DHC-8-402 Dash 8, G-JECF
During approach the aircraft experienced a failure of the number 1 Input Output Processor (IOP 1). The flight crew became distracted with this failure and were unaware that the altitude select mode of the flight director had become disengaged and that the aircraft had descended below its cleared altitude. Descent continued until, alerted by an EPGWS warning, the pilots climbed the aircraft and re-established the glidepath. The investigation found that the IOP 1 failure was caused by intermittent electrical contact arising from cracked solder on two pins of a transformer on the IOP power supply module. It was further determined that there was a lack of appropriate operational guidance available to flight crews to deal with such avionics failures. Three Safety Recommendations have been made.
DHC-8-402 Dash 8 G-JECF 06-12.pdf (894.67 kb)