Re: JPI vs EI (flyv35b) 11. 10:44 PM - Re: JPI vs EI (TeamGrumman@AOL.COM) ________________________________ Message 1 _____________________________________ Time: 01:03:23 AM PST US From: TeamGrumman@AOL.COM Subject: TeamGrumman-List: JPI vs EI --> TeamGrumman-List message posted by: TeamGrumman@aol.com There is a saying, "If a man has a watch, he'll always know what time it is. If he has two watches, he'll never be quite sure." For a long time now, it's been my contention that the JPI reads 50 degrees higher than the EI. We're talking CHT. Question is, which one is reading right? The EI uses a probe that sits in the CHT well and measures the temp inside the well. The JPI places the thermal couple against the top of the well and measures by direct contact. For just as long, I've been waiting until I have an EI to use back-to-back with the JPI. As luck would have it, one of my customers replaced the US-8A EI with a JPI 700. The #3 CHT generally runs about the same as #2. I replaced the #3 JPI probe with a CHT probe from an EI. I stole some power from the main bus and a ground from the avionics rack and put the EI on the glare shield. I ran the wire to the probe along the outside of the fuselage, taped in place. The JPI probe was nylon wire tied under the #3 cylinder to measure the temp of the air leaving the #3 cylinder. It was about 1 inch from the fins. Here are the results. Condition, Altitude, IAS, OAT, RPM, CHT #1, CHT #2, EI-CHT #3, CHT #4, (JPI #3 under cyl) Before starting, 1550, 0, 83, 0, 84, 84, 76, 84, (84) IDLE, 1550, 0, 81, 1000, 268, 256, 244, 265, (177) Runup, 1550, 0, 82, 1800, 356, 331, 321, 343, (209) Straight-Level, 3500, 132, 71, 2700, 423, 424, 350, 410, (186) Straight-Level, 6000, 130, 65, 2750, 430, 430, 357, 415, (186) Climb ..............., 7000, 110, 61, 2590, 426, 430, 367, 416, (200) Climb ..............., 9000, 102, 54, 2560, 445, 447, 382, 430, (207) Climb ............, 10500, 102, 48, 2570, 438, 447, 378, 433, (205) Climb ............, 11500, 102, 43, 2580, 430, 436, 370, 430, (200) Climb ............, 12800, 100, 39, 2550, 420, 428, 363, 418, (196) Climb ............, 13700, 100, 35, 2600, 414, 418, 356, 408, (191) Strght-Level, 14100, 114, 36, 2680, 400, 408. 344, 400, (179) Strght-Level, 13500, 120, 38, 2700, 387, 397. 334, 394, (170) Strght-Level, 12500, 122, 41, --------, 387, 400. 335, 395, (170) Strght-Level, 10500, 127, 46, --------, 397, 405. 340, 398, (170) Strght-Level, 7500, 133, 60, --------, 417, 425. 355, 412, (179) Roll-out . . . , 1550, 0, 80, 1000, 291, 286, 274, 294, (205) As you can see, EI-CHT #3 is up to 74 degrees cooler than JPI-CHT #2. Even before start-up, the EI probe was 8 degrees cooler. On roll-out, the EI was still about 10 derees cooler. Apparently the EI probe is not as linear as the JPI probe. As for the temp under the #3 cylinder, the temp under climb and cruise conditions was consistently 230-240 degrees cooler than #2 JPI-CHT. And, 60-70 degrees less with the EI. So, when you are using a JPI and the CHT is 450, is it really 450? Or is it 380? I think what it comes down to is, what type of probe was used for the original certification and how did they determine that 450 (or 500) is the max recommended temperature. Gary ________________________________ Message 2 _____________________________________ Time: 05:57:53 AM PST US From: "Dave" Subject: TeamGrumman-List: Aileron Trim --> TeamGrumman-List message posted by: "Dave" I was at a fly-in yesterday and saw a Cheetah with an in-flight adjustable trim tab on the LH aileron. I never found the owner of the airplane to find out more about it. Does anyone know of an STC for this mod?? Dave McKnight Tiger N880DM ________________________________ Message 3 _____________________________________ Time: 06:07:38 AM PST US From: "flyv35b" Subject: Re: TeamGrumman-List: Aileron Trim --> TeamGrumman-List message posted by: "flyv35b" A company in FL called Aero-Trim (a one man operation) sells the STC and parts. The price is pretty high for a rather cheap set of components. Cliff A&P/IA ----- Original Message ----- From: "Dave" Subject: TeamGrumman-List: Aileron Trim > --> TeamGrumman-List message posted by: "Dave" > > I was at a fly-in yesterday and saw a Cheetah with an in-flight adjustable > trim tab on the LH aileron. I never found the owner of the airplane to > find out more about it. Does anyone know of an STC for this mod?? > > Dave McKnight > Tiger N880DM > > > ________________________________ Message 4 _____________________________________ Time: 06:19:01 AM PST US From: "flyv35b" Subject: Re: TeamGrumman-List: JPI vs EI --> TeamGrumman-List message posted by: "flyv35b" > As you can see, EI-CHT #3 is up to 74 degrees cooler than JPI-CHT #2. > Even > before start-up, the EI probe was 8 degrees cooler. On roll-out, the EI > was > still about 10 derees cooler. Apparently the EI probe is not as linear > as > the JPI probe. As for the temp under the #3 cylinder, the temp under > climb and > cruise conditions was consistently 230-240 degrees cooler than #2 JPI-CHT. > And, 60-70 degrees less with the EI. The EI may be linear, just a lower slope "curve" or straight line. But compared to what as you mention below? > So, when you are using a JPI and the CHT is 450, is it really 450? Or is > it > 380? I think what it comes down to is, what type of probe was used for > the > original certification and how did they determine that 450 (or 500) is the > max > recommended temperature. The type of probe and instrumentation used during certification testing would be interesting to know and how it might compare to either the JPI or EI probes. I'm sure that neither one of these 2 systems was used as neither company was in existence when the engine was certified. Another point, the FAA has allowed use of one or both of these systems for STC certification testing with calibrated instrumentation (how that is done I'm not sure) and both companies had instrumentation that is approved for replacement of the original primary EGT and CHT instrumentation (all analog instruments to my knowledge). Cliff ________________________________ Message 5 _____________________________________ Time: 07:53:47 AM PST US From: "923te" <923te@cox.net> Subject: TeamGrumman-List: Extra seat available to AYA Convention --> TeamGrumman-List message posted by: "923te" <923te@cox.net> If anyone needs a ride to the AYA convention between Oklahoma and Sacramento I have seats available in my Tiger. I could swing up to Kansas or Texas. Regards, Ned ________________________________ Message 6 _____________________________________ Time: 09:13:55 AM PST US From: Gil Alexander Subject: Re: TeamGrumman-List: JPI vs EI --> TeamGrumman-List message posted by: Gil Alexander Gary... It seems like EI is the only manufacturer that does not use a CHT probe with a spring to maintain contact with the bottom of the cylinder well. The pictures at JPI web site http://www.jpitech.com/probes/images/200/probe_25.jpg and the Chief aircraft picture of the EI probe - shows no spring. http://www.chiefaircraft.com/Aircraft/EngineInstruments/Images/EI_P100.jpg HOWEVER, EI makes this CHT probe - and calls it military style... http://www.chiefaircraft.com/Aircraft/EngineInstruments/Images/EI_P101.jpg and needs this adapter... http://www.chiefaircraft.com/Aircraft/EngineInstruments/Images/EI_A101.jpg Perhaps you need to do the test with $16 extra per CHT probe and use the Military style CHT probe (apparently AN5541-1 specification)? Alcor shows the spring on this drawing.... http://www.alcorinc.com/db/images/drawing/86251.pdf I presume the standard EI configuration shipped is the cheaper version without the spring. Since a MIL Spec. measurement method exists, I would bet Lycoming used the spring loaded probes for their testing... This seems to be shown in the Lycoming Flyer when they talk about BAYONET CHT probes http://www.prime-mover.org/Engines/Lycoming/Flyer/Operation.html ...It would seem to me that it can't be a bayonet without the spring.... ....gil in Tucson Just getting ready to install Insight (GEM) probes... that do come with springs...: ) At 06:18 AM 6/26/2005, you wrote: >--> TeamGrumman-List message posted by: "flyv35b" > > > > As you can see, EI-CHT #3 is up to 74 degrees cooler than JPI-CHT #2. > > Even > > before start-up, the EI probe was 8 degrees cooler. On roll-out, the EI > > was > > still about 10 derees cooler. Apparently the EI probe is not as linear > > as > > the JPI probe. As for the temp under the #3 cylinder, the temp under > > climb and > > cruise conditions was consistently 230-240 degrees cooler than #2 JPI-CHT. > > And, 60-70 degrees less with the EI. > >The EI may be linear, just a lower slope "curve" or straight line. But >compared to what as you mention below? > > > So, when you are using a JPI and the CHT is 450, is it really 450? Or is > > it > > 380? I think what it comes down to is, what type of probe was used for > > the > > original certification and how did they determine that 450 (or 500) is the > > max > > recommended temperature. > >The type of probe and instrumentation used during certification testing >would be interesting to know and how it might compare to either the JPI or >EI probes. I'm sure that neither one of these 2 systems was used as neither >company was in existence when the engine was certified. Another point, the >FAA has allowed use of one or both of these systems for STC certification >testing with calibrated instrumentation (how that is done I'm not sure) and >both companies had instrumentation that is approved for replacement of the >original primary EGT and CHT instrumentation (all analog instruments to my >knowledge). > >Cliff ________________________________ Message 7 _____________________________________ Time: 10:25:39 AM PST US From: TeamGrumman@AOL.COM Subject: Re: TeamGrumman-List: Aileron Trim --> TeamGrumman-List message posted by: TeamGrumman@aol.com In a message dated 6/26/05 5:58:21 AM, ddmcknight@alltel.net writes: > I was at a fly-in yesterday and saw a Cheetah with an in-flight adjustable > trim tab on the LH aileron.=A0 I never found the owner of the airplane to=20find > out more about it.=A0 Does anyone know of an STC for this mod?? > Although this seems like a good idea, I've never found one that didn't affect the yaw on the plane. Yes, I said yaw. For some reason, having the trim hangin out from under the aileron affects the trim and aerodynamics on that aileron. I tried everything to get one particular plane straight and couldn't. To install the electric trim, you have to cut a hole in your aileron and run wires. That's right, cut a hole in a perfectly good aileron. I have had two planes with no provision to remove the aileron for the aileron AD. On one, I had to remove the aileron trim mechanism and that required drilling out the rivets in the aileron. As you can imagine, it stretched the hell out of the aluminum on the aileron. Like the avionics master, there is no justification for it other than compicating a very simple system. Save you money and buy a panel mounted GPS or panel mounted intercom. ________________________________ Message 8 _____________________________________ Time: 10:36:48 AM PST US From: TeamGrumman@AOL.COM Subject: Re: TeamGrumman-List: JPI vs EI --> TeamGrumman-List message posted by: TeamGrumman@aol.com In a message dated 6/26/05 9:14:38 AM, gilalex@earthlink.net writes: > Since a MIL Spec. measurement method exists, I would bet Lycoming used the > spring loaded probes for their testing... > First of all, I take what Lycoming recommends with a grain of salt. There is much too much evidence that some of their recommendations (i.e., shock cooling) don't really exist. And, their blanket recommendations on leaning do not coincide the recent testing (i.e., GAMI). That said, I serious doubt that spring loaded thermal couples were ever used by the military. Any probe inserted into the CHT well is a bayonet. The other probe fits under the spark plug. ________________________________ Message 9 _____________________________________ Time: 11:03:17 AM PST US From: Gil Alexander Subject: Re: TeamGrumman-List: JPI vs EI --> TeamGrumman-List message posted by: Gil Alexander Gary, The probes have an official, govt. published AN spec. (AN5541-1) that would have been created in the 40's(?) - Army-Navy=AN -- before there was a US Airforce?? The AN specs. went obsolete for govt. use when they got replaced by MSxxxxx specs., a long time ago..... These spring loaded thingies, and the threaded holes in cylinder heads for them, have been around a longggg.... time. Physical contact, vs. hanging around in a hot well, seems to make much more sense for repeatable temperature readings, since IR temperature sensors didn't exist pre-war (the WWII war...) I'll see if we still have a copy of the AN-5541 spec. on file at work..... gil A At 10:36 AM 6/26/2005, you wrote: >--> TeamGrumman-List message posted by: TeamGrumman@aol.com > > >In a message dated 6/26/05 9:14:38 AM, gilalex@earthlink.net writes: > > > > Since a MIL Spec. measurement method exists, I would bet Lycoming used the > > spring loaded probes for their testing... > > > >First of all, I take what Lycoming recommends with a grain of salt. There >is much too much evidence that some of their recommendations (i.e., shock >cooling) don't really exist. And, their blanket recommendations on >leaning do not >coincide the recent testing (i.e., GAMI). > >That said, I serious doubt that spring loaded thermal couples were ever used >by the military. Any probe inserted into the CHT well is a bayonet. The >other probe fits under the spark plug. > > ________________________________ Message 10 ____________________________________ Time: 01:17:21 PM PST US From: "flyv35b" Subject: Re: TeamGrumman-List: JPI vs EI --> TeamGrumman-List message posted by: "flyv35b" > Gary... It seems like EI is the only manufacturer that does not use a CHT > probe with a spring to maintain contact with the bottom of the cylinder > well. EI also sells the military style bayonet probe. It's their P-101. The most common one is their P-100. As I recall they said there wasn't much difference in the readout between them, but I have never tried to verify that. Cliff ________________________________ Message 11 ____________________________________ Time: 10:44:23 PM PST US From: TeamGrumman@AOL.COM Subject: Re: TeamGrumman-List: JPI vs EI --> TeamGrumman-List message posted by: TeamGrumman@aol.com I think the question should be, if the FAA sets their temperature limits based on the some arbitrary guidline that was established with the probes that read 70 degrees lower, then it would be impossible to pass the climb/cooling tests with the probes that read 70 degrees higher. Why do I care? If I use the JPI probes in comparison to guideline using the lower reading probes, my cowling will never pass the climb cooling test. Right now, I climb out at 110 knots, full rich, and even with 80 OAT, I can over temp on the JPI quite easily. The EI probe, on the other hand, barely gets to 400 degrees. Gary