Would you cycle the gear?

I had an interesting experience the other day.

I was with a student in one of our club Arrows. We put the gear down
and got green lights for the 2 mains, but not for the nose.

The nose green light was flashing, as was the yellow "gear in transit"
light. Both were flashing about twice per second, and in opposition
(i.e. as the green went on, the yellow went off, and vice versa).

We ran the checklists in the POH, but did not try to cycle the gear. My
theory at the time was that since we had indication of both mains down
and locked, we should probably not mess with things any more.

On the one hand, cycling it might have fixed whatever was wrong.

On the other hand, what we had now (both mains down and locked) was not
only a survivable configuration, but one which would result in
relatively minor damage if the nose gear was indeed not locked (prop
strike). If something was jammed mechanically, cycling it could have
possibly resulted in no gear at all, or (worse) asymmetric extension).

We told the tower what was going on and requested a low pass so they
could look under the plane to see what was there. Tower reported all
three gear appeared to be down, so I just landed as gently as I could.
I was relieved when everything held together.

The maintenance people were unable to reproduce the problem and the
plane was returned to service. Best guess is a slight misalignment of
one of the limit switches.

What would you have done? Would you have cycled the gear hoping to fix
the problem, or would you have accepted the possible unlocked nosegear
in exchange for the known locked mains?

For those that are worried about such things, the outfall of our
declaring an emergency was about 2 minutes worth of paperwork. The fire
truck followed us to the ramp and the crew asked us a couple of
questions for their report. The tower also shut the runway until the
airport operations folks did a FOD inspection and declared it open again
(which must have taken all of about a minute).

"Roy Smith" wrote in message
...
I was with a student in one of our club Arrows. We put the gear down
and got green lights for the 2 mains, but not for the nose.
We told the tower what was going on and requested a low pass so they
could look under the plane to see what was there. Tower reported all
three gear appeared to be down, so I just landed as gently as I could.
I was relieved when everything held together.
What would you have done? Would you have cycled the gear hoping to fix
the problem, or would you have accepted the possible unlocked nosegear
in exchange for the known locked mains?

I'd have made the same decision as you - stick with what seems to be a
pretty good situation (instead of risking cycling the gear and ending up
worse off), get the tower to have a shufti at your dangly bits, and on
receiving a promising report from them, attempt a gentle approach, holding
the nose off for as long as is practical.

The only thing I'd be tempted to do in addition, assuming your airfield is
big enough, you're experienced enough, and there's enough time to make it a
reasonably safe manoeuvre, is to make a power-off, glide landing, and to get
the second pair of hands in the cockpit (in this case your student) to crank
the propeller with the starter so it's roughly horizontal and thus won't
bash the runway. A prop strike will generally shock-load the engine and
necessitate a complete strip down.

This said, the usual rules apply: if in doubt, take the approach that is
most likely to get you walk away from the "landing", and if that means
shock-loading the engine, so be it.

For those that are worried about such things, the outfall of our
declaring an emergency was about 2 minutes worth of paperwork. The fire
truck followed us to the ramp and the crew asked us a couple of
questions for their report. The tower also shut the runway until the
airport operations folks did a FOD inspection and declared it open again
(which must have taken all of about a minute).

First rule of declaring an emergency: never, ever be afraid to do it. The
ATC people would rather you promptly report something that turns out to be a
false alarm, as it gives them more time to figure out what to do with that
line of 767s that's coming up fast behind you than would be the case if you
landed with a nasty splat on only 66.67% of your wheels. And even if the
fire crew's talents aren't needed, they get a bit of training value out of
the exercise. Of course, if you do it three times a week because of poor
maintenance, they have the right to be peeved :-)

D.

David Cartwright wrote:



The only thing I'd be tempted to do in addition, assuming your airfield is
big enough, you're experienced enough, and there's enough time to make it a
reasonably safe manoeuvre, is to make a power-off, glide landing, and to get
the second pair of hands in the cockpit (in this case your student) to crank
the propeller with the starter so it's roughly horizontal and thus won't
bash the runway. A prop strike will generally shock-load the engine and
necessitate a complete strip down.

Have you ever actually attempted to stop the prop while in flight?

In article ,
Roy Smith wrote:
The nose green light was flashing, as was the yellow "gear in transit"

There were two options: Cycle the gear, and try an emergency extension.
There are so many different gear systems out there it's hard to say what
would help.

I'd say a bad limit switch is a reasonable guess, but I wouldn't be so
quick to rule out an actual failure to lock. Some tiny last bit of
travel to get a cam overcenter or a lock in place.

Hydraulic and combination electric/hydraulic runs the risk of running
out of fluid if there's a leak. That's the case in the Arrow, right?
On the other hand, isn't the fluid just there to hold the gear *up*? In
theory it should just fall down (spring assist?). Some of the big Cessnas
can 'blow' the gear down with compressed gas if the hydraulics run out.

My Comanche's gear is all mechanically interconnected, and there is only
one down light. If it didn't light my first thought would be to slow way
down and try again (slowing down is part of the emergency extension anyway),
and follow through on the manual extension lever to help the electric motor.
If I felt the downlock through the lever I'd be tempted to leave the motor
engaged, since it helps hold the gear in place, and there's likely not much
more I could do with the lever alone. You can't re-engage the motor in
the air, you have to jack it up. After the flight you probably install one
of those little parabolic mirrors on the left wingtip for checking the
gear (every PA-24 I've flown but my own has had one

The Mooney is similar to the Comanche (ie I see no harm in cycling it,
other than the battery drain, since those big motors draw more than the
alternator can continuously supply). My brief Mooney gear training did
not include any caveats about the manual extension being "weaker" than
electric extension, so I'd be tempted to try it. It's a cable you pull
sort of like starting a lawnmower, and you get a gear down indication
through a little window. You *can* go back to electric gear in the air
if you change your mind.

--
Ben Jackson

http://www.ben.com/

I was with a student in one of our club Arrows. We put the gear down
and got green lights for the 2 mains, but not for the nose.

The nose green light was flashing, as was the yellow "gear in transit"
light. Both were flashing about twice per second, and in opposition
(i.e. as the green went on, the yellow went off, and vice versa).

The maintenance people were unable to reproduce the problem and the
plane was returned to service. Best guess is a slight misalignment of
one of the limit switches.

What would you have done? Would you have cycled the gear hoping to fix
the problem, or would you have accepted the possible unlocked nosegear
in exchange for the known locked mains?

My experience with an Arrow is that it's usually a misallignment of the
microswitches which causes the 'gear not-locked' indication(s).

Something else to try is to use the emergency 'drop-gear' lever and
also some porpoising to nudge the wheel into the locked-position.

On Tue, 30 Mar 2004 11:09:45 -0700, MikeM wrote:


Have you ever actually attempted to stop the prop while in flight?

Yup. Was the proud holder of a student certificate at the time.

Did it a 2 1/2-year-old Malibu Mirage at an altitude of approx. 5 feet
AGL at the approach end of a 4000 ft runway. While I secured the
engine, and then held the nose off, the guy in the right seat reached
between my knees and bumped the prop.

Engine had a little over 6 hours SNEW. Wouldn't have attempted it by
myself (moot point, at that time, I wasn't insurable in it by myself).

No nose indication on downwind. Guys on the ground reported that it
looked like it was down and was pointing in the proper direction (nose
wheel rotates about 90 degrees during extension/retraction) Retracted
landing gear, right seater verified pump operation sounded "normal".

Made one extra circuit around the pattern with the emergency checklist
in my lap. Emergency extension per the checklist netted no nose
indication. Retracted landing gear, tried one more normal extension,
right seater again verified pump cycled on and off normally. Did a
pre-final approach briefing discussing precisely who was doing what
and when.

Had three green when the airplane coasted to a stop. Have absolutely
no idea when in the sequence of events during touchdown when the light
lit and the gear horn stopped blowing. CFII/ATP-rated pilot in the
right seat didn't either. While not legally PIC, I remained the
PilotOperatingTheControlsAndMakingAllTheDecisions.

If I would have been without experienced help in the other front seat,
there is no way I would have screwed around with trying to "save" the
engine/prop.

FWIW, in the Arrow scenario, if the nose gear looked good from the
ground, and the green light/in transit light was cycling as described,
I would have landed with no attempt to "cycle the gear", holding the
nose off.

If the three green lights aren't lit in an Arrow, the pump will be
running (accompanied by the in transit/pump light). Worn bushings in
the nose trunnion pivot/retract/extend/downlock assembly will often
first cause the "cycling" effect when turning a corner on the ground.
First time it happened to me (Fall of 1989 in a Turbo 'Toga SP) I'm
pretty sure I pee-ed a little.

When the pump light is lit, hydraulic pressure will indeed assist in
helping the nose gear stay extended.

TC

(Ben Jackson) wrote in news:Wljac.38295$JO3.30797@attbi_s04:

Hydraulic and combination electric/hydraulic runs the risk of running
out of fluid if there's a leak. That's the case in the Arrow, right?
On the other hand, isn't the fluid just there to hold the gear *up*?

Right. It's held up by hydraulic pressure, falls down by gravity and
spring assist (if the pump isn't working).

The nose gear is the most problematic, because it has less "free fall"
weight and more air resistance. Personally, I would have gone out of the
pattern and "played with it" a bit. Retract it, then drop it again at low
airspeed with a small pull-up right at the end. Unlike a Cessna 210 (for
example) if the pump is dying or the the fluid is leaking out, it's not
really going to get any worse.

But there *is* a small chance of mechanical damage that is limiting
transit, and it might jam. Of course, in that case, the nose gear probably
isn't locked now anyway.

NONE of that is to say that you decision was in any way incorrect. Any
such decision is a guess based on limited information and I believe either
choice is justified.

-----------------------------------------------
James M. Knox
TriSoft ph 512-385-0316
1109-A Shady Lane fax 512-366-4331
Austin, Tx 78721
-----------------------------------------------

Ahh, come on guys!
You go up to altitude and stall the airplane.
The reduced air pressure against the nose gear allows the spring and
gravity to force the gear forward.
If you still have a gear unsafe/in transit light, declare your emergency
and land as described.
This is common practice, though not publish, for some aircraft
(AeroCommander 112, for example).

I'm a bit confused. Why would you fail to follow the POH directions under
"Emergency Landing Gear Extension" in Section 4? For reference it says...

5. Reduce speed below 100 mph
6. Move landing gear selector switch to gear down position
7. If gear has failed to lock down, raise emergency gear lever to
"Override Engaged" position
8. If gear has still failed to lock down, move emergency gear lever to
"Emergency Down" position
9. If gear has still failed to lock down, yaw the airplane abruptly from
side to side with the rudder.

NOTE If all elctrical power has been lost, the landing gear m ust be
extended using the above emergency procedures. The landing gear position
indicator lights will not be operative.




"Roy Smith" wrote in message
...
I had an interesting experience the other day.

I was with a student in one of our club Arrows. We put the gear down
and got green lights for the 2 mains, but not for the nose.

The nose green light was flashing, as was the yellow "gear in transit"
light. Both were flashing about twice per second, and in opposition
(i.e. as the green went on, the yellow went off, and vice versa).

We ran the checklists in the POH, but did not try to cycle the gear. My
theory at the time was that since we had indication of both mains down
and locked, we should probably not mess with things any more.

On the one hand, cycling it might have fixed whatever was wrong.

On the other hand, what we had now (both mains down and locked) was not
only a survivable configuration, but one which would result in
relatively minor damage if the nose gear was indeed not locked (prop
strike). If something was jammed mechanically, cycling it could have
possibly resulted in no gear at all, or (worse) asymmetric extension).

We told the tower what was going on and requested a low pass so they
could look under the plane to see what was there. Tower reported all
three gear appeared to be down, so I just landed as gently as I could.
I was relieved when everything held together.

The maintenance people were unable to reproduce the problem and the
plane was returned to service. Best guess is a slight misalignment of
one of the limit switches.

What would you have done? Would you have cycled the gear hoping to fix
the problem, or would you have accepted the possible unlocked nosegear
in exchange for the known locked mains?

For those that are worried about such things, the outfall of our
declaring an emergency was about 2 minutes worth of paperwork. The fire
truck followed us to the ramp and the crew asked us a couple of
questions for their report. The tower also shut the runway until the
airport operations folks did a FOD inspection and declared it open again
(which must have taken all of about a minute).

In article %0ibc.61265$K91.149112@attbi_s02,
"William W. Plummer" wrote:

I'm a bit confused. Why would you fail to follow the POH directions under
"Emergency Landing Gear Extension" in Section 4?

We did indeed pull out the book and read those instructions. We
followed all of them except for the one which said to raise the
emergency gear lever. We had the mains down and locked and didn't want
to do anything which might compromise that.

Was that the right decision? In retrospect, I'm not sure, but that's
what we were thinking at the time.