I finally have N84MR back, after having been separated from my toy for almost a month. This is a collection of anecdotes & trivia that relate to the work done, etc. ThereÂ’s stuff in here thatÂ’s very general, and some PIREPS on the ARNAV Engine Monitoring and GPSS, as well as Â“The Transponder ProblemÂ”.
I chose this time to have a bunch of work done because I was going to be traveling abroad for a few weeks, and it seemed like an efficient way to do things. The plan was for the airplane to be ready on my return in three weeks; but Murphy loves airplanes almost more than anything else, and so I had to wait an extra week.
With a little over 146 hours on the meter when the work began, I had a few squawks to take care of. Some were cosmetic; a few were slightly more significant. The single most important squawk I had was The Transponder Problem, which has been driving me crazy. [ItÂ’s been described at length in other posts. The short version is that I have heard ATC tell me that theyÂ’ve lost my transponder too often.] I wanted a 50-hour inspection on the engine.
Beyond the bug fixes and routine maintenance, I had a few upgrades to install: The ARNAV Engine Monitor, GPSS, and an antenna connection for a handheld radio.
The work was done at two locations:
My Authorized Cirrus Service Center was to deal with most of the squawks, the 50-hour inspection, Cirrus Service Advisories, and the Engine Monitor; and
An avionics shop they use was to attack the rest Â– GPSS, antenna connection, Audio Panel Beep (see below), a weak COMM2, and adjustment of the HSI flux gate.
I donÂ’t let just anyone fly my airplane; but I was going to be far away when N84MR had to go to the avionics shop (a Â½ hour flight away). For that, I enlisted the help of a friend/CFII who has received training from Wings Aloft and who regularly instructs in an SR20. So far, she is the only person (other than I) who has flown my airplane since I brought it back from the factory.
The engine monitor behaves pretty much exactly the way Del Fadden and Peter Morton describe. ItÂ’s a real joy to have and to use. My only negative first impression was that the graphics look a little cheesy Â– low resolution, as though displayed on a TV screen and not a Hi-Res-Super-TFT-LCD. As far as I know, the LCD screen itself is capable of much crisper stuff, so my guess is that this was done to save memory or possibly to keep the code running as fast as it needs to.
One surprise early on was that this installation requires the addition of a second temperature probe to be mounted on the outside of the airplane. The ARNAV either cannot or just does not use the OAT probe that is already on the left front cowl of my SR20. The new probe goes on the right side, mirroring the position of the original. ItÂ’s a much lower profile device, too Â– it looks good.
The (tons of) additional data available when you have this feature installed allows me to use the LOP leaning techniques espoused by John Deakin. I think heÂ’s a real guru of piston engines, and what he writes makes a lot of sense. If you havenÂ’t read his stuff, do yourself a favor and look for anything he writes among the great http://www.avweb.com/toc/columns.html Avweb Columns. (No, I donÂ’t work for Avweb). In this regard, I am convinced that the leaning method described by ARNAV for Best Economy is in error; IÂ’ll post separately on that.
I have some early questions about the Engine Monitor functions. These may be bugs, or just me not understanding something, so IÂ’ll list them here (and maybe someone can confirm the problem or explain the solution to me).
Â· If you turn on the Engine Monitor while the engine is not running, the Fuel Flow on the Â“sharedÂ” screens (the ones which also show map data) shows a flow of 12.0 GPH. The full-screen Monitor correctly shows 0.0 GPH.
Â· At all times while the engine IS running, the fuel flow seems to be indicated correctly. ThatÂ’s great, except that the information apparently comes from the same turbine-driven flow-sensor that feeds the analog Â“steam gaugeÂ” supplied by the factory. No problem, but the steam gauge has always indicated zero during engine idle/low RPM operation, and Â“kicks inÂ” only at 6 or so GPH. So what? Well, the explanation IÂ’d been given is that the sensor couldnÂ’t respond to such low flows because the little turbine wouldnÂ’t turn, and so the meter reads zero. But clearly the sensor IS seeing the flow. Stay tuned.
Â· Fuel Fill page Â– This is the page one uses to declare the amount of fuel just added; either F for Full, or specify # of gallons. The only problem is that I couldnÂ’t find an Â“OOPSÂ” option. I got into the page while messing around, and couldnÂ’t get out of it without specifying something. I wound up specifying Full, and thereby destroyed my fuel totals so far.
ENGINE VIEW PC SOFTWARE
I must emphasize that this is a first impression.
I must SURELY be doing something very wrong here! I spent the extra $295 for this software, and my initial reaction is Â“For What?Â”. I sat in the airplane with my laptop PC hooked up via serial cable to the little DB-9 connector that was added (in an easy-enough-to-reach-yet-inconspicuous-spot), and went through the motions of downloading the data from the ARNAV system into my PC.
The software came on a 3.5 inch diskette Â– I havenÂ’t seen software issued on those in quite a while. I was looking forward to downloading lots of good data that would give me my first real insight into my engineÂ’s behavior over several hours Â– two lines of data per minute – hundreds of records in all. I followed the instructions (such as they were Â– no manual, and tiny readme file); and got a whole 8 records loaded into an application that seemed to crash each time I tried to do anything. I can only hope that some essential component is missing, or that somewhere there is a manual that explains all. I tried to find that out by going to the http://www.arnav.com ARNAV website, where sure enough they have a link for Pilot’s Operating Handbook for Cirrus SR20/SR22 EngineView; but it goes nowhere! GRRR!
One possibility Â– I got the wrong software completely. The software, and the notes that come with it, refer to the Cessna 208 and the PT-6 engine; IÂ’d be greatly comforted by that, except that the same document refers to the SR20/22 also. Anyway, stay tuned.
The Transponder Problem
My avionics guy is very scientific in his approach to everything. He started out by taking some measurements (using an ATC 601 Transponder Ramp Checker, or a very similar name). He quickly established that the transponder was pumping 168 watts into the antenna, which was Â“on the moneyÂ”. He then took a reading at various precisely noted locations around the antenna, and felt that the readings were low, but noted that RF readings taken in this way are not very meaningful except as a comparative measurement (i.e. to see if changing something produces any results).
He then followed the procedure recommended by Cirrus for improving the ground plane Â– quite a lot of work, involving adding 3 square feet of aluminum mesh as a bigger, better ground plane. After that, he repeated his tests. All the readings were now better than double what they were before he upgraded the ground plane.
The proof of the pudding will be whether this makes a difference. Since yesterday, IÂ’ve done 3, 30-minute flights with my transponder being monitored by ATC. So far, so good. Stay tuned.
The installation is really neat Â– looks as though it is an original factory installation. I put the GPSS switch just to the left of the Flap Switch. Since itÂ’s far from my normal scan down there, I didnÂ’t bother to add a dimmer switch Â– I didnÂ’t want an extra dimmer switch anyway, and for technical reasons the GPSS LEDs wonÂ’t dim properly if theyÂ’re tied to the bolster panel avionics dimmer control. Besides, the Flap LEDs donÂ’t dim.
Regarding operation of the GPSS, I did try it briefly, but I think I might be experiencing some finger-trouble, otherwise known as a need to RTFM. Stay tuned.
Handheld Antenna Connection
Options are somewhat more limited for Cirrus than for a metal-bodied airplane. The preferred method for providing a handheld antenna connection is to add an antenna; but that is not easy (issues with structural location, ground planes, etc.) The worst method is a simple T-connector in the antenna coaxial cable Â– that degrades radio performance by wreaking havoc with the RF signal (impedance mismatches /reflections). Reputable avionics shops will refuse to do such an installation.
That leaves a switched splitter Â– a little box that costs $75. It presents a jack that looks exactly like a stereo earphone jack on a Walkman. Mine is mounted in another easy-enough-to-reach-yet-inconspicuous-spot. When you plug the supplied antenna cable into the jack, it switches the antenna from the panel radio to the cable you just plugged in. The other end of that cable goes to the handheld radio. In other words, the antenna is connected to either the handheld or the panel radio, but never both at the same time.
Works a treat, but the little box in question is an Allied Signal/Bendix King KX99 Splitter. It is no longer made. I know someone who says he has them in stock Â– IÂ’d be happy to provide the info if you email me.
Audio Panel Beep
In reading some of the documentation I got with the airplane, I found that the Garmin 340 Audio Panel has an option to provide the pilot with an audio “beep” to confirm key presses. It seems like a good idea to me - on rare occasions I’ve accidentally switched from COM1 to COM2 when I bumped the switch inadvertantly (usually in turbulent conditions). Anyway, it turns out to be an easy enough option to set, but worthwhile only if your avionics person is “in there” anyway, otherwise it would be hard to justify the labor. Although it’s a small thing, I like it, and I’m glad I had it done.
IÂ’d better stop for now Â– thereÂ’s a limit to the amount of cra… er, data, the Internet can accept in one day.