Price to install GNX 375

[nels]

Does anyone have an idea of cost to install a GNX 375?

[Ross Taylor]

Our estimate was for 16 hours of labor, plus the GNX 375 and antenna, for a total cost of about $10,325.  Now that it's in the shop, and work is underway, I'm sure we're going to top that - they could not put the 375 where planned (in place of the old GPS) because of depth restrictions behind the panel and they're moving our Comm 2 radio to the right.  We also added a G5 after getting the initial estimate, but I just gave you the 375 estimate numbers here.

[nels]

Ross, did you purchase the 375 then have them install it? I believe the list for the 375 is 7995 but typically on sale at 6995. I’m pretty certain that is the kit including tray and antenna. With those numbers in mind and the 16 hrs quoted labor would put a shop rate at 150 to 200/hour. Is that the quoted rate at your shop or is there more hardware that I’m not accounting for?

[bradp]

Rule of thumb for avionics - take the cost of the hardware and add 0.5-1x that cost to get the total.  Works for almost everything.

In all seriousness for a GTX 375 install hours depend on...

1) Do you have a WAAS antenna that can be used or antenna install required (no sharing signals each device requires its own). 2-3 hrs

2) RG-58 or RG-400 currently installed?  If you need a RG-400 run (interior out and back in 2-4 hrs), wire run 2-4 hrs.  Most installers will not re-use RG-58.

3) What is your CDI source?  G5, GI-106 or other?  Harness takes 2-3 hrs to make. 

4) Transponder wiring and antenna - need a run of RG-400 / blade antenna or can existing be reused (depends on what the STC calls for) +/- another 2-3 hrs

5) Hardwiring alerts to audio panel?

6) Configuration / bluetooth

7) 413 check. Logbook entries.

See how labor time can add up for one of these seemingly simple boxes...

[Baker Avionics]

On 12/1/2019 at 11:42 AM, nels said:

Ross, did you purchase the 375 then have them install it? I believe the list for the 375 is 7995 but typically on sale at 6995. I’m pretty certain that is the kit including tray and antenna. With those numbers in mind and the 16 hrs quoted labor would put a shop rate at 150 to 200/hour. Is that the quoted rate at your shop or is there more hardware that I’m not accounting for?

Where are you "purchasing" the GNX375 and then choosing where to have it installed?

[Baker Avionics]

On 12/1/2019 at 1:11 PM, bradp said:

Rule of thumb for avionics - take the cost of the hardware and add 0.5-1x that cost to get the total.  Works for almost everything.

In all seriousness for a GTX 375 install hours depend on...

1) Do you have a WAAS antenna that can be used or antenna install required (no sharing signals each device requires its own). 2-3 hrs

2) RG-58 or RG-400 currently installed?  If you need a RG-400 run (interior out and back in 2-4 hrs), wire run 2-4 hrs.  Most installers will not re-use RG-58.

3) What is your CDI source?  G5, GI-106 or other?  Harness takes 2-3 hrs to make. 

4) Transponder wiring and antenna - need a run of RG-400 / blade antenna or can existing be reused (depends on what the STC calls for) +/- another 2-3 hrs

5) Hardwiring alerts to audio panel?

6) Configuration / bluetooth

7) 413 check. Logbook entries.

See how labor time can add up for one of these seemingly simple boxes...

The installation manual calls for a 91.411 and 413 check to be completed per the STC, correct? Oh and you are not allowed, per the manual, to use RG58.  RG400/142 is required.

4.1.5 GPS/SBAS Antenna Cable Installation
Installation approval for the GPS antenna is not supplied through this STC. Refer to Section 4.7.1 for GPS
antenna installation guidance. This section provides information on the GPS antenna cable installation.
NOTE
GPS/SBAS antenna cable loss must be between 1.5 dB and 6.5 dB in order to
maintain proper rejection of interference signals. If RG-142B or RG-400 is used, it
must be between 6.5 and 35 feet long to meet the cable loss requirement. For longer
lengths, use low-loss double or triple-shielded, 50 Ω coaxial cable.
It is permissible to temporarily locate the GPS antenna with a coaxial cable connected to the GNX 375 and
check the GPS performance as described in Section 6.4.3. Once the antenna mounting position has been
established, route the coaxial cable from the antenna to the GNX 375. Proper selection of coaxial cable and
assembly of connectors is critical to GPS signal performance.
An acceptable connector used to connect the coaxial cable to the GPS/SBAS antenna is listed in Table 4-2.
Table 4-2 GPS Antenna TNC Connector
Item Amphenol P/N
Connector, TNC, Male, Crimp 31-4452
Additional loss from coaxial connectors and adapters, such as TNC to BNC, should be considered when
computing cable loss. A typical loss of 0.2 dB can be used for each connection. To maintain integrity of the
190-02207-A4 GNX 375 Part 23 AML STC Installation Manual
Rev. 4 Page 31
SBAS signal, the GPS antenna coaxial cable must have a minimum of two shields (e.g., RG-400 or
RG-142B).
For very short runs, where the loss is less than 1.5 dB, additional cable should be used to increase the loss to
within 1.5 dB and 6.5 dB. This additional cable may be coiled, taking into account the minimum bend radius
of the cable.
During the post-installation checkout, susceptibility to harmonics of VHF COM transmitters will be
evaluated. If problems arise, then better isolation, or distance, may be required between the GPS and COM
antennas, or a 1575.42 MHz notch filter (Garmin P/N 330-00067-00) may be installed in series with the
antenna coax of the VHF COM transceiver to reduce or eliminate the harmonic interference.
4.1.6 Transponder Antenna Cable Installation for GNX 375
NOTE
The maximum dB loss allowed from the transponder antenna to the GNX 375 is 2.0 dB.
Installation approval for the transponder antenna is not supplied through this STC. Refer to Section 4.7.2 for
GNX 375 transponder antenna installation guidance. This section provides information on the transponder
antenna cable installation.
As shown in Table 4-3, RG-400 or equivalent cable must be used and meet the permitted attenuation
requirements (with connectors). When cable loss is calculated, refer to Table 4-4 for loss at each connection.

 

6.5 Ground Check – Transponder Performance
6.5.1 Regulatory Tests
With the transponder operating in an airborne state by placing it in Ground Test mode (refer to Section
5.4.5), the following regulatory tests are required to be performed. The Altitude Reporting Equipment Test is
required to be performed for each altitude source interfaced to the transponder, including the GAE. These
regulatory tests require the use of a Mode S transponder ramp tester, such as an Aeroflex IFR-6000 or TIC
TR-220. Specific instructions for operating the ramp tester are contained in the applicable operator's manual.
1. Altitude Reporting Equipment Tests in accordance with 14 CFR Part 91.411 and Part 43
Appendix E.
2. ATC Transponder Tests and Inspections in accordance with 14 CFR Part 91.413 and Part 43
Appendix F.

 

It shouldn't be extra and be sure to have them identify IF there are leaks and issues prior to the installation.  Just between us chickens

Edited December 10, 2019 by Baker Avionics
Misspelled word

[AV8R-IA]

Does anyone have a copy of the GNX 375 install manual that you can share? Thanks.

[PT20J]

If you just want one for reference, you might find one on the web. But, Garmin updates some manuals fairly frequently, so finding the latest is a challenge. Garmin dealers are prohibited from giving you a copy, but they should be able to tell you what the latest revision number is.