Piper Aztec F Model Dual Hydraulics(1976-1981) STC

[Keith]

I am interested in obtaining information about what is involved in
placing a hydraulic pump on the right engine in a Piper Aztec F
airplane that just has a single hydraulic pump on the left engine.
Specifically, who makes the kit for this and what are the approximate
hours needed to install . I would also appreciate knowing where I can
find information on the specific STC (Supplemental type Certificate).

Please respond via kw436 'at' hotmail.com

Thanks,
Keith

[Kyler Laird]

(Keith) writes:

>I am interested in obtaining information about what is involved in
>placing a hydraulic pump on the right engine in a Piper Aztec F
>airplane that just has a single hydraulic pump on the left engine.
>Specifically, who makes the kit for this and what are the approximate
>hours needed to install . I would also appreciate knowing where I can
>find information on the specific STC (Supplemental type Certificate).

http://google.com/search?q=PA-23+hydraulic+pump+stc

http://www.ecn.purdue.edu/~laird/flying/Aztec/ScottM/pa23_stc.html

Sierra Industries,Inc., P.O. Box 5184, Uvalde, TX 78802
http://www.sijet.com/main.htm

SA2442WE: Reissued 10/10/86.
PA-23-235, -23-250, -E23-250
Installation of dual hydraulic pump.


The Zee Company, Inc., 123 Braniff Drive, San Antonio, TX 78216

SA339SW: Reissued 9/20/77.
PA-23 Series
Electrical hydraulic pump.


--kyler

[Frank Ch. Eigler]

> I am interested in obtaining information about what is involved in
> placing a hydraulic pump on the right engine in a Piper Aztec F
> airplane that just has a single hydraulic pump on the left engine.
> [...]

Given the hand pump and CO2 backups for the Aztec's hydraulics, how
much benefit do you expect from a backup hydraulic pump? How
frequently do failures occur in light twins' hydraulic systems that
could have been prevented by a backup pump?

- FChE

[Kyler Laird]

(Frank Ch. Eigler) writes:

>Given the hand pump and CO2 backups for the Aztec's hydraulics, how
>much benefit do you expect from a backup hydraulic pump? How
>frequently do failures occur in light twins' hydraulic systems that
>could have been prevented by a backup pump?

Good questions. I don't know the answers but here are some things I've
considered when thinking about another pump for my Aztec...

The CO2 is a last-ditch measure. Once it's blown, that's it. I would
be very reluctant to use it not only because it makes a mess but also
because once it's used gear retraction is not an option. What if you
blow it and one of the mains doesn't lock? It can also be misused -
blow it without the gear handle down and that's it.

The hand pump takes a lot of effort. We've had several gear problems
and I'm the one who gets to pump the gear while it's on jacks. Even
leaned over at the most comfortable pumping position, it's not fun and
it takes a lot of effort to get it to lock.

Sure, either of these methods *can* work, but in a stressful situation
(which is what it's likely to be if you're doing this), it's an
additional problem - another link in a chain. I would hate to have to
do a single-engine go-around while pumping the gear.

I have shutdown my left engine and landed. It was "just" a turbo
problem but I opted to shut the engine off. (I disabled the turbo but
still had low turbo oil pressure and I didn't want to run it even with
the wastegate open.) I was high and had plenty of time to think about
things before landing in nice flat Kansas City. Compared to not
having any heat in the middle of winter, losing the engine was a minor
problem.

However...if I had been further along my route, into the Rockies,
landing at an unfamiliar airport with high surrounding terrain, this
would have been a little trickier.

BTW, I like the idea of an electric pump for the backup. Maybe that
is getting completely ridiculous, but if both engines do die, I'd
like to still have easy flap control.

--kyler

[[email protected]]

On Wed, 11 Feb 2004 10:47:31 GMT, (Keith)
wrote:

>
>I am interested in obtaining information about what is involved in
>placing a hydraulic pump on the right engine in a Piper Aztec F
>airplane that just has a single hydraulic pump on the left engine.
>Specifically, who makes the kit for this and what are the approximate
>hours needed to install . I would also appreciate knowing where I can
>find information on the specific STC (Supplemental type Certificate).

I'm pretty sure that it was a factory option, I sure don't recall
seeing an STC/337 in the records of the ones I worked on.

If you could get your hands on the original drawings/docs (on an Aztec
that can be iffy) and the OEM parts needed (even from a salvage yard
as need be) you don't need an STC. Just a basic logbook entry/w&b
revision.

TC