AD/PR/36 Blade Counterweight Capscrew Holes (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.

Propellers - Variable Pitch - Dowty Rotol

AD/PR/36 Blade Counterweight Capscrew Holes 13/2006 TX

Applicability:

All Dowty R321/4-82-F/8, R324/4-82-F/9, R333/4-82-F/12 and R334/4-82-F/13 propellers, if blades are installed with serial numbers (S/N) A156121 through A156132, A156137 through A156160, A156165 to A156168, A156177 through A156184, A156194 and A156196 through A156200.

Note 1:  These propellers are known to be installed on, but not limited to CASA 212, M7 Aerospace (formerly Fairchild, Swearingen) SA227TT, SA227AT and SA227AC, and BAE Systems (formerly British Aerospace) Jetstream 3100 and 3200 series aeroplanes.

Requirement:

1.    Identify the propeller blades that have a serial number listed in the applicability section of this AD and inspect the affected blades in accordance with Dowty Propellers Alert Service Bulletin (ASB), as applicable.

2.    If discrepancies are found, re-machine the counterweight attachment holes.

Note 2:  Contact Dowty Propellers, for advice.

3.    Do not install any of the listed S/N propeller blades on an aircraft unless the blade has been inspected and, if necessary, reworked in accordance with the requirements of this AD.

Note 3:  EASA EAD No: 2006-0326-E dated 23 October 2006 refers.

Compliance:

1.    Before further flight after the effective date of this AD.

2.    Before further flight after the effective date of this AD.

3.    From the effective date of this AD.

This Airworthiness Directive becomes effective on 27 October 2006.

Background: One propeller blade has recently been identified after delivery from Dowty Propellers where the blade counterweight capscrew holes have not been correctly drilled.  If the capscrew holes are not machined to their required depth, it may appear that the capscrew has been correctly assembled, but the counterweight will not be properly retained.  This condition, if not corrected, could result in failure (due to fatigue) of one or more capscrews, release of the counterweight during propeller operation and consequent risk of injury to aircraft occupants and persons on the ground.  Dowty has concluded that the problem is associated only with blades manufactured between April and July 2006, identified by serial number in the applicability section of this AD.  Since an unsafe condition has been identified that is likely to exist or develop on other aircraft that have these propeller blades installed, this AD is issued to require the identification, inspection and, where necessary, rework of the affected propeller blades.

James Coyne
Delegate of the Civil Aviation Safety Authority

25 October 2006