Backup for dropping the gear

There are a lot of things that are not redundant.

The lesson to learn is to know the systems of your plane very, very, well.
This is not an easy task, nor is it common between planes.

You should know all the systems, and the what-if scenarios that go with
them. This includes the mechanical systems. Like how the cables and
pushrods are run through the plane.

For example: What if you pump down the gear but do not get a green
light? Do you cycle the gear? Answer - it depends. You need to give
thought to the possibility that cycling the gear may lose what little
hydraulic fluid you have left. When the hydraulic system runs more
than one thing, you need to worry about what else you might lose.
There is no one pat answer that fits all planes. Reading the emergency
procedures is great - except the emergency procedures have difficulty
determining which combination of failures has happened. You really
need to understand the systems.




In article ne.com, Andrew
Gideon wrote:
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I've been reading the POH for my club's 182RG, and I find myself surprised.
The manual gear extension replies upon the same hydrolic pressure system as
the powered mechanism.

Isn't that insufficiently redundant?

I'm not sure what I expected - perhaps something purely mechanical. But I
didn't expect a lone pressure system to be a single point of failure.

Is this normal?

- Andrew

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"d b" wrote in message
ink.net...

You should know all the systems, and the what-if scenarios that go with
them. This includes the mechanical systems. Like how the cables and
pushrods are run through the plane.

Reminds me of a story about the Aztec, on which I did my inital MEP
training.

The procedures go something like this:

To extend the gear, you move the gear selector lever to "down".

In case of failure of the engine-driven hydraulic pump:
1. move the gear selector lever to "down"
2. Extend handle of manual backup pump
3. Pump mumble times to extend gear
4. Stow handle

In case of failure of the hydraulic system
1. move the gear selector lever to "down"
2. actuate the emergency gear extension system
(AFAIR that releases something and the gear drops under gravity)

Not just one backup, but two! But I've only heard of one undercarriage
incident with the aircraft: As the pilot retracted the gear, the gear
selector lever came off in his hand, detaching at a point behind the
panel...

Julian Scarfe

"Julian Scarfe" writes:

In case of failure of the hydraulic system
1. move the gear selector lever to "down"
2. actuate the emergency gear extension system
(AFAIR that releases something and the gear drops under gravity)

"actuate" here means "reach under the left seat, flip up the door, and
yank the ring(?)". It causes CO2 to be released from a small tank into
the hydraulic system, making a mess and eliminating further worries
about what to do with the gear or flaps. Gravity plays a minor role.

Realize also that the Aztec is somewhat unique in that it can land and
roll out on retracted gear. Sure, you'll be replacing lots of stuff as
a result but at least it'll roll instead of skid.

--kyler

"Julian Scarfe" writes:

In case of failure of the hydraulic system
1. move the gear selector lever to "down"
2. actuate the emergency gear extension system
(AFAIR that releases something and the gear drops under gravity)

"Kyler Laird" wrote in message
...

"actuate" here means "reach under the left seat, flip up the door, and
yank the ring(?)". It causes CO2 to be released from a small tank into
the hydraulic system, making a mess and eliminating further worries
about what to do with the gear or flaps. Gravity plays a minor role.

That's the one. It did sound like a desperation measure.

Julian