All talk and no listen...

Updated: Jan 3, 2019

We had a communication issue on-board, whereby we were stuck on permanent transmit whenever power was applied to the aircraft.

The fault lay somewhere in the beam or further aft. With this fault anyone who was connected to the aircraft comms were able to transmit externally to anyone who was listening. Disconnecting transmit/receive capability from anyone other than pilot and copilots stations seems to have brought it back to doing what it should. With further checks there's no signal coming out of the VHF unit unless you press the PTT button on the control yoke.

While this may sound like a relatively simple job to carry out. It involved a fairly in depth strip of internal panels to gain access to the various control boxes and cabling that connects the system.

Pilots and copilots radio and intercom gubbins feed down under the pilots seat. So to gain access, you must remove the side panel and stick your head/arms through the gaps in the framing.

The wiring at the vry back is what we're after. The chains and the pushrod in the centre of shot are aileron and elevator controls.

Between the spars on the port wall is mounted this control box. This controls both feeds in the aircraft - intercom and radio and decides who can transmit or receive while making sure everyone can still talk to each other. Thankfully it hadn't gone pop.

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