1AD/PR/32 - Blade Pitch Seizure

COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 107 CIVIL AVIATION SAFETY AUTHORITY

SCHEDULE OF AIRWORTHINESS DIRECTIVES

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Propellers - Variable Pitch - Dowty Rotol

AD/PR/32 Blade Pitch Seizure 4/97

Applicability: All R/354/4-123-F/13, R354/4-123-F/20, R375/4-123-F/21, R389/4-123-F/25,

R389/4-123-F/26 or R390/4-123-F/27 propellers fitted to SAAB 340 A or B series aircraft.

Requirement: Modify or de-modify (as applicable) the propeller pitch change mechanism in accordance with Dowty Aerospace Mandatory SB SF340-61-88 dated Jan 23/97.

Note: UK CAA AD 002-11-96 dated 2 November, 1996, refers.

Compliance: Unless previously carried out, incorporate as specified in the Requirement Document paragraph D.

This Airworthiness Directive becomes effective on 27 March 1997.

Background: The manufacturer has advised that during ground running a propeller which had recently been modified to SB SF340-61-79 status, suffered a seizure of the propeller pitch change. This occurred when the slide block, attached to the crosshead by coiled springs, became detached and allowed the crosshead to turn and contact the blade root inner sleeves which then locked the propeller blades in a fixed position.