Ad/F100/72 - Landing Gear - Brake Control Levers (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 F100 (F28 Mk 100) Series Aeroplanes

AD/F100/72 Landing Gear - Brake Control Levers 11/2005

Applicability:

Fokker Aircraft B.V. Model F28 Mark 0070 and Mark 0100 aeroplanes serial numbers 11244 through 11585.

Requirement:

1.    Inspect the brake control levers for excessive wear in accordance with Section 3. Accomplishment Instructions of Fokker Service Bulletin (SB) F100-32-142 dated 12 August 2005 or a later CAA-NL approved revision and when no significant wear is found on the brake control levers, no further action is required and the aircraft may be returned to service.

(a)   When the remaining material thickness is determined to be less than 2 mm (0.08 inch), replace the affected brake control levers with serviceable parts in accordance with Section 3 of the Accomplishment Instructions of Fokker SB F100-32-142 or later CAA-NL approved revision.

(b)   When the remaining material thickness is determined to be between 2 mm (0.08 inch) and 4 mm (0.16 inch), replace the affected brake control levers in accordance with Section 3 of the Accomplishment Instructions of Fokker SB F100-32-142 or later CAA-NL approved revision.

Note:  CAA-NL AD NL-2005-011and EASA Reference No 2005-2602 dated 29 August 2005 refers.

Compliance:

1.    Within the next 1,500 flight cycles or 12 months after the effective date of this directive, whichever occurs first.

(a)   Before further flight.

(b)   In accordance with the schedule as indicated in paragraph B(9) of Section 3 of the Accomplishment Instructions of Fokker SB Fl 00-32-142 or later CAA-NL approved revision.

This Airworthiness Directive becomes effective on 27 October 2005.

Background: After landing, the flight crew of a Fokker 100 (F28 Mark 0100) noted that an extreme difference in pedal angle was required to achieve equal brake action on the left hand (LH) and right hand(RH) Main Landing Gear (MLG) brakes.  The brake temperature of the LH brake system was reported to be higher than that of the RH brake system.  During the subsequent troubleshooting, it was noted that the attachment holes in the control levers of the RH MLG (Normal and Alternate) brake cables were worn out to an extent that imminent failure was likely to occur.  The aircraft (and the affected levers) had accumulated 21,460 flight hours and 15,583 flight cycles. Further investigation showed that the abnormal brake behaviour had been caused by a (unrelated) failure of the RH Normal Brake Control Valve. Fokker Services have determined that a disconnect of one or two of the lower cables would not affect the intended braking action on the MLG involved.  However, this condition, if not corrected, can lead to unintended (uncommanded) braking due to the loss of cable tension on the lower side of the levers, possibly resulting in loss of control of the aircraft during the take-off run, landing roll-out or taxiing.  Since an unsafe condition has been identified that may exist or develop on aircraft of the same type design, this Airworthiness Directive requires a one-time inspection and, if necessary, replacement of the brake control levers.

James Coyne
Delegate of the Civil Aviation Safety Authority

16 September 2005