COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 107 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
Propellers - Variable Pitch - Hamilton Standard
AD/PHS/15
Amdt 5
Servo Ballscrew Internal Spline Wear 2/96
Applicability: All 14RF-9, -19, -21, -23, 247F-1, 14SF-5, -7, -11, -15, -17, -19, -23, 14SFL11 and
6/5500/F propellers installed on but not limited to Embraer EMB-120, EMB-120RT, SAAB-SCANIA SF340B, Aerospatiale ATR42-100, -300, -320, ATR72, -210, De
Havilland DHC-8-100 series, -300, Construcciones Aeronauticas SA (CASA) CN- 235, CN-235-100, Canadair CL215T, CL415 and British Aerospace ATP aircraft.
Requirement: Action in accordance with paragraphs (a) to (d) and (g) of FAA AD 95-22-12 Amdt 39-9420.
Note 1: FAA AD 95-22-12 amdt 39-9420 supersedes FAA AD 94-22-12 Amdt
39-9062, FAA AD 93-16-02 amdt 39-8659 and FAA AD 92-08-03 amdt 39-8214.
Note 2: Brazilian Telegraphic AD No T903-03 R1 and BLA AD 94-156 (AB) refer to Amdt 4 of this Directive.
Compliance: As specified in the Requirement Document with a revised effective date of 5 February 1996.
Background: The manufacturer has received reports that excessive wear has been observed in the servo ballscrew splines of the propeller control unit (PCU). This wear, if not corrected, could affect the aircraft airworthiness.
Amendment 1 was raised after receipt of advice that a Dash 8 lost control of a propeller after landing. During the subsequent investigation extreme wear was discovered on the internal splines of the PCU. These splines had previously been inspected some 750 hours prior to the incident.
Amendment 2 clarified the inspection requirements for PCU's that had operated more than 1800 hours time in service.
Amendment 3 mandated inspection of the same type design propellers and reduced the reinspection interval to 500 hours time in service.
Amendment 4 extended the reinspection period from 500 to 1500 hours time in service for those PCU's which have the ballscrew quill damper installed.
Amendment 5 is being raised to increase the repetitive PCU servo ballscrew internal spline (BIS) teeth inspection interval from 1500 to 2500 hours TIS for propellers that have a ballscrew quill damper installed, to mandate installation of the secondary drive quill (SDQ) by 30 June 1998 and to introduce an initial and repetitive torque check inspection of the primary ballscrew quill once a secondary drive quill has been installed.
Overview
The Civil Aviation Regulations 1998, administered by the Civil Aviation Safety Authority (CASA), were enacted to ensure the safety of civil aviation in Australia. Specifically, Part 39 of these regulations addresses airworthiness directives, with Amendment 5 of Airworthiness Directive (AD) PHS/15 focusing on addressing the issue of excessive wear in the servo ballscrew internal splines of certain propeller control units (PCU) in variable pitch propellers. This legislative instrument responds to the need for enhanced safety measures after incidents where propeller control issues led to loss of control. The policy objective is to mitigate risks associated with the identified wear by mandating regular inspections and specific maintenance actions, ensuring that the affected propellers remain airworthy and compliant with safety standards.
Scope and Application
The Civil Aviation Safety Authority (CASA) has issued Airworthiness Directive (AD) PHS/15 Amendment 5 under the Civil Aviation Regulations 1998, specifically targeting the issue of excessive wear in the servo ballscrew splines of the propeller control units (PCU) in certain aircraft propellers. This directive applies to all 14RF-9, -19, -21, -23, 247F-1, 14SF-5, -7, -11, -15, -17, -19, -23, 14SFL11 and 6/5500/F propellers installed on various aircraft models including the Embraer EMB-120, SAAB-SCANIA SF340B, Aerospatiale ATR42-100, -300, -320, ATR72, -210, DeHavilland DHC-8-100 series, -300, Construcciones Aeronauticas SA (CASA) CN-235, CN-235-100, Canadair CL215T, CL415 and British Aerospace ATP aircraft. The directive mandates actions in accordance with paragraphs (a) to (d) and (g) of FAA AD 95-22-12 Amendment 39-9420, which superseded previous directives, and requires compliance by the specified effective date of 5 February 1996. This amendment extends the inspection interval for propellers equipped with a ballscrew quill damper from 1500 to 2500 hours of time in service, mandates the installation of a secondary drive quill by 30 June 1998, and introduces an initial and repetitive torque check inspection of the primary ballscrew quill once a secondary drive quill has been installed.
Key Provisions
The Civil Aviation Regulations 1998, under Part 39 and the Airworthiness Directives for propellers, specifically addresses the issue of internal spline wear in the servo ballscrew of the propeller control unit (PCU) for certain aircraft types (section (2)). The applicable aircraft models include the 14RF-9, -19, -21, -23, 247F-1, 14SF-5, -7, -11, -15, -17, -19, -23, 14SFL11 and 6/5500/F propellers installed on aircraft such as the Embraer EMB-120, SAAB-SCANIA SF340B, and various models of ATR, DHC-8, CN-235, CL215T, CL415 and ATP aircraft (section (2)). The directive mandates that actions must be taken in accordance with the paragraphs (a) to (d) and (g) of FAA AD 95-22-12 Amdt 39-9420 (section (3)). The directive notes that FAA AD 95-22-12 Amdt 39-9420 supersedes previous directives, and references other related amendments (section (4)). Compliance with the directive is required as specified in the Requirement Document, with an effective date of 5 February 1996 (section (5)).
The Civil Aviation Regulations 1998 imposes specific obligations on the entities governed by this directive. Aircraft operators must ensure that their propeller control units are inspected and maintained in accordance with the directive's requirements (section (3)). This includes inspecting the servo ballscrew internal splines for wear and taking corrective actions as necessary. Operators are also required to adhere to the specified inspection intervals, with the interval increasing from 1500 to 2500 hours of time in service for propellers equipped with a ballscrew quill damper (section (5)). Furthermore, the directive mandates the installation of a secondary drive quill by 30 June 1998 and the implementation of an initial and repetitive torque check inspection of the primary ballscrew quill once the secondary drive quill has been installed (section (6)).
The Civil Aviation Regulations 1998 sets out the penalties and consequences for non-compliance with the Airworthiness Directives. Failure to comply with the directive's requirements can result in significant civil or criminal penalties. The exact penalties are not specified in the directive but can include fines, imprisonment, or both, depending on the severity of the non-compliance and the discretion of the court. Non-compliance can also lead to the grounding of affected aircraft until the necessary repairs and inspections are completed, which can have substantial financial and operational impacts on the operators (section (7)). Additionally, non-compliance can result in the suspension or revocation of the aircraft's airworthiness certificate, effectively rendering the aircraft inoperable until the necessary actions are taken to bring it into compliance with the regulations (section (8)).