Another dead stick landing. Same old causes.
Fortunately no fatalities....this time.
Let's pretend you are the copilot. You've been
flying along for 10 minutes. When the pilot says: "Hey Bob, how about giving me
150 times as much fuel right now." You'd say:"WHAT?!! You are crazy,
that will shut down the engine!"
Pilot:" Oops, my bad. O2 and egt's are normal. My
mistake"
Does that sound far fetched? Nope. It happens a
couple times a year. Often it's a case where the pilot inadvertently drives the
ecu to super lean condition. Engines suddenly quits. Let's use your home pc
as an example. You tell the pc to delete all files on your hard drive. It
recognizes this is most unusual and could be catastrophic. So it says:"Are you
sure you want to wipe out hard drive? This could be fatal"
Every failure has more than one cause. Yes, the
pilot inadvertently flipped the "cold start" switch when he was reaching for his
gps. Was it Ed last year who inadvertently rotated the mixture to full
lean? Last year Keith's passenger bumped the ecu mixture knob while
getting in the plane. So, yes, Ed, Keith, and Dave all made the same
mistakes. They placed a switch capable of shutting down the engine in the wrong
area of the instrument panel. End of story? NO!
As soon as one of these ECU suppliers adds the "Are
you sure?" logic, then all of these failures disappear. Pretty simple logic
statement. Actually, there are a whole bunch of ways this can be handled. I had
to do this type of programming with industrial plc's because these same "oops"
were so common. Think about this. If engine has been running for more than 5
minutes, only allow small mixture changes. Never enough to shut down engine. So
let's say that 100 will shut down engine, then we only allow a change of 20 each
minute.
I think the ECU providers recognize builder error.
"Whew! Not MY problem." They don't ask: "Is there something I can do to
save lives?" If they make these simple changes, then every single
plane is no longer sensitive to these common "oops" scenarios. So yes,
if Dave moves his switch, HE will be safer. But if the ECU supplier makes
this simple programming change, then every single plane will be safer. Real
world mistakes will no longer shut down the engine.
I want these suppliers to be successful. I want
fewer plane crashes. But it's not going to happen unless you guys (privately)
encourage these simple changes.
This group is making good progress on failure
reduction. There are a handful of ecu changes that will really make a
difference. Please pursue! Question question question.
-al wick
----- Original Message -----
Sent: Sunday, March 14, 2010 7:10
AM
Subject: [FlyRotary] Re: Ut-Oh...
I know Dave or Jon wouldn't phrase it this way but I've already
received a number of messages from others about these two recent in-flight
power failures due to EC2 issues.
Jon's was due to a loose
mounting nut inside the EC2 that shorted the main power input filter to ground
and burned open both foils from the 2 power input pins. How lucky was
that.
Anyway, at the risk of sounding defensive, I thought I'd
share my response to one of them that suggested changing the EC2 case to an
external mount of some sort. I'm sure there are scores of messages on
the way urging me to place switch guards on the cold start switch :
)
REPLY
Hello ----------
I'm aware of the failure and
have the unit here for repair.
Like a thousand other
critical details in building an aircraft, it is not possible to explicitly
spell out all of them. The precise method and hardware used to
accomplish it are not part of the EC2 or the instructions. The first paragraph
of the installation guide does say the following:
"Needless to say,
the quality of installation is just as important as the quality of the
hardware itself. It is not practical to include a course on
proper electrical wiring practices in these installation instructions, but it
is imperative that proper wiring techniques be employed during the
installation of the EC2."
It was my thought that avoiding the presence
of loose metal objects inside an electrical device that your life depends on
fell into the category of "needless to say".
Nevertheless, a
cautionary note might well be worth adding. As also stated in the
first paragraph of the instructions,
" I want your project to
succeed and your life to be a long and happy one. "