Garmin

Bartman

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Mar 27, 2018
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as I understand it, if the unit is TSO'd it can legally be installed in any certified aircraft with a 337 form that references the TSO. a TSO is a more broad authorization than an STC which is airframe specific.

did I get that right Bob?
 

Bob Turner

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Apr 4, 2018
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I don't think so. TSO is only a form of "part" approval. "This item meets applicable standards."

A radio does not need a TSO, at least under part 91. Usually, a different radio is considered a minor alteration - a logbook entry.

Other than the strange ADS-B application, the 337 is limited to major repairs and alterations. A valid 337 must cite "approved data". A TSO is not approved data - it is more like a manufacturing and sale approval.

Caveat - there are folks who know this stuff better than me - I pay attention, but I do not always have the correct answer.
 

Bob Turner

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Apr 4, 2018
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Here is an example: wheels are TSO'd. The Scout has somewhat limited choices for wheels, brakes, and tires. I forget the details, but if you have a 6:00 Cleveland TSO wheel, you cannot simply slide it on and be legal. It has to be within the part number series approved for that aircraft.

Cub guys go through this. You cannot remove the 8:00x4 wheel and brake and replace with 6:00x6 TSO Cleveland. You also need to purchase the STC for the alteration.
 

Big Ed

N50247 - '79 Super D
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Jul 20, 2020
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237
Location
Tampa, FL
My avionics shop recently installed a Garmin 225 in my Decathlon with the following logbook entry:

Installed Garmin GTR225 p/n 011-02718-00 s/n xxxxxxxxx in radio stack at frame station # -6.0. Installation done in accordance with Garmin installation manual p/n 190-01182-02 Revision H, dated September 2017. Determined not to be a major alteration.
 
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