Backup for dropping the gear

"Andrew Gideon" wrote in message
online.com...
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.

I'm not sure there's enough standardization in gear retraction/extension
systems to say what's "normal". However, certainly the lack of redundancy
is common enough on light planes. In fact, not only is the gear on my
airplane designed similarly, the flaps and elevator trim use the same
hydraulic system. A failure in the hydraulic system that takes out certain
lines, and/or results in a loss of fluid would affect all three systems
simultaneously.

Occasionally you might find a "fail safe" system like the one on the Lance
that Paul mentions, but as he even points out, those systems come with their
own issues. Aircraft designers often come to the conclusion that the extra
complexity, cost, and weight isn't worth the marginal increase in safety.

Especially when one considers just how dangerous a gear-up landing *isn't*,
it's not hard to see why that conclusion is reached so often. As far as I
know, such "insufficiently redundant" systems are more common than
"sufficiently redundant" ones.

Pete

"Peter Duniho" wrote in message

I'm not sure there's enough standardization in gear retraction/extension
systems to say what's "normal". However, certainly the lack of redundancy
is common enough on light planes. In fact, not only is the gear on my
airplane designed similarly, the flaps and elevator trim use the same
hydraulic system. A failure in the hydraulic system that takes out
certain
lines, and/or results in a loss of fluid would affect all three systems
simultaneously.


I suppose you could also run the brakes off the same hydraulic system as the
gear, too. After all, if the gear fails you won't be needing any brakes. :-)

In article ,
"C J Campbell" wrote:


I suppose you could also run the brakes off the same hydraulic system as the
gear, too. After all, if the gear fails you won't be needing any brakes. :-)

The B-24 I used to fly is like that. Brakes, flaps, landing gear and
bombbay doors all on the same system. There is one engine driven pump
(#3 engine), an electric pump and a hand-pump. There are also 2
accumulators. If you have pressure in the accumulators you will have
one shot at the brakes...release the brakes and you release the
pressure. The copilot will be pumping like crazy on the handpump about
then. G The gear will freefall into position (the nose gear has to be
manually thrown out), and the flaps can be pumped down using the
handpump.

I only had one problem with the hydraulics. The main feed line from the
engine driven pump cracked at an elbow filling the bombbay with
hydraulic fluid...took less than a minute to pump all the fluid out
rendering us helpless. Luckily we had just landed and were taxiing to
parking when it failed. Mixtures to "cutoff" and coasted to a stop.
Had just enough time to say "WHEW!" before the airplane started rolling
backward due to a very slight grade on the taxiway. NOT a good feeling.
G The crewchief was scrambling trying to get out to throw himself
under the wheel as a chock when we came to a stop. If the crack had
opened just a minute or two before I probablyl would've parked the
airplane in the same gas station Southwest did a few years back.

--
Dale L. Falk

There is nothing - absolutely nothing - half so much worth doing
as simply messing around with airplanes.

http://home.gci.net/~sncdfalk/flying.html

"C J Campbell" wrote in message
...
I suppose you could also run the brakes off the same hydraulic system as
the
gear, too. After all, if the gear fails you won't be needing any brakes.
:-)

Well, actually...the brakes do use the same reservoir for their hydraulic
fluid. But all pressure for the brakes comes from the master brake
cylinders, not the hydraulic pump used for the other three systems. Only a
leak in the hydraulic line between the master and slave cylinders for the
brakes would cause any trouble with the brakes (by emptying out the brake
lines, along with the rest of the hydraulic system).

Again speaking only of light planes, I doubt there are any that use a
hydraulic pump to operate the brakes.

As for whether you'd need the brakes, I guess that depends on whether the
gear fails in the up position, or down.

Pete