COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
Fokker F100 (F28 Mk 100) Series Aeroplanes
AD/F100/5 Powerplant - Lower Cowl Door Engagement 1/99
Applicability: Fokker F28-100 and F28-70 series aircraft, serial numbers 11244 through 11469, 11471, 11474 through 11483, 11489, 11490, 11491, 11494, 11498, 11499, 11501,
11502, 11504, 11506, 11507, 11512 through 11515, 11517, 11520, 11528, and
11537.
Requirement: 1. Modify the hook and latch assembly of the lower cowl doors in accordance with the instructions in Part 1 of the Accomplishment Instructions of Fokker Service Bulletin SB F100-71-019 dated 21 March 1996.
Note: The accomplishment of Part 1 of Fokker SB F100-71-003, dated 14 April 1989, or Revision 1 dated 08 August 1989, or Revision 2 dated 21 November 1994 is considered an acceptable means of compliance for this requirement.
2. Inspect both engine’s lower cowling door hook and latch assemblies in accordance with Part 2 of the Accomplishment Instructions of Fokker SB F100-71-019 dated 21 March 1996.
3. Modify the lower cowl door’s mid clevis fitting in accordance with the Accomplishment Instructions of Fokker SB P41230-71-07 dated 15 February 1996.
Note: RLD Airworthiness Directive 1989-049/3 (A) dated 28 June 1996 refers.
Compliance: 1. Unless already accomplished, on a limited number of aircraft as applicable, within 2500 flight cycles of the last inspection performed in accordance with BLA 89- 049/2.
2. Within 2500 flight cycles since new or since last inspection in accordance with BLA 89-049/2 as applicable.
3. Following the discovery of a cowl mismatch during accomplishment of Requirement 2. above.
This Airworthiness Directive becomes effective on 28 January 1999.
Background: Experience has shown that an aerodynamic gap/mismatch may exist between the fixed engine cowl and the lower cowl door. Should this mismatch exceed a certain value, one or more hooks may not engage properly. This degrades the redundancy of the lower cowl door engagement in the closed position and could lead to an unsafe condition. This Directive introduces a one time inspection and corrective action if necessary, to measure the gap/mismatch on applicable aircraft. This Directive also introduces a modification to the hook and latch assembly on a limited number of the applicable aircraft.
Overview
The Civil Aviation Regulations 1998, enacted by the Australian Parliament, regulate the safety of civil aviation and the maintenance of aircraft airworthiness. Among the various provisions, Part 39 - 105 deals with specific directives issued by the Civil Aviation Safety Authority (CASA) to address safety issues. One such directive, AD/F100/5, pertains to Fokker F100 (F28 Mk 100) series aeroplanes, specifically targeting a known issue with the lower cowl door engagement. This directive was introduced to address the potential risk of an aerodynamic gap or mismatch between the fixed engine cowl and the lower cowl door, which could prevent proper hook engagement and compromise the door's redundancy in the closed position, potentially leading to an unsafe condition. The directive mandates specific modifications and inspections to ensure compliance and mitigate this safety risk.
Scope and Application
The Civil Aviation Regulations 1998, specifically Part 39 - 105, apply to the Fokker F100 (F28 Mk 100) series aeroplanes, with a focus on particular serial numbers of the F28-100 and F28-70 models. These regulations mandate specific modifications and inspections to the lower cowl door engagement of these aircraft to ensure airworthiness and safety. The directive is applicable to aircraft with serial numbers ranging from 11244 to 11537, excluding certain numbers within that range. The compliance requirements include modifying the hook and latch assembly of the lower cowl doors in line with Fokker Service Bulletin SB F100-71-019, inspecting the engine’s lower cowling door hook and latch assemblies as per the same bulletin, and modifying the lower cowl door’s mid clevis fitting according to Fokker SB P41230-71-07. The directive became effective on 28 January 1999 and requires compliance within certain flight cycle limits post the last inspection under BLA 89-049/2. This Airworthiness Directive addresses potential safety issues arising from an aerodynamic gap/mismatch between the fixed engine cowl and the lower cowl door, which could compromise the safety of the aircraft.
Key Provisions
The main operative sections of the Civil Aviation Regulations 1998, specifically the Airworthiness Directive AD/F100/5, require modifications to the hook and latch assembly of the lower cowl doors of certain Fokker F100 series aeroplanes, and inspections of the same. These requirements are detailed in section 1 of the directive. Additionally, section 3 mandates modifications to the lower cowl door's mid clevis fitting. The modifications and inspections are to be carried out in accordance with specific Fokker service bulletins dated between 1989 and 1996.
These obligations are imposed on the owners and operators of the specified Fokker F28-100 and F28-70 series aircraft with serial numbers ranging from 11244 to 11537. The compliance dates vary based on the aircraft’s flight cycles and the date of the last inspection in accordance with BLA 89-049/2. Specifically, modifications to the hook and latch assembly must be performed within 2500 flight cycles of the last inspection or since new, whichever is applicable. Furthermore, the inspection of the engine's lower cowling door hook and latch assemblies must be done within 2500 flight cycles since new or since the last inspection. If a cowl mismatch is discovered during the inspection, the mid clevis fitting must be modified accordingly.
Failure to comply with these requirements may result in significant safety risks, as an aerodynamic gap or mismatch exceeding a certain value can cause hooks to fail to engage properly. This can compromise the redundancy of the lower cowl door engagement in the closed position, potentially leading to unsafe conditions. While specific penalties are not detailed in the text, non-compliance with airworthiness directives can result in severe consequences, including aircraft grounding, fines, and other regulatory actions by the Civil Aviation Safety Authority (CASA). The directive emphasizes the importance of adhering to these requirements to ensure the continued airworthiness and safety of the affected aircraft.