04.MO-2016-81.05

Isi rekomendasi

After completion of the modification, the investigation revealed that in the modified CVR wiring system of the aircraft, the microphones lines of the SIC, PIC and spare line, were directly hooked to the channel 1 (SIC), 2 (PIC) and 3 (spare) of CVR audio line respectively. As the result, the incoming audio communication and other audio which generated by the aircraft system were not accommodated into the CVR. In addition, it was found that the CVR CAM channel was filled by the engine noise therefore the other station calling or aircraft system sound was not recorded in the CVR. To record audio in the cockpit to the CAM channel of the CVR, the modification probably only rely on the cockpit area microphone input. This design resulted in the any audio in the cockpit was covered by engine noise while the engines were running. The improper modification leads to the CVR important information was unavailable during the investigation. Therefore, KNKT recommend to review the CVR wiring design so all of the required voices are accommodated in the CVR in all flight phase.