Reverse Vacuum Damging to Instruments?

[O. Sami Saydjari]

Recently, I had an A&P put the wrong vacuum pump into my Piper Turbo
Arrow 3 (the work was done about 3 weeks ago). When I started the
engine, the wrror was obvious because none of the vacuum instruments
functioned. The D.G. was spinning wildly. The A&P was there when I
started my engine and saw this. The engine was running for only about 2
minutes. We shut it down and he replaced the vacuum pump with one that
turned in the correct direction.

When I asked if running the vacuum backwards could have damaged any of
my instruments, he said that he did not know for sure, but that I should
bring it back if I had problems.

I have not noticed anything really significant...but then again, I have
only hhad the plane a few weeks...so I am not sure what the average
precession is on the D.G. Also, I do not know what subtle damage might
have been done that will reduce the life of my instruments in the long
term. Can someone please tell if they know for sure one way or another
if the event was potentially damaging to my instruments?

-Sami

[BTIZ]

step one, be sure the error is documented.. service invoice or something, or
the log book entry that the original pump was changed, and then another
entry when the 3rd pump is installed to include part numbers.

step two, find a new A&P

BT

"O. Sami Saydjari" > wrote in message
...
> Recently, I had an A&P put the wrong vacuum pump into my Piper Turbo
> Arrow 3 (the work was done about 3 weeks ago). When I started the
> engine, the wrror was obvious because none of the vacuum instruments
> functioned. The D.G. was spinning wildly. The A&P was there when I
> started my engine and saw this. The engine was running for only about 2
> minutes. We shut it down and he replaced the vacuum pump with one that
> turned in the correct direction.
>
> When I asked if running the vacuum backwards could have damaged any of
> my instruments, he said that he did not know for sure, but that I should
> bring it back if I had problems.
>
> I have not noticed anything really significant...but then again, I have
> only hhad the plane a few weeks...so I am not sure what the average
> precession is on the D.G. Also, I do not know what subtle damage might
> have been done that will reduce the life of my instruments in the long
> term. Can someone please tell if they know for sure one way or another
> if the event was potentially damaging to my instruments?
>
> -Sami
>

[James M. Knox]

"O. Sami Saydjari" > wrote in
:

> I have not noticed anything really significant...but then again, I
> have only hhad the plane a few weeks...so I am not sure what the
> average precession is on the D.G. Also, I do not know what subtle
> damage might have been done that will reduce the life of my
> instruments in the long term. Can someone please tell if they know
> for sure one way or another if the event was potentially damaging to
> my instruments?

Interesting question. What he wound up doing (it sounds like) is
getting the inlet/outlet connections on the pump switched. [Lots of
these pumps are used for both vacuum and pressure applications, just a
matter of which hose goes where.]

Did it hurt anything? Hard to say. Simply running the gyro backwards
in each instrument should have caused no damage whatsoever. The cause
for concern is that he not only pumped unfiltered (outside) air into the
gyros, he also pumped all the crud that may have been in the lines back
into the gyros. It doesn't take much of this at all to take years off
the lives of the gyro bearings.

Suggestons:

1. As a minimum, have the filters replaced (both canister and finger)
BEFORE you run it again. [Why do I feel it's already too late.] No
need to pull all the crud BACK through the gyros AGAIN! And the crud is
now between the filters and the gyros.

2. Call one of the major gyro house's support numbers and ask their
opinion.

3. Document it.



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

[Javier Gorordo]

Depends on the vacuum system in your a/c. I'd expect a pressure relief
or check valve of some sort would be there to prevent this kind of
thing. Anything in the POH?



"O. Sami Saydjari" > wrote in message >...
> Recently, I had an A&P put the wrong vacuum pump into my Piper Turbo
> Arrow 3 (the work was done about 3 weeks ago). When I started the
> engine, the wrror was obvious because none of the vacuum instruments
> functioned. The D.G. was spinning wildly. The A&P was there when I
> started my engine and saw this. The engine was running for only about 2
> minutes. We shut it down and he replaced the vacuum pump with one that
> turned in the correct direction.
>
> When I asked if running the vacuum backwards could have damaged any of
> my instruments, he said that he did not know for sure, but that I should
> bring it back if I had problems.
>
> I have not noticed anything really significant...but then again, I have
> only hhad the plane a few weeks...so I am not sure what the average
> precession is on the D.G. Also, I do not know what subtle damage might
> have been done that will reduce the life of my instruments in the long
> term. Can someone please tell if they know for sure one way or another
> if the event was potentially damaging to my instruments?
>
> -Sami

[RV6John]

Putting the wrong direction pump on would not cause the any significant
problem. The engine still turns the same way. It is just a factor of pump
longevity. The other post speculating that the lines were hooked up backwards
is more serious if that occured. The suction regulator is not designed to let
out air, it lets it in to regulate suction. Reversing the lines could seriously
"over-boost" the gyros. I agree if this is the case, talk to an instrument
shop. The key question is what did the suction gauge say. If it read zero
during the run, bad problem, hoses were reversed. If it read normal 5.0-6.0
inhg then no damage done. But you probably have a worn out DG. (I have had DGs
spin around when they start to fail.)
Good luck,
John A&P, IA

[O. Sami Saydjari]

Just to be clear, I do not think he reversed the inlet and outlet
connections. What happened is that he put on a Lycoming vacuum pump
that turned the opposite direction from the proper pump meant for my
Continental Engine in my Piper Turbo Arrow III (TSIO-360-FB). My POH
does not seem to have a schematic of the vacuum system, so I am not sure
exactly what went on with the air flow with respect to the filters.

-Sami
N2057M, Piper Turbo Arrow III

James M. Knox wrote:

> "O. Sami Saydjari" > wrote in
> :
>
>
>>I have not noticed anything really significant...but then again, I
>>have only hhad the plane a few weeks...so I am not sure what the
>>average precession is on the D.G. Also, I do not know what subtle
>>damage might have been done that will reduce the life of my
>>instruments in the long term. Can someone please tell if they know
>>for sure one way or another if the event was potentially damaging to
>>my instruments?
>
>
> Interesting question. What he wound up doing (it sounds like) is
> getting the inlet/outlet connections on the pump switched. [Lots of
> these pumps are used for both vacuum and pressure applications, just a
> matter of which hose goes where.]
>
> Did it hurt anything? Hard to say. Simply running the gyro backwards
> in each instrument should have caused no damage whatsoever. The cause
> for concern is that he not only pumped unfiltered (outside) air into the
> gyros, he also pumped all the crud that may have been in the lines back
> into the gyros. It doesn't take much of this at all to take years off
> the lives of the gyro bearings.
>
> Suggestons:
>
> 1. As a minimum, have the filters replaced (both canister and finger)
> BEFORE you run it again. [Why do I feel it's already too late.] No
> need to pull all the crud BACK through the gyros AGAIN! And the crud is
> now between the filters and the gyros.
>
> 2. Call one of the major gyro house's support numbers and ask their
> opinion.
>
> 3. Document it.
>
>
>
> -----------------------------------------------
> James M. Knox
> TriSoft ph 512-385-0316
> 1109-A Shady Lane fax 512-366-4331
> Austin, Tx 78721
> -----------------------------------------------

[O. Sami Saydjari]

Unfortunately, I did not think to look over at the vacuum gauge
immediately. When I saw the DG spinning wildly, I shut it down
immediately. -Sami

RV6John wrote:

> Putting the wrong direction pump on would not cause the any significant
> problem. The engine still turns the same way. It is just a factor of pump
> longevity. The other post speculating that the lines were hooked up backwards
> is more serious if that occured. The suction regulator is not designed to let
> out air, it lets it in to regulate suction. Reversing the lines could seriously
> "over-boost" the gyros. I agree if this is the case, talk to an instrument
> shop. The key question is what did the suction gauge say. If it read zero
> during the run, bad problem, hoses were reversed. If it read normal 5.0-6.0
> inhg then no damage done. But you probably have a worn out DG. (I have had DGs
> spin around when they start to fail.)
> Good luck,
> John A&P, IA

[G.R. Patterson III]

"O. Sami Saydjari" wrote:
>
> Just to be clear, I do not think he reversed the inlet and outlet
> connections. What happened is that he put on a Lycoming vacuum pump
> that turned the opposite direction from the proper pump meant for my
> Continental Engine in my Piper Turbo Arrow III (TSIO-360-FB). My POH
> does not seem to have a schematic of the vacuum system, so I am not sure
> exactly what went on with the air flow with respect to the filters.

If the pump is being turned backwards, it will no produce any appreciable air
flow in either direction.

George Patterson
A diplomat is a person who can tell you to go to hell in such a way that
you look forward to the trip.

[Orval Fairbairn]

In article >,
"G.R. Patterson III" > wrote:

> "O. Sami Saydjari" wrote:
> >
> > Just to be clear, I do not think he reversed the inlet and outlet
> > connections. What happened is that he put on a Lycoming vacuum pump
> > that turned the opposite direction from the proper pump meant for my
> > Continental Engine in my Piper Turbo Arrow III (TSIO-360-FB). My POH
> > does not seem to have a schematic of the vacuum system, so I am not sure
> > exactly what went on with the air flow with respect to the filters.
>
> If the pump is being turned backwards, it will no produce any appreciable air
> flow in either direction.
>
> George Patterson
> A diplomat is a person who can tell you to go to hell in such a way that
> you look forward to the trip.

A dry pump will probably didintegrate when spun backwards. I had that
happen years ago, and replaced it with a wet pump, which has operated
flawlessly ever since.