Previous TY91/TY92 Service Bulletins for pilots
TY91 and TY92 VHF Radios
Software versions run numerically, the higher the number the more recent the release – so the latest software will always include all the features of earlier versions.
12/11/2019 version 1.12 – Current software version
A small number of TY91 and TY92 radios have been found to intermittently mistune the receiver frequency, although the control head has selected, and is displaying the intended channel. The symptoms are that the wanted channel is not received, and depending on the mistune, a different channel might be received. If the mistuned channel is not active, the radio would appear silent. Reselecting the channel, transmitting on the channel, or powering the radio off and on generally corrects the problem.
Software version 1.12 introduces a change to the tuning mechanism to correct this problem. No other radio features are affected, and this software change has no effect on radios that are not experiencing this issue.
06/05/2019 version 1.11
Reduces the susceptibility to incorrect squelch opening on aircraft with very high levels of RF noise radiating from the ignition system. It also has minor improvements to audio performance on received signals.
14/05/2018 version 1.10
Reduces background noise from electrically noisy installations and changes the scaling of the receiver volume control (radio volume now increases more quickly with clockwise rotation).
08/07/2017 version 1.8
Version 1.8 software corrects an error in the power-up behaviour of the radio.
13/04/2015 version 1.7
This improves radio squelch, reducing unwanted interference from external sources.
05/05/2014 version 1.5
This adds self clearing of warning messages and also a configurable microphone gain control.