Commonwealth legislation

AD/F50/33 Amdt 1 - Landing Gear - Extension/Retraction Control

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This Airworthiness Directive requires Fokker F27 Mk 50 (F50) operators to either rewire the landing‑gear DOWN solenoid to the emergency DC bus or replace the landing‑gear selector valve with a modified part. It applies to aircraft serial numbers 20103–20197 and is effective 25 June 1992.

The stated purpose is to prevent an inadvertent UP selection caused by a leaking pilot valve when the DOWN solenoid is de‑energised. Operators pay for and implement the corrective wiring or part change by following the cited Fokker Service Bulletins.

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AD/F50/33 Amdt 1 - Landing Gear - Extension/Retraction Control

COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY

SCHEDULE OF AIRWORTHINESS DIRECTIVES

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Fokker F50 (F27 Mk 50) Series Aeroplanes

AD/F50/33

Amdt 1

Landing Gear - Extension/Retraction Control 7/92

Applicability: F27 Mk 050 aircraft Serial Numbers 20103 to 20197 inclusive.

Requirement: 1. Connect the DOWN solenoid of the landing gear selector valve to the EMERGENCY DC bus No 2 instead of DC bus No 2 as outlined in Fokker Service Bulletin F50-32-013 dated 16 October 1989, or

Note: AD/F50/33 covers Requirement 2 of the RLD Airworthiness Directive, Flight Manual amendment A/ANF 2750/10 has been issued to cover Requirement 1 of the RLD Airworthiness Directive.

Replace the Landing Gear Selector Valve P/N 114044002 with a modified Valve P/N 114044003 as outlined in Fokker Service Bulletin F50-32-016 dated 23 December 1991. Compliance with SB F50-32-016 and removal of the Flight Manual amendment A/ANF 2750/10 is an alternative means of compliance with this AD.

Note: RLD Airworthiness Directive BLA 89-138 Issue 3 refers.

Compliance: The Compliance of the original issue of this Directive was prior to 15 March 1990.

This amendment is effective from 25 June 1992.

Background: Fokker have found that an inadvertent UP selection of the landing gear selector valve is possible as a result of a leaking pilot valve at the moment the DOWN solenoid is de-energised. The original issue of this Directive required modification to the system wiring to prevent such an occurrence.

Amendment 1 is issued to advise of an alternative method of compliance and increases the serial number range of aircraft affected.

Source text

Sourced from the Federal Register of Legislation (legislation.gov.au), CC BY 4.0.

1 AD/F50/33 Amdt 1 - Landing Gear - Extension/Retraction Control