HSI Overhaul NSD 360a
 

My unit has started to drift out of direction accuracy to the point the slave unit no longer compensates - suspect new bearings and overhaul needed. Has anyone experince of an overhaul organisation in the UK doing this type of work and pricing?

Nowhere in the UK. I have the same HSI and had the same problem.

www.avionik.de

The fixed mine for under €400 including shipping etc and did it in a week. An overhaul exhange from the USA was $3500 plus shipping and taxes.

Many thanks I will follow up your link - what was needed to fix your unit?

In those HSI units there is an optical sensor that controls the syncing. When it fails the HSI will no longer sync and makes it look like the gyro has failed. When it goes completely the rotating card just spins round and round. It is a common fault with them and would be my first bet. After that it is a gyro unit which from memory was about €300.

Beyond that I can't be much help, it's all a block box to me!!

There is a UK company called Pandect that can fix mechanical avionics for less than one might expect.

Are they JAR approved? Do you have details?

HSI
 

What type of aircraft was it in...

Mine is in a Piper Arrow 201T