FADEC thoughts & details (long)

I just read the detailed article about FADEC in the 9/14/01 issue of GA News (“http://www.generalaviationnews.com/editorial/searchnews.lasso?-database=flyer_articles.fp5&-response=news_detail.html&-layout=web&-sortField=date&-sortOrder=descending&-sortField=time&-sortOrder=descending&-op=eq&author=James%20Wynbrandt&-maxRecords=1&-token.searchparms=%2523James%2520Wynbrandt%2523%2523%2523%252310%2523&-searchGiving Up Control” by James Wynbrandt, p.27). This article goes into quite a bit of detail about the operational aspects and tradeoffs of the Aerosance FADEC that will most likely be coming to a Cirrus near you soon. Anyone considering FADEC should definitely read that article.

I was initially gung ho about FADEC and have since regressed to just “gung.” The deletion of the “ho” is based on “giving up control,” thus I think the article is perfectly titled.

Let me preface this with my personal bias, which is that I personally like having lots to do in the airplane, and this includes managing power to meet my needs. IÂ’m going to kinda miss the prop control, gear, cowl flaps, etc. in my Bonanza 36, but I also recognize that there are a lot of times I wonÂ’t miss them at all. And those times (busy IFR) are important times. So can I give up the mixture control too?

IÂ’m a believer in running lean of peak EGT, with good experience with my IO-520 with GAMIjectors. It really does keep the CHTs down and definitely saves on gas, to the tune of 10% or so. So one question is does FADEC implement a lean of peak mode of operation?

Based on the article, I think not. The article states that there are two modes of operation, and these modes are based on RPM. The article states that if you are above 2300 RPM it figures you want best power and adjusts the fuel flow for that. Below 2300, it adjusts for best economy. This was on an IOF-550L (F=FADEC). Would the same threshold RPM and/or method apply for the IOF-550N on the SR22? DonÂ’t know.

The test aircraft had a manual prop control, but the article states that on new installations (as opposed to retrofits) that an “electronic propeller control” is part of the installation. Would this apply to the Cirrus or would the throttle/prop linkage or some other automatic RPM control be retained? DonÂ’t know.

There is also a 1 in. x 3 in. “health status annunciator” (HSA) installed in the panel. Where on the densely packed Cirrus panel would this annunciator live? DonÂ’t know.

A really nice feature is an engine diagnostics capability that “continuously captures CHT, EGT, fuel pressure, manifold pressure, voltage, RPM, percentage of power” and more. This can be downloaded into a laptop computer. Will this port be available? Will this data be available for display, perhaps on the Arnav? The article states they are “working with MFD manufacturers to display the FADEC data,” but will Arnav take $ out of their own pockets to implement the FADEC data rather than sell their own engine monitoring kits? DonÂ’t know.

Read the http://www.generalaviationnews.com/editorial/searchnews.lasso?-database=flyer_articles.fp5&-response=news_detail.html&-layout=web&-sortField=date&-sortOrder=descending&-sortField=time&-sortOrder=descending&-op=eq&author=James%20Wynbrandt&-maxRecords=1&-token.searchparms=%2523James%2520Wynbrandt%2523%2523%2523%252310%2523&-searcharticle (at www.generalaviationnews.com) and youÂ’ll probably come to the same conclusion that I did, which is that all the benefits outweigh the disadvantage of losing the mixture control. Given their stated cruise fuel savings of up to 15%, either they are running lean of peak or the efficiencies of the computer control at rich of peak operation still meet or beat manual lean of peak operation anyway.

Some other questions that are worth considering.

As Aerosance improves the system, will field upgrades be available that amount to chip replacements?

Will there be any access to the parameters in the system, much like automotive computer systems that can be fine-tuned by mechanics with the appropriate equipment and knowledge?

Finally, what becomes of the pneumonic “GUMP”? What are we left with in the Cirrus? Just “G” it seems! I can just see my passengers looking askance at me as I turn final and emit a few guttural “G” sounds.

One of the chief advantages of FADEC, I think, will be that manufacturers will no longer be able to blame engine problems on pilot technique. Now it’s their technique – hard-wired in.