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/F100/16 Elevator BCU Backlash Remover Mechanism 4/99
Applicability: F.28 Mk.0100 aircraft, all serial numbers, if equipped with Menasco Aerospace Elevator Booster Control Unit (BCU), P/N 23400-4 or P/N 23400-5, serial numbers MC-001 through MC-288, that have not been modified in accordance with Fokker Service Bulletin (SB) F100-27-061 dated 2 March 1994 and Menasco Aerospace SB 23400-27-15 dated October 1993.
Requirement: 1. Perform an operational check for backlash in the elevator mechanical control system in accordance with Part 1 of the Accomplishment Instructions of Fokker SB F100-27-052 Revision 1 dated 29 March 1994.
2. Inspect the elevator BCU backlash remover mechanism P/N 12777-( ) in accordance with Part 2 of the Accomplishment Instructions of Fokker SB F100-27- 052 Revision 1 dated 29 March 1994. Note: If no anomalies are detected during this inspection, continue with appropriate trouble-shooting procedures in accordance with the Aircraft Maintenance Manual.
3. Replace any affected bolts with airworthy parts in accordance with the Aircraft Maintenance Manual.
Note: RLD BLA 93-051/3(A) refers.
Compliance: 1. Before 500 flight cycles or 60 calendar days, whichever occurs first, since the last inspection in accordance with Requirement 1. Thereafter at intervals not to exceed 500 flight cycles or 60 calendar days, whichever occurs first.
2. Before further flight if, during an inspection in accordance with Requirement 1, any backlash is detected in the control column.
3. Before further flight if, during an inspection in accordance with Requirement 2, either bolt P/N NAS6204C22D or P/N NAS6204C13D cannot move freely or is found corroded.
This Airworthiness Directive becomes effective on 22 April 1999.
Background: During maintenance on an F.28 Mk.0100, the pivot bolts and bushes of the backlash remover lever mechanism on the elevator Booster Control Unit were found to be corroded. A subsequent investigation uncovered similar cases with other operators. This particular mechanism prevents backlash in the elevator control forces when the elevator BCU is not hydraulically powered, providing the pilot with full manual control of the elevator system. Corrosion on these bolts and bushes causes the backlash remover mechanism to stick, which results in deteriorated elevator control when the BCU is in MANUAL mode.
Overview
The Civil Aviation Regulations 1998, administered by the Civil Aviation Safety Authority, were enacted to ensure the safety of civil aviation in Australia. One of the specific legislative instruments under this Act is the Airworthiness Directive AD/F100/16, which addresses a critical safety issue concerning the Fokker F100 (F28 Mk 100) series aeroplanes. This directive was introduced in response to the discovery of corrosion in the pivot bolts and bushes of the elevator Booster Control Unit (BCU) backlash remover mechanism, which can lead to a loss of elevator control and compromised flight safety. The directive aims to mandate inspections and repairs to prevent such safety hazards, ensuring that affected aircraft meet the necessary airworthiness standards. Compliance with these requirements is essential for maintaining the structural integrity and operational safety of the aircraft in question.
Scope and Application
The Civil Aviation Regulations 1998, specifically Part 39 - 105, which includes the Airworthiness Directive AD/F100/16 concerning Fokker F100 (F28 Mk 100) Series Aeroplanes, applies to all F.28 Mk.0100 aircraft equipped with the Menasco Aerospace Elevator Booster Control Unit (BCU) with particular part numbers and serial numbers, provided they have not undergone specific modifications referenced in certain service bulletins. This legislation is of Commonwealth reach and pertains to the safety and airworthiness of aircraft within Australia, ensuring that the specified Fokker F100 aircraft meet necessary safety standards to prevent operational issues such as elevator control malfunctions due to corrosion or mechanical failure of the elevator BCU backlash remover mechanism. The directive mandates specific operational checks and inspections to be conducted at regular intervals to ensure continued airworthiness, with compliance required before certain flight cycle thresholds or specific time periods, depending on the condition of the inspected components. The directive does not explicitly mention any exclusions or exemptions, but its application is inherently limited to the specified aircraft and conditions as outlined in the directive.
Key Provisions
The Civil Aviation Regulations 1998, under PART 39 - 105, provide detailed provisions regarding the airworthiness of Fokker F100 (F28 Mk 100) series aeroplanes. Specifically, AD/F100/16 pertains to the elevator BCU backlash remover mechanism for certain F.28 Mk.0100 aircraft. These aircraft must be equipped with a Menasco Aerospace Elevator Booster Control Unit (BCU) with specified part numbers and serial numbers, and must not have been previously modified as per certain service bulletins issued in 1994. The directive requires an operational check for backlash in the elevator mechanical control system and an inspection of the elevator BCU backlash remover mechanism. If no anomalies are found during the inspection, appropriate troubleshooting procedures should be followed. Any affected bolts must be replaced with airworthy parts.
Under these regulations, operators of the affected aircraft have specific obligations. Firstly, they must conduct an operational check for backlash in the elevator mechanical control system and inspect the elevator BCU backlash remover mechanism as per the specified service bulletins. These checks must be performed before 500 flight cycles or 60 calendar days, whichever occurs first, since the last inspection. If backlash is detected during these inspections, further checks must be conducted before the aircraft can be flown again. Additionally, if bolts P/N NAS6204C22D or P/N NAS6204C13D are found to be corroded or unable to move freely, they must be replaced before further flight.
Failure to comply with the requirements set out in this airworthiness directive can result in serious consequences. While the regulations do not explicitly detail specific penalties, non-compliance with airworthiness directives can lead to enforcement actions by the Civil Aviation Safety Authority (CASA). Such actions may include fines, operational restrictions, or even grounding of the aircraft until compliance is achieved. The seriousness of these consequences underscores the importance of adhering to the stipulated requirements to ensure the continued safety and airworthiness of the aircraft.