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Instrument replacement

Our maintenance shop recently wrote a logbook entry declaring our Cessna 172R unfit for IFR because they discovered that the installed AI was not a Cessna original and was not “approved according to the type certificate”.

This surprises me a bit. On a light aircraft (ELA1, even), do you really need a modification approval or STC to replace the AI with another model as long as it is TSO’d and the component has the appropriate paperwork?

We’re talking a bog standard vaccuum-driven AI here. No flight director or connection to an autopilot system.

At some previous time in the life of the aircraft the original AI had for whatever reason been replaced by a Sigma-Tek AI. The replacement may even have been done before part-M came into force. (I haven’t checked the paperwork in that amount of detail.)

ESKC (Uppsala/Sundbro), Sweden

If the papers of the AI replacement were ok (new purchase of a certified AI? CoC in the logs?), change shop if you can.

Last Edited by at 01 Feb 08:24

Sad to gear that the maintenance shop does not do a serious work. You can use CS-STAN and more precisely CS-SC401b to approve this AI.

ESSZ, Sweden

You maintenance shop should have given you the option of replacement of the AI with the one quoted in the type certificate or doing about one hour of paperwork to clear the item under CS-STAN.

If you had been my customer I would have expected you go for option two.

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