AD/F50/92 Amdt 2 Engine Mounting Frame Welds (Cth)

AIRWORTHINESS DIRECTIVE

On the effective date specified below, and for the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/F50/92 Amdt 1 and issues the following 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/F50/92 Amdt 2 Engine Mounting Frame Welds 2/2006

Applicability:

Model F27 Mk.050, 0502, and 0604 aircraft, all serial numbers.

Requirement:

Action in accordance with the requirements of Netherlands CAA AD NL-2005-015.

Note 1:  AD NL-2005-015 may be obtained by contacting CASA e-mail address [email protected].

Note 2:  Fokker Service Bulletins F50-71-048 and F50-71-049; and Fokker Component Service Bulletins F8200-035-71-10 and F8200-035-71-11; or later
CAA-NL approved revisions, refer. 

Compliance:

For the inspection requirement:  Within 2 calendar months after 1 September 2005.

The compliance time remains unchanged by this issue of the Directive.

This Amendment becomes effective on 16 February 2006.

Background:

Welding defects were discovered during recent scheduled X-ray inspections of F50 engine mounting frames.  Investigation revealed that during manufacture of the frames, when tubes were welded to the end fittings, movement of the electric arc resulted in some welds running beside the borderline for a part of the tube circumference.  The defective welding process appears to have occurred at some of the welds in an unknown number of engine mounting frames.  This condition, if not corrected, could lead to failure of an affected engine mounting frame.

Amendment 1 changed the Requirement paragraphs specified in Paragraph e. of the original issue.

Amendment 2 is issued in response to a new CAA-NL AD.  Previous AD
NL-2005-07 was issued to require a one-time inspection for improper welds, while the new AD further specifies the criteria and compliance times for the follow-up NDT inspection, and repair or replacement of engine mount frames, as necessary.

David Villiers
Delegate of the Civil Aviation Safety Authority

21 December 2005