Walter Atkinson, one of the APS (a/k/a GAMI) guys posted these comments on the Lancair Pilots (LOPA) Forums . Walter generously gave me permission to re-post his comments here.
In reply to:
<Re: engine efficiency w/FADEC>
It would be good to remember that to this date, no one has produced an internal combustion engine that has any better BSFC than the TCM and Lycoming engines we are currently using. Not GM, not Honda, not Toyota, not anyone. We complain about how old the technology is in these engines, but so far, there’s not a single gasoline auto engine that is as efficient.
That’s a fact.
FADEC is a remarkable achievment, but IMO, it falls short of being a viable option in aviation. You will lose a LOT of capability with FADEC.
In reply to:
<When asked to elaborate, this was his response>
Before I answer, let me say that I am very impressed with Aerosance’s achievement. It was no small task. In many ways they have made some impressive advances.
That said, and having read the installation manual and studied the trouble-shooting guide (6" thick publication) my educated opinion is that I think it is simply unworkable in the field. I am concerned that there are going to be darned few places where one will be able to get service on the system as it is now configured. It’s a migrain of electrical connections and has multiple failure points which will probably make the system have dispatchability problems
From an operational perspective, it is my educated opinion that they have missed the mark of usefulness. It runs ROP at high powers, and LOP at low powers. It doesn’t take advantage of the natural efficiency of the engine at optimal cruise powers.
At 75% power, an IOF-550 WILL burn 19.2 gph. PERIOD. The pilot can do nothing about it. At 65% power it will be SLOW because FADEC WILL run LOP at 65% and below. That will be slow. And, the pilot can do nothing about it.
I ask the Lancair crowd these questions:
Did you by a Lancair to go slow?
Are you happy with the range a fuel burn of 19.2 gph will give you if you want to go fast?
These are not my opinions. They are the facts taken directly from the FADEC manual. I have no choice but to take the FADEC manual at its word.
Very, very soon there will be a much better option which allows the pilot to retain full control. PRISM. Under PRISM a Lancair will be able to cruise at very, very high power settings on less fuel than we are currently using. I am very familiar with the system and have been flying at above 90% power for a number of hours during testing. George Braly has his engine at approx. 1500 hours that has been run at above 85% it’s entire life. Not a single cylinder has been changed and nothing other than routine maintenence has been preformed. At 1000 hours a teardown was done and all measurements were within NEW limits. It was simply re-assembled and it continues on.
FADEC will burn 19.2 gph to get 75% or 225 HP. PRISM will allow the same IO-550 to operate at 95% power on the same 19.2 gph with lower CHT’s! That’s 286 HP. It’s being done. A PRISM operated engine will produce 75% power on 15 gph.
The beauty of this is that the flying public will have a choice as to which they’d rather have. 225 HP on 19.2 gph or 225 HP on 15 gph. Not to mention the ability to cruise at much higher powers than heretofore unmanageable. Can you imagine how fast a Lancair IVP will be while producing 286 HP? WOW! And all the while with lower CHTs.
I’ve seen it work.
Disclaimer: I do not work for GAMI and have no business affiliation with them in any way. I have been privy to their research from the early stages.
FADEC is a fine accomplishment of engineering prowess. In my oinion, they’ve missed the operational mark and I fear those operating the system will have significant maintenance problems–even with the above-average A&P.
In reply to:
(the comments in astericks are quotes posted by Walter)
You only have to forget just once to enrichen the engine on decent .
That’s an interesting concern. I run my IO-550 LOP in cruise the vast majority of the time. I NEVER richen the mixture in the descent. I do not touch the mixture from LOP cruise, through the let-down, approach, and landing until I’m at the hangar ready to shut down. I’ve never had an engine quit from this practice.
I think a Cirrus did that and wound up in a field at the end of a “practice” power off situation.
Something else had to be wrong.
I would think that dependability of FADEC would be good. Electronic ignition has proven itself in other engines and with what they are having to go through to get certification makes me comfortable with FADEC.
What makes you think it will be dependable? It’s cetiabnlynot electronically simple. There are something on the order of 29 sensors and 165 electrical connections living in a hostile, under-cowl environmen. Automotive ignition systems are not like aircraft ignition systems in their specific needs. Besides, if your electronic ignition in you Honda quits, you just pull over. Certification has nothing to do with whether or not the system will do what the pilot needs or wants.
If short range when going fast is OK with you and being very slow when high in a NA airplane is OK with you, then FADEC will make you happy. If you choose fast, it will be very rich and the maintenance problems associated with that will be an issue.
If your major issue is a fear of the Reb Knob and you are not interested in learning how to manage the Red Knob properly, then you will likely be happy with TCM’s version of FADEC.
It certainly will apply to a segment of the pilot population. I’m just not in that segment. Time will tell if my maintenance concerns are unfounded. For ten grand PLUS installation (which, so far as I know, has only been successfully accomplished in Fairhope, Alabama) I’ll let someone else try it.
In reply to:
- Maybe I need to look harder but I just don’t see or hear anyone else so down on FADEC. *
Please understand, I am not DOWN on FADEC. This thing was designed by a bunch of really smart folks and they’ve done some really good work–in some ways.
OTOH, I was compelled to do more than just believe the advertising hype. It was my responsibility to learn about it. To study it. In doing so, I learned some things that are not mentioned in the advertising hype. There are other, much more significant concerns on my part about the system which I discussed with them directly. They have not addressed those concerns. Time will tell as to whether or not my concerns are ill-founded. To my knowledge, there are only a handfull of FADEC controlled airplanes in private hands. I only know of one Bonanza, the first airplane certified for FADEC.
As I said, it’s not for me in it’s current configuration. Three years ago, I told Steve Smith that I thought that in it’s current configuration it was unworkable in the field. I have seen nothing change which would disswade me from that opinion. That saddens me.
I’m not DOWN on FADEC; I am reasonably educated about it and have studied it’s operating parameters rather than just read the TCM print media ads. That is the basis for my opinion.
In reply to:
As you are aware, there are two separate issues concerning engine longevity and TCM’s recent problems.
There are some issues which NO amount of pilot input will affect. Exhaust valve assembly practices come to mind.
There are, indeed, things a pilot can do to extend the life of his engine and reduce maintenance costs. The primary thing he can do is manage the mixture in such a way as to limit the internal cylinder pressures. That alone seems to be the most important thing a pilot needs to understand.
The bad news is that requires a modicum of understanding and as you experienced, a willingness to study just a teeny bit!
This concept is not compatible with the desire to have one “accelerator pedal” in an airplane.
In reply to:
Let me try to use a little less bandwidth and answer several of you with one message.
- TCM injector tolerances are not very tight. In measuring ten sets of injectors at random, only 3 sets were found to have close enough FF tolerances to allow smooth LOP operation. That means that 70% of them are out of their own tolerance range.
Further, TCM has no ability to tweak nozzels like GAMI does. If they’re off, they can only send you a whole new set. Again, with a 30% chance that they will be adequate.
George Braly is one picky fellow. He is NOT going to release a Beta Version of PRISM. About six months ago, he had a revelation on how to reduce the entire system down to just a very few wires–thus reducing the failure modes and increasing the reliablity to something far better than any system we have ever seen. That improvement will be well worth the wait. The system is working. It is under certification testing now. Also, recently a new, more robust pressure tranducer design came available. The hold-up for some time was the FAA’s rules on Certification standards. To what level did it have to be certified?? The cost is expected to come in at about the same cost as maintaining a set of Bendix Mags to TBO.
PRISM is nothing like FADEC and doesn’t attempt to accomplish the same end. PRISM does one thing. It adjusts timing to control internal cylnder pressures. In doing so, it will not allow detonation to exist! It also will adjust the timing of each individual cylinder. This allows the pilot the FULL use of the mixture based on the mission requirements while protecting the engine from a ham-fisted pilot error. You simply will not be able to MAKE your engine detonate by screwing up. It will NOT allow it. All the while, the engine will continue to run. PRISM will allow higher takeoff HP and higher Cruise HP on less fuel as a result of maintaining the ThetaPP at the optimal point after top dead center. We demonstrate this during the class with an engine running on PRISM.
Ultimate Engines builds a very good engine. The way they re-do the valve geometry addresses the dreaded TCM VD (valve disease) problem and our experience is that long cylinder life is the happy result. I feel very comfortable and confident flying behind an Ultimate Engine. Ultimate offers an extended warranty to anyone who has attended the APS class and operates their engine according to our recomendations. That’s putting their money where our mouth is! They tell me that that has cost them ZERO, since the combiniation of their engine building methods and our operating techniques seems to result in excellent engine longevity.
Advanced Pilot Seminars is not owned by nor presented by GAMI. John Deakin nor I work for GAMI or own any stock in GAMI. APS is owned and presented by John Deakin, myself, and George Braly, (who is a principle in both). Tim Roehl at GAMI is kind enough to host the Seminars and allow us the use of the Carl Goulet Memorial Engine Test Facility during the classes (which we pay for). We are all good friends, and as such have close personal relationships—but it’s not a GAMI school! I wouldn’t want them to get blamed for me!
The exaust plumbing lives a tough life. BUT, the temperature of the exhaust plumbing is nowhere near the temperature of the exhaust gasses within. The pipes are hundreds of degrees cooler than the exhaust gasses. A thermal boundary layer protects the plumbing in the same way that a thermal boundary layer protects the cyinder fomr the 3500 degree combusiton gasses. The ceramic coating does seem to help keep the temperature under the cowl moderated somewhat. This could be a very good thing in a plastic airframe!
I hope this answered all of the issues asked of me in the above posts.
Thanks to Walter for this insight and his permission to re-post, and the Lancair Forum for provoding the venue, and John Deakin and George Braley for their landmark work in the LOP area and publicizing it.
