backup for vacuum pump/attitude indicator failure

[Kelly]

I would be interested in getting opinions about backup systems for a
vacuum pump failure and/or AI failure. I have a 172P with a single
vacuum pump system, standard instruments otherwise, and a Garmin 430.
I am most concerned about having a good backup if I lose a vacuum pump
or AI in IMC. I have been thinking about either a Garmin 396/496 or
the electric AI available from Sporty's. Looks like I could get a 396
or installed electric AI for about the same price ($2200 or so). While
I haven't seen the panel page/"6-pack" page on the 396 or 496, I have
read (in Aviation Consumer) that it's good enough to keep control of
the airplane in an emergency situation. Obviously, the 396/496 has a
number of other neat features such as inflight weather, terrain info,
etc. Any suggestions on which way to go with this.

BTW, I had also considered the Precise Flight backup vacuum system for
a while, and it certainly is cheaper (around $700 installed). However,
I was concerned by the fact that it would do nothing for you in the
event of failure of the AI vs. the primary vacuum pump.

Thanks.
Kelly

[[email protected]]

: BTW, I had also considered the Precise Flight backup vacuum system for
: a while, and it certainly is cheaper (around $700 installed). However,
: I was concerned by the fact that it would do nothing for you in the
: event of failure of the AI vs. the primary vacuum pump.

The DG will still work though. In something like the 172 (or my Cherokee), that's a good chunk of the necessary gyro for IMC.

What about a non-TSO'd electric AI? Seems like one should be able to install one of those for backup purposes.

-Cory

--

************************************************** ***********************
* Cory Papenfuss, Ph.D., PPSEL-IA *
* Electrical Engineering *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

[Frank Ch. Eigler]

"Kelly" > writes:

> I would be interested in getting opinions about backup systems for a
> vacuum pump failure and/or AI failure. I have a 172P [...]

Considering the nature of the 172, you likely don't engage in too much
heavy duty IMC, so backup equipment could be of the "help me land now"
kind rather than "help me fly for a few hours more" kind.

> [...] While I haven't seen the panel page/"6-pack" page on the 396
> or 496, I have read (in Aviation Consumer) that it's good enough to
> keep control of the airplane in an emergency situation. [...]

You should also consider the iQue3600a, which has essentially the same
aviation features as the 396, at half the price, and with ground-side
utility as PDA and car GPS. (The other backup technologies you
mentioned have no separate ground utility.)

In any case, you should test it out. Borrow someone's
296/396/496/iQue or other portable aviation GPS, set it up in your
cockpit, go under the hood and do some partial-panel with a mostly
covered-up instrument panel. An hour or two might suffice.


- FChE

[Robert M. Gary]

I wouldn't bother with a backup vac system because its use is limited.
A backup pump won't cure a dead AI. I would buy the Sporty's backup AI.
For under $2K and next to no labor (just a couple power hookups ) you
get full, 100% AI redudency.

-Robert, CFII


Kelly wrote:
> I would be interested in getting opinions about backup systems for a
> vacuum pump failure and/or AI failure. I have a 172P with a single
> vacuum pump system, standard instruments otherwise, and a Garmin 430.
> I am most concerned about having a good backup if I lose a vacuum pump
> or AI in IMC. I have been thinking about either a Garmin 396/496 or
> the electric AI available from Sporty's. Looks like I could get a 396
> or installed electric AI for about the same price ($2200 or so). While
> I haven't seen the panel page/"6-pack" page on the 396 or 496, I have
> read (in Aviation Consumer) that it's good enough to keep control of
> the airplane in an emergency situation. Obviously, the 396/496 has a
> number of other neat features such as inflight weather, terrain info,
> etc. Any suggestions on which way to go with this.
>
> BTW, I had also considered the Precise Flight backup vacuum system for
> a while, and it certainly is cheaper (around $700 installed). However,
> I was concerned by the fact that it would do nothing for you in the
> event of failure of the AI vs. the primary vacuum pump.
>
> Thanks.
> Kelly

[Todd W. Deckard]

I would be skeptical that the derived attitude indications based on GPS
course, speed and altitude changes would be
sufficient in an upset. A vacuum failure can be insidious and the airplane
will likely be in an unusual attitude
before you deduce the problem. I would be curious if anyone has
experimented with this in earnest.

The MTBF of a dry pump may be as low as 400 hours. I believe the backup
electrical AI can be used as a replacement
for your turn-and-bank indicator. I do not have one, but it would afford a
tremendous piece of mind and I am convinced
your scan would pick up the inconsistency sooner than the cross check
afforded by the standard six pack. Our aircraft have
an electric backup vacuum source (which would require you to recognize the
failure and flip the switch). The electric
source does not generate the minimum 4.5lbs/in/in but I have never
investigated how this might affect the instrument
performance.

Regards,
Todd

[A Lieberma]

(Frank Ch. Eigler) wrote in
:

> Considering the nature of the 172, you likely don't engage in too much
> heavy duty IMC, so backup equipment could be of the "help me land now"
> kind rather than "help me fly for a few hours more" kind.

Why would you say this based on a model of a plane?

Original poster sounded like an owner, not a renter looking to upgrade /
install backup redundancy.

I own a Sundowner (might as well say a 172 equivelant) and do hard IMC as
much as I can so I have been following this thread rather closely myself.

Just because it's a C172 doesn't mean the plane won't be flown in hard IFR
on a frequent basis unless of course it's not an IFR certified bird in
which that kinda plane shouldn't be anywhere near a cloud anyway.

Allen

[wise purchaser]

Why not install a 4 inch Venturi on the side or the belly of the
aircraft ( 50 bucks aircraft spruce) then route to a selector valve
then you could switch between engine pump or venturi. This will drive
BOTH AI and the DG.

Or you could install the venturi to drive a back up CHEAP ( older type;
black face) Gyro Horiz. I am sure an instrument shop will sell you one
at a good price as every one wants a color faced type.

Now what about BACK UP electrical power thats CHEAP and portable!


I use one in my Airplane it provides 5 hours of FULL Avionics power !
It cost LESS than 30 bucks to make and all parts are from WAL - MART!


Hint: GARDEN TRACTOR

[Frank Ch. Eigler]

A Lieberma > writes:

(Hm, I am talking to myself. :-)

> > Considering the nature of the 172, you likely don't engage in too much
> > heavy duty IMC, so backup equipment could be of the "help me land now"
> > kind rather than "help me fly for a few hours more" kind.
>
> Why would you say this based on a model of a plane? [...] Just
> because it's a C172 doesn't mean the plane won't be flown in hard
> IFR on a frequent basis [...]

The inherent limitations of range and speed complicate bad weather
diversion planning, power limits altitude reach and icing risk
exposure, small amount of redundancy turns malfunctions into
emergencies. So sure, it can be flown in hard IFR on a frequent
basis, but such greater risks have to be accepted.

- FChE

[Jim Macklin]

Hint, unless a homebuilt, all parts must be approved parts.


My vote for safety and redundancy would be for the Sporty's
AI [not as a replacement for T&B] and the 496 GPS. The 496
is aviation, marine and highway, it is your XM radio too.

Unlike the emergency attitude indicators used in jets, the
Sporty's AI does not have a separate battery for power.
You can have your shop create a redundant power source with
a small battery that will be charged from the bus, but
isolated if the alternator fails.



"wise purchaser" > wrote in message
ps.com...
|
|
| Why not install a 4 inch Venturi on the side or the belly
of the
| aircraft ( 50 bucks aircraft spruce) then route to a
selector valve
| then you could switch between engine pump or venturi.
This will drive
| BOTH AI and the DG.
|
| Or you could install the venturi to drive a back up CHEAP
( older type;
| black face) Gyro Horiz. I am sure an instrument shop will
sell you one
| at a good price as every one wants a color faced type.
|
| Now what about BACK UP electrical power thats CHEAP and
portable!
|
|
| I use one in my Airplane it provides 5 hours of FULL
Avionics power !
| It cost LESS than 30 bucks to make and all parts are from
WAL - MART!
|
|
| Hint: GARDEN TRACTOR
|

[Blanche]

Concerning the scan to recognize a failure...In addition to the
backup, Precise Flight also offers a lamp that is triggered by
vacuum pump failure. An immediate warning rather than waiting to
discover it. True, it doesn't offer any redundancy, but minimizes
the time to identify a problem.

Of course I recognized my AI failure immediately -- I was turning
right and the AI turned left....

[Jose[_1_]]

> Hint, unless a homebuilt, all parts must be approved parts.

Is this really true? I cannot mount an unapproved CD player someplace
so that it won't flop around in flight?

Jose
--
"Never trust anything that can think for itself, if you can't see where
it keeps its brain." (chapter 10 of book 3 - Harry Potter).
for Email, make the obvious change in the address.

[Doug[_1_]]

My Husky had a really nice minimal IFR panel. A KX155 Nav/Com, a King
KLN90B (with its own seperate CDI), and a Century I autopilot that was
all electric and worked off the turn and bank. Loose the electric and
you still have the DG and AI. Loose the vacuum and you still have the
autopilot and the turn coordinator AND the GPS (which can work as a DG,
sort of). Top that all off with a handheld radio (with its own antenna)
and a handheld GPS (with it's own permanently mounted outside antennae)
and its pretty damn backed up.

[Stan Prevost[_1_]]

Just a little story about flying with failed instruments.

I was flying with an instrument student, and had been telling him the
importance of the gyroscopic instruments to maintaining control of the
airplane in the clouds. So I covered up one gyro, he kept flying along
fine. He was under the hood, we were flying mostly straight and level,
maybe some simple level turns, don't remember all the details now. Then I
covered up the second gyro. He kept flying along fine. So I covered the
third gyro, expecting him to soon wind up in a spiral dive. He kept flying
along fine. So finally I asked him how he was doing it. I had forgotten
about the GPS. He was watching the TRK number on the GPS, and that was
giving him essentially the same data as the DG, although with a slower
update rate. Along with the pressure instruments, he was doing just fine.




"Kelly" > wrote in message
ups.com...
>I would be interested in getting opinions about backup systems for a
> vacuum pump failure and/or AI failure. I have a 172P with a single
> vacuum pump system, standard instruments otherwise, and a Garmin 430.
> I am most concerned about having a good backup if I lose a vacuum pump
> or AI in IMC. I have been thinking about either a Garmin 396/496 or
> the electric AI available from Sporty's. Looks like I could get a 396
> or installed electric AI for about the same price ($2200 or so). While
> I haven't seen the panel page/"6-pack" page on the 396 or 496, I have
> read (in Aviation Consumer) that it's good enough to keep control of
> the airplane in an emergency situation. Obviously, the 396/496 has a
> number of other neat features such as inflight weather, terrain info,
> etc. Any suggestions on which way to go with this.
>
> BTW, I had also considered the Precise Flight backup vacuum system for
> a while, and it certainly is cheaper (around $700 installed). However,
> I was concerned by the fact that it would do nothing for you in the
> event of failure of the AI vs. the primary vacuum pump.
>
> Thanks.
> Kelly
>

[Jim Macklin]

yes


"Jose" > wrote in message
m...
|> Hint, unless a homebuilt, all parts must be approved
parts.
|
| Is this really true? I cannot mount an unapproved CD
player someplace
| so that it won't flop around in flight?
|
| Jose
| --
| "Never trust anything that can think for itself, if you
can't see where
| it keeps its brain." (chapter 10 of book 3 - Harry
Potter).
| for Email, make the obvious change in the address.

[Kelly]

Thanks for all the helpful comments so far. In thinking about what you
all have said, with my current setup (and yes I am an owner), I would
realistically have a DG with either a vacuum pump failure or AI
failure. In the case of a vacuum pump failure, I could still get
current ground track from the 430. And, obviously with the AI failure
alone, I would still have the DG.

While I don't do a lot of flying in actual IMC, I do enough that I'm
willling to spend some extra money to hopefully prevent a major problem
in the event of vacuum pump failure. I don't know about the rest of
you, but if I encounter a situation where I end up flying partial
panel, I plan to get in VMC ASAP, or if I can't do that, land.

I haven't yet flown with any of the Garmin handhelds, but my guess (and
I could certainly be off on this) is that would be harder to use the
panel page on the handheld as a backup versus having a backup electric
AI and thus the traditional instrument panel gauges and layout that I
trained on. The electric AI from Sporty's also has the ball
inclinometer built into it and can replace the turn coordinator.

So, if anyone else wants to weigh in on best bang for the buck backup,
here again are the options in contention:

1. Engine driven backup vacuum (such as Precise Flight)
2. Electric AI
3. Garmin 396/496
4. $2 failed-instrument covers (I need these anyway, but I had to
throw this in as an option).

Thanks again.

Kelly

[Jose[_1_]]

>> Is this really true? I cannot mount an unapproved CD
>> player someplace
>> so that it won't flop around in flight?
> yes

Actually, I spoke to our FSDO not too lona ago with this very question,
and the answer came back that it is legal to do so. The =installation=
needs to be approved (the installer can self-approve) but the device
being installed need not be an approved device, so long as it is not
powered directly by the aircraft system (cigarette lighter power is ok).

They are concerned that the installation not interfere with flight
controls and such. They are concerned that a non-approved device not
take the place of an approved instrument, but according to my FSDO, once
I explaned all we wanted to do (install an electric backup AI), they
were ok with it.

YMMV

Jose
--
"Never trust anything that can think for itself, if you can't see where
it keeps its brain." (chapter 10 of book 3 - Harry Potter).
for Email, make the obvious change in the address.

[Jose[_1_]]

> 4. $2 failed-instrument covers (I need these anyway, but I had to
> throw this in as an option).

5: MSFS and practice. :)

Jose
--
"Never trust anything that can think for itself, if you can't see where
it keeps its brain." (chapter 10 of book 3 - Harry Potter).
for Email, make the obvious change in the address.

[Mike Spera]

Kelly wrote:

> I would be interested in getting opinions about backup systems for a
> vacuum pump failure and/or AI failure.
..stuff snipped
Looks like I could get a 396
> or installed electric AI for about the same price ($2200 or so). While
> I haven't seen the panel page/"6-pack" page on the 396 or 496, I have
> read (in Aviation Consumer) that it's good enough to keep control of
> the airplane in an emergency situation. Obviously, the 396/496 has a
> number of other neat features such as inflight weather, terrain info,
> etc.

Funny you should ask. I covered up my AI and DG and tried flying via the
panel page on my 396. Downright freaky. I figured the lag would not be
too bad but it really does present a challenge. I suppose with practice
it might do. But in bumpy IMC I might be chasing the TC and altimeter
indications all over the place. The 496 has a faster refresh that may
make this less of an issue.

On the other hand, the lag might keep me from overworking the controls
as I often do in IMC on a bumpy day. You won't correct for every little
deviation because the unit won't update that fast.

I like the idea of that little box that had solid state gyros in it and
you would velcro to the floor and hook up to a PDA. Instant electric
gyros without the gyro wear and tear. If only you could USB the signal
into the 396...

Good Luck,
Mike

[Newps]

>>> Is this really true? I cannot mount an unapproved CD player someplace
>>> so that it won't flop around in flight?
>>
>> yes

Not true in the slightest. You want to velcro your CD player to the top
of the glareshield or maybe to the floor have at it. I have my
satellite radio attached to the far left side of the panel with that two
sided 3M sticky tape they give you with the radio. That stuff is better
than screws because when I want to remove it you'll never know it was
there and if you've worked with that tape before you know how solid it
is. I run the power, antenna and audio out cables under the glareshield
and then out to where they need to go.

[dlevy[_1_]]

I've been struggling with the same issue. I have a 396 but not a 430. I
also want more utility out of my airplane.

I finally said screw it..... I ordered the electric backup attitude
indicator from Sporty's. $1,871.45 with the AOPA discount. All of the
other options are not really usable. This way I have two indicators inches
apart that require no switching, batteries, cables, etc....


"Kelly" > wrote in message
ups.com...
>I would be interested in getting opinions about backup systems for a
> vacuum pump failure and/or AI failure. I have a 172P with a single
> vacuum pump system, standard instruments otherwise, and a Garmin 430.
> I am most concerned about having a good backup if I lose a vacuum pump
> or AI in IMC. I have been thinking about either a Garmin 396/496 or
> the electric AI available from Sporty's. Looks like I could get a 396
> or installed electric AI for about the same price ($2200 or so). While
> I haven't seen the panel page/"6-pack" page on the 396 or 496, I have
> read (in Aviation Consumer) that it's good enough to keep control of
> the airplane in an emergency situation. Obviously, the 396/496 has a
> number of other neat features such as inflight weather, terrain info,
> etc. Any suggestions on which way to go with this.
>
> BTW, I had also considered the Precise Flight backup vacuum system for
> a while, and it certainly is cheaper (around $700 installed). However,
> I was concerned by the fact that it would do nothing for you in the
> event of failure of the AI vs. the primary vacuum pump.
>
> Thanks.
> Kelly
>

[Maule Driver]

I have the precise flight setup. I've never had to use it but, my sense
is that the vacuum failure light may be the most valusable component.

Blanche wrote:
> Concerning the scan to recognize a failure...In addition to the
> backup, Precise Flight also offers a lamp that is triggered by
> vacuum pump failure. An immediate warning rather than waiting to
> discover it. True, it doesn't offer any redundancy, but minimizes
> the time to identify a problem.
>
> Of course I recognized my AI failure immediately -- I was turning
> right and the AI turned left....

[Dave Butler[_1_]]

Maule Driver wrote:
> I have the precise flight setup. I've never had to use it but, my sense
> is that the vacuum failure light may be the most valusable component.

The light is good if you don't have one.

----
Directed to the OP (I'm sure MD knows this):
If you go with the Precise Flight, be sure you check the shuttle valve
frequently as described for preflight in the POH Supplement. The shuttle
valve can stick and then when you need it, it doesn't work. Just the act
of checking it causes the valve to operate and probably helps keep it
from sticking.

Also be sure you understand the operating limitations - altitudes and
power settings where it works and doesn't.

[Andrew Gideon]

On Sun, 19 Nov 2006 16:45:31 -0600, Jim Macklin wrote:

> yes

See the current "Tech Topics" article in CPA Magazine. It's not quite as
clear-cut an answer as this.

- Andrew

[Andrew Gideon]

On Mon, 20 Nov 2006 13:43:01 -0500, Dave Butler wrote:

> Also be sure you understand the operating limitations - altitudes and
> power settings where it works and doesn't.

I have to say: I don't like this system. One time when you want happy
gyros is when low and busy...like on a missed approach. But the
full-throttle of the missed means that the gyros are spinning down.

Plus, of course, there's the fact that it does nothing for an AI or
plumbing failure.

- Andrew

[Andrew Gideon]

On Mon, 20 Nov 2006 10:49:16 -0600, dlevy wrote:

> I finally said screw it..... I ordered the electric backup attitude
> indicator from Sporty's. $1,871.45 with the AOPA discount. All of the
> other options are not really usable. This way I have two indicators
> inches apart that require no switching, batteries, cables, etc....

I'm leaning towards one of the portable GPS units that come with the
ability to use an electronic "gyro" (no parts actually spinning). They
tend to be more expensive than the Sporty's AI, but not by that much. And
they tend to have some fun additional features (ie. weather, HITS, and
even traffic).

But what I most like about this solution is that it's not just an
AI/vacuum backup. It is also backing up electrical power and GPS.

- Andrew

[dlevy[_1_]]

I have a lowrance 100 and a palm with hanger18 software for backup attitude.
It's a cable nightmare and the palm has to have fresh batteries. It's not
real reliable either.

Imho, nothing beats the Sporty's option.

"Andrew Gideon" > wrote in message
...
> On Mon, 20 Nov 2006 10:49:16 -0600, dlevy wrote:
>
>> I finally said screw it..... I ordered the electric backup attitude
>> indicator from Sporty's. $1,871.45 with the AOPA discount. All of the
>> other options are not really usable. This way I have two indicators
>> inches apart that require no switching, batteries, cables, etc....
>
> I'm leaning towards one of the portable GPS units that come with the
> ability to use an electronic "gyro" (no parts actually spinning). They
> tend to be more expensive than the Sporty's AI, but not by that much. And
> they tend to have some fun additional features (ie. weather, HITS, and
> even traffic).
>
> But what I most like about this solution is that it's not just an
> AI/vacuum backup. It is also backing up electrical power and GPS.
>
> - Andrew
>

[Robert M. Gary]

Blanche wrote:
> Concerning the scan to recognize a failure...In addition to the
> backup, Precise Flight also offers a lamp that is triggered by
> vacuum pump failure. An immediate warning rather than waiting to
> discover it. True, it doesn't offer any redundancy, but minimizes
> the time to identify a problem.
>
> Of course I recognized my AI failure immediately -- I was turning
> right and the AI turned left....

The concern about noticing a failed pump quickly is one of the reasons
I got the voice annunciator system. That and the gear warning horn is
hard to distinguish from the stall horn. I now have something like 8
channels hooked up and I like it.

-Robert