COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
Bombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes
AD/DHC-8/10 Uncommanded Engine Power Roll Back 13/89
Applicability: All DHC 8 Series aircraft Serial No’s 3 through 134 not incorporating de Havilland modification 8/0886.
Requirement: To eliminate the potential for uncommanded engine power roll back following inadvertent selection of the MAX/RDC PWR switch, perform an electrical continuity check to ensure that the MAX/RDC PWR switch cannot incorrectly connect 28 VDC power to the Engine Electronic Fuel Control.
Note: Canadian AD CF-89-13 and DHC SB 8-73-10 refer.
Background: One instance of uncommanded engine power roll back has been reported following inadvertent crew selection of the MAX/RDC PWR switch. Investigation determined that the roll back resulted from 28 VDC being incorrectly fed to the Engine Electronic Control unit when the MAX/RDC PWR switch was inadvertently selected. The cause was traced to a 28 VDC wire which had mistakenly been connected to the MAX/RDC PWR switch during manufacture.