AD/SF340/81 Amdt 1 - Pitot Static Tubes (Cth)

COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES

AIRWORTHINESS DIRECTIVE

For the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/SF340/81 and issues the following AD under subregulation 39.1 (1) of CAR 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.

SAAB SF340 Series Aeroplanes

AD/SF340/81 Amdt 1

Pitot Static Tubes 10/2002

Applicability: Model SF340A aeroplanes, serial numbers (S/N) 004 through 159 inclusive and Model 340B aeroplanes S/N 160 through 459 inclusive.

Requirement: Modify the pitot static system in accordance with Saab Aircraft AB Mandatory Service Bulletin SAAB 340-34-145 dated 1 October 2001.

Note: LFV AD 1-167 refers.

Compliance: Before 31 January 2003.

This Amendment becomes effective on 3 October 2002.

Background: The Swedish Luftfartsverket has advised that operators have reported a number of events involving erroneous airspeed indications. In some instances all three airspeed indication systems failed simultaneously. Typically, during descent from cruise altitude one or more airspeed indicators incorrectly show gradually decreasing airspeed, at lower altitudes the correct airspeed is again displayed and no fault can be detected once the aeroplane is on the ground. Investigation revealed that the cause of the incorrect airspeed displays is ice forming in the pitot static tubes.