Overview

The Airworthiness Directive (AD) issued by the Civil Aviation Safety Authority (CASA) in 2006, specifically AD/CESSNA 337/27, aims to address safety concerns associated with the seat adjustment mechanisms in Cessna 337 Series aeroplanes. This directive was introduced to mitigate the risk of accidents resulting from seat adjustment mechanism failures, a problem that has been historically linked to several incidents. The AD mandates regular inspections and maintenance of the seat adjustment mechanisms to ensure they meet specific criteria for airworthiness. The overarching policy objective is to maintain and enhance aviation safety by preventing potential mechanical failures that could compromise the structural integrity and safe operation of the aircraft. Compliance with this directive is essential for operators of the specified Cessna models to ensure the continued airworthiness of their aircraft.

Scope and Application

The AD/CESSNA 337/27 Amendment 1 applies to all aircraft within the specified model and serial number range of the Cessna 337 series aeroplanes, mandating comprehensive maintenance and inspection protocols to ensure their airworthiness. This legislative instrument is issued under the Civil Aviation Regulations 1998, which are overseen by the Civil Aviation Safety Authority, and therefore have a national reach across Australia. The requirement applies to both private and commercial operators of these aircraft, and compliance is necessary for the continued airworthiness certification of affected aircraft. Notably, this legislation does not apply to any other models or series of aircraft outside the specified Cessna 337 series. The compliance schedule is stringent, with specific timelines for inspections and modifications based on the aircraft’s operational history, ensuring that the seat adjustment mechanisms are thoroughly maintained to prevent potential accidents.

Key Provisions

The legislative instrument F2006B08246 (AD/CESSNA 337/27Amdt 1) pertains to the maintenance and modification of the seat adjustment mechanisms for specific models of Cessna 337 Series aeroplanes. The primary focus is on ensuring the safety of these aircraft through the inspection and repair of their seat adjustment systems (Part 1) and modifying the seat adjustment mechanisms to limit seat travel (Part 2). The affected models include a range of serial numbers from 337 to T337H-SP and F337E to F337H, among others. Part 1 of the directive mandates several critical inspections and repairs. Firstly, it requires the measurement of each hole in the seat track for excessive wear (Section 1(a)). If the wear exceeds 10.67mm (0.42") to a depth of 3.81mm (0.15"), the seat track must be replaced before further flight. Additionally, the seats must be visually inspected for debris that could prevent the engagement of seat pins (Section 1(b)), and any such debris must be removed before further flight. Vertical play in the seats must be eliminated, and the depth of seat pin engagement must be measured, requiring repairs if the engagement is less than 3.81mm (0.15") (Section 1(c)). Seat rollers must be checked for flat spots, and any worn rollers or washers must be replaced (Section 1(d)). The wall thickness of the roller housing and tang must be measured, with replacement of the roller housing necessary if the tang thickness is less than half of the housing thickness (Section 1(e)). The springs that keep the lock pins in position must be checked for positive engagement, and any defective springs must be replaced (Section 1(f)). Lastly, the seat tracks must be visually inspected for cracks, with any limitations due to cracking to be endorsed on the Maintenance Release, and any cracked rails to be replaced (Section 1(g)). Compliance with these requirements is essential for the operators and maintainers of these aircraft. For aircraft with less than 1000 hours of time in service as at 28 January 1988, compliance must be achieved before reaching 1100 hours of service (Section 2(a)(i)). For aircraft with more than 1000 hours of time in service as at 28 January 1988, compliance is required at the next inspection for Maintenance Release issue after 28 January 1988 (Section 2(a)(ii)). Thereafter, compliance is necessary at each inspection for Maintenance Release issue closest to a 100-hour inspection interval or every 12 months, whichever is earlier (Section 2(a)(iii)). Until 30 June 1989, compliance with Part 2 of the directive is acceptable if required components from Part 1 are not yet available (Section 2(b)). Failure to comply with the provisions of this legislative instrument may result in serious safety risks, including potential accidents due to seat adjustment mechanism failure. The specific consequences and penalties for non-compliance are not detailed within the text of the instrument but would typically involve enforcement actions by the Civil Aviation Safety Authority (CASA). These actions could include fines, orders for corrective action, or other regulatory measures to ensure adherence to the safety directives.