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©2013 Mastery Flight Training, Inc. All rights reserved.
FLYING LESSONSFLYING LESSONS for December 19, 2013 suggested by
this week’s aircraft mishap reports FLYING LESSONS uses the past
week’s mishap reports to consider what might have contributed to
accidents, so you can make better decisions if you face similar
circumstances. In almost all cases design characteristics of a
specific make and model airplane have little direct bearing on the
possible causes of aircraft accidents, so apply these FLYING
LESSONS to any airplane you fly. Verify all technical information
before applying it to your aircraft or operation, with
manufacturers’ data and recommendations taking precedence. You are
pilot in command, and are ultimately responsible for the decisions
you make.
FLYING LESSONS is an independent product of MASTERY FLIGHT
TRAINING, INC. www.mastery-flight-training.com
This week’s lessons: I was flying a Beechcraft A36 Bonanza home
from Thanksgiving with my wife and our son aboard. Somewhere over
Indiana the Bonanza’s attitude indicator (AI) began to tumble.
The indications began slowly, but very soon the “artificial
horizon” (to use the archaic term) was pitching up and down in very
distracting oscillations.
Click on the photo or the link below to see video of the failure
indications.
See www.youtube.com/watch?v=SRwuiQ9Yus0
I immediately knew something was wrong, however, because the
airplane’s KFC225 autopilot—which references the AI—disconnected as
soon as the instrument’s gyroscope lost stabilization. Although the
Flight Director command bars remained elevated (making it look like
the autopilot might still be operating), the autopilot
disconnected. The AP annunciator extinguished and the Autopilot
Disconnect horn chirped.
The airplane was trimmed for level flight before the AI failed,
so it was still trimmed after—any loss of control would have been
entirely my fault. All I had to do was to keep from making gross
control inputs and the airplane’s natural pitch and yaw stability
would keep me upright and straight. The Bonanza is neutrally to
slightly negatively stable in roll, so it was important to keep the
wings level. I did so by holding heading with rudder instead of
trying to make small corrections with the yoke—this made my inputs
less likely to impact all three axes of flight, and the Beechcraft
aileron/rudder interconnect tended to coordinate small rudder
pressure inputs as well.
Four things were going for me (and my passengers): 1. I was in
visual meteorological conditions (VMC). Attitude control meant
looking outside
the airplane.
2. I regularly practice partial panel flight (flight by
reference to some, but not all of the basic instruments). This
keeps my scan sharp, and probably at least as importantly,
emphasizes the need for very light, very small inputs on the
controls in partial panel flight.
3. The A36’s heading indicator is electric, not air-driven. It
continued to work, making identification of the failed instrument
easier and partial panel control much less challenging.
4. The autopilot disconnect told me immediately that the gyro
had failed—or at least that something had changed and I needed to
find out what it was.
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©2013 Mastery Flight Training, Inc. All rights reserved.
A quick scan at the usual suspect, the gyroscope’s air source
(an instrument air pump in the case of this A36, a vacuum pump in
most light airplanes), revealed indications of normal air pressure.
The late-model Bonanza’s INSTR AIR light was not illuminated. It
appeared the gyroscope itself had failed, not the source that
drives it.
Regardless, and even though I was virtually certain it would
make no difference, I activated the airplane’s standby instrument
air pump. The STBY AIR annunciator lit up, and the instrument air
gauge showed a very slight uptick in pressure—both expected
indications. Also as expected, nothing changed with the AI. The
wild gyro oscillations, as seen in the video, continued. I turned
off the back-up air pump.
That’s easy to fix. I always fly with a stack of “sticky notes”
handy for a number of purposes. One is to quickly cover up a failed
instrument. Look again at the video, then see this picture (right)
to see how much easier it is to fly “partial panel” without the
distraction of the gyrating gyro. See
www.youtube.com/watch?v=SRwuiQ9Yus0
CAUTION: I don’t use the standard “soap dish”-style instrument
covers. One of my former supervisors found out the hard way that
the glass in the face of some AIs is thin enough that a good push
to stick on the “soap dish” can break the instrument glass. The
Federal Air Regulations required a report to Air Traffic Control
and terminating flight when it was no longer equipped for the type
of flight operation (in this case, IFR). The airplane’s Limitations
also require a functioning AI for IFR flight. Luckily, I was in
very clear skies and flying directly toward the center of a dry
high pressure system. I called up the satellite imagery on my
Garmin 796 hand-held and confirmed there wasn’t a cloud in the sky
between my position and home. I continued the trip home VFR.
Not working in our favor: the airplane did not have a back-up
attitude indicator and the attitude-based autopilot was
functionally unable to re-engage. In a real pinch I could have
called up a synthetic vision presentation on the 796, at least for
basic attitudinal orientation.
An FAA/AOPA report tells us we don’t do all that well at
identifying failed instruments, or flying by reference to a partial
panel after an instrument quits. See
www.thomaspturner.net/FAA%20Partial%20Panel%20Performance%20Study.pdf
There is no checklist for “attitude indicator failure” in the
A36’s Pilot’s Operating Handbook. It’s unlikely one exists in the
handbook for the airplane you’re flying. This is one of those
things we’re expected to consider ahead of time to develop a course
of action. Your personalized checklist might include, however:
1. Maintain control of the airplane. Do not retrim unless you
(or the autopilot) was retrimming at the time the failure occurred.
Keep the trim set until you need to change it with a change in
flight conditions. Use very light control inputs and limit use of
the ailerons.
2. If you have an autopilot and it’s still working, use it.
Right or wrong, we IFR pilots often pride ourselves on our ability
to fly partial panel so much that we’re unwilling to do the one
thing that will save our lives—turn on the autopilot. Don’t be a
hero. Use it.
3. Identify the failed instrument. Crosscheck supporting
instruments to determine which, if any, has/have failed.
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©2013 Mastery Flight Training, Inc. All rights reserved.
4. Confirm the failure. Check other indications, such as an
instrument air pressure or vacuum gauge, or electrical indicators
with electrical instruments. If you need more help to confirm,
smoothly level the wings by reference to the attitude indicator.
Then check the turn coordinator/turn and bank, and the heading
indicator. If two indicators agree then it’s a good bet the third
has failed.
5. Cover the failed instrument. Remove the distraction of a dead
or wobbly indicator.
6. Use backups, if available. Activate backup instrument air or
electrical sources. Switch your scan to backup instrumentation if
you have it and it’s placed within your primary scan. Don’t forget
“unofficial” aids, like GPS for heading and handhelds, even your
iPad, for attitude.
7. Use known combinations of power, flaps and gear position, and
as best as possible, pitch attitudes to cautiously control the
airplane through the remainder of your flight. Aerodynamics don’t
care what an attitude indicator or other failed instrument says—the
aircraft will still respond predictably to changes in power,
configuration and attitude.
8. If you’re in VMC, stay in VMC, even if that means going well
out of your way to land.
9. If you’re in IMC, aim for VMC. Again, don’t be a hero. Aim
for clear skies. For U.S. pilots, FAR 91.7 virtually requires
it.
See
www.ecfr.gov/cgi-bin/text-idx?c=ecfr&sid=3efaad1b0a259d4e48f1150a34d1aa77&rgn=div5&view=text&node=14:2.0.1.3.10&idno=14#14:2.0.1.3.10.1.4.2
10. If you can’t remain in VMC, declare an emergency. Take any and
all help you can get
to make a safe arrival at the nearest airport with above-minimum
weather (the higher the better). Choose an approach with vertical
guidance to help you fly your approach (this is much more common
now with the proliferation of approach-certified GPS).
Before an instrument fails, prepare for your passengers’ (and
your) survival: • Know how your instruments are powered, and how to
operate the back-ups that exist in
the aircraft you’ll fly. See Section VII, Systems Description,
of the POH if one exists for the aircraft.
• Know the requirements and failures modes of any autopilot on
board, including which instruments are sensed for what autopilot
modes and what autopilot degradation occurs with each type of
instrument failure. Read the autopilot supplement to the POH.
• Know precisely the effect changes in power, flaps and (as
applicable) landing gear position, and pitch attitude have on
airspeed and rate of descent or climb. Commit these numbers to
memory, and use them if your ability to monitor performance through
the flight instruments is degraded.
• Faithfully conduct the Before Takeoff operational checks of
your flight instruments, and terminate flight before it starts if
an instrument doesn’t pass inspection.
• Regularly practice partial panel flight with a safety pilot or
flight instructor. The cost of an hour of instruction every six
months or so is much less than the expense of adding back-up
instrumentation to an airplane, and may be worth much more in an
emergency. It may be your only option if you are not sole owner of
the airplane(s) you fly.
• Keep sticky notes or some other instrument cover immediately
at hand, to cover up a distracting failed instrument or
instruments.
Surviving instrument failure in flight, especially at night
and/or in instrument meteorological conditions (IMC), is a matter
of being ready for the event before it happens—not waiting until
the failure occurs to see how good you are. Comments?
[email protected]
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Debrief: Readers write about recent FLYING LESSONS: FLYING
LESSONS cheerleader (I mean that in a good way) Bill Caton
writes:
Another great issue!! I particularly like the last section on
go/no go decisions. To me, this is the most stressful part of
flying. Susan and I are flying to Palm Springs 12/31 with a
stopover in Phoenix Goodyear airport for the Baylor Fiesta Bowl
game. Tickets and hotel have been purchased. I started thinking
weather a day or so ago and how unpredictable it is this time of
year. Fortunately we will be travelling to a part of the country
where better weather is more consistent. This article is a great
reminder that no risk is worth it for a game. The game is the only
thing with a hard deadline.
I hope it all comes together for you and Susan, Bill. Yes, we’ll
be exploring ways to stack the deck as much as possible toward “go”
with preflight planning and preparation, in upcoming editions of
FLYING LESSONS Weekly.
Reader Ed Bodkin chimes in:
Tom, I have been flying for 45 years. USMC, American Airlines,
and now a Baron 58. I like your approach to flying... Common Sense!
Belly Barometer. This is a business fraught with rules, nuances
etc., most of which I can’t remember. If it feels bad, appears to
be stupid, it probably is! Keep up the good work.
Thanks, Ed! We’ll get to more Debrief items next time.
“Great investment, Tom! Thanks for all you do!!”—Don Bowles
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Thank you, generous supporters
Merry Christmas to all who observe, and happy holidays and best
wishes for a new year filled with enjoyable and safe flying to all.
Thanks very much for your Debrief comments, your kind words and
your support each week, both moral and financial. It makes doing
this worth it.—tt
Share safer skies. Forward FLYING LESSONS to a friend.
Personal Aviation: Freedom. Choices. Responsibility. Thomas P.
Turner, M.S. Aviation Safety, MCFI 2010 National FAA Safety Team
Representative of the Year 2008 FAA Central Region CFI of the
Year
FLYING LESSONS is ©2013 Mastery Flight Training, Inc. Copyright
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