AD/F100/86 Flight Controls Horizontal Stabilizer Control Unit (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 F28 Series Aeroplanes

AD/F100/86 Flight Controls - Horizontal
Stabilizer Control Unit 1/2008

Applicability:

Fokker Aircraft B.V. F28 Mark 0100 aircraft.

Requirement:

1.    Perform a one-time inspection of the lower bolts of the Stabilizer Control Unit dog-links in accordance with the Accomplishment Instructions of Fokker SBF100-27-91 dated 31 August 2007 or later approved revision.

2.    When a failed bolt is found, replace the bolt with a serviceable part.

3.    Install a tie-wrap through the lower bolts of the Stabilizer Control Unit.

Note:  EASA AD 2007-0287 dated 15 November 2007 refers.

Compliance:

Within 6 months after the effective date of this AD, unless previously accomplished.

This Airworthiness Directive becomes effective on 17 January 2008.

Background:

In January 1996, Fokker issued Service Bulletin (SB) SBF100-27-069 (referencing Menasco, now Goodrich, SB 23100-27-19) to introduce an inspection of bolt Part Number (P/N) 23233-1 for cracks after the examination of a failed bolt.  Additionally the same SB introduced a lower torque value for these bolts.

During recent inspections it was found that some of these bolts, that connect the horizontal stabilizer control unit actuator with the dog-links, were broken.  This condition, if not corrected, could lead to partial loss of control of the aircraft.

Since an unsafe condition has been identified that continues to exist or develop on other aircraft of the same type design, this AD requires an integrity check by a re-torque in accordance with SBF100-27-091 and the installation of a tie wrap through the bolt, which will act as a retainer for the bolt and nut.  The key function for this tie-wrap is to keep the bolt in place in the event the bolt head fails.

David Punshon
Delegate of the Civil Aviation Safety Authority

26 November 2007