----- Original Message -----
Sent: Wednesday, June
03, 2009 8:16 AM
Subject: [FlyRotary]
Incident No. 5119
Certainly not trying to “TOP”
Al’s door incident – by the way, good airman ship and decisions,
Al! Glad the damage was no worst that it was.
But several folks who were not at the Texas
Round up have asked about the “Ed’s Incident”. For
those of you who were at the roundup, you will probably want to skip this
repeat.
Incident No. 5119
One the way to Texas
I had an incident that ended up in with me and aircraft making a 7 mile engine-out
glide into Craig Field (Selma,
Alabama). Again – NO!
It was not fault of the engine or even the subsystems. But, the complete
answer is not provided until after my litany of the conditions and symptoms
– can you figure it out?
I took off on Thursday AM planning on
stopping in Mississippi
to join up with Charlie England and Tracy. After spending the night
there, we all three would head for Texas.
But, the weather (as you are aware) has been laying over the southeast for days
with rain and more rain – but I launched into it anyway as past Atlanta, GA
things were forecast to improve..
Other than dodging lines of clouds and a
bit of scud running, but not much, I landed at Alexandria
City to the southwest of Atlanta, GA
to take on fuel. I then climbed back in and fire it up and took
off.
I noticed that during climb-out the engine
would occasionally miss and thought the fuel might have had a bit of water in
it, but was not really concerned. So I fly on for approx another 45
minutes and had just passed Selma, Alabama and old Craig Air Force base, and turned west
toward Mississippi,
when more symptoms began to occur.
It started to act like a case of SAG
(fouled spark plugs) where the rpm will drop a bit – not dangerous - just
nerve racking. But, shortly things began to go beyond the SAG symptoms,
so I though I might have an injector problem (like one sticking open or not
opening at all). Since our injectors are in pairs, I tried turning off
one figuring if things got better, then that pair might have a bad injector.
So I turned off one pair and sure enough
the symptoms abated a bit (more on this later) so I figured I had a bad
injector in that pair. To be certain I turned this “bad” pair
back on and turn off the “good” pair expecting the symptoms to
really get bad as I would now be running on only the “bad” pair
– much to my surprise when I turned off the “good” pair
– the symptoms also abated. So that indicated it was not an
injector problem – but what?
About this time, I decided to turn the
aircraft back around toward Craig Field and dodging clouds headed back with the
engine progressively getting worst. It appeared to be a fuel problem (and
while that is ultimately the subsystem affected - it was not the root
cause). The fuel pressure was ranging from zero to 80 psi, other
electrical things were also misbehaving. I check the voltmeter thinking
perhaps the alternator had died – but it showed 14 volts. So back
to the fuel system.
Finally, the engine just stops with
the prop standing still - like a hood ornament, I’m at around 4500-5000
MSL at this point having lost some altitude dodging a cloud (good old GPS just
kept pointing to Craig Field). At that time I am 7 miles out from Craig
Field at 4500 msl with at stopped prop, a crippled seat cushion and a dry
mouth. Yes, I know I’ve been there before, but I don’t think
you ever get “use” to it. I recalled thinking things just
can’t get worst when they very shortly and suddenly - did.
I keyed the radio and made a call to Craig
Field at 4 miles on the GPS (I’m starting to get good at this) but before
I could get their reply, I heard a “CLANK”
(without the engine running you can hear things like that) like a relay
springing open (it was) and the entire panel goes dead!!!! No
radio, no engine instruments, not even a stinking LED was lit – only the
battery powered GPS. Can you spell “total electrical
failure?” Talk about a lonely feeling – amazing how
comforting having lights on and radio – you could almost convince
yourself this was just a practice engine-out landing, but not when the panel
goes dark. No engine gauges, no radio, nada!
Well not being one inclined to panic (but
I seriously considered it for a moment {:>)), I continued toward Craig field
– I mean like there were lots of other alternatives. Well Once
again I found myself in the “fortunate position” of being too high,
too much altitude. So I put in 40 degs of flaps to steepen my rate of descent.
But, then I decided this time that rather than do the 360 I had done on a previous
Incident to lose “excessive” altitude, I would try to glide - a
more or less - regular traffic pattern.
However, I neglected to remember to
retract the flaps. So I found myself on the downwind around mid-field at
pattern altitude (which felt normal) until I suddenly realized that you CAN NOT
maintain that pattern altitude without an engine!!! Duh!
I knew I could never make it to the far
end of the runway before turning base (toward the runway), so I started my turn
immediately, to make matters a bit worst - I had been paralleling the runway on
the downwind leg a bit too close – must have been the comforting feeling
of being close to safety. This position naturally required a tighter turn
and as I turned I saw I was likely to miss the runway and land in the grass. So
I though I need to steepen this turn further (this is called COFFIN CORNER),
but fortunately glanced at my airspeed indicator to see it only registering 80
MPH and my rate of descent (normally 400-500 feet per minute) up to over 1000
feet per minute. The seat cushion suddenly vanished from this universe.
But the REAL danger in this
situation, as you all know, is your airspeed gets low, you are in a steep bank
which greatly raises the stall speed - meaning at 80 mph you are close to
a stall in a steep turn while your are not in straight and level. So I
immediately straighten out of the turn – the little voice saying
“better to land in the grass than get their concrete runway all messed
up”. So the immediate danger of a stall was adverted, but I was
still pointed toward the ground with a sink rate twice as high as normal (and
I’ve manage a few hard landings even with a normal sink rate).
The hardest thing to do when you are
sinking at a 1000 fpm a couple hundred feet above the ground (with your nose
already pointed at the ground) is to push the stick forward steeping the dive
even more. But, I manage to do that and picked enough air speed and
energy to flair to a nice touch down – not even a bump. I’ve
always been amazed at what total concentration does to improve you landing
{:>).
Rolled to the end of the runway and had
energy to roll off onto the taxiway. Got out, check under the
aircraft for any evidence of leaks and started pulling the aircraft toward the
far –off – hangar which had an airplane parked in front of
it. A nice looking young woman comes riding a bicycle out to meet
me. Hopped off and holding out her hand said “Hi I’m Angie,
looks like we’ll be spending time together” – so things are
starting to look up {:>)
So pulled the aircraft in to the hangar
where the mechanic came over and ask what the problem was. Well, I looked
at the volt meter and it said the battery was dead. Mechanic put on a battery
charger and announced “Yep! The battery is dead”. So we both
concluded that the alternator must have failed and not being able to replenish
the drain on the battery by all the electrical systems such as fuel pumps,
injectors, ignition coils, etc had drained the battery.
However, there were a few problems with
the analysis of a failed alternator. First, the low voltage warning light
never came on to warn of an alternator problem, 2nd I never notice
the voltmeter showing anything other than what it should for alternator voltage
– like around 14 volts. While checking the voltage after the
Mechanic had charged the battery, I noticed down below that the
“essential bus” switch was in the battery rather than the
alternator position, so flicked it back to the alternator position figuring I
must have accidentally kicked it while getting to some stuff in the baggage
compartment of my RV-6A.
It was getting late and being a bit tired
not to mention stressed, I needed to get a rental car and a motel for the
night. Did that, eat dinner and went to bed after sitting down and
drawing out a problem tree with the entire major elements of the electrical
system.
So next morning I show up at the hangar
early and meet Ben, the mechanic, the battery had received a charge of only 45
minutes the evening before, So I suggested we charged it for another hour and
try to start the aircraft. Ben suggested a real stress test of the
battery and NOT charge it anymore. Made sense, so we rolled the aircraft
out of the hangar. I hopped in, threw a half dozen switches and punched
the starter button. The engine started on the first prop blade rotation
– so the battery was clearly OK.
The engine is humming like a top. So I looked over at the
voltmeter expecting it to show only around 12.8 volts instead of the 14 volts a
functioning alternator would produce. Much to my and Ben’s surprise
the alternator voltage read 14 volts. We loaded the alternator by turning
on the both l00 watt landing lights, all fuel pumps, the pitot heat, etc.
The alternator voltage only drops perhaps 0.4 volts clearly indicating the
alternator could carry the load and was OK.
So here I am – battery is OK, alternator is OK
– engine is purring normally, so clearly this was all a figment of my
deteriorating brain cells. I loaded up the aircraft and launched to do a
few circuits of the airport – I did so and all was operating normally and
so I radio them I was head onward to Texas.
While flying, my mind could not let go of the problem and finally the light
came on.
The essential bus switch had (for my
entire 10 + years of flying) been in the alternator position. The purpose
of this switch is to isolate the battery from the alternator should the
alternator fail - to prevent an alternator problem from draining the battery.
So in event of an alternator problem, you move the switch from alternator to
battery. Its call the essential bus because you only have the essential
things drawing from the battery so you wont’ drain it as quickly.
The idea is to give you time (generally around 30 minutes) to find a safe place
to land in case of alternator failure.
Well, at some point I had either (not
paying attention) turned the switch to battery thinking I was turning the
voltmeter switch to battery - or accidentally had move the switch from
alternator to battery without noticing it by kicking it, etc. However, it
was sort of protected in its position from accidental activation. It must have
happened during refueling – as I got approx 45 minutes down the road on
the battery after take off before quality battery time started to
deteriorate. As the battery voltage fell due to the load (and no
alternator link to replenish it), electrical things (mainly computers first)
started acting up until they could not longer run the engine. The injectors
would not open fully, etc. Then as the voltage level further decreased,
the master relay which the battery held closed and which connected the (fully
functional) alternator to the rest of the electrical system - opened up and
removed ALL power from the electrical system. So no radio, no gauges,
etc.
Oh, another little factor that may
have contributed, the voltmeter has a tiny toggle switch by it marked ALT BAT1
BAT2 for checking alternator battery 1 and battery 2 (which I no longer fly
with) voltages. Down below It a couple of inches and off to the right is
the essential bus normal size toggle switch – also marked ALT BAT1
BAT1. I normally never touch it and don’t even think about
it. But I could have reached for the voltmeter toggle thinking to check
my battery voltage (which I do as a regular thing) and perhaps distracted by
something reach a bit further down and instead moved the essential bus switch
from Alternator to Battery cause this entire event. I know that I did not
consciously do it. So it is either accidental or absence minded
activation - either way ends with the same results {:>)
Now it became clear why it didn’t
matter which pair of fuel injectors I turned off – turning off either
pair improved the situation because it slightly reduced the electrical load by
a few amps – and the engine ran slightly better for a few moments.
The same thing had happened when turning off one of the EFI fuel pumps –
but what threw me was the alternator voltage continued to be normal during this.
After I knew the cause (switch in wrong
position), I decided the problem was fixed so no reason to return to NC, and I
just continued on to Texas.
I know some of you may think that removing
my second battery was a mistake – but, consider this, having another
battery could have meant I would have been much further from a suitable
airfield before they both went south. On the other hand, it might have
caused me to at least think to throw the essential bus switch to the second
battery and have the Light bulb come on. Who really knows. But, I
have in mind a simply addition to my electrical circuit that should help in the
future.
I do want to state that this time when the
problems started I DID switch fuel tanks – but naturally it had no effect
because this time it turned out, it was not a fuel problem – not the root
cause at least.
So what are the lessons learned:
- Put
EVERY critical switch on your before-takeoff Check list
- Perhaps
put a guard around such critical switches to force conscious activation
- Don’t
(hard not to) get overly focused on what you think is the problem –
consider other possibilities. I thought it was a fuel problem (I
even switched fuel tanks this time) – it turned out to be electrical
in its root cause.
- While
the fuel pressure was jumping all over the place and the EGT was erratic
and engine surging strongly indicating a fuel problem – the ultimate
cause was electrical. Once the voltage got below a certain point the
EC2 was still trying to pull the injectors open, but with the voltage so
low it could not do it properly.
- When
the battery voltage dropped below a certain point, the master relay
released and removed the alternator from the electrical system and the
panel went dark – even though the alternator was still working
- Immediately
turn to the nearest airfield when serious problems occur - THEN work on
fixing them. I only delayed for perhaps 2-3 minutes, but that could
have made a difference.
- Watch
out for Coffin Corner turn
when turning base to final – airspeed really bleeds off fast with no
engine pulling you along (and especially with flaps deployed!)
- IF
you change your mind about landing approach type - remember to reconfigure
your aircraft for the last decision – I had left my flaps deployed
when I should have remembered to retracted them. Did that help
prevent a Coffin Corner stall and spin or would it have put me closer to
it?
- You
must increase airspeed over the wing to get the sufficient energy to over
come a high sink rate. Pulling back on the stick when the ground is
staring you in the face is the natural reaction – but, pushing
forward to lower the nose is the correct action – providing of
course you have sufficient altitude!
- Battery life –
I had a two year old 680 odyssey battery which I maintain a trickle charge
on whenever I’m not flying. With two EFI fuel pumps, boost
pump, injectors, coils, EC2 and radio and just having started the engine
before take off – this battery lasted 55 minutes. Well, the
last 5 minutes was not quality battery time. So in my case, 30
minutes appears to be a very realistic battery life. In fact, had I
turned off one EFI pump and the boost pump would have gained a few more
miles. But, if I had recognized the need to turn them off at that
time (I normally turn them off at cruise altitude), then I would have
known how to “fix” the problem.
- I’ve
decided to add a Schokkty diode between my essential bus and the
alternator – so that as long as the alternator is producing
sufficient voltage, then the battery will be getting some charge to
replace the drain. I’ve also decided to make that switch
position a check-list item.
So what it boils down to – if
I had recognized early on that it was an electrical problem and not focused so
much on the fuel system, I may have noticed the essential bus switch in the
wrong position. Force yourself to examine other possible causes (easy to
say – harder to do).
NEVER, NEVER forget that flying the
airplane is the first and only priority in this type of situation
NEVER, NEVER forget that saving your butt
is the ultimately end-all priority. When I decided that landing on the
grass was preferable to putting a hole in their concrete – I just may
have made a life-saving decision.
If anybody else wants to pick up this
baton – I’m ready to hand it over – what? no volunteers?
{:>)
So that’s my story and I’m
sticking to it.
Fly safe, guys!!
Ed
Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com
http://www.andersonee.com
http://www.dmack.net/mazda/index.html
http://www.flyrotary.com/
http://members.cox.net/rogersda/rotary/configs.htm#N494BW
http://www.rotaryaviation.com/Rotorhead%20Truth.htm