COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
Beechcraft 18 Series Aeroplanes
AD/BEECH 18/17
Amdt 4
Aircraft Modification, Inspection and Retirement
9/81
Applicability: All models Beech 18 Series.
Requirement: 1. In accordance with a scheme approved by the Secretary, modify the wing by installing an external strap reinforcement covering the lower cap of the main spar welded truss over both the centre-section and outer-wing.
Note 1: The following strap modifications are currently approved by the Secretary:
- Dee Howard Company, San Antonio, Texas-Scheme holding United States Supplemental Type Certificates - SA832SW and SA895SW in combination.
b. Hamilton Aircraft Company, Tucson, Arizona-Scheme holding United States Supplemental Type Certificate - SA2000WE.
2. Inspect the following areas using visual methods together with dye penetrant or magnetic particle methods, to detect fatigue cracking of the wing main spar truss lower cap. All welded joints in the vicinity of these positions shall be inspected.
- Wing Stations 0, 28, 44, 61 and 81.
b. Both sides of the centre-section to outer wing joint.
c. Each welded joint area in the outer wing including the welded bosses for the horizontal through bolts.
d. The outer wing joint between the welded truss and the aluminium alloy riveted structure.
3. a. For aeroplanes incorporating the Dee Howard Company STCs SA832SW and SA895SW in combination visually inspect in situ the external strap modification for cracks and/or corrosion, using appropriate optical aids. Pay particular attention to welds at end fittings, bends in the strap, forward and aft edges and the strap sections normally covered by the locating clips.
3. b. For aeroplanes incorporating the Hamilton Aircraft Company STC SA2000WE, visually inspect in situ the external strap modification for cracks and/or corrosion.
4. Retire aircraft from service.
COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
Note 2: This Directive is aimed at modifying and inspecting the wing so that a measure of main spar fail-safe capability is achieved. In order to maintain the necessary full limit load residual strength in the event of a spar truss tube failure it should be noted that the maximum gross weight of any Beech 18 variant is limited to 4490 Kg (9900 lb.). This does not endorse weight increases for aircraft certificated below this figure.
Compliance: 1. Before issue of Certificate of Airworthiness.
2. At intervals not exceeding 300 hours time in service.
3. a. At intervals not exceeding 100 hours time in service.
3. b. At intervals not exceeding 300 hours time in service.
4. Before exceeding 10000 hours time in service after strap modification or before 20000 hours time in service after manufacture, whichever occurs first.
Background: In service failure of a modification strap has occurred in an overseas aeroplane due to stress corrosion cracking emanating at edge of strap.
Overview
The Civil Aviation Regulations 1998, administered by the Civil Aviation Safety Authority (CASA), was enacted to ensure the safety of civil aviation within Australia. Among its many provisions, Part 39 - 105 includes the Schedule of Airworthiness Directives, which aims to maintain the airworthiness of aircraft through various regulatory requirements and safety measures. The specific Airworthiness Directive AD/BEECH 18/17 addresses a critical safety concern for Beechcraft 18 Series aeroplanes, requiring modifications, inspections, and, if necessary, retirement of these aircraft to mitigate the risk of wing main spar failure. This directive was introduced in response to an overseas incident where stress corrosion cracking led to a strap failure, underscoring the need to ensure the structural integrity of the wing main spar truss lower cap for all Beechcraft 18 variants.
Scope and Application
The Civil Aviation Safety Authority's Airworthiness Directive AD/BEECH 18/17 Amendment 4 applies to all models of Beech 18 Series aeroplanes, encompassing both aircraft that have undergone specific wing modifications and those that have not. The directive mandates the installation of an external strap reinforcement on the lower cap of the main spar welded truss over the centre-section and outer-wing, with approved schemes from the Dee Howard Company and the Hamilton Aircraft Company. It also requires inspections for fatigue cracking in specified areas of the wing using various inspection methods. For aeroplanes with specific modifications, additional inspections for cracks and corrosion of the external strap are required at different intervals. Failure to comply with these directives may result in the aircraft being retired from service. This legislation applies across the Commonwealth of Australia and is enforced by the Civil Aviation Safety Authority. The directive does not specify exclusions or exemptions but does establish strict compliance timelines for modifications, inspections, and retirement. Any further details or specifications may be outlined in subordinate instruments issued by the Civil Aviation Safety Authority.
Key Provisions
The Civil Aviation Regulations 1998, as part of the Schedule of Airworthiness Directives, mandates specific modifications and inspections for Beechcraft 18 Series aeroplanes (AD/BEECH 18/17). Firstly, section 1 requires the installation of an external strap reinforcement over the lower cap of the main spar welded truss on both the centre-section and outer-wing, following an approved scheme. These approved schemes are held by the Dee Howard Company (SA832SW and SA895SW) and the Hamilton Aircraft Company (SA2000WE). Secondly, section 2 outlines a detailed inspection procedure using visual methods and dye penetrant or magnetic particle methods to detect fatigue cracking in several specified wing areas. Section 3 further mandates inspections of the external strap modifications for cracks and corrosion, with particular attention to welds and edges, depending on the scheme used. Finally, section 4 requires the retirement of the aircraft from service if it exceeds 10,000 hours after the strap modification or 20,000 hours after manufacture, whichever comes first.
The Act imposes specific obligations on the parties involved. Owners and operators of Beechcraft 18 Series aeroplanes must ensure compliance with the wing modifications and inspections outlined in the Airworthiness Directive. This includes timely installation of the external strap reinforcement, conducting the specified inspections at the prescribed intervals, and retiring the aircraft if it surpasses the stated time thresholds. Additionally, any modifications must adhere to the schemes approved by the Secretary, ensuring that the modifications are carried out by certified and authorised companies.
Failure to comply with the provisions of the Airworthiness Directive can lead to significant consequences. While the regulations do not explicitly state offences or penalties, non-compliance can result in the grounding of the aircraft, which is a severe civil aviation consequence. Additionally, continued operation of a non-compliant aircraft may lead to safety hazards, potentially resulting in criminal charges for endangerment or neglect. The specific civil or criminal penalties would depend on the jurisdiction and the extent of the non-compliance, but they can include fines, imprisonment, or both. The overarching aim is to ensure that all Beechcraft 18 Series aeroplanes meet the required safety standards to prevent structural failures in service.