Page:Report of the Board of Inquiry into the Helderberg air disaster.djvu/43

Rh deposit of sea water chemicals, the transfer from the lifting tackle to the transport container was performed under the water. Once on board the ship the sea water was replaced with de-ionised water whilst ensuring non-entry of air into the recorder unit. Ice made from de-ionised water was progressively added to maintain the temperature within the range of 4 to 12°C. The CVR, in the transport container, was then flown to the Operator's suitably equipped laboratory for removal of the tape. All metal tools used for this process were de-magnetised. The tape was removed with the unit submerged in deionised water and cleaned in such water by winding it from one reel to another after which it was dried in a vacuum chamber with periodic nitrogen purging. After drying the tape was hand carried to a NTSB laboratory in Washington DC for copying and analysis.

Examination of the recorder revealed impact damage to the outer casing. It had been exposed to heat as evidenced by blistering of the paint. The insulation of electrical wiring found attached to the mounting rack plug was scorched. The solder of some electrical wire joints had melted which was a further indication that the unit had been exposed to heat. The melting point of the solder is 183°C. The interior of the unit was covered with an oily soot, ingress of which was probably through an aperture in the front cover. The plastic blanking plug