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February
2011
Honey, We've
Lost the Prop!...
(A true, in-flight
emergency)
AN ENGINE FAILURE while
in flight is every pilot's nightmare.
Losing a prop, although the result is the
same, can be way more traumatic as
structural damage may occur, rendering
the aircraft uncontrollable. In
2006, the wooden prop on Marc Zeitlin's
COZY MKIV departed the aircraft while
flying over a California desert. One
of the tips was found embedded in a wing
tip, but fortunately no control loss was
experienced.
Still, Marc was faced
with landing a rather fragile,
high-performance airplane, without power,
in the middle of a desert wilderness.
He did everything right, his airplane
survived virtually intact. More
importantly, he and his wife are alive
today to share the tale. Told in
his words, here is that story.
BANG! Deanie said
"Oh my god - what was that?"
"I'm not
sure". I brought the throttle
back, noticed that the aircraft vibration
had almost completely disappeared, and
that we had started descending and
slowing. I pushed the throttle back
in. The RPM went up but there was
no change in vibration and there no
thrust from the prop.
"I think we lost the
prop. The propeller came off the
engine".
Deanie said, "Oh my
god - what are we going to do?"
"We're going
to land".
I slowed us down to Best
Glide speed and punched the
"Nearest" button on the GPS.
It told me that Desert Center (L64) was
17 NM almost directly ahead of us.
We were at 9500 ft., it was at ~500 ft.
ASL, and there were no hills/mountains in
the way. We also had about a
15 kt. tailwind. A quick
calculation of glide range determined
that we should get there with at least
1000 ft. to spare over the pattern
altitude of 1500 ft. At some point
in there I must have turned off the
autopilot to follow the GPS to L64, but I
don't remember doing it. All this
took about 15 - 30 seconds.
Deanie was asking if I
was going to call ATC. I said I'd
talk to them when I got a chance. Aviate,
navigate, communicate.
I spent the next 30
seconds playing with the throttle and the
controls to try to understand what had
happened and how the plane was doing.
Everything seemed to be working - the
engine was running, the numbers on the
gauges were good, and the plane was
flying fine. We were at 100 mph,
descending at about 600 fpm. No
thrust, though - although I couldn't see
the prop arc (or lack of it), I was
pretty convinced that the prop was gone.
Deanie was very upset,
but she was holding herself together and
letting me do what I had to do. I
spent a few seconds every minute or so
telling her that everything was OK - the
plane was flying, and we were going to
land at an airport.
After a minute or two, I
felt stable enough to get on the radio.
I tuned in 121.5 and said "Mayday,
Mayday, COZY N83MZ is 15 miles northwest
of Desert Center at 8500 ft. with engine
trouble. We're going to land at Desert
Center". An aircraft replied
(commercial jet, I believe) and relayed
our call to LA Center, who then responded
to us. They got all our info and
had us squawk 7700. They
asked for Souls on Board and our
intentions, and I told them that I
believed that we could make it to L64 and
land there.
Although I had asked
Deanie to look at the chart and give me
the field elevation, runway length, and
CTAF for L64 (more to give her something
to do than anything else), ATC read me
the info too. I dug out a pen and
Deanie wrote down LA Center's phone
number - they asked me to call them when
we were on the ground to let them know we
were safe.
We were getting closer to
L64 (and lower, obviously), and although
I could see Interstate 10 to the south, I
was having a little trouble finding Desert
Center. Deanie was still very
nervous and shaking, and I kept telling
her that everything was fine, we were
just going to make a normal landing.
I found the strip, picked a landing
direction, and we arrived over the field
at about 3500 ft. - 2000 ft. to spare.
Since we were high and had the field
made, I put the nose gear down so I
wouldn't have to think about it anymore.
Deanie was already
nervous enough, so I explained we would
come in high and I might have to slip to
get down, so if we get a bit sideways,
it's on purpose and OK. She knows
what a slip is. I did a standard
left pattern for runway 23, albeit high,
so I kept it a little wide. As I
turned base I thought I was still high.
I put the landing brake down, but after
about 10 seconds and turning final, I
brought it back up. There was a
touch of crosswind, but other than that
it was a completely normal approach and
landing. We touched down about 1000
ft. down the 4200 ft. runway and I rolled
to the end and off onto the single
taxiway.
We were on the ground and
safe. From the time of the
"BANG!" to rolling to a stop,
we had been in the air for approximately
12-13 minutes. Things happened
slowly - there was time to think, time to
evaluate, time to react, and time to
decide.
We unbuckled and hugged
for a couple of minutes - I told Deanie
that everything was OK - we were safe,
unhurt and on the ground (albeit pretty
much dead center in the middle of
nowhere). That was all that
mattered.
I got out of the plane
and called ATC to tell them we were on
the ground and safe, and to thank them
for their help.
I then gave the plane a
once over. Checking the engine, my
suspicion was correct - everything aft of
the prop was gone. No spinner, no
crush plate, no prop blades, no prop hub
- nada, zip, zilch, zero, nothing.
All six prop bolts had broken at the base
of the threaded portion deep within the
extension bushings. The threads
were all still in place in the bushings.
One bushing was
substantially deformed as the bolt tore
out - it must have been the last bolt to
go. A cursory view inside the cowl
didn't indicate any major damage.
As I was marveling at
this - the forces required to tear prop
bolt completely off, I happened to look
down the wing at the right winglet. I was
greeted by the view of a missing lower
winglet, as well as a chunk torn off the
trailing edge of the wing (and a tiny
corner of the aileron). As the prop
departed, it apparently took about 80% of
the right lower winglet with it. The
blade had torn off the trailing edge of
the wing just behind the rudder
cable conduit - 1/2" further forward
and I wouldn't have had a working rudder
on the right side.
I took the top cowl off -
as far as I could tell, there was
essentially no damage. Nothing
shook loose, nothing cracked, nothing
moved. I spent some time evaluating
the wingtip damage as well - we had flown
for 13 minutes like that, and I had no
inkling from the aircraft's performance
or behavior that anything was wrong.
Cause:
While my original theory
was that a blade broke, I'm now 99.99%
convinced that it was a prop bolt
torque issue. My big error in
judgment was in not landing at Twentynine
Palms, where there's an FBO, a town, and
which we were right over when the problem
manifested itself. (Well before the big
BANG, there were several periods of small
vibrations in the aircraft, corrected by
adjusting the power. ed.) The
decision to continue on and land at
Blythe was stupid, and could have cost us
far more than a lost day and an airplane
parked in the middle of nowhere. Deanie
has tried to make me feel better about it
by saying that we might have landed,
found nothing, and then had the prop
disappear as we were taking off, which
would have been worse.
Maybe so, but far more
likely is that by that time the problem
was large enough so that I would find
something and ground the plane in
civilization, with an intact wing and
winglet (and prop extension and spinner).
But I'll never know.
For the longer, original
description of this incident, you can go
to: Marc Zeitlin's website
http://www.cozybuilders.org/
Story and pictures
copyright : Marc Zeitlin.
Used with permission.
The communication between
ANOTHER pilot in trouble and ATC can be
heard here:
http://www.funplacestofly.com/blog.asp?ID=305
This
is worth listening to!
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