1AD/F100/26 - MLG Main Fitting Sub-Assembly

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

SCHEDULE OF AIRWORTHINESS DIRECTIVES

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Fokker F100 (F28 Mk 100) Series Aeroplanes

AD/F100/26 MLG Main Fitting Sub-Assembly 4/99

Applicability: F.28 Mk.0100 aircraft, all serial numbers equipped with Messier-Dowty MLG Part Number (P/N) 201072011, 201072012, 201072013, 201072014, 201072015, or

201072016; and Messier-Dowty MLG Main Fitting Sub-Assemblies P/N 201072283, 201072284, and 201251258.

Requirement: 1. Inspect MLG Main Fitting Sub-Assemblies, P/N 201072283, 201072284, and 201251258, in accordance with Part A.(3) of Section 3 of the Accomplishment Instructions of Messier-Dowty Service Bulletin (SB) F100-32-86.

2. Re-inspect and rework in accordance with Parts A.(4) and/or A.(5), as applicable, of Section 3. Accomplishment Instructions of Messier-Dowty SB F100-32-86. Report findings to Messier-Dowty Limited, or to the regional Messier-Dowty Customer Support Centre.

Note: RLD BLA 1996-133(A) refers.

Compliance: 1. For affected Parts fitted to aircraft, within six months of the effective date of this Directive.

For affected Parts not fitted to an aircraft, within six months of the effective date of this Directive or before flight, whichever occurs last.

Note: There is a possibility of the above parts being held as spares. These parts could be affected by the same problem, hence a requirement to inspect such stocks prior to use.

2. Before further flight, if any defects are found during the inspection in accordance with Requirement 1.

This Airworthiness Directive becomes effective on 22 April 1999.

Background: A report has been received of a cracked main fitting sub-assembly of a Messier- Dowty MLG installed on a F.28 Mk.0100 aircraft. The crack extended from the area of the side stay attachment lug to the base of the main fitting. Apparently, the crack initiated from the bottom of the affected lug’s internal diameter. Investigation revealed that the failure was caused by corrosion of the area, resulting from damage to the surface protection during honing of the bushes.