Someone on the GNS480 yahoo group posted some text this morning from
Garmin Service Bulletin #621, to the effect that the GNS480 does not
comply with the TSO, and that it reverts to TSO C129 type operations,
for example requiring alternate airports to have ground-based
approaches, having alternate means of navigation installed, RAIM
prediction required.

The text as posted says when flight-planning for a LNAV/VNAV or LPV
approach, we should use RAIM prediction from Garmin Prediction Program
006-A0154-02, so it seems it's still possible to use the LNAV/VNAV and
LPV approaches.

The poster says the referenced prediction program is supposed to be
available for download Nov. 1.

I haven't received this Service Bulletin, I'm just going by what was
posted in the yahoo group.

Can anyone confirm they've also received this service bulletin, or have
any more details?

Thanks, Dave

Dave Butler wrote:
> Someone on the GNS480 yahoo group posted some text this morning from
> Garmin Service Bulletin #621, to the effect that the GNS480 does not
> comply with the TSO, and that it reverts to TSO C129 type operations,
> for example requiring alternate airports to have ground-based
> approaches, having alternate means of navigation installed, RAIM
> prediction required.

Here's the followup after discussing with my avionics installer:

During some testing, Garmin found a problem with GNS480 in a "high-noise
environment". As a temporary measure, avionics installer will send us a
new Approved Flight Manual Supplement (AFMS) which needs to be filed
with the POH in the plane, and a logbook entry to the effect that the
AFM has been updated.

Some PC software for RAIM prediction will be available for download.
Before launching, one should run the RAIM prediction software for the
proposed route. [This leads me to speculate that the problem is in the
RAIM prediction software in the GNS480.]

Owners should receive the Service Bulletin by snail-mail from Garmin.

My avionics guy said the AD requires discontinuing the use of the 480
for any IFR operation until the AFM update is received.

-Robert

"Robert M. Gary" > wrote:

> My avionics guy said the AD requires discontinuing the use of the 480
> for any IFR operation until the AFM update is received.
>
> -Robert
>

There's no AD. Just a service bulletin. The Garmin letter today said there will be a SAIB issued.

Mike Adams wrote:
> "Robert M. Gary" > wrote:
>
>
>> My avionics guy said the AD requires discontinuing the use of the
>> 480 for any IFR operation until the AFM update is received.
>>
>
> There's no AD. Just a service bulletin. The Garmin letter today said
> there will be a SAIB issued.

Correct. My partners and I have decided not to get the AFMS change. We
operate only Part 91. We've pinged the avionics installer to ask whether
there's any reason that's a bad idea. No answer yet, but I expect not to
update the AFMS. DGB

Dave Butler wrote:

> Correct. My partners and I have decided not to get the AFMS
> change. We operate only Part 91. We've pinged the avionics
> installer to ask whether there's any reason that's a bad idea.
> No answer yet, but I expect not to update the AFMS.

If the unit doesn't comply with the TSO, it doesn't comply with the
TSO. It doesn't matter whether you're Part 91 or not. You can't change
reality by ignoring the SB that informs you of the lack of compliance
on the basis of the part under which you operate. You have a navigator
that is not C146a compliant, so you're installation is no longer
approved for IFR unless you fall-back to C129a, which you do by
changing your AFMS. You can choose to ignore the rule, and most likely
nothing bad will happen, but don't pretend you'll be legal.

Mike Granby wrote:
> Dave Butler wrote:
>
>
>>Correct. My partners and I have decided not to get the AFMS
>>change. We operate only Part 91. We've pinged the avionics
>>installer to ask whether there's any reason that's a bad idea.
>>No answer yet, but I expect not to update the AFMS.
>
>
> If the unit doesn't comply with the TSO, it doesn't comply with the
> TSO. It doesn't matter whether you're Part 91 or not. You can't change
> reality by ignoring the SB that informs you of the lack of compliance
> on the basis of the part under which you operate. You have a navigator
> that is not C146a compliant, so you're installation is no longer
> approved for IFR unless you fall-back to C129a, which you do by
> changing your AFMS. You can choose to ignore the rule, and most likely
> nothing bad will happen, but don't pretend you'll be legal.

The 480 is still certified under TSO C146, the subject line of this
thread notwithstanding.

Dave Butler wrote:

> The 480 is still certified under TSO C146, the
> subject line of this thread notwithstanding.

But it doesn't meet the requirements of the TSO, but Garmin have been
granted a temporary deviation which requires the modification to the
AFMS. So the argument still applies. If you don't make the mod, you
have a non-TSOed GPS and a non-approved installation.

Mike Granby wrote:
> Dave Butler wrote:
>
>
>>The 480 is still certified under TSO C146, the
>>subject line of this thread notwithstanding.
>
>
> But it doesn't meet the requirements of the TSO, but Garmin have been
> granted a temporary deviation which requires the modification to the
> AFMS. So the argument still applies. If you don't make the mod, you
> have a non-TSOed GPS and a non-approved installation.

I disagree, but am listening. Do you think a manufacturer can decertify
a TSO'd piece
of equipment by just issuing a SB? I don't think so.

Dave Butler > wrote:

> Do you think a manufacturer can decertify a TSO'd piece
> of equipment by just issuing a SB? I don't think so.

I'm with you, Dave. Unless I receive an AD that declares my installation
no longer airworthy, a service bulletin alone does not "decertify" the
equipment.

Mike

"Mike Granby" > writes:

> If the unit doesn't comply with the TSO, it doesn't comply with the
> TSO. [...]

One expects Garmin will promptly correct whatever 480 bugs have popped
up. Otherwise they'll have some $serious reckoning to do for all the
customers who purchased the unit because of that TSO.

- FChE