AIRWORTHINESS DIRECTIVE
On the effective date specified below, and for the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/CESSNA 206/54 Amdt 1 and issues the following AD under subregulation 39.1 (1) of CASR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.
Cessna 206 Series Aeroplanes
AD/CESSNA 206/54
Amdt 2
Horizontal Stabilizer Front Spar 9/2004
Applicability: All models of Cessna 206 aircraft.
Requirement: Visually inspect the front and rear faces of horizontal stabilizer front spar assembly centre section for cracks around the cut-out in the front spar web. Refer to Figure 1 below.
It should be noted that for models manufactured from 1968 onwards the horizontal stabiliser front spar would be of a three-layer design. This means that the centre laminate will effectively be hidden by the two outer laminates, making inspection of the centre laminate almost impracticable. The centre laminate should be inspected as far as practicable without disassembly of the spar.
Any cracks in the front spar web must be repaired before further flight, and a defect report must be submitted.
Note 1: Access can be achieved by the removal of the fillet fairing. The front face of the front spar is easily seen. The rear face may be seen via a hole in the upper surface of the horizontal stabilizer using an inspection mirror and torch.
Note 2: This inspection may require some experimenting with lights and mirrors to obtain some certainty in the results of the inspection. The inspection would be much easier to conduct with the use of a borescope.
Compliance: a. For aircraft with less than 10000 hours time in service, inspect before exceeding 10000 hours total time in service, and thereafter at intervals not exceeding 110 hours time in service.
b. For aircraft with 10000 or more hours time in service, inspect before 18 March 2002, and thereafter at intervals not exceeding 110 hours time in service.
This Amendment becomes effective on 2 September 2004.
Background: Reports have been received of cracking of the horizontal stabilizer front spar on Australian registered Cessna 210s. Both front and rear spars must be serviceable for the horizontal stabilizer to carry ultimate load. The front spar forms part of the horizontal stabilizer’s primary load path, and loss of strength in this area could be catastrophic.
It should be noted that this Airworthiness Directive mandates an inspection requirement already stated in the manufacturer’s maintenance data.
Amendment 1 of this Airworthiness Directive was issued to highlight that later models have been manufactured with horizontal stabiliser spars containing three layers, making the centre laminate almost impossible to inspect. This amendment provided guidance on inspection of the three layer configuration. Compliance times were unchanged.
Amendment 2 of this Airworthiness Directive is issued to increase the recurrent compliance interval from 100 hours to 110 hours time in service to allow the inspections required by this Airworthiness Directive to be aligned with scheduled maintenance.
The original issue of this Airworthiness Directive became effective on 6 March 2002. Amendment 1 of this Airworthiness Directive became effective on 1 December 2003.
David Villiers
Delegate of the Civil Aviation Safety Authority 21 July 2004
The above AD is notified in the Commonwealth of Australia Gazette on 11 August 2004
Overview
The Civil Aviation Safety Authority (CASA) issued Airworthiness Directive AD/CESSNA 206/54 Amdt 2 on 2 September 2004 to address a safety issue identified in the horizontal stabilizer front spar of all models of Cessna 206 aircraft. This directive revokes the previous amendment (AD/CESSNA 206/54 Amdt 1) and introduces new inspection requirements for the front and rear faces of the horizontal stabilizer front spar assembly centre section, specifically around the cut-out in the front spar web. The underlying problem this directive seeks to mitigate is the risk of catastrophic failure due to cracking in the horizontal stabilizer front spar, which is integral to the primary load path of the horizontal stabilizer. The policy objective is to ensure the ongoing airworthiness of the affected aircraft by mandating regular inspections and repairs as necessary.
The directive applies to all Cessna 206 models and requires inspections before certain time intervals, depending on the aircraft’s total time in service. For aircraft with less than 10,000 hours of service, inspections must be conducted before exceeding 10,000 hours and then at intervals not exceeding 110 hours. For those with 10,000 or more hours, inspections must occur before 18 March 2002 and then at intervals not exceeding 110 hours. This legislative instrument was enacted under the authority of the Civil Aviation Act 1988 and aims to harmonise inspection intervals with scheduled maintenance to enhance safety without undue disruption.
Scope and Application
The Airworthiness Directive (AD) AD/CESSNA 206/54 Amdt 2 applies to all models of Cessna 206 aircraft, ensuring that the inspection and maintenance requirements specified are adhered to by the operators and owners of these aircraft. This directive, issued by the Civil Aviation Safety Authority (CASA), mandates visual inspections of the front and rear faces of the horizontal stabilizer front spar assembly centre section for cracks around the cut-out in the front spar web. The AD specifically targets models manufactured from 1968 onwards, which have a three-layer design that complicates the inspection process. Operators must inspect the aircraft before exceeding 10000 hours of total time in service and subsequently at intervals not exceeding 110 hours. This directive aims to ensure the structural integrity of the horizontal stabilizer, which is crucial for the safe operation of the aircraft. While the AD itself does not specify any exclusions or exemptions, compliance is subject to the conditions outlined in the directive and any relevant maintenance schedules or manufacturer’s recommendations.
Key Provisions
The Airworthiness Directive AD/CESSNA 206/54 Amdt 2 (AD), issued under the Civil Aviation Safety Regulations 1998 (CASR), pertains specifically to all models of Cessna 206 aircraft. This AD requires an inspection of the front and rear faces of the horizontal stabilizer front spar assembly centre section for any cracks around the cut-out in the front spar web (section 2). This requirement is crucial due to the potential catastrophic loss of strength in the front spar, which forms part of the horizontal stabilizer's primary load path. The inspection is mandated to ensure the spar's integrity, especially for later models which have a three-layer design that makes the centre laminate difficult to inspect.
The AD imposes specific obligations on the operators and maintainers of the Cessna 206 aircraft. Primarily, these parties must visually inspect the front and rear faces of the horizontal stabilizer front spar assembly centre section (section 2). For aircraft with less than 10,000 hours of total time in service, the inspection must occur before the aircraft exceeds 10,000 hours and thereafter at intervals not exceeding 110 hours (section 3(a)). For aircraft with 10,000 or more hours of total time in service, the inspection must be conducted before 18 March 2002, and then at intervals not exceeding 110 hours (section 3(b)). Any detected cracks must be repaired before further flight, and a defect report must be submitted (section 2). Operators and maintainers are advised to remove the fillet fairing for better access and use tools such as inspection mirrors, torches, or borescopes to ensure thorough inspection, especially given the difficulty in inspecting the centre laminate in the three-layer design.
Breaching the requirements set out in this AD can have serious legal and safety consequences. Non-compliance with the mandated inspections and repairs could lead to the aircraft being deemed unsafe to fly, potentially resulting in severe penalties. While the AD itself does not explicitly state the penalties for non-compliance, failure to adhere to such safety mandates could result in enforcement actions under CASR, which might include fines or other regulatory sanctions. The safety implications of not addressing cracks in the horizontal stabilizer front spar are potentially catastrophic, underscoring the importance of strict compliance with the AD's requirements.