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