AD/F50/93 Propeller Blade De-icer Boot (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.

Fokker F50 (F27 Mk 50) Series Aeroplanes

AD/F50/93 Propeller Blade De-icer Boot 3/2006

Applicability:

Fokker Aircraft B.V. Model F27 Mark 050, Mark 0502 and Mark 0604 aircraft equipped with Dowty Propellers (formerly Dowty Aerospace Gloucester) Type R.352 or R.410 series propellers.

Requirement:

1.    Check the maintenance records to determine whether Minnesota Mining and Manufacture Co. (3M) 1300L adhesive has been used to fit the de-icer assemblies (boots) to the propeller blades.  If it has been positively established that Bostik 2402 adhesive has been used, no further action is required by this directive.

2.    If 3M 1300L adhesive has been used, inspect the propeller blade de-icer assemblies (boots) in accordance with the accomplishment instructions of Dowty Propellers Service Bulletin (SB) F50-61-158 dated 30 September 2005 or a later EASA-approved revision.

3.    When, during the inspection in accordance with requirement 2 of this AD, any signs of lifting or bubbling are found, replace the affected de-icer boot in accordance with Dowty Propellers Specification PS 5723 (attached to Dowty
SB F50-61-158 as Appendix 1), latest revision.

4.    3M 1300L adhesive not to be used to fit de-icer boots to propeller blades on Fokker F27 Mark 050, 0502 and 0604 series aircraft.

Note:  CAA Netherlands AD NL-2005-016 EASA approval No. 2005-6448 dated
15 December 2005 refers.

Compliance:

1.    Within 30 days after the effective date of this directive.

2.    Within the next 650 flight hours after the effective date of this directive, and thereafter at intervals not exceeding 650 flight hours.

3.    Before next flight.

4.    As of the effective date of this directive.

This Airworthiness Directive becomes effective on 16 March 2006.

Background: Since May 2003, there have been three events with Fokker 50 (F27 Mark 050) aircraft, where the propeller blade de-icer assembly overshoe (boot) detached during flight.  Two impacted the fuselage, causing considerable damage but did not penetrate, one hit a passenger cabin window, shattering the pane and penetrating into the fuselage, thereby injuring two passengers.  All of the affected boots had been fitted using 3M 1300L adhesive.  A thorough safety analysis has shown that this condition, if not corrected, could result in a hazardous event, including the possibility of passengers being seriously or fatally injured.  Since an unsafe condition has been identified that may exist or develop on aircraft of the same type design, this AD requires a repetitive inspection of the propeller blade de-icer assembly.  In addition, the continued use of 3M 1300L adhesive for fitting propeller blade de-icer boots is no longer authorized.

James Coyne
Delegate of the Civil Aviation Safety Authority

1 February 2006