The First Edition of SEA Tech Talk


We are introducing a weekly post that expands on the avionics technical topics that we’ve encountered during the week.

This week’s Tech Talk includes: KT-74 ADS-B STC,  KHF-950 SB notes, Cage Locking Attitude Indicators.


Bendix/King is shipping and SEA has started selling the KT-74 transponder. The KT-74 is described as “ADS-B Ready” and the install manual provides instructions to install it as such.

However, at this time the KT-74 is only a Mode S Transponder replacement for the KT-76A & KT-76C. Although the KT-74 has ADS-B capabilities, there is no STC currently available for the transponder.

Bendix/King has informed us that an AML-STC will be issued soon. SEA will announce the KT-74 as ADS-B Ready once the STCs have been released.

A Few Notes on the KHF-950 SB

Why is the mod level important on the KTR-953 and KAC-952 HF components?

Previously, SEA answered the FAQ: “Can the KTR-953 and KAC-952 be mounted in different locations in an aircraft?“. The answer to that question details the service bulletin (mod) levels that each unit must have incorporated for this installation scenario to be possible.

In addition to what these service bulletins offer in the way of installation flexibility, improper performance and actual unit failure can occur if the units are mismatched. That is, using a KTR-953 unit without SB 8 connected to a KAC-952 unit with SB 9,10 is not ideal. Southeast Aerospace has actually seen units fail in the field when mismatched in this manner as well.

Cage Locking Attitude Indicators

Should all cage-able attitude indicators be locked when handled, transported, or stored?

No, not all and they could be damaged if you do.

Many legacy electromechnical attitude gyroscopic instruments include a caging device to hold the gimbals in place and ‘force’ the gyro gimbals to return to their home position. This instantly erects or resets the unit by pulling the caging knob. Some caged gyros include a cage lock mechanism, some do not. Some people believe that a cage-able gyro should always be in the locked position when handling, transportation, or storage takes place. This is not always the case. Continue Reading>>


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