Haydn
Ask your phd freind if the Manufacturer of the fire extinguisher have a o/h or required maintenance dose this have to be done under awb 26 003.
Then ask him dose it have to be placed on the m/r in part 1 as required at tne release of the aircraft.
Then ask him if it is on the m/r how is it then released.
Still waiting for the link.
Oh and while your asking him ask him what is required by the owner of the aircraft in regrads to maintence and what responsibility that owner has in law to work carried out on that aircraft.