AD/BN-2/85 Elevator Tip Assemblies (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.

Pilatus Britten-Norman BN-2 Series Aeroplanes

AD/BN-2/85 Elevator Tip Assemblies 7/2009 DM

Applicability:

Model BN2A-8, -9, -20, -21, -26, -27 and BN2B-20, -21, -26, -27 and BN2T,
BN2T-2, -2R, -4R and -4S Islander aircraft, all serial numbers.

Requirement:

1.    Visually inspect for deformation of shape and signs of concavity of the elevator tip assemblies (top and bottom surfaces) as instructed in paragraphs 6 and 9 of Britten-Norman Aircraft Service Bulletin (SB) BN-2/SB 313 issue 3, or later EASA approved issue.

a.     If any sign of concavity is found, inspect for delamination of the elevator tip as instructed in paragraph 9 of SB BN-2/SB 313 issue 3, or later EASA approved issue.

b.    If delamination is found, replace the elevator tip with a serviceable one in accordance with drawing NB-31-235 or NB-31-873, as applicable to the aircraft model.

c.     If no delamination is found, inspect for delamination of the elevator tip as instructed in paragraph 9 of SB BN-2/SB 313 issue 3, or later EASA approved issue.

2.    Replace the elevator tip with a serviceable one in accordance with drawing
NB-31-235 or NB-31-873, as applicable to the aircraft model.

After the effective date of this Directive, installation of an elevator tip on any aircraft is prohibited unless the tip has been inspected in accordance with SB BN-2/SB 313 issue 3, or later EASA approved issue, and determined to be free of concavity and delamination.

Note:  EASA AD 2009-0105 refers.

Compliance:

1.    At the next A-check (daily check) after 27 May 2009.

1.a. Before further flight.

1.b. Before further flight.

1.c. At intervals not to exceed 50 flight hours until accomplishment of Requirement 2.

2.    Within 6 months after 27 May 2009.

This Airworthiness Directive becomes effective on 27 May 2009.

Background:

A report was received of deformed Glass Fibre Reinforced Plastic (GFRP) elevator tips being found on in-service aircraft.  The outboard 3-inches of the elevator tip assembly profiles (top and bottom surfaces) had changed from being convex profiles to concave profiles.  There is concern that this condition could potentially result in, or be caused by, internal structural delamination and/or failure.  Such a failure could have a serious effect on aircraft handling and could potentially result in loss of control of the aircraft.

David Villiers
Delegate of the Civil Aviation Safety Authority

22 May 2009