AD/ERJ-170/4 Flight Guidance Control Unit (Cth)

AIRWORTHINESS DIRECTIVE

For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.001(1) of CASR 1998.  The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.

Embraer ERJ-170 Series Aeroplanes

AD/ERJ-170/4 Flight Guidance Control Unit 5/2007 DM

Applicability:	ERJ-170(  ) model aeroplanes.
Requirement:	Carry out a functional test to check the engagement of the Flight Guidance Control System (FGCS) channels in accordance with Embraer Service Bulletin 170-22-0003, original issue, dated 9 November 2006 or further revisions approved by the Brazilian Agência Nacional de Avição Civil (ANAC).
Note 1:  For the purpose of this Directive, a functional check is defined as: "A quantitative check to determine if one or more functions of an item perform within specified limits.”
Note 2:  ANAC AD 2006-11-02 refers.
Compliance:	Within the next 300 hours time in service (TIS), after the fist issue of an Australian Certificate of Airworthiness, and thereafter, at intervals that do not exceeds 600 hours TIS.
This Airworthiness Directive becomes effective on 4 April 2007.
Background:	The ANAC has received reports that some “caution” messages issued by the FGCS are not displayed on aircraft equipped with EPIC software load 17.3 or 17.5.  Therefore, following a possible failure on one FGCS channel during a given flight, such a failure condition will remain undetected or latent in subsequent flights.  If another failure occurs on the second FGCS channel, the result may be a command hard-over by the autopilot.
Since this condition may affect the safety of the aeroplane, this Directive requires the repetitive functional testing of the FGCS.  Further rulemaking is anticipated when a terminating action is developed.

Charles Lenarcic
Delegate of the Civil Aviation Safety Authority

27 March 2007