jimosborn

Dunno about the seat-belt airbag but be aware that AoA systems DO NOT require an STC, not even field approval for the install; only a logbook entry by any A&P. Took 'em a while but FAA finally figured it out and got that one right. Please read the FAA Letter of Clarification Cheers!

Jose, with due respect (and I say that with all sincerity) your understanding of AoA is exactly backwards. Unfortunately what you DON'T know about AoA is stunning, and that's not a put-down; rather it's that your education in very basic aerodynamics regarding angle of attack is sorely deficient. Please, please, for the sake of yourself and your loved ones, do spend some time to truly study the relationship between airspeed, wing loading and AoA. With respect to AoA devices, just two weeks ago the FAA sent out a general aviation safety “fact sheet” identifying several technologies the agency says can help significantly curb the fatal accident rate. The top two devices named are seat-belt airbags and angle-of-attack indicators. Too, a liberal education on the subject is available here; http://www.ballyshannon.com/aoa.html Cheers!

Here's a Strength of Materials chart originally published by Pratt & Whitney in "The Aircraft Engine", included in (and lifted from) John Deakin's "Pelican's Perch #18" on AvWeb. http://www.avweb.com/news/pelican/182084-1.htm Puts into perspective why it is so important to maintain CHTs below 400dF for long cylinder life. CHEERS!

Glad to hear the mag issues are resolved, Gary, and that she's running better than ever. I sure expected some noticeable CHT improvement with proper timing though. Not sure how much difference changing the plugs will make but from my own experience with leaking baffles I suspect replacing the front doghouse baffling will yield a remarkable improvement in CHT..... chip, chip, chip away! Do keep us informed of your progress; inquiring minds and all that! Cheers!

Gary, any news on your CHT issue after getting the mag problem straightened out? Cheers!

Holy Mackerel, that's incredible.... just jaw dropping incredible! No wonder you and we who've weighed in on the subject have been scratching heads! Does makes me feel a little better for sermonizing about a possible timing issue though. Sounds like your A&P is a whole bunch smarter than the so-called mechanic who did the mags earlier. Hope the entire CHT issue is then resolved, and we're looking forward to hearing the results. Cheers!

Gary, have you had a chance to fly and evaluate your CHT situation since re-timing, including a JPI download? Cheers!

I believe GAMI considers a spread greater than .5 to be prime a candidate for their unique fix. A spread of .2 or .3 is rather common after installing GAMIs in the IO-550 engine. Based on my experience with them in a P-Baron, I'll give GAMI a five-star rating. Cheers!.

Gary, it will indeed be interesting to see the difference after re-timing. Do you know if your A&P is using a digital timing device? I ask because those are infinitely more accurate than other methods, particularly so is using the fairly new and simpler to use Rite-Systems kit -- http://www.ritesystem.net/index.htm Too, 17o & 18o BTC is quite retarded from 25o factory specs, thus I'd expect to see much higher EGTs and lower CHTs than yours show - exactly opposite of what I thought was going on in your situation - therefore my specific curiosity about how timing is being measured. Regardless of method, if you've not seen it done before and have opportunity to be there, it will be quite educational to observe the mag timing exercise in process. Cheers!

Beyond assuring that your very expensive 930 is correct in all parameters, who really cares about % HP? Seriously...... MP, RPM, FF, CHT sure, but knowing the percent of horsepower that a given power setting produces has no practical value! My approach is to find the sweet spot for current conditions and fly that. Cheers

Palm Beach Area Code is 561 Cheers!

Guys & gals; There's a wonderful article by John Deakin posted on AvWeb in his "Pelican's Perch #18" titled "Mixture Magic" that deals with the entire combustion subject - fuel, timing etc. It's a hugely important tutorial for pilots all. Among other essential learning it contains a graph depicting what happens to cylinder materials when overheated - sobering stuff for those routinely seeing temps above 400oF. Enjoy the class! http://www.avweb.com/news/pelican/182084-1.html Cheers!

Cheers! Jim

Wow Kurt, those extremely high CHTs are horrible; no wonder you were near panic. 14 gph, full rich, WOT for a 180 hp engine is quite low; should be more like 16 -18 gph. Too, a properly set up fuel delivery system should yield EGTs in the neighborhood of 1200o - 1300o F. What kind of EGTs were you seeing both today and in those earlier scenarios? Good that you are having timing looked at. Surprisingly small advances in mag timing affects CHT adversely, yet timing seems a too frequently ignored troubleshooting item. Hope you get it all straightened out soon.... and please share your findings. Cheers

Cheers. Jim Osborn

Sean: I think you're right about way too lean! I don't have actual specs but can vouch for Mike's 250 ROP recommendation as being bankable. Too, target EGT at that point should be somewhere in the 1250o to 1300o range. Now all this is predicated on proper fuel flow setup, which for your engine @ SL, WOT, 2700rpm should be about 18 gph - or a bit less but not less than 16 gph . Do you have a FF indicator to validate that? Symptoms at first-glance suggest low fuel flow as the prime suspect But conflictingly your comment about fouled plugs during taxi suggests FF being amply rich. If amply rich, we are then alerted to the possibility of magneto timing being too far advanced, which will always be reflected in higher than normal CHT and lower than normal EGT. TCDS E-286 specifies 25o BTC for the O-360-A1D engine. Cheers

Actually Alpha Systems does offer an optional heated mast; I know Fred Scott has it on his King Air.

Definitely not just you, Jim. Ercoupe is a very nice little airplane, one having architectural balance that Mooney destroyed with the single tail design. Too, when you consider that Ercoupe went into production prewar 1940, it was far and away more modern than any competitor of the era... all metal, low wing (fabric covered), trailing-link tricycle landing gear, side-by-side seating, nearly 360o visibility, wheel vs. stick control, and stall/spin resistant. Then of course its famous totally integrated flight controls, sans rudder pedals. With all that innovation I guess we could comfortably say that for his time designer Fred Weick was every bit as visionary as people like Burt Rutan is in ours.

Jose; if I correctly understand your question, you are attempting to determine CG range for M20K at weights above 2900 lbs when MGTOW has been increased to 3130 lbs; is that correct? If so, the short answer is +44.74 to +49.30. Dunno why it isn't addressed in the TCDS but the calculation is fairly straight forward. AFT CG is fixed at 49.3 regardless of weight, so the problem is to determine FWD CG slope at weights above 2900 lbs. In other words, how much further aft is the FWD CG limit at 3130 lbs, than it is at 2900 lbs? First we need to determine the existing slope profile based on straight-line variation, per TCDS instruction; to wit: FWD CG Limit @ 2900 lbs = +43.5 FWD CG Limit @ 2360 lbs = +40.6 Normal Slope 540 lbs + 2.9 variation Divide 2.9 by 540 = .00537 per lb weight gain, multiply by 230 lb total wt. gain = +1.235 slope continuum to 3130 lbs, thus...... FWD CG Limit @ 2900 lbs = +43.500 Slope continuum to 3130 lbs = + 1.235 New FWD CG @ 3130 lbs = +44.735 = MGTOW CG range +44.74 to +49.30. Hope this answers your question, Jose. Perhaps someone will create and post a graphic spreadsheet on this. Cheers

Gary, glad to hear of some progress. You sure had an interesting experience with the separated MAP line... appreciated seeing #25 JPI download, about which I posted a few thoughts. BTW, what was your cruise FF and altitude during that event? Further to musing your CHT issue, if you are inclined to post them I'd like also to see JPI data from the two previous flights, plus #26 if and when that comes about... including FF and ALT for those as well. Cheers!

Slow flight, but not at all on the edge of stall, nor is calibration imprecise... the one-time baseline calibration procedure is designed strictly to define Optimum Angle of Attack (OAA) and consists of determining the point at which, at any given power setting, the airplane is neither climbing or descending. The logic, as I understand it, is that this establishes a data point from which actual stall AOA plus every other user-defined calibration point will be accurate within a very narrow range, regardless of weight, wing loading etc. Moreover, the user may redefine his/her calibration points at will. Aural alerts (especially "Slow Sarah" sweetly saying "getting slow"... whenever that's the case) are exclusive to Alpha Systems electronic units, and in my opinion, a truly immeasurable safety feature since the single most common - and deadly - aspect of stall-spin accidents is distraction. Cheers!

Oscar, sorry I don't have the Alpha Systems install manual handy, but in situations like you describe I recall there are instructions that allow elongating the mounting slot if that becomes necessary. It shouldn't be at all difficult to do; just make sure that everything else has been done in sequence and the system is ready for calibration. Cheers!

Norbert, there has been a huge amount of information on AoA for GA published within the past two years, largely the result of research and mentoring by Fred Scott from VA and Tom Rosen from CA who were motivated to take up the mantle and "do something" by the loss of two close friends each, veteran pilots all, who succumbed to turn-to-final stall spin accidents. In collaboration with Mark Korin of Alpha Systems, AOPA Safety Foundation, FAA and a host of volunteer professionals, including retired professor Dr. David Rogers who taught at the Naval Academy and is intimately familiar with Aerodynamics for Naval Aviators, Fred & Tom embarked on a mission to educate and encourage the use of AoA by the GA community. Inasmuch as Fred and Tom are both Beech owners (King Air and Bonanza respectively), most of this has been posted on Beech-Talk and Beech-list.org forums. Here's the link to Fred's website with many subjects internally cross-linked. http://www.ballyshannon.com/aoa.html Welcome, and congratulations on your timely interest in the world of practical AoA systems. Jim Osborn

Guys and Gals: Don't miss the HUGE significance of what happened immediately afterwards. Per Gary's JPI download, at time 57:18 #1 EGT was running 1307o. After the MAP tube separated, EGT peaked at 1467o; a full 160o hotter than cruise, which means the engine previously had been operating at least 160o ROP. Then, less than one minute later @ 58:48, notice that EGT dropped 54o below peak; meaning it was then running 54o lean of peak (LOP)....... from that point forward, and with no apparent change in power setting until descending, CHTs steadily shed nearly 100o. Again... with NO power changes beyond un-commanded leaning caused by a blown MAP line that's piped into the induction system! Now if there be skeptics regarding the value of LOP in terms of better engine health (cooler, cleaner, leaner), then one need look no further than this graphical evidence for a favorable reading, brought about in this case by mechanical happenstance. Cheers folks.